University of North Florida
Browse the Citations
-OR-

Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

View Stuart Chalk's profile on LinkedIn

Interface

Classification: Hardware -> Interface

Citations 130

"Coupling Of Membrane Introduction With Mass Spectrometer (MIMS)"
Chem. Listy 2000 Volume 94, Issue 2 Pages 123-128
P. Broz, E. Drbalkova, P. Janderka, P. Sitko, and J. Vrestal

Abstract: The described interface for membrane introduction mass spectrometry (MIMS) makes it possible to directly determine concentrations of organic substances in water solution without any pre-concentration technique. Some nonpolar, semipolar and semivolatile substances were chosen as examples for demonstration of the MIMS function. Various kinds of membranes were tested. The detection limit, calibration curves and mutual interference of substances were determined for benzene, naphthalene and propnn-1-ol, Ion current intensities were measured in thr SIM mode. Hydrolysis of ethyl acetate with NaOH was chosen as an example of in-situ kinetic study using MIMS.

"Flow Injection Fourier Transform Infrared Determination Of Caffeine In Coffee"
Vib. Spectrosc. 1999 Volume 21, Issue 1-2 Pages 143-150
Zouhair Bouhsain, Jose M. Garrigues, Salvador Garrigues and Miguel de la Guardia

Abstract: A fully automatized procedure has been developed for the Fourier transform infrared (FT-IR) spectroscopic determination of caffeine in coffee samples. The method involves the online extraction of caffeine with CHCl3. Samples, weighed inside empty PTFE cartridges of 0.5 cm internal diameter (i.d.) and 1.5 mL volume, were humidified with four drops of 0.25 M NH3. The cartridge was installed in a flow manifold, in which samples were extracted in a closed-flow system with 1 mL CHCl3, during 6 min. Four hundred microliters of the extract were introduced in a microflow cell and absorbance measured as a function of time at 1659 cm-1, with a baseline established between 1900 and 830 cm-1, thus providing a fiagram. Peak height values of the Fl recordings, obtained for samples, were interpolated in an external calibration line established from standard solutions of caffeine in CHCl3,. The method provided a limit of detection (LOD) of 9 mg L-1 caffeine, a relative standard deviation of 0.6% for five independent measurements of a solution containing 1 mg mL-1 and a sampling frequency of the whole procedure of 6 h-1. Results obtained for market samples agree well with those found by the official chromatographic-spectrometric method, but involving a drastic reduction of solvents, from the 200 mL ether and 50 mL CHCl3, required for each sample preparation by the reference procedure to less than 30 mL CHCl3, necessaries for the whole determination of caffeine in a sample, also including standards and carrier solution.
Caffeine Coffee Spectrophotometry

"Gradient Elution Techniques For Capillary Electrochromatography"
J. Chromatogr. A 2000 Volume 887, Issue 1-2 Pages 115-124
Catherine A. Rimmer, Stephanie M. Piraino and John G. Dorsey

Abstract: Capillary electrochromatography (CEC) is a rapidly maturing technique, but still in need of further instrumental development and in need of unique applications that are not possible by traditional pressure-driven LC. We review the development of gradient elution schemes for CEC, beginning with pH gradients initially developed for capillary electrophoresis. Step gradients are the most easily instrumentally implemented, but provide less flexibility in separation than continuous gradients. Pressure-assisted CEC is easily adapted to gradient elution schemes, but does not offer the advantages of very high column efficiency provided by totally electro-driven mobile phases. The development of flow injection interfaces allows a true solvent gradient to be generated by Ir-LC pumps, with the mobile phase drawn into the separation capillary by pure electroosmotic flow. While requiring both a CEC instrument and a traditional pump or pumps capable of generating the gradient, this method offers advantages of greatly reduced column handling, prolonging column lifetimes, and allows simple autosampling. We also discuss voltage gradients, which provide a mobile phase velocity gradient.

"Water Solubilization Of Ethanol And BTEX From Gasoline: On-line Monitoring By Membrane Introduction Mass Spectrometry"
Analyst 2002 Volume 127, Issue 2 Pages 230-234
Rosana M. Alberici, Cleidiane G. Zampronio, Ronei J. Poppi and Marcos N. Eberlin

Abstract: The solubilization of ethanol and the aromatic hydrocarbons benzene, toluene and the isomeric ethylbenzene and xylenes (BTEX) in water in contact with commercial samples of ethanol-containing Brazilian gasoline was monitored on-line by membrane introduction mass spectrometry (MIMS) and BTEX and ethanol concentrations in water after prolonged contact were measured by flow injection analysis (FIA) coupled with MIMS (FIA-MIMS). The cosolvent effect of ethanol, which is known to increase BTEX solubility in water, was also found to speed up BTEX solubilization as compared with ethanol-free gasoline. The ethanol cosolvent effect was also compared with that of methyl tert-butyl ether (MTBE). Chemometric multivariate analysis applied to FIA-MIMS mass spectra of the ethanol-BTEX aqueous solutions formed after prolonged contact with gasoline samples showed that identical samples cluster closely whereas small variances in BTEX composition occurring among and within the three different types of ethanol-containing Brazilian gasoline are easily detected as they cause great dispersion in the chemometric plots.

"Anomalous Behaviour Of The Quartz Crystal Microbalance In The Presence Of Electrolytes"
Analyst 2000 Volume 125, Issue 5 Pages 785-787
Roberto Etchenique and Thomas Buhse

Abstract: Quartz crystal microbalance (QCM) impedance analysis was used as a microgravimetric tool for thiol adsorptions in a flow injection system. The presence of electrolyte was found to interfere with the proper measurement of the deposited mass and resulted in an error of more than 70%. Aqueous solutions of 1:1 electrolytes, of up to 6 mM can cause mass errors as high as 60 ng cm-2, that is the equivalent of a monolayer of medium sized molecules. 1:2, 1:3, and 2:2 electrolytes yield even higher errors. The interference is mainly due to the mechanical elasticity of the Gouy Chapman diffuse double layer and cannot be excluded even by using sophisticated QCM impedance methods.

"Combination Of Flow Injection With Capillary Electrophoresis - Part 7. Microchip Capillary Electrophoresis System With Flow Injection Sample Introduction And Amperometric Detection"
Anal. Chim. Acta 2000 Volume 422, Issue 1 Pages 71-79
Chong-Gang Fu and Zhao-Lun Fang

Abstract: A microchip-based capillary electrophoresis (CE) system with amperometric detection, combined with flow injection (FI) sample introduction, was constructed from components readily available in the analytical laboratory. An H-channel configuration was used with separation capillary positioned between two tubular side-arms, and a falling-drop interface connected to one side-arm was developed to achieve electrical isolation between the FI and CE systems. End-column amperometric detection was accomplished with separation voltage decoupled from the detection system, employing a microdisk working electrode positioned immediately outside the capillary outlet in the other side-arm, which functioned as a large-volume reservoir. Sample dispersion in the FI system and the FI-CE interface was minimized by intercalating the sample zone between two air segments. Performance of the FI-CE amperometric system was demonstrated by separation of sugars. Separation of sucrose and glucose was performed with a 5 cm, 25 µm i.d. capillary with 1.7 kV separation voltage in about 60 s (40 µm plate height for glucose), achieving a sampling frequency of over 65 h-1. Responses for sucrose and glucose were linear in the range of 10^-1000 µM with sensitivities of 0.011 and 0.025 nA µM-1. Detection limits (S/N = 3) were 2 µM for sucrose and 1 µM for glucose. Peak height precisions were 2.1 and 2.4% RSD (n = 9) for sucrose and glucose, respectively.
Glucose Sucrose Amperometry Electrophoresis

"Interfacing Flow Injection Analysis (sequential Injection Analysis) And Electro-thermal Atomic Absorption Spectrometry Determination Of Trace-levels Of Cr(VI) Via On-line Pre-concentration By Adsorption In A Knotted Reactor And By Liquid-liquid Extraction"
Anal. Chim. Acta 2000 Volume 422, Issue 1 Pages 47-62
Steffen C. Nielsen and Elo H. Hansen

Abstract: Two time-based flow injection pre-concentration procedures are described for the analysis of ultra-trace-level concentrations of metal ions, as exemplified for the determination of Cr(VI). While the first approach exploits pre-concentration by on-line formation and extraction into MIBK of the non-polar complex formed of Cr(VI) ions with ammonium pyrrolidine dithiocarbamate (APDC), the second one is based on formation of the same complex compound and adsorption of it in an incorporated knotted reactor which is subsequently eluted by a discrete volume of ethanol. In both cases, the detection of the analyte in the eluent is executed by electrothermal atomic absorption spectrometry (ETAAS). Using a newly developed syringe pump based FI-system, FIAlab-3500, the present communication discusses and emphasizes the performance of these on-line pre-concentration/separation procedures. Particularly, the interface between the FI-system and the detector ensuring reliable, effective and robust operation of the automated combination is detailed, because this calls for an intelligent coupling of the continuously operating FI-system with the discontinuously working ETAAS instrument. In this context, a unique application of the liquid-liquid separator used is described. The operational characteristics obtained were as follows. For the FI-system with liquid-liquid extraction the enhancement in sensitivity of Cr(VI) for 99 s sample aspiration at a flow rate of 5.5 mL min-1 was 18-fold as compared to direct introduction of 40 µl samples, yielding a detection limit (3s) of 3.2 ng L-1. The sample frequency was 10.9 h-1. By employing the adsorption procedure the enhancement in sensitivity of Cr(VI) was 19-fold as achieved after pre-concentration for 60 s at a sample flow rate of 5.0 mL min-1 as compared to direct introduction of 40 µl samples, yielding a detection limit (3s) of 6.7 ng L-1. The sample frequency was 13.8 h-1. The procedures were applied for the assay of Cr(VI) in a NIST reference material with good recoveries in both instances.
Chromium(VI) Spectrophotometry

"Monitoring Of The Degradation Of Phenols By Rhodococcus Bacteria By Using Micellar Electrokinetic Chromatography"
J. Sep. Sci. 2002 Volume 25, Issue 15-17 Pages 1129-1135
Maria Kulp, Irina Vassiljeva, Raivo Vilu, Mihkel Kaljurand

Abstract: Capillary electrophoresis can be a valuable tool for on-line monitoring of bioprocesses. The degradation of selected phenolic compounds by Rhodococcus bacteria was monitored in a microreactor interfaced by a membrane dialysis device and a homebuilt microsampler to a capillary electrophoresis unit. The use of this specially designed sampling device enabled rapid consecutive injections to be performed without high voltage interruptions. No additional sample preparation was required. In this particular case the time resolution of monitoring was about two hours but it could be reduced to as short as a couple of minutes. The analytes were detected at a µg/mL level with a reproducibility of about 20%. To demonstrate the potential of CE in understanding processes of biological and environmental interest, analysis of the degradation of selected environmentally hazardous phenols was carried out. Besides biodegradation, different competitive processes during which phenols were removed from the reactor were considered.

"Flow Injection Analysis Capillary Electrophoresis System With Hydrodynamic Injection"
Anal. Chim. Acta 1999 Volume 378, Issue 1-3 Pages 55-62
Petr Kuban, Reza Pirmohammadi and Bo Karlberg

Abstract: A flow injection analysis-capillary electrophoresis (FIA-CE) system with hydrodynamic injection has been developed. Sample is injected in an electrolyte carrier solution pumped continuously in the FIA part of the system. The interface, connecting the FIA and the CE system moieties, accommodates one end of the separation capillary and a platinum electrode. The other capillary end and the second platinum electrode are immersed in a separate vial containing electrolyte solution. Carrier outflow from the interface is provided by a pinch valve. When the sample plug in the carrier passes the capillary end in the interface, the pinch valve is closed and a fraction of the sample is forced into the capillary. The high voltage supply, shut off during this sample introduction cycle, is then resumed and separation takes place in the capillary. Repeated sample injections in one electrophoretic run are facilitated. The overall repeatability, expressed as relative standard deviation for eight consecutive injections of 50 mg L-1, was about 3%. Quantitative analyzes can be accomplished ~5 times faster than that obtained using conventional CE instrumentation. The developed instrument was used to determine common inorganic cations (Na+, K+, Ca2+, Mg2+) in water and soft drink samples.
Sodium Potassium Calcium Magnesium Soft drink Water Electrophoresis

"Nonconventional Samplers In Capillary Electrophoresis"
Crit. Rev. Anal. Chem. 1999 Volume 29, Issue 1 Pages 29-68
Ruth Kuldvee and Mihkel Kaljurand

Abstract: Developments in nonconventional sample introduction in capillary electrophoresis have focused on the possibility of forcing the sample stream to pass the separation capillary inlet. The advantages of such input devices are the absence of a voltage rise/drop time during sampling, ease of operation because no vial manipulations are involved, and ease of automation and computerization. However, besides these the main advantage of such input devices seems to be the fact that they facilitate easy, multiple input from a single sample vial. This opens the possibility of monitoring the concentration changes taking part in inside the vessel -an important task for -analytical biotechnology. This article describes some possible designs of CE nonconventional samplers and discusses applications of such samplers in sample preparation, in coupling CE with flow injection analysis (FIA) and HPLC, in multiple input experiments (with or without stacking) for reduction of detection limits and for monitoring of reaction kinetics.
Electrophoresis

"Towards The Most Rational Use Of Robotics Within The Overall Analytical Process"
Anal. Chim. Acta 1999 Volume 384, Issue 2 Pages 117-125
M. D. Luque de Castro and A. Velasco-arjona

Abstract: An overview is presented in which the use of robots in the analytical field is critically considered. Monotask use of robotics and the implementation of robotics sample pretreatment are discussed, as well as the overall robotics development of the analytical process as compared with the joint use of robotics and flow injection in an integrated fashion (an example of hybridisation of discontinuous and continuous approaches).

"Optimization Of Hollow Cathode Diameter For Particle Beam/hollow Cathode Glow Discharge Atomic Emission Spectrometry"
Spectrochim. Acta B 2000 Volume 55, Issue 6 Pages 599-610
Melissa A. Dempster and R. Kenneth Marcus

Abstract: An evaluation of the effect of cathode diameter on analyte emission intensity for the particle beam/hollow cathode glow discharge atomic emission spectroscopy (PB-HC-AES) system is described. A high-efficiency thermoconcentric nebulizer is used to generate a fine aerosol of the aqueous solution flowing at rates of similar to 1 mL/min. Desolvation and use of a momentum separator/particle beam interface serves to introduce analyte particles into a heated HC glow discharge source for subsequent vaporization, atomization and excitation. The effects of discharge gas (He) pressure and current on emission responses for sodium and copper are evaluated in flow injection mode using 200 µL injection volumes for a series of fixed-length (25 mm) cylindrical HC having inner diameters of 2, 3, 5 and 7 mm. Analytical response curves obtained with the 2 mm i.d. HC for sodium and copper yield detection limits of 0.6 and 1.3 ppb in elemental Na and Cu, respectively, with less than 10% relative standard deviation (RSD) for triplicate injections over a concentration range of 0.5-20 ppm.

"Chronocoulometric Flow Injection Analysis With Solvent Polymeric Membrane Ion Sensors"
Anal. Chim. Acta 2002 Volume 459, Issue 1 Pages 11-17
Concepción Sánchez-Pedreño, Joaquín A. Ortuño and Jorge Hernández

Abstract: A method to carry out chronocoulometric measurements with solvent polymeric membrane ion sensors in flow injection systems has been developed. For this, a double potential step was synchronised to the passage of the sample plug through the detector cell. A four-electrode potentiostat with ohmic drop compensation and a new flow-through cell to incorporate the four-electrode and the membrane were developed. A plasticized poly(vinyl chloride) (PVC) membrane containing TBATBP was used and the procedure was applied to the determination of tetraethyl-ammonium. The effect of the electrochemical and flow injection variables was studied. In the selected conditions, a linear relationship between the quantity of electricity and tetraethyl-ammonium concentration was obtained in the range 5 x 10^-7-5 x 10^-5 M. The detection limit was 7 x 10^-8 M. Good repeatability and between day reproducibility were obtained. The potential application to other quaternary ammonium ions including acetylcholine was also studied. (C) 2002 Elsevier Science B.V. All rights reserved.

"Application Of Automated Flow Injection Analysis To Drug Liberations Studies With The Franz Diffusion Cell"
Pharmazie 2001 Volume 56, Issue 10 Pages 787-789
Solich, P.; Ogrocká, E.; Schaefer, U.

Abstract: The flow-injection method with sensitive fluorimetric detection is used to monitor the liberation profiles of a topical dermatological formulation containing the model compound salicylic acid. The connection of a standard Franz diffusion cell with the automated flow-injection system enables an acquisition of multi-point liberation data in a form of series of fluorescence peaks in a short time. Examples of liberation profiles for a topical dermatological formulation containing salicylic acid are shown.
Salicylic acid Pharmaceutical Fluorescence

"Multidimensional Analysis Of Poly(ethylene Glycols) By Size Exclusion Chromatography And Dynamic Surface Tension Detection"
Anal. Chem. 2000 Volume 72, Issue 18 Pages 4372-4380
Keith E. Miller, Emilia Bramanti, Bryan J. Prazen, Marina Prezhdo, Kristen J. Skogerboe, and Robert E. Synovec

Abstract: Substantial improvements in a multidimensional dynamic surface tension detector (DSTD) are presented. Rapid, online calibration and measurement of the dynamic surface tension for high-performance liquid chromatography separations is achieved. Dynamic surface tension is determined by measuring the differential. pressure across the liquid-air interface of repeatedly growing and detaching drops. Continuous surface tension measurement throughout the entire drop growth (50 ms to 2 s) is achieved, for each eluting drop, providing insight into the kinetic behavior of molecular orientation processes at the liquid-air interface. Three-dimensional data are obtained, with surface tension first concerted to surface pressure, which is plotted as a function of elution time axis versus drop time axis. Two key innovations will be reported. First, a novel calibration procedure is described and implemented. Differential pressure signals from three drops (mobile phase, standard in mobile phase, and analyte in mobile phase) are utilized to make the dynamic surface tension measurement, thereby eliminating the need for optical imaging, and viscosity and hydrostatic pressure corrections, as required by other methods. Only pressure signals from one mobile-phase drop and one standard drop pressure signal are required, while the analyte drop pressure signal is measured along the chromatographic time axis. Second, corrections for drop elongation are not required, because the drops are precisely detached bq an air burst actuation method in a regime were the surface tension forces significantly dominate gravitational forces. Drops that would fall with a volume of similar to 10 µL due to gravity are precisely and repeatedly detached earlier at a volume of 2 µL. The sensitivity and unique selectivity of the DSTD opens up new possibilities in the analysis of small molecular weight polymers of varying degrees of surface activity, as illustrated for the size-exclusion chromatography analyzes of complex poly(ethylene glycol) (PEG) samples. Using partial least squares for data analysis, polydispersity of complex PEG samples is determined at a relative precision of similar to 1%.

"Reduction Of Signal Suppression Effects In ESI-MS Using A Nanosplitting Device"
Anal. Chem. 2001 Volume 73, Issue 23 Pages 5635-5644
Eric T. Gangl, Meg Annan, Neil Spooner, and Paul Vouros

Abstract: Electrospray ionization mass spectrometry is a valuable tool in the identification and quantification of drug metabolites in biological fluids. However, there are many instances where matrix components present in these fluids interfere with analyte detection and prevent the acquisition of accurate or complete results. In some instances, the matrix can suppress ionization to such an extent that analytes are completely undetectable by MS. In this work, we investigate how ionization and ion-transfer efficiencies are affected by drastically reducing the flow into the MS. A post-column concentric flow-splitting device was constructed to allow the measurement of analyte signal and ionization suppression across a range of flow rates (0.1-200 µL/min). Using this device, the effects of flow rate on signal intensity and ionization suppression were measured in analytical experiments that included flow injection analysis MS, post-column addition LC-MS, and on-line LC-MS analysis of metabolites generated from rat liver microsomes. The device used to deliver 0.1 µL/min flows is referred to as a nanosplitter because it achieved high split ratios (2000: 1), producing flow rates comparable to those observed in nanoelectrospray. The nanosplitter maintained chromatographic integrity with high fidelity and allowed the direct comparison of analyte signal across a range of flow rates (0.1-200 µL/min). A significant improvement in concentration and mass sensitivity as well as a reduction in signal suppression is observed when the performance at 200 versus 0.1 µL/min flow rate is compared. Using this specially designed concentric splitting device, the advantages of ultralow flow ESI were easily exploited for applications employing large bore chromatography.

"Packed Column Supercritical Fluid Chromatography/mass Spectrometry For High-throughput Analysis. Part 2"
Anal. Chem. 1999 Volume 71, Issue 19 Pages 4223-4231
Manuel C. Ventura, William P. Farrell, Christine M. Aurigemma, and Michael J. Greig

Abstract: A supercritical fluid chromatograph was previously interfaced to a mass spectrometer (SFC/MS) and the system evaluated for applications requiring high sample throughput using negative-mode atmospheric-pressure chemical ionization (APCI) (Ventura et al. Anal. Chem. 1999, 71, 2410-2416). This report extends the previous work demonstrating the effectiveness of SFC/MS, using positive ion APCI for the analysis of compounds with a wide range of polarities. Substituting SFC/MS for LC/MS results in substantial time saving, increased chromatography efficiency, and more precise quantitation of sample mixtures Flow injection analysis (FIA) also benefits from our SFC/MS system. A broader range of solvents is compatible with the SFC mobile phase compared with LC/MS, and solutes elute more rapidly from the SFC/MS system, reducing sample carryover and cycle time. Our instrumental setup also allows for facile conversion between LC/MS and SFC/MS modes of operation.

"Determination Of Diamino Acids In Peptidoglycans From Anaerobic Bacteria"
Amino Acids 2001 Volume 21, Issue 3 Pages 221-235
S. Satyanarayana, J. S. Grossert, S. F. Lee, R. L. White

Abstract: Peptidoglycans isolated from two Fusobacterium species of anaerobic bacteria were analyzed for constituent amino acids. Hydrolysis conditions were varied to optimize the yield of diamino acids from peptidoglycan. The o-phthalaldehyde derivatives of the diamino acid stereoisomers were separated by high-performance liquid chromatography (OPA-HPLC), and variations in the relative areas of the two peaks noticed during analysis of solid samples were attributed to sampling errors. Co-derivatization/injection experiments using standards of the meso and rac forms separated from commercial mixtures demonstrated that meso-2,6-diaminopimelic acid and meso-lanthionine were peptidoglycan components in Fusobacterium varium and Fusobacterium nucleatum, respectively. The protonated molecules of 2,6-diaminopimelic acid and lanthionine were detected in peptidoglycan hydrolyzates by off-line, flow injection electrospray mass spectrometry (ESI-MS). In ESI-MS-MS experiments under identical collision-induced dissociation (CID) conditions, peptidoglycan-derived and standard diamino acids exhibited similar fragmentations. Fragmentation pathways are proposed for each diamino acid. The results confirm that the meso forms of two different diamino acids are utilized in the peptidoglycans of Fusobacterium species.
Amino Acids Bacteria Bacteria Mass spectrometry

"Characterization Of Responses To Injection Of Microliter Samples And To Peak-shaped Input Signals For Inductively Coupled Plasma/atomic Emission Spectrometry"
Anal. Chim. Acta 1988 Volume 215, Issue 1 Pages 143-153
H. C. Smit and P. J. H. Scheeren

Abstract: The use of inductively-coupled plasma/atomic emission spectrometry for dynamic measurements, e.g., as a detector in high-performance liquid chromatography or flow injection analysis with introduction of microliter samples, requires specification of the dynamic properties of the detector. A model of the transfer function in ICP/AES, based on the Γ-distribution, is described. The two important parameters of the model are easily evaluated in practice, so that the response of an ICP/AES detector to introduction of microliter samples and the influence on peak-shaped injections are readily calculated.
Spectrophotometry

"Coupling Of Continuous Separation Techniques With Unsegmented Flow Systems"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 425-434
M. D. Luque de Castro and M. Valcárcel*

Abstract: Different ways of coupling continuous separation techniques are reviewed. Sections are included on gas - liquid/liquid - liquid coupled interfaces and gas - liquid/solid - liquid and liquid - liquid/solid - liquid coupled techniques, and some of their applications are cited. (33 references). A review with 33 references. An overview of the potential of combined continuous separation techniques is presented. The different possible types of interface (gas-liq., liq.-liq., and solid-liq.) were associated in different ways and nos. depending on the particular problem to be solved. A complementary or synergistic effect was accomplished in all instances, which testifies to the interest in coupled continuous separation techniques.

"Flow Injection Atomic Spectrometry: A New Analytical Technique"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 75-85
Julian F. Tyson*, S. R. Bysouth, E. A. Grzesczyk and E. Debrah

Abstract: The literature on flow injection analysis coupled with atomic spectrometry is reviewed. Several types of closed-loop recirculating manifolds for particular applications are described, viz, for calibration, dilution, acid-leaching of Ca, and Ag matrix removal in AAS. The performance of each of the manifolds was satisfactory at recirculating flow rates up to 10 mL min-1. (75 references). Much of the recent research in analytical atomic spectrometry has been concerned with problems of a practical nature. In particular, the inaccuracies arising from a variety of matrix effects and the limitations of sample introduction systems have provided a considerable driving force for recent developments in the various techniques. The philosophy of attempting to eliminate, or compensate for, interferences by procedures implemented at the atomization stage has had success for electrothermal atomization atomic absorption spectrometry but has proved of limited utility for other techniques. Despite considerable efforts, solid-sample introduction is still best done by procedures whose initial stage is dissolution There is a steady growth in the flow injection atomic spectrometric literature and a survey of the ~50 publications in 1990 shows that much of the interest is now centered on coupling pre-concentration and matrix removal procedures with atomic spectrometry, although there is still work concerned with the basic characteristics of flow injection introduction, such as the reduction in sample loading, online dilution for calibration purposes and the ability to handle small sample volumes, being published. The role of the flow injection valve as an interface between flow systems is highlighted. This interface allows independent optimization of the various flow systems coupled in this fashion. Several possible applications of recirculating closed-loop manifolds are described. These include the serial dilution of a stock standard for calibration purposes and to establish a working detection limit. This is illustrated by the dilution of a 2.45 mg L-1 solution of magnesium by a factor of 2.20 per injection. This procedure established a detection limit for the instrument involved of between 4.2 and 5.2 ng mL-1. The online acid leaching of calcium from charcoal is shown to be sufficiently precise for the basis of a rapid screening procedure and the determination of copper in matrixes containing up to 50 g L-1 silver is made possible by the online precipitation of the matrix as the chloride in a circulating loop containing a filter column of nylon fibers. The additional possibilities afforded by these designs of manifold and the great variety of manifolds described in the literature suggest that flow injection atomic spectrometry may be emerging as an analytical methodology analogs to the variety of procedures encompassed by terms such as liquid chromatography in the vocabulary of the analytical methodology for molecular species.
Copper Calcium Spectrophotometry Spectrophotometry

"Online Monitoring Of Flowing Samples Using Solid-phase Micro-extraction Gas Chromatography"
Anal. Chim. Acta 1993 Volume 284, Issue 2 Pages 265-273
Safa Motlagh and Janusz Pawliszyn*

Abstract: The solid-phase micro-extraction (SPME) device was constructed by replacing the metal wire plunger assembly of a Hamilton 7105-N syringe with a poly(dimethylsiloxane)-coated fiber (6 cm x 253 µm o.d.) with a silica core (141 µm o.d.) partially inserted into a 30 gauge, 15 cm-long stainless-steel sheath. The SPME was supported in a solution of toluene (0.1 ppm) which was agitated by magnetic mixing, intrusive mixing or sonication (details given). After the extraction period, the SPME fiber was inserted into the injector of a Varian 6000 gas chromatograph for analysis of the adsorbed material on a SPB-1 column (15 m x 0.53 mm i.d.; 0.5 µm) operated with temperature programming from 0-211°C (held for 1.25 min) at 25°C/min, He as carrier gas (4.2 ml/min) and FID. Cryogenic focusing was used to cool the column below room temperature to trap the volatiles in a narrow band at the head of the column. Sonication was the most efficient and convenient agitation method (toluene equilibrated in 1 min) and was applied to continuous-flow (16 ml/min) experiments (details given); magnetic stirring was not efficient and intrusive mixing caused sample heating. The method allows GC to be incorporated into a FIA system.
GC Sample preparation

"Notched Broad-band Excitation Of Ions In A Bench-top Ion-trap Mass Spectrometer"
Anal. Chim. Acta 1995 Volume 303, Issue 2-3 Pages 149-162
Manish H. Soni, Philip S. H. Wong and R. Graham Cooks*

Abstract: Selected ion-monitoring, tandem MS and mass-selective ion-molecule collisional applications of the title technique were demonstrated over the mass range 0-650 Da, with a 600 kHz pulse width and a He reverse-flow (2 ml/min) dual membrane sample introduction system with 70 eV EI. A variety of model volatile organic molecules in aqueous and aqueous 1% methanol were introduced using a flow injection system as described by Bauer and Cooks (Am. Lab., Oct 1993) and detected to parts per quadrillion levels.
Organic compounds Mass spectrometry Mass spectrometry

"Online Interface Between Microdialysis And Capillary Zone Electrophoresis"
Anal. Chim. Acta 1995 Volume 307, Issue 2-3 Pages 217-225
Mark W. Ladaa, Gabrielle Schallera, Marie H. Carrigerb, Thomas W. Vickroyb and Robert T. Kennedya,*

Abstract: A flow-gated, on-line interface between a microdialysis sampling probe and capillary zone electrophoresis with UV absorption detection was characterized and applied. Electrophoresis conditions were chosen so that ascorbic acid migrated in 42-100 s with 65000-120000 theoretical plates. These results were obtained using a 25 µm inner diameter capillary with an inlet to detector length of 15 cm and electric field strength of 400-600 V cm-1. Theoretical plates, migration times, and peak areas for ascorbic acid injected on-line from the interface were the same as those obtained for off-line injections. The system allowed step changes in ascorbic acid concentration to be followed with 85 s time resolution when the dialysis flow-rate was 79 nl min-1. The time resolution was improved to 65 s when the dialysis flow-rate was 155 ni min-1. The relative standard deviation for peak heights was 3.8% and a linear response over the physiologically relevant range for ascorbic acid was observed. At 79 nl min-1 the relative recovery of the probe was 98%. The high relative recoveries improved detection limits, simplified quantification, and resulted in decreased disturbance to the system being studied when compared to the more conventional dialysis flow-rates of 0.5-1 µL min-1. As a demonstration of the system, ascorbic acid in the caudate nucleus of rat brain was detected and monitored in response to systemic amphetamine injections and anaesthetic overdoses. This system is the first to demonstrate high relative recoveries and high time resolution simultaneously with microdialysis sampling.
Electrophoresis

"Characterization Of A Membrane Interface Designed For Analytical Scale Sample Introduction Into A Mass-spectrometer"
Anal. Chim. Acta 1996 Volume 327, Issue 1 Pages 1-16
Ashok R. Dongré and Mark J. Hayward*

Abstract: A membrane interface has been constructed for analytical scale sample introduction into a mass spectrometer. The interface was designed to be easy to use while achieving the following two goals: (i) to improve the mass transport efficiency of the analyte from the sample solution to the mass spectrometer ion source and (ii) to improve performance while reducing the sample sizes utilized for routine direct analyzes with membrane introduction mass spectrometry (MI/MS). In order to systematically characterize this interface, a variety of key mass transport parameters including membrane thickness, temperature, analyte flow rate, and pneumatic assist carrier gas flow rate have been examined. Interface characterization studies have focused primarily on two analytes, benzene and ethanol. These two analytes were chosen to compare the relative importance of each of the key mass transport parameters for the two most common applications of MI/MS, environmental analyzes and fermentation monitoring. The results of these studies suggest that mass transport of the analyte from solution phase to the membrane (including the use of the thin layer approach), membrane dimensions and membrane temperature are among the more important factors affecting analyte response and limits of quantification. Other significant results suggest that, when given a warm unrestricted path from the membrane to the ion source, the permeation (flux) of water from the aqueous matrix may be a major factor affecting the mass transport of analyte from the membrane to the ion source of the mass spectrometer. The comparison of the effects of the key mass transport parameters for environmental analyzes and fermentation monitoring shows that each of these two applications depend on a markedly different set of parameters for achieving optimal performance.
Organic compounds Fermentation broth Mass spectrometry

"Enhancing The Performance Of Membrane Introduction Mass Spectrometry By Organic Carrier And Liquid Chromatographic Separation"
Anal. Chim. Acta 1997 Volume 337, Issue 2 Pages 165-172
Shi Ouyang, Yong Hong Chen* and Yan Xu*

Abstract: A method of membrane introduction mass spectrometry with liquid chromatographic separation (LC/MIMS) for the analysis of volatile organic compounds (VOCs) in water has been developed. The method not only inherited all the advantages of membrane introduction mass spectrometry by flow injection analysis (FIA/MIMS), but also expanded the application of MIMS to the determination of compounds with identical quantitation ions. Because the quantitation by LC/MIMS is based on two-dimensional identification (retention time (t-r) and mass-to-charge ratio (m/z)), it provides a tangible approach to the analysis of VOCs in complex aqueous samples. In this work, a C-18 column and a mobile phase (methanol/water) were used for chromatographic separation. A mixture of eighteen VOCs was determined within 28 min. The method has linear dynamic ranges of 3-4 orders of magnitude and sub-ppb-level detection limits. In comparison with the EPA method 524.2 (a purge-and-trap GC/MS method), it requires less analysis time and no sample pretreatment.
Organics, volatile Environmental Mass spectrometry

"New Interface For Coupling Flow Injection And Capillary Electrophoresis"
Anal. Chim. Acta 1997 Volume 337, Issue 2 Pages 117-124
Petr Kuban, Anders Engström, Joanna C. Olsson, Gunnar Thorsén, Robert Tryzell and Bo Karlberg*

Abstract: The plexiglass interface allowed the inlet of the capillary electrophoretic column to be immersed in the effluent from the FIA system. When the sample plug eluted from the FIA system a small fraction was electrokinetically introduced into the column. The performance of the interface was evaluated by analyzing a mixture of 10 anions. A sample volume of 50 µL was injected into a carrier stream (2.7 ml/min) of 60 µM-cetyltrimethylammonium bromide/10 mM chromate/15 mM boric acid of pH 7.5. A potential of 25 kV was applied across the column (80 cm x 50 µm i.d. x 375 µm o.d.; 45 cm to detection window) and indirect UV detection was at 372 nm. The detection limits were 0.1-0.3 µg/ml and the RSD (n = 30) were <2.1%. The sampling frequency was 150/h. The coupled FIA-capillary electrophoresis system was used to determine anion concentrations in drinking and rain water samples.
Anions Water Rain Electrophoresis

"Combination Of Flow Injection With Capillary Electrophoresis. 1. The Basic System"
Anal. Chim. Acta 1997 Volume 346, Issue 2 Pages 135-143
Zhao-Lun Fang, Zhi-Song Liub and Qi Shen

Abstract: A flow-through conical reservoir was used to couple a flow injection (FI) system to a CZE system. The reservoir was attached to the outlet of the FI system. One end of the capillary column was positioned in the conical reservoir together with a grounded electrode. Samples were injected into the FI system and transported to the reservoir. Here, a portion of the sample plug was electrokinetically injected into the capillary. The same electrolyte was used as the carrier stream for the FI system and the running buffer. The system was demonstrated using benzoic acid and benzoic acid/magnolol mixtures as model analytes and 25 mM sodium tetraborate at pH 9.3 as the carrier/running buffer. Sample volumes of 40 µL were injected into the carrier stream (0.7 ml/min). The electrophoretic separations were performed on an uncoated capillary of 35 cm x 75 µm i.d. with an applied voltage of 12 kV (also injection voltage) and on-column UV detection at 224 or 254 nm. The precision of the coupled system was evaluated by repeated measurement of the peak heights and retention times for 200 mg/l benzoic acid. The RSD (n = 7) were 2.1% for peak heights and 0.4% for retention times. Similar measurements for a mixture of 150 mg/l benzoic acid and 140 mg/l magnolol yielded RSD (n = 7) of 2.3% for peak heights. The sampling frequency was 18/h.
Benzoate Magnolol Electrophoresis Spectrophotometry

"Combination Of Flow Injection With Capillary Electrophoresis. 3. Online Sorption Column Preconcentration Capillary Electrophoresis System"
Anal. Chim. Acta 1997 Volume 355, Issue 2-3 Pages 135-143
Heng-Wu Chen and Zhao-Lun Fang*

Abstract: A combined flow injection (FI)-capillary electrophoresis (CE) system with a split-flow interface reported previously was used for online pre-concentration of pseudoephedrine by solid phase extraction on a micro-column packed with C-18. Aqueous samples were loaded on the column at 1.0 mi min-1 for 90 s and eluted by a mixed eluent of 40% 62.5 mM acetate buffer (pH 4.0) and 60% acetonitrile at 0.2 mi min-1. A zone-sampling approach was employed to sample 45 µl of the most concentrated zone of the eluate, which was injected into the FI-CE split-flow interface using a phosphate buffer carrier, with a 25 µl water zone preceding the sampled eluate zone to achieve enhanced field amplification effects. Sensitivity enhancements of 60 fold (180 fold with 4 min sample loading) were thus achieved with a sample throughput of 9 h-1 and 4.7% relative standard deviations (n = 10, 2 µg mL-1 pseudoephedrine) for peak area evaluation, without significant degradation of column efficiency. 16 References
Pseudoephedrine Electrophoresis Sample preparation

"Effect Of Mobile Phase Composition On The Electrochemical Cell Conversion Efficiency In Electrochemistry/mass Spectrometry"
Anal. Chim. Acta 1998 Volume 369, Issue 3 Pages 253-262
Merle Regino, Carol Weston and Anna Brajter-Toth*

Abstract: A new electrochemical flow-through cell has been recently developed and characterized for online EC/MS experiments with thermospray and particle beam LC-MS interfaces. It was discovered in this work that the mobile phase composition had a significant effect on the sensitivity in the online EC experiments with the new flow-through electrochemical cell. An application of hydrodynamic EC methods is illustrated in the optimization of EC/MS measurements using different mobile phases including aqueous, non-aqueous, and mixed mobile phases.
Mass spectrometry Mass spectrometry Electrochemical analysis

"Combination Of Flow Injection With Capillary Electrophoresis. 4. Automated Multicomponent Monitoring Of Drug Dissolution"
Anal. Chim. Acta 1998 Volume 376, Issue 2 Pages 209-220
Heng-Wu Chen and Zhao-Lun Fang*

Abstract: The combined flow injection-capillary electrophoresis (FI-CE) system, described previously in this series, was used in connection with a drug dissolution testing system to automatically monitor the dissolution process of multicomponents. Samples from the dissolution medium were withdrawn at fixed intervals through an online membrane filter to load the sample loop of an injection valve, from which 25 µL samples were injected into a carrier buffer and transported into a split-flow interface coupling the FI and CE systems. Trimethoprim (TMP) and sulfamethoxazole (SMZ), the two active components in a sulfatrim tablet formulation dissolved in 0.1 mol L-1 HCl, were introduced into a short silica separation capillary of 14.5 cm effective length by electrokinetic means, separated at a constant voltage of 1.0 kV by capillary zone electrophoresis, using a phosphate running buffer (pH 6.5), and the separated constituents recorded continuously, using an UV detector at 224 nm. The signals were recorded within a testing period of 65 min. By partially overlapping the separation zones of neighboring samples, a high sample throughput of 60 h-1 was achieved with single-vessel dissolution and 48 (24 duplicates) h-1 with dual-vessel dissolution The reproducibility of the FI-CE system, obtained using TMP and SMZ standards within the testing period was 1.6 and 0.8% relative standard deviation (RSD) with peak height evaluation, and 2.0 and 1.1% RSD (n=72), respectively, for peak area. Good agreement of results was obtained between those using the reported method and a standard liquid chromatography method.
Trimethoprim Sulfamethoxazole Pharmaceutical Electrophoresis

"Online Monitoring Of Chloramine Reactions By Membrane Introduction Mass Spectrometry"
Talanta 1991 Volume 38, Issue 2 Pages 195-200
Tapio Kotiaho, Anita K. Lister, Mark J. Hayward and R. Graham Cooks*,

Abstract: Membrane introduction mass spectrometry has been applied to on-line monitoring of the reaction of monochloramine with hydrogen chloride. The detection limit for monochloramine introduced by a sheet-membrane direct-insertion probe and measured by electron impact ionization and selected ion detection was found to be 0.7 mg/l. Formation of dichloramine, trichloramine and molecular chlorine in response to the addition of hydrogen chloride to the monochloramine solution was measured on-line. The flow-through membrane introduction mass spectrometry method for detection of chloramines and characterization of their chemistry has minimal memory effects, high molecular specificity, high speed of analysis owing to fast response times, and low detection limits.
Chloramines Mass spectrometry

"Ion Mobility Spectrometry As Flow Injection Detector And Continuous-flow Monitor For Aniline In Hexane And Water"
Talanta 1992 Volume 39, Issue 5 Pages 459-467
Gary A. Eiceman*, Lizbeth Garcia-Gonzalez, Yuan-Feng Wang and Bobby PittmanG. Edward Burroughs,

Abstract: Ion mobility spectrometry (IMS) was used as a flow injection detector to quant. examine the ionization chemical of aniline in hexane. A 5 µL sample was vaporized at 15-90-s intervals in a flowing air stream and analyzed with an IMS equipped with acetone reactant ion chemistry, ambient temperature drift tube and membrane-based inlet. Precision was 3-11% relative standard deviation for 1-100 ppm aniline in hexane with 90-s injection intervals and detection limits were ~0.5 ppm with 5 µL injections. Matrix effects with amine and organic solvent mixtures were observed and corrected for low and medium proton affinity interferences with standard addition methods. Pronounced fouling of the IMS occurred when a continuous water flow was introduced for aqueous flow injection IMS. Continuous water monitoring without degraded IMS performance was possible by sampling air flow-through a Silastic tube immersed in an aqueous sample.
Aniline Organic compound Water Spectrometry

"Application Of The Slotted Quartz Tube In Flow Injection Flame Atomic Absorption Spectrometry"
Talanta 1992 Volume 39, Issue 6 Pages 581-587
Shukun Xu, Lijing Sun and Zhaolun Fang

Abstract: The feasibility and performance of a combination of a slotted quartz tube and flow injection in flame AAS was studied. A five- to six-fold improvement in tube life was observed relative to continuous aspiration. Flow-impact systems were not needed, so that it was possible to achieve larger enhancement factors without loss of precision. Sensitivity enhancement factors of 3.1, 5.5, 5.3 and 4.0 were obtained for 1.0 mg L-1 of Cu, 1.0 mg L-1 of Pb, 0.1 mg L-1 of Cd and 1.0 mg L-1 of Au with coefficient of variation of 1.3, 1.1, 1.6 and 1.7%, respectively. When the method was applied to the determination of heavy metals in urine, improved tolerance to matrix interference was observed. Recoveries obtained by treating urine samples with 0.1 mg L-1 of Cu and Pb and 0.01 mg L-1 of Cd were 100 to 102%. The slotted quartz tube has been applied to flow injection flame atomic-absorption spectrometry (FI-FAAS) showing several important advantages. The tube life was improved by a factor of 5-6 compared to conventional continuous aspiration. Flow impact systems were found not to be necessary in the applications so that larger enhancement factors may be achieved without sacrifice in precision. For 1.0 mg/L copper, 1.0 mg/L lead, 0.1 mg/L cadmium, and 1.0 mg/L gold sensitivity enhancement factors of 3.1, 5.5, 5.3 and 4.0 were obtained with precisions of 1.3%, 1.1%, 1.6% and 1.7% RSD (n = 11), respectively. Application of the slotted quartz tube FI-FAAS method to the determination of heavy metals in urine has shown improved tolerance to interfering matrixes. Recoveries obtained by spiking undiluted urine samples with 0.1 mg/L copper and lead, and 0.01 mg/L cadmium were in the range 100-102%.
Copper Lead Urine Spectrophotometry

"Comparison Of Photometry And Conductometry For The Determination Of Total Carbonate By Gas Permeation Flow Injection Analysis"
Talanta 1993 Volume 40, Issue 6 Pages 831-840
Vlastimil Kub&aacute; and Purnendu K. Dasgupta*,

Abstract: A manifold for the flow injection determination of total carbonate (i.e, dissolved CO2) in acidified sample solution is described (diagram given). Sample solution was mixed with 0.5 M phosphoric acid modifier/conditioning reagent and the mixture was pumped through a tubular Si membrane permeation device (120 mm x 0.4 mm), which allowed the pre-concentration. of CO2 in a suitable receptor solution before its photometric or conductometric determination. For the photometric determination the receptor solution was 50 µM-cresol red in carbonate/bicarbonate buffer (pH 9) and the change in absorbance at 434 nm was measured. The best receptor solution for the conductometric determination was 1-10 mM tris(hydroxymethylamino)methane. Interference from sulfite and sulfide was eliminated using sulfuric acid/potassium permanganate as the modifier/conditioning reagent. To avoid interference from cyanide, a more complex manifold was required to allow oxidation under alkaline conditions before sample acidification. The conductometric method provided better day-to-day reproducibility, sensitivity and detection limits than the photometric method.
Carbonate Spectrophotometry Conductometry

"Performance Of An Ion Trap Mass Spectrometer Modified To Accept A Direct Insertion Membrane Probe In Analysis Of Low Level Pollutants In Water"
Talanta 1993 Volume 40, Issue 7 Pages 1031-1039
Scott J. Bauer and R. Graham Cooks

Abstract: Modifications to a Finnigan ITS40 ion trap mass spectrometer are described which allow its use with a direct insertion probe. Details are given of the fabrication of a membrane probe for such an instrument. The membrane probe, which includes facilities for heating the fluid, employs a tubular membrane which is located just outside the electrode structure of the ion trap. Direct analysis of organic compounds in aqueous solution is demonstrated using a silicone membrane, with compounds such as benzene, chlorobenzene and dichloroethene being studied below the 1 ppb level. The effects of operating parameters including probe temperature, ion trap temperature, solution flow rate, mass spectrometer scan speed, and instrument tune procedures are explored in detail. Optimum performance characteristics are identified and trace level detection of eight organic compounds in the parts per trillion range is demonstrated. In seven of the eight cases studied, detection limits are below the EPA practical limit of quantitation levels. It is shown that the most sensitive mode of operation is when steady state passage of the analyte across the membrane is achieved, however, the time required for this is long in the case of some samples, and a dynamic flow injection analysis procedure is then favored. Use of the modified inlet system for solid sample introduction via a standard solids probe is also demonstrated. [References: 19]
Benzene Chlorobenzene Dichloroethene Water Mass spectrometry

"Hyphenated Flow Injection Systems And High Discrimination Instruments"
Talanta 1995 Volume 42, Issue 2 Pages 151-169
M. D. Luque de Castro and M. T. Tena,

Abstract: A review is presented of state-of-the-art FIA coupled to instruments capable of providing multidetection and/or multi-information. Tables are presented of the methods of FIA coupled with ICP-AES, ICP-MS, FTIR, MS, MECA, NMR and flame IR emission spectrometry with references. Interfaces, sample introduction, sample handling, online separation processes and speciation studies are discussed. (190 references).
Mass spectrometry Mass spectrometry Nuclear magnetic resonance Spectrophotometry Spectrophotometry Spectrophotometry

"Determination Of Hydrazine Derivatives By Flow Injection Analysis With Spectrophotometric Detection"
Talanta 1995 Volume 42, Issue 10 Pages 1465-1469
M. I. Evgen'ev, S. Y. Garmonova, I. I. Evgen'eva and H. C. Budnikov

Abstract: A diagram is presented of a flow injection manifold used in the spectrophotometric determination of hydrazine-based drugs. The method was based on the reaction of 4-chloro-5,7-dinitrobenzofurazan (DNBF) with the hydrazine derivatives. The 0.02 M DNBF acetonitrile solution was injected directly into a carrier solution of the hydrazine derivatives (concentration range 0.15-4 µg/ml) and the absorbance at 510 nm was measured. For the determination of 1-hydrazinophthalazine hydrochloride in apressin drug, powdered tablets containing ~10 mg of the drug were diluted to 100 mL with water. The mixture was shaken, filtered and a 5 mL portion was diluted to obtain a final solution containing ~1 µg/ml drug. For the determination of hydrazine drugs in plasma, urine and albumin, 1 mL TCA was added to 4 mL sample followed by centrifugation at 6000 rpm. The supernatant was neutralised with 0.5 mL acetate buffer of pH 5.5 and analyzed by the above procedure. The calibration graphs were linear from 0.15-4 µg/ml, with sampling rates of 28-32/h. Interferences from other compounds are tabulated. Flow injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.0 µg mL-1 of hydrazine derivatives, with sampling rates of up to 28-32 samples h-1. Interferences from amino compounds, benzoic acids, aliphatic amines and ammonia have been evaluated. The procedure has been applied to the determination of hydrazine derivatives in serum, urine, apressin drugs and artificial mixtures. (16 references)
Drugs Hydrazine Blood Serum Urine Pharmaceutical Blood Plasma Spectrophotometry

"Online Coupling Of Gas Diffusion To Capillary Electrophoresis"
Talanta 1998 Volume 45, Issue 3 Pages 477-484
Petr Kuban and Bo Karlberg*

Abstract: Online gas diffusion has been coupled to a capillary electrophoresis system (CE) via a specially designed interface. The sample is merged with a modifying solution, e.g., a strong acid, in a flow system to transform the analytes of interest into their respective gaseous forms. These transformed, gaseous analytes permeate through a PTFE membrane into an acceptor stream comprising of a tris-buffer. The continuously flowing acceptor stream is led into an injector forming an integrated part of a flow injection analysis (FIA) system. The sample receiving carrier stream in the FIA system, a chromate buffer, brings the sample, 50 µl, to the FIA-CE interface into which one end of a separation capillary has been inserted. A small portion of the injected sample enters the capillary (electrokinetic injection) and separation takes place. A UV detector is placed at the other capillary end and a run potential of 25 kV is applied to two platinum electrodes positioned in the flow system. Multiple sample injections can be performed in one uninterrupted electrophoretic run. A typical sampling frequency is 15 h-1; each run may result in quantitation of at least five anions. The overall repeatability is in the range 1.8-3.6% (RSD). The technique has been applied to the analysis of real samples such as soft drinks, vinegar and wine. Selective discrimination of anions which are unable to form volatile species is accomplished. No off-line sample pre-treatment is needed.
Anions Soft drink Food Wine Electrophoresis

"Flow Injection Atomic Absorption Spectrometry With Air Compensation"
Analyst 1987 Volume 112, Issue 3 Pages 271-276
Ignacio L&oacute;pez Garc&iacute;a, Manuel Hern&aacute;ndez C&oacute;rdoba and Concepci&oacute;n S&aacute;nchez-Pedre&ntilde;o

Abstract: The introduction of air to compensate for the solvent flow being less than the nebulization rate was evaluated in this study. The flow injection manifold (described) was connected to the spectrometer via a T-piece, through which air or water could be drawn for compensation. By using Ca standards, the system was optimized with respect to sample size and flow rates. It was found that air compensation avoided sample dilution (as in solvent compensation), giving improved precision and sensitivity over other compensation methods through greater peak height and area response. Higher levels of interferents could also be tolerated.
Calcium Spectrophotometry

"Overview Of Analytical Methods For Elemental Speciation"
Analyst 1992 Volume 117, Issue 3 Pages 563-570
Jon C. Van Loon and Ronald R. Barefoot

Abstract: A review is presented, with 64 references, with discussion of sampling selective extraction, coupled instrumental methods (chromatography coupled with, e.g., AAS or ICP), electrochemical methods and FIA in elemental speciation. Various methods for determining the elements most frequently studied are described. A review with 64 references. This paper describes a selection of the major developments in the field of anal. methodology for elemental speciation over the period from Jan. 1986 to Dec. 1990. Methods for a number of elements are highlighted. Judging by the number and diversity of published reports, there has been increasing interest and activity in the development of new and modified anal. methods. Further, it is very encouraging to observe the number of papers concerned with the accuracy and precision of such anal. methods, and with comparisons between two or more methods. Among electrochemical methods of analysis, anodic stripping voltammetry has provided an important basis for measurements of concentrations of labile metals in aqueous media. The fastest growing area of method development is the coupling of separation methods, usually chromatography, with a single- or multi-element detector. Most importantly, inductively coupled plasma mass spectrometry has recently been described as a very sensitive, multielement detector. The success of a coupled method is greatly dependent on a suitable interface. Several papers have been published recently describing useful interfaces. Chemical extraction procedures continue to occupy an important place. Applications of analytical elemental speciation methods have included environmental, biologocal, clinical, and geological samples. Methods for elements most frequently studied are discussed.
Voltammetry Mass spectrometry Sample preparation

"Flow System For Liquid Sample Introduction In Arc-spark Excitation Sources"
Analyst 1996 Volume 121, Issue 12 Pages 1923-1927
Carlos Roberto Bellato and Celio Pasquini

Abstract: A flow system, based on the monosegmented flow analysis approach, is described for the automated delivery of liquid samples to arc/spark excitation sources commonly used with plane grating spectrographs. The sample (50 µL) was carried between two air segments into the path of the excitation source via a hole drilled in a conventional graphite electrode. The arc/spark is applied to excite the sample for a pre-set time interval and the light emitted is integrated. A diagram of the flow system is given. The throughput was 25 samples/h. The flow system was used in the determination of Al, Pb and mixtures of Hf and Zr in aqueous solution (results presented and discussed).
Aluminum Lead Hafnium Zirconium Spectrophotometry

"Online Sample Pre-treatment Systems Interfaced To Electrothermal Atomic Absorption Spectrometry"
Analyst 1998 Volume 123, Issue 4 Pages 561-569
Jos&eacute; Luis Burguera and Marcela Burguera

Abstract: A review with 98 references. Atomic spectrometric techniques working with a continuous supply of sample, such as flame atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry, are well suited for online connection through flow injection arrangements. For the determination of elements at lower concentrations, electrothermal atomization is often needed owing to the requirement for better detection limits. However, connecting a batch technique such as electrothermal atomic absorption spectrometry to a continuous-flow or a flow injection system presents some fundamental difficulties, making it a real challenge for the anal. chemist to design suitable interfaces. There are different ways of interfacing the systems to each other; the available versions use either online sample treatment with off-line measurement or are completely online arrangements. Complex samples cannot be directly processed by this technique owing to severe matrix interferences, which were not minimized despite the development of efficient background correction devices. Successful matrix separation can be achieved online through solvent and sorbent extraction, precipitation and coprecipitation, volatile compound generation and liquid chromatography Also, transformation of the sample and/or its fractions into a form that can be analyzed in a graphite furnace often requires unpleasant, tedious and time-consuming digestion procedures. Microwave heating has emerged as a means of dramatically improving leaching, mineralization or digestion processes and has frequently been used with in-batch or online systems. This paper outlines the most recent advances in the development of flow injection-graphite furnace interfaces and also describes the online sample pre-treatment systems developed so far for electrothermal atomic absorption detection.
Spectrophotometry Sample preparation

"Investigation Of Small Volume Cloud Chambers For Use In Inductively Coupled Plasma Nebulisation"
J. Anal. At. Spectrom. 1987 Volume 2, Issue 8 Pages 823-828
Phillip L. Kempster, Jacobus F. Van Staden and Henk R. Van Vliet

Abstract: The characteristics of three small volume cloud chambers, constructed with the aim of reducing sample wash-in and wash-out times in inductively coupled plasma atomic emission spectrometry were investigated, and compared with the characteristics of a commercially available 110 mL double-barrel type cloud chamber. Analytical performance was evaluated with respect to drainage, nebulisation efficiency, sensitivity, precision, detection limits, wash-in and wash-out times and the evaluation of volatilisation interferences from phosphate and aluminium on calcium, as well as the effect of sodium on calcium emission intensity.
Spectrophotometry

"Effects Of Capillary Diameter On Thermospray Sample Introduction In Inductively Coupled Plasma Atomic-emission Spectrometry"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 6 Pages 799-802
John A. Koropchak, Henry Aryamanya-Mugisha and Daniel H. Winn

Abstract: By using the flow injection ICP-AES system described by Koropchak and Winn (Anal. Chem., 1986, 58, 2558), the effect of decreasing the exit orifice diameter on thermospray vaporization was investigated for standard solution in dilute HNO3. For a diameter of 50 µm, the analyte transport efficiency is increased to ~50% and the signal-to-noise ratio is enhanced up to 40-fold. From cascade impactor studies, improvements in aerosol characteristics are required for more efficient utilization of the transported analyte for signal production. The use of gases of high thermal conductivity, e.g., H, as aerosol carriers is suggested.
Spectrophotometry

"Analysis Of Solutions Containing High Levels Of Dissolved Solids By Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1988 Volume 3, Issue 4 Pages 547-550
Robert C. Hutton and Andrew N. Eaton

Abstract: Solutions used for analysis by inductively coupled plasma mass spectrometry (ICP-MS) are often restricted to those containing low amounts of dissolved solids (0.2%m/V). This is primarily due to problems associated with matrix deposition on the sampler orifice. The effect of the volatility of the matrix is considered in relation to this problem. Techniques which utilise the injection of limited sample volumes into the ICP system such as flow injection (FI) are shown to be particularly effective in minimising such effects when refractory matrices are to be analyzed. Data are presented illustrating the analysis of two different matrix types, i.e., brine and aluminium. The results indicate that such samples can be routinely analyzed by ICP-MS at up to 1.5-2.0%m/V of total dissolved solids if suitable sampling procedures are employed.
Mass spectrometry

"Evaluation Of Three Low-volume Interfaces For Organic Solvent Introduction To The Inductively Coupled Plasma - Applications To Flow Injection"
J. Anal. At. Spectrom. 1989 Volume 4, Issue 4 Pages 341-345
Timothy J. Brotherton, Peter E. Pfannerstill, John T. Creed, Douglas T. Heitkemper, Joseph A. Caruso and Sotiris E. Pratsinis

Abstract: Three low-volume sample delivery systems (described and illustrated) were evaluated for continuous solution nebulization and for flow injection introduction into the ICP: (i) a cooled mini-spray chamber, (ii) a desolvation interface, and (iii) a partial-suction injector. Each system was operated under the same conditions (tabulated). The max. solution delivery rates for each interface were >2 mL min-1 for both methanol and acetonitrile. Calibration graphs were rectilinear over three to four orders of magnitude in each instance. Detection limits under continuous solution nebulization conditions were in the mid- to sub ng mL-1 range. Flow injection peak widths were narrower for (i), (ii) and (iii) than for systems involving spray chambers with larger volume.
Spectrophotometry

"Determination Of Trace Metals In Volatile Organic Solvents Using Inductively Coupled Plasma Atomic-emission Spectrometry And Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 1 Pages 23-28
Steve J. Hill, James Hartley and Les Ebdon

Abstract: A desolvation system is described to facilitate the introduction of volatile organic solvents in plasmas which utilizes Peltier coolers to reduce the temperature of an Al heat sink interface placed between the heated spray chamber and the plasma torch (details given). The system was applied in the determination of trace metals in ethyl ether under optimum conditions (tabulated) by ICP-AES and ICP-MS. Results were more sensitive than those using a conventionally-cooled mini-spray chamber, with detection limits in the low- to sub µg L-1 range. Flow injection techniques were also used to reduce the amount of volatile organic solvent entering the plasma. In addition to achieving an enhancement in plasma stability, it was found that smaller sample loops (50 µL) facilitated faster flow rates, resulting in better-shaped transient peaks and reduced memory effects. A desolvation system has been designed to help facilitate the introduction of volatile organic solvents into inductively coupled plasmas. The system utilizes Peltier coolers to reduce the temperature of an interface placed between a heated spray chamber and the plasma torch. The interface consists of a drilled aluminum block that acts as a heat sink and through which pass glass cooling tubes. The Peltier coolers are mounted around the block, sandwiched between the block itself and a series of copper cooling plates. The optimum conditions necessary for the determination of trace amounts of metals in di-Et ether are discussed and the results obtained using these conditions compared with those obtained using a conventionally cooled mini-spray chamber. Detection limits, using the system in conjunction with continuous nebulization, were found to be in the low to sub µg L-1 range for inductively coupled plasma mass spectrometry. Flow injection techniques have also been used to reduce the amt. of volatile organic solvent entering the plasma. In this instance the volatile solvent (di-Et ether) was carried in a stream of less volatile solvent (2-ethoxyethanol) to the plasma. The effects of varying the sample loop volume have been investigated, and the results compared with those obtained using continuous-flow nebulization. The results indicated that, in addition to achieving an enhancement in plasma stability, smaller sample loops (50 µL) facilitate faster flow rates, which result in better shaped transient peaks and reduced memory effects.
Organic compound Mass spectrometry Spectrophotometry

"Determination Of Impurities In Organometallic Compounds Dissolved In Ethyl Ether By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 6 Pages 895-989
Steve J. Hill, James Hartley and Les Ebdon

Abstract: The sample (10 to 25 µL) was injected into a carrier stream of 2% HNO3. By incorporating a membrane drying tube for desolvation, the detection limits for Al, Cu, In, Pb and Zn were between 0.5 and 1.0 ng l-1. The recoveries were from 92.6 ± 8.6% to 107.6 ± 10.3% for 8.2 ± 0.8 to 96.1 ± 10.7 ng l-1. The method was applied to trimethylgallium and methyl-lithium. A novel method of introducing organometallic samples dissolved in volatile organic solvents into an inductively coupled plasma mass spectrometer is described and characterized. Small volumes of organic solvent are injected into a carrier stream of dilute nitric acid (2%) using a flow injection valve. The uptake rates employed are typical of those used for aqueous samples (1-4 mL min-1) and the volume of sample used is such that the plasma remains stable throughout the study. The optimum operating conditions for this process, determined using the variable step size simplex procedure, are discussed in detail. The detection limits obtained are in the ng mL-1 range; they were compared with those obtained using a modified sample introduction system incorporating a membrane dryer tube for desolvation. This modification improves the sensitivity to facilitate detection limits at the sub ng mL-1 level. Finally the determination of metallic impurities present at levels of the order of 1 ng mL-1 in two organometallics, trimethylgallium and methyllithium, both stabilized in di-Et ether, is reported.
Aluminum Copper Indium Lead Zinc Inorganic compound Inorganic compound Inorganic compound Mass spectrometry

"Performance Of A Modular Thermospray Interface For Signal Enhancement In Flame Atomic Absorption Spectrometry Coupled Online To Flow Injection [analysis] Or Liquid Chromatography"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 659-664
Erik H. Larsen and Jean-Simon Blais

Abstract: A simple and inexpensive thermospray interface is described that was connected to a flame AAS system without modification of the nebulizer and burner assembly. Details are provided of its construction and performance characteristics. The interface provided improved signal-noise and signal enhancement in a flow injection - AAS system with rectilinear calibration and detection limits of 1.9 ng of Cd, 8.5 ng of Cu and 27 ng of Pb. The use of the interface to couple HPLC to AAS was demonstrated for the determination of metallothioneins in biological samples.
Cadmium Copper Lead Biological Spectrophotometry

"Online Thermospray Continuous Volatilization Of Cobalt, Aluminum And Chromium Volatile Chelates And Determination By Heated-quartz-tube Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1993 Volume 8, Issue 4 Pages 665-669
Maria S. Jim&eacute;nez, Jos&eacute; M. Mir and Juan R. Castillo

Abstract: A system for the introduction of gas-phase metal samples into an AAS is described. Analyte solutions at an appropriate pH for complex formation were pumped through one channel of a flow injection system and 0.5 mL portions were injected into the chelating reagent stream. The reactor has a sample loop (50 µL) and the complex was injected into an air-flow, transported into the thermospray (24 cm x 0.5 mm) and the vapor introduced into a quartz tube in the spectrometer heated in an air - acetylene flame. Optimum operating parameters and interference effects are examined and analytical parameters compared with analyzes using a nebulizer for sample introduction.
Cobalt Aluminum Chromium Spectrophotometry

"Automatic Preparation Of Milk Dessert Slurries For The Determination Of Trace Amounts Of Aluminum By Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 1 Pages 55-59
Marco A. Z. Arruda, Mercedes Gallego and Miguel Valc&aacute;rcel

Abstract: Yogurt was manually homogenized and aspirated into a 200 µL sample loop of a flow injection system at 1.5 ml/min. The sample was injected into a carrier stream (0.7 ml/min) of 0.2% HNO3 which merged with a chemical modifier stream (0.3 ml/min) of 0.1 M magnesium nitrate/10 mM palladium nitrate. The solution passed through a mixing chamber and was loaded into a sample cup for 2 min (2 ml). The solution was analyzed for Al by ETAAS (furnace conditions tabulated). The calibration graph was linear for 40-400 µg/l of Al with a detection limit of 6 µg/l. The effects of foreign ions on the method are discussed.
Aluminum Food Spectrophotometry

"Liquid Sample Introduction Devices In Flow Injection Atomic Spectroscopy"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 7 Pages 473-477
J. L. Burguera and M. Burguera

Abstract: A review is presented of the advantages of using FIA manifolds as sample introduction devices (SID) for atomic spectroscopy. The development and current status of SID in atomic spectroscopy is discussed. The three types of SID, volume-based, time-based and volume and time-based devices are outlined in detail with emphasis on their reliability, sample and reagent consumption, degree of flexibility, robustness and automation capabilities. (76 references).
Spectrophotometry

"Evaluation Of A Microconcentric Nebulizer-cyclonic Spray Chamber For Flow Injection Simultaneous Multielement Inductively Coupled Plasma Optical Emission Spectrometry"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 5 Pages 483-488
Terrance D. Hettipathirana and David E. Davey

Abstract: Merits of a µconcentric nebulizer and a cyclonic spray chamber for sample introduction to simultaneous multielement inductively coupled plasma optical emission spectrometry (ICP-OES) were evaluated. Sample delivery was both continuous and by flow injection (FI). All signal profiles were acquired and processed in the time-resolved mode. At solvent flow rates of 0.1 and 1.0 mL min-1, solvent transport efficiency to the ICP is ~90 and 50%, respectively. As a consequence, improvements in detection limits were observed compared with those using a conventional concentric nebulizer. Application of Sc as an internal standard to improve precision with FI sample delivery was also studied.
Metals Spectrophotometry

"Merging Zones Flow Injection For The Determination Of Ultratraces Of Bismuth By Volatile Species Generation Atomic Absorption Spectrometry Using Sodium Tetraethylborate(III)"
J. Anal. At. Spectrom. 1998 Volume 13, Issue 5 Pages 431-435
J. Pablo Valles Mota, M. Rosario Fern&aacute;ndez de la Campa and Alfredo Sanz-medel

Abstract: The generation of a volatile Bi compound by its reaction in aqueous solution with sodium tetraethylborate(III) has been achieved using a flow injection (FI) system with injection of Bi and NaBEt4 solutions in a 'merging zones' mode. This vapor generation (VG) system has been successfully interfaced with an atomic absorption spectrometric (AAS) detector for the determination of low levels of the metal. A detection limit of 0.8 µg L-1 (0.56 ng) of Bi was obtained after optimization of the chemical and instrumental parameters. This volatile species generation with AAS detection showed a precision of ±2.9% at the 40 µg L-1 level of Bi and a sample throughput of about 100 samples h-1 was observed Interference studies were carried out for many potentially interfering elements. The proposed FI-VG-AAS method proved to be very selective for the determination of Bi and so it has been successfully applied to the determination of ultratraces of Bi in human urine after simple 1+1 dilution without any other pretreatment; the detection limit in real urine samples was 1.6 µg L-1. Bismuth recoveries of 100% were found in spiked urine samples and also excellent agreement was achieved between results obtained by FI-VG-AAS and those obtained by ICP-MS for real urine samples. Finally, the proposed procedure was applied to the study of urinary clearance of Bi in three different people after intake, at therapeutic doses, of colloidal Bi subcitrate (CBS).
Bismuth Urine Spectrophotometry

"Design And Evaluation Of An Interface Between A Continuous-flow System And A Graphite Furnace Atomic Absorption Spectrometer"
Anal. Chem. 1988 Volume 60, Issue 13 Pages 1354-1357
Kenneth Backstrom and Lars Goran Danielsson

Abstract: The interface (described with diagram) includes two microcomputer-controlled six-port valve injectors mounted on flow injection analysis-05 analyzer.s and connected in series for the sample and rinsing solution, and an air flow pump. The operation of the interface and optimization of the system are discussed. The interface has been used to connect a two-step extraction system to a graphite furnace for the AAS determination of heavy metals.
Metals, heavy Spectrophotometry Sample preparation

"Flow Injection Analysis And Real-time Detection Of RNA Bases By Surface-enhanced Raman Spectroscopy"
Anal. Chem. 1990 Volume 62, Issue 18 Pages 1958-1963
Fan Ni, Rongsheng Sheng, and Therese M. Cotton

Abstract: Surface-enhanced Raman scattering (SERS) spectroscopy has been successfully interfaced with a flow injection analysis system to detect RNA bases in real time. Four of the major base components of RNA, uracil, cytosine, adenine, and guanine, were introduced into the flow injection system and were mixed with a Ag sol prior to SERS measurements. Several experimental parameters including pH, temperature, flow rate, and tubing materials were examined, and their impact on the SERS spectra is presented here. The feasibility of interfacing flow injection based SERS detection methods with liquid or high performance liquid chromatography for the detection of individual components in a complex mixture is also assessed.
Bases, RNA Raman HPLC

"Determination Of Monosaccharides In Cellulosic Hydrolysates Using Immobilized Pyranose Oxidase In A Continuous Amperometric Analyser"
Anal. Chem. 1990 Volume 62, Issue 24 Pages 2688-2691
Lisbeth Olsson, Carl Fredrik Mandenius, and Jindrich Volc

Abstract: Purified pyranose oxidase (details given) was immobilized on controlled pore glass by using the glutaraldehyde activation method and stabilized by co-immobilization with catalase. For the determination of glucose, xylose and galactose, the immobilized enzyme reactor was installed in a pseudo flow injection system and oxygen consumption was measured with an amperometric electrode (Clark-type). The electrode response after partial transfer of the sample through a dialysis membrane was rectilinear from 0.6 to 30, 1.0 to 50 and 2.0 to 100 mM, respectively. The analytical system was tested for bioreactor monitoring on laboratory scale by interfacing with a 10-l fermenter containing spent sulfite liquor, and no adverse effects were observed with regard to pyranose response; after 2000 injections into the enzyme reactor the decay of enzyme activity was 17%. This analytical system has also been applied to the continuous monitoring of ethanolic fermentation.
Monosaccharides Glucose Galactose Xylose Amperometry

"Pulsed Sample Introduction Interface For Combining Flow Injection Analysis With Multi-photon-ionization Time-of-flight Mass Spectrometry"
Anal. Chem. 1992 Volume 64, Issue 7 Pages 769-775
Alan P. L. Wang and Liang Li

Abstract: Sample molecules carried by a liquid carrier (e.g., methanol at 0.5 mL min-1) were vaporized by passage through a heated capillary tube to form aerosol droplets which were entrained in the sample vaporizer of a high-temp. pulsed nozzle. The vapor was injected into the time-of-flight mass spectrometer at a repetition rate determined by the ionization source. The interface described was used to detect both volatile and non-volatile compounds, including those of environmental and biological significance. The average coefficient of variation was 4 to 8%. There were no memory effects or severe peak tailing, and cluster formation during supersonic jet expansion was not a problem. The detection limits for aniline, tryptamine and indole-3-acetic acid were 3, 4 and 140 ng, respectively. The calibration graphs were rectilinear over two-orders of magnitude of analytical range. A pulsed sample introduction (PSI) interface is developed to combine flow injection analysis with a time-of-flight mass spectrometer. In PSI, sample molecules carried by a liquid carrier such as methanol at a flow rate of 0.5 mL/min are vaporized by passing through a heated capillary tube and then through a sample vaporizer of a high-temp. pulsed nozzle. The resulting sample vapors are introduced into the mass spectrometer in a pulsed form and ionized by laser-induced multiphoton ionization. The applicability of this interface for the detection of volatile and nonvolatile compounds is studied. It is found that a variety of chemicals including molecules with environmental or biological significance can be studied by this method. Preliminary studies of the performance of this interface are reported. It is shown that reproducible results from repeated injection of the same concentration. of samples can be readily obtained. The average relative standard deviation is in the range of 4-8%. No memory effects and severe peak tailing are found with this PSI interface. The detection limits of the present technique are compound dependent. For aniline, tryptamine, and indole-3-acetic acid, the detection limits are found to be 3, 140, and 4 ng, respectively. Excellent linearity over two orders of magnitude of analytical range can be obtained for quantitation. It is also shown that cluster formation during the supersonic expansion is not a major problem in this technique.
Methanol Environmental Biological Mass spectrometry

"Thermospray - Micro-atomizer Interface For The Determination Of Trace Cadmium And Cadmium Metallothioneins In Biological Samples With Flow Injection - And High Performance Liquid Chromatography - Atomic Absorption Spectrometry"
Anal. Chem. 1992 Volume 64, Issue 24 Pages 3197-3201
K. A. High, Richard Azani, A. F. Fazekas, Z. A. Chee, and J. S. Blais

Abstract: A description is given of a micro-atomization interface (made from quartz tubes) which is fuelled by hydrogen and can operate with 100% aqueous mobile phases used in HPLC. The system was optimized for the detection of Cd (total and bound soluble) in mussels and animal tissues, using flow injection AAS, or for the determination of metallothionein-bound Cd (isoforms I and II) in horse kidney, using HPLC - AAS. The detection limit obtained for Cd in the flow injection mode was ~2.2 orders of magnitude lower than that obtained with a conventional flame AAS detector, and 27-fold lower than that obtained by a thermospray-enhanced flame AAS system . Similar detection limits were obtained for the determination of metallothionein-bound Cd in the HPLC - AAS mode. A flexible thermospray-microatomization interface providing a high signal/noise ratio for flow injection atomic absorption spectrometry (AAS) and HPLC-AAS was designed and optimized for the determination of soluble Cd and Cd-metallothioneins (MTs). The interface, built from inexpensive quartz tubes, Swagelok fittings and thermoelectric wires, comprised 4 compartments: (1) a thermospray inlet; (2) a premixing tube in which the vaporized mobile phase was homogeneously mixed with preheated H; (3) a combustion chamber in which the fuel/sample mixture was mixed with O and pyrolyzed; and (4) a quartz tube (vapors retainer) mounted in the AAS analysis beam. This approach proved to more efficient than conventional flame AAS detection, due to the fact that the H/O flame (1900-2000°C), which pyrolysis mol. interferents to transparent CO2 and water vapors, is positioned remotely from the AAS optical beam. In this configuration, spectral interferences which are usually observed in flame and graphite furnace atomization were essentially eliminated. In flow injection (FI) mode, the response to Cd was linear from the limit of detection (71 pg) to 6 ng. The interface was optimized for the FI anal. of centrifuged mussel extracts, before and after ultrafiltration of the bound-Cd fraction on a 1000 MW cutoff membrane. During FI analyzes of these crude samples, matrix effect reduced the sensitivity by 13.2%, requiring calibration by standards addition Nonspecific absorption signal was not observed In HPLC-AAS mode, matrix effects in Cd-MTs chromatography bands were negligible. Cd-MTs from horse kidneys and mussels were determined with estimated limits of detection of 10^-40 ng (as protein).
Cadmium Mussel Biological tissue Kidney HPLC Spectrophotometry

"Measurement Of Vanadium, Nickel, And Arsenic In Seawater And Urine Reference Materials By Inductively Coupled Plasma Mass Spectrometry With Cryogenic Desolvation"
Anal. Chem. 1993 Volume 65, Issue 18 Pages 2468-2471
Luis C. Alves, Lloyd A. Allen, and R. S. Houk

Abstract: Addition of a small dose (2%) of H2 to the aerosol gas flow enhanced analyte signals by a factor of 2-3, which compensated for the loss of analyte signal that accompanied earlier efforts at cryogenic desolvation with inductively coupled plasma mass spectrometry (ICP-MS). Vanadium, nickel, and arsenic at microgram per liter levels in urine, river, and seawater reference materials were determined. The polyatomic ions ClO+, CaO+, and ArCl+, which normally cause severe overlap interferences for these elements, were attenuated to manageable levels by cryogenic desolvation. The samples were simply diluted with 1% HNO3 so that the chloride could be removed as HCl. The analytical results obtained for these standard reference materials agreed closely with the certified or recommended values. The detection limit ranges (3s) obtained were 10^-1000 ng L-1 for V, 0.03-20 µg L-1 for Ni, and 4-7000 ng L-1 for As in the original samples. The samples were introduced by flow injection to minimize clogging of the sampling orifice.
Vanadium Nickel Arsenic Sea Urine River Mass spectrometry

"Injection Techniques In Capillary GC"
Anal. Chem. 1994 Volume 66, Issue 20 Pages 1009A-1019A
Konrad Grob

Abstract: Capillary GC is in danger of stagnating and degenerating unless reliable injection methods are developed. Since capillary GC was first developed, problems associated with injection have given the technique a reputation for producing unsatisfactory quantitative results. Unfortunately, injector systems have still not improved, despite the evolution of GC instruments. The main problems with sample injection in capillary GC systems involve separation of sample liquid from the needle, sample evaporation in the needle, solvent and solute evaporation, expansion of sample vapors, sample transfer in splitless injection, and solute reconcentration. The problems associated with flow injection analysis may be resolved by using larger sample volumes, selective sample introduction, and coupled techniques. Although these areas present scope for improvement, there appears to be no serious effort to understand or solve the problems associated with injectors.
GC

"Liquid-interfaced Oscillating Glow Discharge Detector For A Flowing Liquid System"
Anal. Chem. 1995 Volume 67, Issue 5 Pages 878-884
Christopher J. Herring and Edward H. Piepmeier

Abstract: A new liquid-interfaced oscillating glow discharge detector having a frequency and current response to femtomole and picomole quantities respectively of potassium nitrate and sucrose injected into an aqueous flowing eluent is presented. The glow discharge is formed in an argon atmosphere at ambient pressure between a platinum anode and a cathode consisting of an aqueous conducting solution. A detailed description of the appearance of the liquid-interfaced glow discharge at various electrode distances and the occurrence of high-frequency oscillations is given. Copyright 1995, American Chemical Society.
Potassium Sucrose Spectrophotometry

"Evaluation Of Mass Spectrometric Methods Applicable To The Direct Analysis Of Non-peptide Bead-bound Combinatorial Libraries"
Anal. Chem. 1996 Volume 68, Issue 2 Pages 237-242
C. L. Brummel, J. C. Vickerman, S. A. Carr, M. E. Hemling, G. D. Roberts, W. Johnson, J. Weinstock, D. Gaitanopoulos, S. J. Benkovic, and N. Winograd

Abstract: A model angiotensin II receptor antagonist acid (preparation details given) was attached to 50 µm Sasrin polystyrene beads using dicyclohexylcarbodi-imide as coupling agent. A single bead was exposed to 1% TFA in CH2Cl2 for 15 min, the solution dried and the residue extracted with 10 µL acetonitrile. A 1 µL portion was introduced by flow injection microspray, into a triple quadrupole MS (Perkin-Elmer Sciex, Thornhill, ON, Canada) for molecular mass analysis using electrospray ionization (ESI) mode and tandem MS operating with collision-induced dissociation procedures (operating details given) for structural information. For MALDI MS, a single bead was placed on a stainless steel substrate and the target molecule was removed by exposure to 3 µL 1% TFA in CH2Cl2 and activated with 0.5 µL 2,5-dihydroxybenzoic acid in acetone. Structural information was obtained by analysis of metastable ions formed in the field-free drift region of the TOF analyzer (operating conditions given). TOF SIMS measurements were made with a single bead on a Si wafer, saturated with CH2Cl2 and TFA vapors in equilibrium with 15% TFA in CH2Cl2, for 2 h. The wafer was transferred to a Kratos Prism TOF mass spectrometer (Kratos, Manchester, UK) and the secondary ions produced extracted at 7.2 keV into a reflectron TOF analyzer.. Each procedure appears to offer a viable screening strategy of non-peptide libraries without the need for additional molecular tags.
Mass spectrometry

"Eluent Jet Interface For Combining Capillary Liquid Flows With Electron-impact Mass-spectrometry"
Anal. Chem. 1996 Volume 68, Issue 4 Pages 675-681
Charles E. Kientz, Albert G. Hulst, Ad L. De Jong, and Eric R. J. Wils

Abstract: A new interface based on an eluent jet in combination with a conventional gas chromatography momentum separator for use with electron impact mass spectrometry is described. The formation of the eluent jet is based on radio frequency inductive heating. The aerosol formation in the; interface is discussed in relation to commercial particle beam (PB) interfaces. The interface is tested in combination with electron impact mass spectrometry using flow injection analysis at now rates in the range of 5-15 µL/min commonly encountered in microcolumn liquid chromatography. Electron impact spectra at 1-10 ng levels are found to be comparable with reference spectra. In the single-ion mode, 50 pg of caffeine is detectable with a signal-to-noise ratio of 3:1. Contrary to many other PB systems, linear calibration plots are obtained in the tested range of 3-200 ng of caffeine.
Caffeine GC Mass spectrometry

"Determination Of Lead In Copper-based Alloys Using A Modified Quartz Atom Trap And Flow Injection Flame Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1989 Volume 335, Issue 6 Pages 566-567
D. Thorburn Burns, N. Chimpalee and M. Harriott

Abstract: Copper alloy (0.1 to 0.5 g) is dissolved in 4 mL of concentrated HCl and 2 mL of concentrated HNO3 and the solution is diluted to 100 mL with water. A 250 µL aliquot of solution is injected into a flow of water (7.2 mL min-1) via a mixing coil (10 cm x 0.8 mm) into the described apparatus (Anal. Abstr., 1989, 51, 1B96) and aspirated at 6.9 mL min-1 into an air - acetylene flame; the absorbance is measured at 283.3 nm. The calibration graph is rectilinear up to 10 µg mL-1 of Pb. No interference is observed. The method is less sensitive (detection limit 0.13 vs. 0.09 µg mL-1) than the conventional direct aspiration method, but is faster (200 vs. 50 samples h-1), the life of the quartz tube atom trap is extended, and the necessity of cleaning of the trap is reduced.
Lead Alloy Spectrophotometry

"Flow Injection Analysis. A Useful Alternative For Solving Analytical Problems"
Fresenius J. Anal. Chem. 1990 Volume 337, Issue 6 Pages 662-666
M. Valc&aacute;rcel and M. D. Luque de Castro

Abstract: This review includes the consideration of flow injection analysis (FIA) as an interface (with, e.g., spectrometry), and a range of problems that can be solved by FIA, e.g., broadening the analyte concentration. range in routine control, removal of matrix interference, and direct analysis of heterogeneous samples. (45 references).

"Determination Of Six Arsenic Species By High Performance Liquid Chromatography-hydride Generation-atomic Absorption Spectrometry With Online Thermo-oxidation"
Fresenius J. Anal. Chem. 1993 Volume 346, Issue 6-9 Pages 643-647
M. A. L&oacute;pez, M. M. G&oacute;mez, M. A. Palacios and C. C&aacute;mara Contact Information

Abstract: Anion-exchange HPLC has been coupled to online thermo-oxidation and hydride generation-atomic absorption spectrometry (HG-AAS) for the speciation of As(V), As(III), MMA, DMA, AsB and AsC. The thermoreactor consists of a loop of PTFE tubing dipped in a powdered-graphite oven heated to + 140°C. Samples and persulfate solution run together into the thermo-reactor. The thermo-oxidation conditions were optimized using a FIA system. The chromatographic and chemical parameters affecting hydride generation efficiency were optimized. The overlap of the As(III) and AsB peaks made it necessary to determine AsB as the difference between absorbance in the presence and in the absence of thermo-oxidation. The thermo-conversion efficiencies were above 96%. Recoveries were around 100% and detection limits below 1 ng. The proposed method is rapid, sensitive and precise (RSD about 5%), making it suitable for online determination in environmental samples.
Arsenic(3+) Arsenic(5+) Arsenoβine Monomethylarsine Dimethylarsenic Arsenocholine Environmental HPLC Spectrophotometry

"Coupling Continuous-flow Systems To Instruments Based On Discrete Sample Introduction"
Fresenius J. Anal. Chem. 1998 Volume 362, Issue 1 Pages 58-66
M. Valc&aacute;rcel, Mercedes Gallego, Angel R&iacute;os

Abstract: The interfaces between low-pressure continuous sample treatment systems and high-level information instruments such as gas chromatographs, capillary electrophoresis equipment and graphite furnace atomic spectroscopic instruments, which are characterized by conventional discrete sample introduction devices, are presented. The present and future developments are discussed of (directly) linking real samples and those analytical equipments with the main objective of avoiding or minimizing manually implemented preliminary operations of the analytical process
GC Electrophoresis Spectrophotometry

"Some Observations On The Sensitivity Of Flow Injection Techniques For Atomic Absorption Spectrophotometry"
Microchem. J. 1989 Volume 40, Issue 2 Pages 233-241
Carbonell, V.;De La Guardia, M.;Salvador, A.;Burguera, J.L.;Burguera, M.

Abstract: Means of improving sensitivity of flow injection AAS systems are discussed, including use of T-connector interfaces, different carriers and flow compensation solvents. The optimized system was applied in the determination of Mn and Cu in sewage sludge.
Copper Manganese Sludge Spectrophotometry

"Online Multielement Preconcentration And Inductively Coupled Plasma Atomic Emission Spectrometric Determination Of Transition Metals Using A Flow Injection Hydraulic High-pressure Nebulization-desolvation Sample Introduction System"
Microchem. J. 1998 Volume 58, Issue 3 Pages 245-250
Attila G&aacute;sp&aacute;r, J&oacute;zsef Posta, Mih&aacute;ly Braun and Csilla S&oacute;gor

Abstract: A method was developed for simultaneous pre-concentration and online determination of 15 transition metals (Ag, Au, Cd, Cr, Cu, Fe, In, Ni, Pb, Pd, Pt, Ti, Tl, V, Zn). A polyether-ether-ketone (PEEK) loop as pre-concentration unit introduced by the authors earlier was used for the multielement flow injection (FI) pre-concentration of transition metal-pyrrolidinedithiocarbamate complexes. The pre-concentrated complexes were eluted with iso-Bu Me ketone and introduced into the inductively coupled plasma with a hydraulic high-pressure nebulizer (HHPN) and desolvation unit. The desolvation system, the use of which was necessary for aerosol of iso-Bu Me ketone eluant, was optimized. The enrichment factors of the 15 transition metals were 14-67 due to 2 min of pre-concentration time.
Metals, transition Silver Gold Cadmium Chromium Copper Iron Indium Nickel Lead Palladium Platinum Titanium Thallium Vanadium Zinc Spectrophotometry

"Flame Atomic Absorption Spectrometric Determination Of Total Chromium And Chromium(VI) In Cigarette Ash And Smoke Using Flow Injection/hydraulic High-pressure Sample Introduction"
Microchem. J. 1998 Volume 58, Issue 3 Pages 251-255
Csilla S&oacute;gor, Attila G&aacute;sp&aacute;r and J&oacute;zsef Posta

Abstract: Total chromium and Cr(VI) contents of cigarets, ash, and smoke formed while burning cigarets were determined The determinations of chromium species were carried out according to procedures developed earlier. Cr(VI) was determined in a combined system, which involves a flow injection (FI) sorption pre-concentration system, hydraulic high-pressure nebulization (HHPN) sample introduction technique, and flame atomic absorption spectrometric (FAAS) detection. The total chromium of samples in Cr(VI) form was determined in this same combined system after ashing cigarets at 800°C [after total conversion of Cr(III) of the sample to Cr(VI)]. It was found that while burning cigarets 0.8-1.2% of the original chromium content of the cigarets comes to smoke in the toxic Cr(VI) form.
Chromium(VI) Chromium, total Smoke Ash Spectrophotometry

"Immobilization Of Linamarase And Its Use In The Determination Of Bound Cyanide In Cassava Using Flow Injection Analysis"
Anal. Biochem. 1988 Volume 172, Issue 1 Pages 89-95
D. Narinesingh*, D. Jaipersad and I. Chang-Yen

Abstract: β-Glucosidase was immobilized (details given) on 2-fluoro-N-methylpyridinium-activated Fractogel support; the gel was washed and packed in nylon columns (5 cm x 2 mm) for use in flow injection analysis. Cassava leaves or tubers were extracted with H3PO4, the extracts were filtered under vacuum and the filtrates were adjusted to pH 7.2 with 1 M NaOH and centrifuged at 3000 rpm for 5 min. Portions (90 µl) of the supernatant solution were injected into the flow injection system, at 30°, and passed (0.33 mL min-1) into the reactor column, or a blank column to correct for free CN-. The solution were then mixed with picrate reagent of pH 10.8 and passed through a coil at 85°C and the absorbance of the complex formed was measured at 525 nm. The calibration graph was rectilinear, for both free CN- and CN- liberated from linamarin, from 1 to 10 mM; the detection limit was 67 ppm. Interference from glucose and acetone was negligible. Extracts from the tubers (cortex and parenchyma) and leaves of Manihot esculenta Crantz (cassava) were analyzed for their releasable cyanide content using flow injection analysis incorporating an immobilized linamarase bioreactor. Linamarase was immobilized under very mild conditions to an activated 2-fluoro-N-methylpyridinium Fractogel support. The released cyanide, which was monitored spectrophotometrically at 525 nm using an alkaline picrate reagent, was found to be highest in the cortex and lowest in the parenchyma.
Cyanide Leaves Tubers Sample preparation Spectrophotometry

"Metalloprotein Separation And Analysis By Directly Coupled Size Exclusion High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectroscopy"
Anal. Biochem. 1990 Volume 186, Issue 2 Pages 187-201
A. Z. Mason*, S. D. Storms and K. D. Jenkins

Abstract: The feasibility of using directly coupled size exclusion high performance liquid chromatography inductively coupled plasma mass spectroscopy (HPLC/ICP-MS) for the separation and subsequent elemental analysis of metalloproteins in biological samples has been studied. Data, on up to eight elements, was acquired simultaneously and the reconstructed elemental profiles from the chromatographed samples were quantified by flow injection analysis. Absolute and relative detection limits, reproducibility, operational dynamic range, and linearity of response were initially evaluated by analyzing standards of metallothionein protein of known elemental composition for Cd, Zn, and Cu. There was evidence of displacement of Zn from the protein during chromatography and the substitution of Cu sequestered from the mobile phase. Cd associated with the protein was fully recovered during chromatography. Memory effects, due to protein adsorption to the glassware in the torch box, were minimal and there was no degradation of the resolution of the chromatographed peak during extended transport through the HPLC/ICP-MS interface. The versatility of the technique has been demonstrated by the quantitative multi-element analysis of cytosolic metal-binding proteins separated from the polychaete worm Neanthes arenaceodentata. Fidelity of analysis has been demonstrated by two independent procedures: first, by comparing the elemental profiles obtained by directly aspirating the HPLC eluant into the ICP-MS to those obtained by collecting fractions and quantifying the metal content of the proteins in the conventional analytical mode; second, by comparing the stable isotopic profiles for 114Cd obtained by simultaneous ICP-MS analysis with radiometric profiles of 109Cd obtained by counting radioactivity associated with collected fractions.(ABSTRACT TRUNCATED AT 250 WORDS)
Proteins, metallo Mass spectrometry HPLC

"Continuous Separation Techniques In Flow Injection Analysis. A Review"
J. Chromatogr. A 1987 Volume 393, Issue 1 Pages 3-23
Miguel Valcarcel and M. Dolores Luque De Castro

Abstract: A review is presented of gas - liquid, liquid - liquid and liquid - solid separation techniques, and their applications in flow injection analysis. Particular attention is paid to the online coupling of HPLC and flow injection analysis. Examples are given. (122 references).
Spectrophotometry

"Belt-speed Programming, A New Technique For Peak Compression In Liquid Chromatography - Mass Spectrometry And Supercritical-fluid Chromatography - Mass Spectrometry With Moving-belt Interfaces"
J. Chromatogr. A 1989 Volume 474, Issue 1 Pages 275-283
E. R. Verheij, G. F. La Vos, W. M. A. Niessen and U. R. Tjaden, J. van der Greef

Abstract: Belt-speed programming was applied for peak compression and to increase the analyte mass flow into the mass spectrometer. HPLC was carried out in flow injection mode without a chromatographic column. The mobile phase was methanol (0.2 mL min-1) with cholesterol as the test compound. SFC was carried out on a column (15 cm x 4.6 mm) of Rosil C18 (8 µm) with a mobile phase (2 mL min-1) of CO2 containing 2% of methanol. Diuron was used as a test compound. The belt speed was regulated between 1.0 and 4.5 cm s-1, and the spectrometer was used in the EI mode (70 eV). Sensitivity was improved.
Cholesterol Mass spectrometry SFC HPLC

"High Performance Liquid Chromatography - Time-of-flight Mass Spectrometry And Its Application To Peptide Analyses"
J. Chromatogr. A 1991 Volume 536, Issue 1-2 Pages 143-153
Richard C. Simpson, W. Bart Emary, Ihor Lys and Robert J. Cotter, Catherine C. Fenselau

Abstract: A continuous-flow probe described by Chen and Cotter (Anal. Abstr., 1989, 51, 5J115) was modified, employing a metal solder seal around the fused-silica capillary at the outlet tip (maintained at 40°C to 60°C) to provide better electrical and thermal conductivity. The probe was used as an interface to couple the HPLC column (20 cm x 0.2 mm) with a mobile phase (1 µL min-1) of 28% acetonitrile - glycerol - trifluoroacetic acid (89.9:10:0.1) to a time-of-flight mass spectrometer. Chromatograms and mass spectra are presented for the analysis of peptides.
Peptides HPLC Mass spectrometry

"Polar, Hydrophilic Compounds In Drinking Water Produced From Surface Water. Determination By Liquid Chromatography - Mass Spectrometry"
J. Chromatogr. A 1991 Volume 554, Issue 1-2 Pages 251-266
H. Fr. Schr&ouml;der

Abstract: Samples from waste water treatment-plants, surface waters and drinking water treatment plants were solid-phase extracted (details given) and the cited compounds were detected and identified by LC - tandem MS coupled online by a thermospray interface (details given). After identification, quantification by direct mixture analysis by the system without derivatization and separation, was possible with the availability of standards and with use of flow-injection analysis (details given). Use of GC - MS (described) was only useful for detection of volatile compounds.
Organics, polar Water Surface Waste LC Mass spectrometry Sample preparation

"Online Continuous-flow Dialysis Thermospray Tandem Mass Spectrometry For Quantitative Screening Of Drugs In Plasma: Rogletimide"
J. Chromatogr. A 1992 Volume 598, Issue 2 Pages 189-194
E. van Bakergem, R. A. M. van der Hoeven, W. M. A. Niessen*, U. R. Tjaden and J. van der Greef, G. K. Poon and R. McCague

Abstract: Plasma (1.26 ml) was introduced into a water air-segmented donor stream (0.42 mL min-1) and passed through a dialysis membrane into a non-segmented water stream (0.6 mL min-1). The acceptor stream was concentrated on a column (12 x 2 mm) of Polysil C8 (63 µm). The trapping column was subsequently desorbed for online separation of rogletimide (I) by HPLC on a column (10 cm x 4.6 mm) of Nucleosil C8 (5 µm) with a mobile phase of 30% methanol in 100 mM ammonium acetate and MS or MS - MS detection. Gluthetimide was used as an internal standard. The calibration graph was rectilinear from 5 (determination limit) to 360 ng mL-1 of I and the coefficient of variation was 5.2% (n = 5) at the 100 ng mg-1 level. The application of a continuous-flow dialysis system, consisting of a membrane dialyzer and a trace enrichment column, in online combination with tandem mass spectrometry via a thermospray interface is described. The method is applied to the quantitation of drugs in complex biological matrixes containing macromol. interferences. The potential of the method is demonstrated by the quant. anal. of the anti-cancer drug rogletimide in the plasma of patients after treatment.
Rogletimide Blood Plasma Mass spectrometry

"Liquid Chromatography-mass Spectrometry In The Pharmaceutical Industry: Objectives And Needs"
J. Chromatogr. A 1982 Volume 251, Issue 2 Pages 141-151
F. Erni

Abstract: The role of liquid chromatography-mass spectrometry (LC-MS) in the analysis of drugs is discussed. The main fields of application are thermally labile compounds, compounds with low volatility and compounds with rather high molecular weights, all of which are not generally suitable for analysis by combined gas chromatography-mass spectrometry. The objectives, needs, limitations and abilities of LC-MS for the analysis of by-products, degradation products, traces of drug substances for pharmacokinetic studies and metabolites in complex matrices are presented. The LC-MS coupling is discussed as a sophisticated LC detector for sensitive and selective quantitative determinations or as an online sample-introduction system for the mass spectrometer to obtain structural information for identification or structural elucidation. LC-MS combined with a flow-switching technique can be used for the analysis of mixtures containing large amounts of components which otherwise would be detrimental to the LC-MS technique. With flow injection techniques the LC-MS interface is used as a sample-introduction system with possibilities for sample preparation, sample clean-up and chemical derivatization.
Drugs Pharmaceutical HPLC Mass spectrometry

"Rapid Analysis Of β-agonists In Urine By Thermospray Tandem Mass Spectrometry"
J. Chromatogr. A 1995 Volume 712, Issue 1 Pages 67-73
J. A. van Rhijn, M. O'Keeffe, H. H. Heskamp and S. Collins

Abstract: A method is described for the analysis of β-agonists in urine of cattle. The method uses solid-phase extraction (SPE), followed by analysis of the resulting extract by flow injection thermospray tandem mass spectrometry (TSP-MS-MS). Sample preparation is performed using a mixed-bed SPE procedure using a sorbent having both hydrophobic and ionic properties. MS-MS analysis following thermospray ionization, is performed in single-reaction monitoring parent mode. In that way isotope dilution can be used for quantitation of clenbuterol. Data are presented on precision and accuracy for clenbuterol and related compounds. Furthermore, data acquisition was performed in full-scan neutral loss mode to indicate the suitability of flow injection analysis (FIA)-TSP-MS-MS for exploratory analysis. Detection of β- agonists in this mode is based on the presence of the N-tert.-butyl- β-ethanolamino moiety and, in that respect, detection of known as well as unknown compounds having this moiety will take place. This feature is exemplified by the analysis of samples containing several compounds.
Clenbuterol Urine Mass spectrometry Sample preparation

"Automated Microanalysis Using Magnetic Beads With Commercial Capillary Electrophoretic Instrumentation"
J. Chromatogr. A 1997 Volume 781, Issue 1-2 Pages 197-204
Leonid G. Rashkovetsky, Yelena V. Lyubarskaya, Frantisek Foret, Dallas E. Hughes and Barry L. Karger*

Abstract: The potential of a new microanalytical method using magnetic beads (MBs) and commercial capillary electrophoresis (CE) instrumentation for performing enzymatic and inhibition assays, as well as for analysis of biological molecules such as antigens, substrates, etc., has been explored. A small quantity of magnetic beads containing immobilized biomolecules was injected into a neutral hydrophilic-coated fused-silica capillary. The short plug (2-3 mm) of beads was held fixed by a magnet placed in the cartridge of the CE system, without the use of frits. The beads could be replaced after each run, eliminating the need to regenerate the solid support. Two protocols were used for analysis: sequential injection (SI) and SI followed by isotachophoretic (ITP) focusing. Alkaline phosphatase (AP) and HIV-protease were used to demonstrate the SI procedure for enzymatic and inhibition assays. The second protocol, SI/ITP, was employed to quantitate an antigen (mouse mAB) using antibodies (sheep IgG towards mouse AB) immobilized on the beads. The MB-CE method, requiring only femtomole (fmol) quantities of material, can potentially be employed in diagnostic and forensic assays, kinetic studies and searching for inhibitors, ligands, receptors, etc.
Enzyme, alkaline phosphatase Enzyme, alkaline protease, HIV Antigen, mAB, mouse Blood Electrophoresis

"Gradient Elution Electrochromatography With A Flow Injection Analysis Interface"
J. Chromatogr. A 1998 Volume 828, Issue 1-2 Pages 105-112
Ashley S. Lister, Catherine A. Rimmer and John G. Dorsey*

Abstract: A flow injection anal.-capillary electrochromatography interface was used for gradient elution capillary electrochromatography giving purely electroosmotic flow through the anal. column. Solvent gradients were generated with a micro-LC system connected to the interface. Injections were carried out online using an inert rotary LC valve controlled by an elec. actuator. Gradient shape was measured from acetonitrile (5% acetone)-water (50:50, v/v) to (100:0) in open tubular experiments When compared to conventional instrumentation, peak tailing and peak width increased slightly using the interface. A test mixture of nine solutes was evaluated in isocratic and gradient elution modes. Using the interface, a gradient of MeCN-water (60:40) to (90:10) provided baseline separation of all nine solutes in under 18 min with good band spacing. Reproducibility of retention times in eight replicate injections is better than 2% relative standard deviation for all solutes. This interface also allows use of autoinjectors and dramatically lessens movement of the packed column, improving column lifetime.
ECC

"Automation Of Pharmaceutical Dissolution Testing By Flow Injection Analysis"
J. Pharm. Biomed. Anal. 1990 Volume 8, Issue 4 Pages 329-336
M. D. Luque de Castro and M. Valc&aacute;rcel

Abstract: The different types of instruments used for monitoring pharmaceutical dissolution testing are presented. Their features and the need for automation are critically discussed. The advantages of flow injection analysis in this respect are illustrated by a variety of examples clearly showing its adaptability to the different problems posed by other automatic and non-automatic alternatives. Existing instruments for monitoring dissolution testing of pharmaceuticals are discussed with particular reference to the need for automation. The application of flow injection analysis to interface between dissolution vessels and analytical instruments is described.
Pharmaceutical

"Dispersion Of Discrete Sample Signals Within Aerosol Spray Chambers: Preliminary Investigations"
Spectrochim. Acta B 1996 Volume 51, Issue 14 Pages 1733-1745
John A. Koropchak*, Salma Sadain and Bogdan Szostek

Abstract: A cylindrical glass spray chamber (14.8 cm x 3.1 cm i.d.) ed a three-plate (separation 1.2 cm) polypropylene baffle gave aerosol particle sizes that were generally too large for diffusion to influence band broadening to an extent that would be significant in mass-senve systems, e.g., flow injection ICP-AES, but such diffusion as did occur would probably be important in particle-number-sensitive detectors. A barrel-type spray chamber with a baffle system and various other structures were used for characterization of band-broadening phenomena occurring within aerosol spray chambers, with an ICP-AES detector used in this case. Absolute values of aerosol particle size distributions from nebulizer/spray chamber systems were measured and found to be affected by the relative positions of impact surfaces with respect to the nebulizer. Smaller particles, but less total mass was observed as the baffle was moved closer to the nebulizer tip. However, based on measurements herein, it does not appear that particle sizes in any case will be small enough within the spray chamber for diffusion to influence band broadening for the bulk of the aerosol mass, as particularly important for mass sensitive detectors such as ICP-AES, although diffusion is likely to be important to particle number sensitive detectors. 26 References
Spectrophotometry

"Characterization Of An Interface For Sample Introduction Into An Inductively Coupled Plasma"
Spectrochim. Acta B 1987 Volume 42, Issue 1-2 Pages 111-118
Anders Gustavsson

Abstract: The interface, which is suitable for connecting an ICP as a concentration.-sensitive detector in HPLC or flow injection analysis, consists of a glass Meinhard concentric nebulizer, a heated aerosol-desolvation chamber, and a jet separator to remove most of the solvent vapor and nebulization gas. Analyte transport efficiencies of ~35% can be attained, with much enhanced aerosol analyte concentration. at acceptable plasma solvent loads by comparison with conventional nebulization systems.
Spectrophotometry

"Flow Injection Thermospray Sample Deposition For Electrothermal-atomization Atomic Absorption Spectrometry"
Spectrochim. Acta B 1988 Volume 43, Issue 8 Pages 983-987
P. C. Bank, M. T. C. De Loos-Vollebregt and L. De Galan

Abstract: Details (with diagram) are given of a system for flow injection of a sample (10 µL) into a thermospray vaporizer for introduction into a pre-heated pyrolytically coated graphite tube furnace. AAS is carried out with deuterium background correction. The characteristic mass for V with peak height measurement is 23 pg, compared with 34 pg by auto-sampling Zeeman AAS; reproducibilities of introduction in the two systems are similar. Sensitivity falls with increasing furnace temperature (>150°C) during deposition, but this problem can be ameliorated by injecting a larger volume, and furnace cycle time is reduced (to, e.g., ~20 s).
Vanadium Ion exchange Spectrophotometry

"Characterization Of A Membrane Interface For Sample Introduction Into Atom Reservoirs For Analytical Atomic Spectrometry"
Spectrochim. Acta B 1988 Volume 43, Issue 8 Pages 917-922
Anders Gustavsson

Abstract: Details are given of an interface, comprising a Meinhard concentric glass nebulizer, an aerosol chamber (Ibid., 1987, 42B, 111) and a separator incorporating silicone rubber membranes (5 µm) supported on polyethylene, for removal of organic solvent from solution before spectrometric analysis. Solvent removal efficiencies for CHCl3 and 1,1,2-trichlorotrifluoroethane at Ar gas flow rates of 0.5 and 1.0 l min-1 ranged from 97.7 to 99.9% and from 79.4 to 94.1%, respectively, at a separator temperature of 20°C. The separator is of particular value for ICP techniques, and can be used to interface flow injection analysis or HPLC with, e.g., AAS or MS.
Spectrophotometry Spectrophotometry

"Flow Injection Thermospray Sample Deposition For Electrothermal-atomization Atomic Absorption Spectrometry"
Spectrochim. Acta B 1989 Volume 44, Issue 6 Pages 571-579
P. C. Bank, M. T. C. de Loos-Vollebregt and L. de Galan

Abstract: The flow injection thermospray introduction system described previously (Ibid., 1988, 43B, 983) has been modified to obtain more reproducible sample deposition on to the wall of a graphite-tube atomizer. Under optimum conditions, viz, a sample flow rate of 0.7 mL min-1, a thermospray vaporizer temperature of 300°C and a deposition temperature of 120°C in the graphite tube, the sensitivities for Ag, Al, As, Au, Cd, Co, Mn, Pb, Ru and V were identical with those obtained by conventional graphite-furnace AAS. The area of spray-deposited material formed on the wall of the graphite tube is independent of sample volume (unlike conventional manual injection), and thus the flow injection thermospray system can be used over wide analytical ranges. Solutions containing up to 2% of NaCl could be injected without plugging of the thermospray vaporizer capillary.
Aluminum Arsenic Gold Cadmium Cobalt Manganese Lead Rubidium Silver Vanadium Spectrophotometry

"Coupling Of HPLC And ICP-AES For Speciation"
Spectrochim. Acta B 1991 Volume 46, Issue 6-7 Pages 1089-1098
F. Laborda and M. T. C. De Loos-Vollebregt, L. De Galan

Abstract: The cross-flow nebulizer and the thermospray vaporizer can both be used as an interface for coupling high performance liquid chromatography with inductively coupled plasma-atomic emission spectrometry. The dispersion and the peak asymmetry are acceptable for both. With the thermospray system the sensitivity is threefold higher and the fraction of methanol in methanol/water mixtures introduced into the plasma can be as high as 75%, compared with 25% for the cross-flow nebulizer. Initial results obtained for the speciation of selenium in (CH3)3Se+, SeO32- and SeO42- are promising.
HPLC Spectrophotometry

"Characterization Of Aerosols Produced By Pneumatic Nebulizers For Inductively Coupled Plasma Sample Introduction: Effect Of Liquid And Gas Flow Rates On Volume-based Drop-size Distributions"
Spectrochim. Acta B 1995 Volume 50, Issue 4-7 Pages 285-303
John W. Olesik* and Lisa C. Bates

Abstract: The effect of liquid sample uptake rate and nebulizer gas flow rate on analyte transport rates and volume based primary and tertiary drop size distributions were studied for two pneumatic, concentric nebulizers with a Scott type spray chamber. Experimentally measured Sauter mean diameters and spans were compared to those predicted by an empirical model. One of the two nebulizers produced analyte transport rates that were a factor of two or more higher than the other nebulizer under all uptake rate and gas flow rates studied, despite that the nebulizers were of the same model. When the sample uptake rate is increased 400% (from 0.4 to 2.0 ml/min) the aerosol transport rate increased by only 60 to 68%. Losses of aerosol of all drop sizes due to secondary and tertiary processes result in a decrease in the sample transport efficiency as the uptake rate is increased. When the nebulizer gas flow rate was increased from 0.4 to 1.0 l/min the analyte transport rate increased more than a factor of five. The increase in analyte transport rate (and efficiency) as the gas flow rate was increased from 0.4 to 0.6 or 0.7 l/min was due to both a larger volume of small primary aerosol drops produced and less severe losses of drops due to secondary and tertiary processes. The relative increase in volume of small primary aerosol drops produced when the nebulizer gas was increased from 0.6 or 0.7 to 1.0 l/min was similar to the relative increase in analyte transport rate. The higher transport rates produced by one of the two nebulizers was due to a higher production/loss ratio due to secondary and tertiary processes for drops of all sizes less than 20 µm in diameter rather than differences in the volume of primary aerosol contained in small drops.
Mass spectrometry Spectrophotometry

"New Developments In Thermospray Sample Introduction For Atomic Spectrometry"
Spectrochim. Acta B 1997 Volume 52, Issue 8 Pages 1087-1104
Timothy Shawn Conver, Jinfu Yang and John A. Koropchak*

Abstract: The status of thermospray sample introduction for analytical atomic spectrometry was last reviewed in 1992. In this review, we summarize developments in this field since that time, including investigations of aerosol generation processes, noise diagnosis and control with inductively coupled plasma-atomic emission or mass spectrometry (ICP-AES/MS), high flow thermospray, the use of dual-stage desolvation systems based on membrane dryers, and the utilization of thermospray with axially viewed ICP-AES. Since a major advantage of methods based on thermospray is improved limits of detection, the emphasis for applications of thermospray with ICP spectrometries remains focused on environmental sample types, particularly with ICP-MS. Relatedly, the use of thermospray as a means for the direct speciation of Se is also under development. (C) 1997 Elsevier Science B.V. 66 References
Spectrophotometry Mass spectrometry Mass spectrometry

"Analytical Characteristics Of A High Efficiency Ion Transmission Interface (S Mode) Inductively Coupled Plasma Mass Spectrometer For Trace Element Determinations In Geological And Environmental Materials"
Spectrochim. Acta B 1998 Volume 53, Issue 6-8 Pages 1087-1107
I. B. Brenner*, M. Liezers, J. Godfrey, S. Nelms and J. Cantle

Abstract: The analytical performance of a high transmission interface (S mode), inductively coupled plasma-quadrupole mass spectrometer (the VGE Plasma Quad 3) was evaluated for multitrace element analysis of geological and environmental materials. The sensitivity, limits of detection (LODs), effect of Ca and Na and other major elements on mass response, background, percentage 156CeO+/140Ce+, 70Ce++/140Ce+, and long- and short-term variations were compared with those obtained with the conventional mode (normal mode). Normal mode sensitivities varied from 20 MCPS ppm-1 (millions of counts per s per ppm) for 9Be+, 70-80 MCPS ppm-1 for 59Co+, 90 for 115In+ and 40-50 MCPS ppm-1 for the heavy masses. S mode sensitivities were 180 MCPS ppm-1 for 59Co+, 350-380 for 115In+ and 140Ce+, 300 MCPS ppm-1 for 208Pb+, and 150 MCPS ppm-1 for 232Th+ and 238U+, i.e. enhancements amounting to 7. Three s normal and S mode LODs are mainly in the 1-2 and 0.1 ppt range, respectively. S mode LODs are enhanced relative to the normal mode, for masses >80 amu, by factors ranging from ~10 to 50. S mode LODs are depressed relative to normal mode LODs for masses <50 amu by a factor of 10, and the extent of depression is related linearly to mass. In the high- and mid-mass ranges, backgrounds were ~10. They were not affected by sample composition: at 8 amu the S mode background for real samples amounted to ~20, whereas at 220 amu it amounted to four counts. S and normal mode percentage 156CeO+/140Ce++ and percentage Ce++/Ce+ ratios were ~1.5%, and temporal variations were insignificant. The percentage RSDs of normal and S mode Sr+, Ag+ and Pb+ isotope ratios were ~0.1%, with the exception of S mode 208Pb+ and 208Pb+/206Pb+ ratios in the presence of NaCl, which were degraded by a factor of ~2. Normal and S mode long-term variations for continuous aspiration of 0.1% NaCl for periods of up to 13 h were mass dependent, varying from 2.5-4% for 7Li+ and 9Be+ to ~2% for the mid-mass range, increasing slightly to ~3% for high masses. Most of this variation occurred during the 1st 100-150 min of the anal. during cone priming. With compensation, normal and S mode long-term percentage RSDs and drift were reduced to 1-2%. These variations indicate that extended periods of S mode anal. can be conducted without periodic recalibration. A calibration procedure, based on spiked HNO3, was validated by analyzing spiked NaCl solutions, standard water and geological standard reference material (SRM) solutions with internal standardization using conventional solution delivery and flow injection. The agreement of the S mode data and the certified and literature values for ultratrace elements, including ppt levels of rare earth elements in the water standards, was satisfactory. An important conclusion is that ion sampling effects in the S mode are minimal and that the enhanced ion transmission interface is not only beneficial for microanalysis using laser ablation, but for geological and environmental type solutions as well. Sensitivity enhancements were preserved and matrix effects were approximately ±20% for solutions containing 0.1-0.2% total dissolved salt concentration. These variations were reduced to <5% with internal standards matched in mass and ionization potential.
Metals, rare earth Environmental Geological Mass spectrometry

"Recent Developments In Flow Injection Atomic Spectroscopy"
Adv. At. Spectrosc. 1998 Volume 4, Issue 1 Pages 177-212
M.D. Luque de Castro, L. G&aacute;miz-Gracia

Abstract: A review, with many refs., is given on the main types of flow injection atomic spectroscopy couplings, namely: flow injection atomic absorption spectrometry, which is the most widely used type of atomic spectroscopic assembly; flow injection flame emission spectroscopy; flow injection atomic fluorescence spectroscopy; and flow injection inductively coupled plasma atomic emission spectroscopy. Special emphasis is placed on new instrument devices, coupling with other techniques and the use of flow injection to improve existing atomic methods.
Spectrophotometry Spectrophotometry Spectrophotometry Fluorescence Spectrophotometry

"Hyphenation Of Sequential- And Flow Injection Analysis With FTIR-spectroscopy For Chemical Analysis In Aqueous Solutions"
AIP Conf. Proc. 1998 Volume 430, Issue 1 Pages 403-406
B. Lendl, R. Schindler, and R. Kellner

Abstract: A survey of the principles of sequential (SIA)- and flow injection analysis (FIA) systems with FTIR spectroscopic detection is presented to introduce these hyphenations as powerful techniques for performing chemical anal. in aqueous solution The strength of FIA/SIA-FTIR systems lies in the possibility to perform highly reproducible and automated sample manipulations such as sample clean-up and/or chemical reactions prior to spectrum acquisition. It is shown that the hyphenation of FIA/SIA systems with an FTIR spectrometer enhances the problem solving capabilities of the FTIR spectrometer as also parameters which can not be measured directly (e.g. enzyme activities) can be determined On the other hand application of FTIR spectroscopic detection in FIA or SIA is also of advantage as it allows to shorten conventional anal. procedures (e.g. sucrose or phosphate anal.) or to establish and apply a multivariate calibration model for simultaneous determinations (e.g. glucose, fructose and sucrose anal.). In addition to these examples two recent instrumental developments in miniaturized FIA/SIA-FTIR systems, a µ-Flow through cell based on IR fiber optics and a micromachined SI-enzyme reactor are presented in this paper.
Sucrose Phosphate Glucose Fructose Sucrose Spectrophotometry

"Thermospray Liquid Chromatography - Mass Spectrometry Of Polar β-blocking Drugs: Preliminary Results"
Biol. Mass Spectrom. 1991 Volume 20, Issue 10 Pages 647-649
M. S. Leloux, W. M. A. Niessen, R. A. M. van der Hoeven

Abstract: The influence of either vaporizer temperature (90 to 120°C) or repeller potential on analyte signals and mass spectra of five β-blocking drugs was investigated by delivering the compounds (200 ng) to a thermospray interface to a triple quadrupole mass spectrometer using flow injection analysis in a stream (1.2 mL min-1) of methanol - 50 mM ammonium acetate (1:1) adjusted to pH 3.0 with formic acid. The fragmentation patterns were strongly dependent on the instrumental parameters which were optimized at 100°C and 50 V for vaporizer temperature and repeller potential, respectively. For LC - MS studies aqueous solution of atenolol (0.2 to 200 ng) and propafenone (200 ng), used as internal standard, were delivered to the interface by HPLC on a column (10 cm) packed with Nova-Pak CN-HP (4 µm) and operated with the same mobile phase but in the ratio 2:3. Absolute detection limits for atenolol were 0.2 ng using selected ion monitoring of m/e 267 or 2 ng for full-scan analysis. The calibration curve was rectilinear over the range 0.2 to 200 ng and the coefficient of variation (n = 8) for the injection of propafenone was 9.6%. Acebutolol, administered orally to subjects, was detected in urine together with its major metabolite diacetolol.
Drugs Urine HPLC Mass spectrometry

"Determination Of Pyrimidine Cyclobutane Dimers By Electrospray Ionization - Ion Trap Mass Spectrometry"
Biol. Mass Spectrom. 1992 Volume 21, Issue 7 Pages 347-352
R. S. Ramsey, G. J. van Berkel, S. A. McLuckey, G. L. Glish

Abstract: The dimers uracil - uracil (I), uracil - thymine (II) and thymine - thymine (III), which are photoproducts of UV-exposed DNA, were detected as the sodiated molecules. Sample solution were introduced either by continuous infusion at 0.5 to 5 µL min-1 to a stainless-steel electrospray (ES) needle, by flow injection of a 0.5 µL fixed volume or by a pneumatically assisted sheath-flow system. Positive ion ES ion-trap MS was performed using aqueous 80% methanol containing 100 µM-Na citrate as ES solution The Na+ maximized the response of the protonated species. The detection limits were 0.2 ng (0.4 µg mL-1) of III and 0.3 ng (0.6 µg mL-1) of I and II. The technique was sufficiently sensitive to detect one dimer per 105 nucleobases in 20 to 30 µg of DNA exposed to low UV fluences. Structural information was obtained by collision-induced dissociation of the adducts formed by adding Li salts to the ES solution
Thymine-thymine Thymine-uracil Uracil-uracil Mass spectrometry

"Combination Of Liquid Chromatography With Mass Spectrometry"
Chem. Labor Betr. 1990 Volume 41, Issue 3 Pages 125-133
Linscheid, M.

Abstract: A review is presented, with 41 references, which includes a discussion on direct-liquid-introduction, moving-belt interfaces, thermospray coupling, monodisperse aerosol generator-based interfaces, atmospheric-ionization, electrospray techniques, flow injection and micro-HPLC.
LC Mass spectrometry HPLC

"Use Of A Flow Injection Sample Manipulator As An Interface Between A High-Performance Liquid Chromatograph And An Atomic Absorption Spectrophotometer"
Clin. Chem. 1981 Volume 27, Issue 9 Pages 1546-1550
BW Renoe, CE Shideler and J Savory

Abstract: We describe an integrated, molecular-absorbance, atomic absorption instrument for studying metal/ligand binding in clinical samples. For an interface between the 'high performance' liquid chromatograph and the atomic absorption instrument we used a flow injection sample manipulator, thus allowing both the chromatograph and the atomic absorption detector to operate at their separate optimum conditions. After specimen separation with a gel permeation column, we measured the molecular components of the column eluate by molecular absorbance spectrometry and the atomic components (calcium and magnesium) by flame atomic absorption spectrophotometry. This instrument system is capable of separating and analyzing multiple components within 20 min of injection of the sample on the column. The chromatograms presented demonstrate the utility of the system for investigating metal binding to a variety of ligands in clinical samples.
Calcium Magnesium Biological material Clinical analysis Spectrophotometry HPLC

"Coupling Continuous Sample Treatment Systems To Capillary Electrophoresis"
Crit. Rev. Anal. Chem. 1998 Volume 28, Issue 1 Pages 63-81
Miguel V&aacute;lcarcel, Angel R&iacute;os, Lourdes Arce

Abstract: The state of the art and prospects for the combined use of continuous sample treatment systems and custom-made and commercially available capillary electrophoresis equipment is presented and discussed. Sample treatment in this separation technique is of great practical relevance by virtue of its inherent shortcomings, which include low sensitivity, small sample volumes, and a marked influence of matrix components. The main technical types of coupling (in-line, on-line, and mixed) are dealt with systematically and compared to manually implemented approaches in order to derive practical conclusions with a view to developing new technical applications and facilitate use by routine laboratories.
Proteins Urine Electrophoresis

"Potentialities Of Electrochemical Detection In Conjunction With Non-aqueous Capillary Electrophoresis"
Electrochim. Acta 1998 Volume 43, Issue 23 Pages 3475-3482
Frank-Michael Matysika,*

Abstract: Electrochemical detection (ED) is applied to non-aqueous capillary electrophoresis (CE) performed in an acetonitrile buffer. The detection is based on a platinum microdisc electrode (d(Pt) = 25 µm) placed close to the capillary outlet of a 75 µm I.D. capillary. The CE-ED measurements can be performed without using an electrical-field decoupler owing to the reduced effect of the high voltage on the detection circuit when using the present detector configuration and non-aqueous separation buffers. The ED system is studied performing hydrodynamic voltammetry in the presence of electroosmotic flow. The exponent of flow rate dependence of the amperometric response is 0.68 for the present detector configuration. Practical applications of non-aqueous CE-ED concerning the analysis of dye substances such as malachite green, crystal violet, methylene blue, rhodamine B and morin are presented. In addition, some pharmaceutically relevant compounds are studied by CE-ED. In particular the capability of non-aqueous CE-ED for purity testing is discussed. By analyzing a 2 mM solution of trimethoprim it is possible to determine a content of 0.001% (2 x 10^-8 M) 2-amino-4-methylamino-5-(3,4,5-trimethoxybenzyl)pyrimidine which is a possible impurity of trimethoprim. No effects of electrode fouling were encountered during CE-ED experiments over measuring periods of several hours.
2-Amino-4-methylamino-5-(3-4-5-trimethoxybenzyl)pyrimidine Pharmaceutical Electrophoresis Amperometry Electrode

"Coupled Flow Injection And High Performance Capillary Electrophoresis In The Analysis Of Traditional Chinese Medicine Cortex Magnoliae Officinalis"
Fenxi Shiyanshi 1998 Volume 17, Issue 2 Pages 1-4
Shen, Q.;Fang, Z.L.

Abstract: A FI-HPCE method was developed for traditional Chinese medicines. A new flow injection sample introduction interface was proposed for capillary electrophoresis. Using the FI-HPCE system, buffer concentration, pH, voltage and percentage of methanol were optimized to sep. magnolol and honokiol from other constituents in Cortex Magnolial Officinalis and their medicinal preparations The sample throughput was 10/h, the relative standard deviation at 138 µg/mL magnolol was 2.1% (n=6) and the recoveries were in the range of 96%~102.9%.
Magnolol Honokiol Chinese Electrophoresis

"Microcomputer-controlled Flow Injection Analyzer"
Fenxi Yiqi 1998 Volume 1998, Issue 4 Pages 19-22
Dong Cunzhi; Zi Yanqin; Chen Liguo; Li Yao

Abstract: A flow injection analysis system was designed. The construction and software were described. The analyzer is controlled by a microcomputer through a special-purpose interface. The functions of the software include pump and valve control, data collection and processing, graphic display, and results printing and output. A library of Chinese characters is provided to display menus and other information in Chinese. The test results showed that the performance of the instrument is fairly excellent.

"Determination Of Calcium And Magnesium In Natural Water By Flow Injection Analysis-inductively Coupled Plasma-atomic Emission Spectrometry"
Guangpu Shiyanshi 1998 Volume 15, Issue 1 Pages 86-89
GONG Qi, MO Haitao, ZHANG Xingui, YI Nianping

Abstract: Flow injection analysis combined with inductively coupled plasma atomic emission spectrometry was adopted for determination of Ca and Mg in natural water. The influence carrier gas pressure and sample exposure time on the analysis signal was studied. The dispersion coefficients of Ca and Mg were estimated by comparison with continuous pneumatic feed. This method can be used for determining high Ca and Mg content of natural water without dilution. Five different kinds of samples were analyzed and the results were identical with those of EDTA titration.
Calcium Magnesium Environmental Spectrophotometry

"Direct Analysis Of Carbon Isotope Variability In Albumins By Liquid Flow Injection Isotope Ratio Mass Spectrometry"
J. Am. Soc. Mass Spectrom. 1996 Volume 7, Issue 6 Pages 605-610
Richard J. Caimi and J. Thomas Brenna*

Abstract: Aqueous protein solutions (2O at a flow rate of 0.5 ml/min. The solution was passed through a pneumatic nebulizer and then sprayed on to a moving steel wire. The coated wire was passed through a 5 cm drying oven, where the solvent was evaporated at 190°C with 100 ml/min counterflowing He, then passed into a combustion furnace. The furnace (15 cm x 2 mm) was maintained at 900°C. The water of combustion was removed and the resulting CO2 gas was directed on to a silica column (5 m x 10 cm i.d.) then to the ion source inlet of a Finnigan-MAT 252 isotope ratio MS (IRMS) System. The IRMS was operated at 6 x 107 torr and an accelerating potential of 8 KV in continuous-flow mode. A summary of isotope ratio analyzes obtained by this method is tabulated; standard deviation was 0.45% (n = 20). The technique was rapid, precise and accurate; data was comparable with data obtained using standard preparation methods using combustion tubes and dual inlet analysis (results are presented and discussed).
Carbon-12 Carbon-13 Albumin LC Mass spectrometry

"Operator-free Flow Injection Analyser"
J. Autom. Methods Manag. Chem. 1991 Volume 13, Issue 4 Pages 143-146
CELIO PASQUINI and LOURIVAL C. DE FARIA

Abstract: A flow injection analyzer. has been constructed to allow an operator-free determination of up to 400 samples. Besides the usual flow injection analysis apparatus, the analyzer. includes a home-made sample introduction device made with three electromechanical three-way valves and an auto-sampler which has been adapted to be commanded by an external digital signal; the analyzer. is controlled by a single board microcomputer. The interface needed to couple the analyzer. component to the microcomputer is also described. The analyzer. was used to determined Cr(VI) with use of diphenylcarbazide solution in 5% acetone and H2SO4 and spectrometric detection; coefficient of variation (n = 15) was 0.5%.

"Automation Of Flow Injection Gas Diffusion Ion Chromatography For The Nanomolar Determination Of Methylamines And Ammonia In Seawater And Atmospheric Samples"
J. Autom. Methods Manag. Chem. 1995 Volume 17, Issue 6 Pages 205-212
STUART W. GIBB, JOHN W. WOOD, R. FAUZI, and C. MANTOURA

Abstract: The automation and improved design and performance of Flow Injection Gas Diffusion-lon Chromatography (FIGD-IC), a novel technique for the simultaneous analysis of trace ammonia (NH3) and methylamines (MAs) in aqueous media, is presented. Automated Flow Injection Gas Diffusion (FIGD) promotes the selective transmembrane diffusion of MAs and NH3 from aqueous sample under strongly alkaline (pH > 12, NaOH), chelated (EDTA) conditions into a recycled acidic acceptor stream. The acceptor is then injected onto an ion chromatograph where NH3 and the MAs are fully resolved as their cations and detected conductimetrically. A versatile PC interfaced control unit and data capture unit (DCU) are employed in series to direct the selonoid valve switching sequence, IC operation and collection of data. Automation, together with other modifications improved both linearity (r2 > 0.99 MAs 0-100 nM, NH3 0-1000 nM) and precision (< 8%) of FIGD-IC at nanomolar concentrations, compared with the manual procedure. The system was successfully applied to the determination of MAs and NH3 in seawater and in trapped particulate and gaseous atmospheric samples during an oceanographic research cruise. (33 References)
Ammonia Amines, methyl Sea HPIC

"Continuous-flow Automated HPLC Analysis Of Fat-soluble Vitamins In Tablets"
J. Chromatogr. Sci. 1978 Volume 16, Issue 12 Pages 616-623
J.W. Dolan, J.R. Gant, N. Tanaka, R.W. Giese and B.L. Karger

Abstract: A prototype automated system involving continuous-flow analysis and high performance liquid chromatography (CFA/ HPLC) has been developed for the analysis of fat-soluble vitamins in individual pharmaceutical tablets. The novel features are the front-end coupling of CFA to HPLC, injection of hexane solutions on reversed phase columns, separation/quantitation of vitamins A, D2 and E within single chromatographic runs for a wide variety of tablets, and a dynamic range sufficient to accommodate the 1000-fold higher levels of vitamins A and E over D2 in the same tablets. The analysis rate is 10 samples per hour, the precision better than 6% for all three vitamins, and the recovery is 70-90% of that obtained by the standard AOAC method. Although the system is a prototype, it already greatly outperforms current manual analyzes which are time consuming, tedious, and demanding in terms of the level of skill and experience of the experimenter. Included in this work are some retention comparisons of commercial columns.
Vitamin A Vitamin D2 Vitamin E Pharmaceutical HPLC

"An Evaluation Of Low Vapor-pressure Liquids For Membrane Introduction Mass-spectrometry"
J. Mass Spectrom. 1997 Volume 32, Issue 12 Pages 1299-1304
R. C. Johnson, K. Koch, N. Kasthurikrishnan, W. Plass, J. S. Patrick, R. G. Cooks

Abstract: Four liquids of low vapor pressure have been examined for use as semi-permeable membranes in the sampling and analysis of volatile organic compounds by the technique of membrane introduction mass spectrometry (MIMS). The chosen liquids are inert and hydrophobic and can be formed to any desired thickness or shape. The selected polymers-polyphenyl ether, alkylated cyclopentane, perfluorinated ether and silicone ed-were supported on a microporous substrate and mounted in a direct insertion membrane probe. Polyphenyl ether, alkylated cyclopentane and silicone oil each formed stable semi-permeable barriers which passed the analytes of interest while discriminating strongly against the water solvent. These highly stable liquids also showed no significant loss of mass or contribution to the background of the mass spectrometer. Optimal injection volumes (2.25 mi) and membrane temperatures (90°C) gave 10%-90% rise times of 44-55 s for the three liquids compared with 35 s for a reference silicone membrane. Comparable detection limits at the low-ppb level were observed for benzene, toluene, trans-1,2-dichloroethylene, chlorobenzene, carbon tetrachloride and nitrobenzene using the silicone reference and alkylated cyclopentane membranes.
Mass spectrometry

"Development Of An Ion-trap Linear Time-of-flight Mass-spectrometer With Electrospray-ionization For Microcolumn Liquid-chromatography Detection"
J. Microcolumn Sep. 1995 Volume 7, Issue 6 Pages 603-610
Randy W. Purves, Liang Li

Abstract: A linear time-of-flight (TOF) mass spectrometer equipped with a quadrupole ion trap for ion storage was developed for mass analysis of ions generated by electrospray ionization (ESI). With this technique, the continuous ion beam from the ESI source is collimated by a set of focusing lenses into the ion trap where the ions are accumulated for a predetermined period of time. Extraction of the ions into the flight tube of the TOF mass spectrometer is achieved by applying a short duration voltage pulse to the exit endcap of the ion trap. The extraction frequency is variable, but is typically set at 10 Hz. It was shown that with a linear TOF mass spectrometer, mass resolution in the range of 600-950 can be routinely obtained. It was also demonstrated that a complete mass spectrum of bradykinin can be obtained with a direct injection of 75 fmol, or 0.5 µL of 150 nM of sample solution. Buffer gas pressure and the energy of the ions entering the ion trap, were found to be the key parameters in obtaining this sensitivity and resolution. In addition, the ESI ion trap/TOF system was developed and applied for microcolumn liquid chromatography detection of a simple protein mixture.
Bradykinin LC Mass spectrometry

"New Nebulizer System: Interface Gives Significantly Lower Detection Limits"
Kemi. Tid. 1988 Volume 100, Issue 9 Pages 51-52
Gustavsson, A.

Abstract: In new nebulizer systems giving significantly lower detection limits for metal atoms and making possible the combination of atomic spectrometric techniques with HPLC and FIA (flow injection analysis), the nebulizer system is set at a distance from the instrument and replaced by an interface. This is the best way to convert and transport the sample into the instrument. Thus, an interface for FAAS (flow atomic absorption spectrometry) having an efficiency of 90-100% thanks to lower liquid flow differs from a 'normal' aerosol chamber by a cone at the entrance by the introduction of extra gas and heat, and by operating the nebulizer with an oxidizing gas (air). In the heating zone, the solvent is evapd. from the aerosol droplets. Alternatively, a jet separation interface, especially for ICP (inductively coupled plasma) techniques with low flow and microwave plasma, comprising two concentric tubes in a vacuum chamber in the path of the aerosol particles gives 35% efficiency and up to 180 times higher analyte concentration in the aerosol. For easier removal of the solvent vapor, a gas excess in the aerosol chamber is used. A membrane interface is also described with 50-70% efficiency and 80-100% solvent removal and 140 times higher analyte concentration. It comprises a membrane separator containing membrane supports of high-density polyethylene and a silicone rubber membrane. It is especially useful in analysis flow techniques, above all 1-step FIA extraction. The system FIA-membrane interface-ICP is well suited for the simultaneous determination of trace amounts of many metals. Thereby the ICP-MS techniques will also be improved.
Metals Spectrophotometry Spectrophotometry

"Sorption Preconcentration And Flame Atomic Absorption Determination Of Chromium(VI) Using Hydraulic High-pressure Sample Introduction"
Magy. Kem. Foly. 1998 Volume 104, Issue 4 Pages 153-163
A. G&aacute;sp&aacute;r, J. Posta and Cs. S&oacute;gor

Abstract: Sorption flow injection (FI) pre-concentration procedure was combined with hydraulic high-pressure nebulization sample introduction (HHPN) and flame atomic absorption spectrometric detection (FAAS). The online FI-HHPN/FAAS system was constructed and a method was developed for online sorption and determination of Cr(VI). A polyether-ether-ketone, PEEK loop pre-concentration unit was used for the sorption of Cr-pyrrolidinedithiocarbamate complexes. The detection limit (3s) of the pre-concentrated 5 mL sample solution containing Cr(VI) was 0.54 ng/mL. The precision was 2.8%RSD for 50 ng/mL Cr(VI) (N=6). The method was applied for the determined of Cr(IV) in some natural samples. It was proved that the total chromium content of the samples containing large amt. of organic materials can quant. be converted into Cr(VI) by ashing at 800°C in the presence of oxygen. Thus trace level total chromium contents of various samples were determined after ashing and sorption pre-concentration in form of Cr(VI).
Chromium(VI) Environmental Sample preparation Spectrophotometry

"Separation Techniques In Flow Injection Analysis"
Flow Injection Atomic Spectroscopy 1989 Volume 7, Issue 1 Pages 157-224
Valcarcel, M.;Gallego, M.

Abstract: A review on the flow based continuous separations coupled online to absorption and inductively coupled plasma and emission atomic spectroscopic instruments. The separation techniques involve solid-liquid (precipitation, ion exchange) or liquid-liquid (extraction) approaches. 69 references.
Spectrophotometry Spectrophotometry Ion exchange

"Direct Analysis Of Organic-compounds In Water By Membrane Introduction Mass-spectrometry Advances In Selectivity And Interfaces"
Process Control Qual. 1995 Volume 7, Issue 3-4 Pages 117-131
J.S. Patrick, P. Wong, C. Xu, M. Soni, N. Kasthurikrishnan, N. Srinivasan and R.G. Cooks

Abstract: An overview of recent advances in membrane introduction mass spectrometry (MIMS) is presented. Particular attention is given to developments in interfaces, improvements in sensitivity and enhancements in selectivity. A new interface is employed which uses pneumatically assisted transport of the analyte to a jet separator interfaced to a benchtop ion trap mass spectrometer. Affinity MIMS, a new experiment which allows selective trapping of analytes (here benzaldehydes) at a chemically modified membrane, is described. Extended loading times followed by release using a chemical agent yields a limit of detection of 10 ppb for benzaldehyde. Notched broad-band excitation using stored waveform inverse Fourier transform (SWIFT) experiments on a benchtop ion trap is also used to enhance selectivity by permitting injection or retention of selected ions within the ion trap. The combination of SWIFT, signal averaging and extended ionization times has allowed the detection of trans-dichloroethene and toluene at 500 parts-per-quadrillion levels in water with no sample pre-concentration. Tandem mass spectrometry of analytes, introduced by MIMS, is also performed using SWIFT on the benchtop ion trap instrument. Both unimolecular dissociations and ion/molecule reactions can be used to characterize analytes. Trace level(10 ppb) analysis of volatile organics in a seawater matrix is described using flow injection sample handling; the matrix causes no changes in permeation rate or detector response relative to an aqueous solution. Methods are discussed for the detection of glycerol and 5-hydroxymethylfurfuraldehyde, a dehydration product of glucose, using MIMS. Finally, information acquired by MIMS is used to provide feedback control of a yeast fermentation. Each of these advances in MIMS finds application in online monitoring of chemical process streams. (52 references)
Organic compounds Fermentation broth Sea Mass spectrometry

"Analysis Of Peptides And Proteins By Capillary Electrophoresis - Mass Spectrometry Using Acidic Buffers And Coated Capillaries"
Rapid Commun. Mass Spectrom. 1991 Volume 5, Issue 10 Pages 484-490
P. Thibault, C. Paris, S. Pleasance, R. M. Caprioli

Abstract: A newly built capillary electrophoresis - MS interface involving ionspray ionization and a coaxial capillary arrangement was used to separate and determine peptides, tryptic fragments and proteins of mol. wt. up to 80 kDa. The interface provides an efficient means of optimizing and calibrating the mass spectrometer by using flow injection analysis, and minimizes peak broadening. Capillary electrophoretic separation of proteins by using a low-pH buffer and a capillary coated with cationic polymer gave better sensitivity and efficiency as compared with similar analyzes at high pH with uncoated capillaries. Pre-formed cationic species are thereby available for MS detection, and the analysis of proteins with high isoelectric points is possible even at low pH. The ability to conduct electrophoresis of globular proteins under acidic conditions permits conformational changes to be monitored in terms of variations in migration times and concurrent changes in the multi-charged ion envelopes. Relatively small amounts of sample are required and successful compromises between scan speed, scan range and separation efficiency are achieved.
Peptides Proteins Electrophoresis Mass spectrometry

"High-throughput Electrospray Mass Spectrometry Of Combinatorial Chemistry Racks With Automated Contamination Surveillance And Results Reporting"
Rapid Commun. Mass Spectrom. 1996 Volume 10, Issue 15 Pages 1894-1900
G. Hegy *, E. G&ouml;rlach, R. Richmond, F. Bitsch

Abstract: A computerized flow injection electrospray-ionization/atmospheric-pressure CI MS system is described for the high-throughput analysis of routine combinatorial chemistry samples in 96-well sample racks. Two workstation-controlled Finnigan MAT SSQ 7000 mass spectrometers form the basis of the system. The user interface is built on the existing Sandoz computer system, and consists essentially of ASCII file exchange (by a dedicated file transfer protocol on a data-exchange area of the PATHWORKS network) between the user PC (running DEC Pathworks V4.1 under Windows) and the MS workstation (running the Finnigan Interactive Chemical Information System V8.1.1 under OSF/1 V2.0). The automation is based on the Unix Bourne shell with most of the central routines being written in Perl V5.002. Much attention is paid to automated surveillance for contamination.
Mass spectrometry

"Rapid Scanning Technique For The Determination Of Optimal Tandem Mass Spectrometric Conditions For Quantitative Analysis"
Rapid Commun. Mass Spectrom. 1997 Volume 11, Issue 6 Pages 593-597
D. L. Hiller, T. J. Zuzel, J. A. Williams, R. O. Cole

Abstract: Many of the challenges posed by the quantitative analysis of drug candidates in biological fluids are met by atmospheric pressure ionization tandem mass spectrometry (MS/MS). However, the development of suitable methodology requires the determination and optimization of many compound-specific instrumental variables. At a minimum, the m/z values of a precursor ion and a product ion, along with the optimum collision energy, must be known in order to construct a suitable method. MS/MS method performance is particularly sensitive to collision energy, which must be near-optimum for each compound analyzed. Conventionally, these instrumental parameters are determined by continuous infusion of a standard solution into the ion source and optimizing each individual parameter. This paper describes the application of a technique based on the triple quadrupole mass spectrometer which streamlines the development of quantitative MS/MS methods. Termed a Q3 CID (collision-induced dissociation) scan, the method involves collection of Q3 spectra with a pressurized collision cell and flow injection sample introduction. Operation in this mode introduces all precursor ions into the collision cell, eliminating the need to perform multiple manual experiments. Data are presented which demonstrate that the majority of the information required to construct an MS/MS quantitation method can be obtained in a single flow injection experiment. Performance of quantitative methods constructed with instrument parameters gathered from positive-ion Q3 CID, compared with that of methods developed using conventional infusion optimization is presented. Limitations and applications particular to bioanalytical quantitation are discussed.
Drugs Mass spectrometry

"An Eluent-jet Interface For Chemical Ionization Mass Spectrometry And Coupling Of Microcolumn Liquid Chromatography With Electron Ionization Mass Spectrometry"
Rapid Commun. Mass Spectrom. 1998 Volume 12, Issue 1 Pages 5-10
Reyer J. Dijkstra, Ben L. M. Van Baar, Charles E. Kientz, Wilfried M. A. Niessen, Udo A. Th. Brinkman

Abstract: An improved eluent-jet interface was used to combine flow injection analysis (FIA) and micro-column liquid chromatography (LC) online with mass spectrometry (MS) in the electron ionization (EI) and solvent-independent chemical ionization (CI) modes. Good results were obtained for a series of pesticides and for 2-(diethylamino)ethanol (DEAE), a precursor of the chemical warfare V-agents. When using single-ion monitoring, 50 pg of DEAE could be detected in the CI mode, and a linear calibration plot was obtained in the test range of 50-1000 pg. EI-MS spectra obtained in both FIA and micro-LC experiments were closely analogous to those in conventional mass spectral libraries.
Pesticides 2-Diethylaminoethanol Mass spectrometry

"Injection Adaptable Fine Ionization Source ('JaFIS') For Continuous-flow Nano-electrospray"
Rapid Commun. Mass Spectrom. 1998 Volume 12, Issue 9 Pages 551-556
Scott Geromanos, John Philip, Gordon Freckleton, Paul Tempst

Abstract: Nanoelectrospray ('nanoES') tandem mass spectrometry of complex peptide mixtures has become a certified, mostly reliable technique for the identification of proteins. The typical low flow rates of nanoES, the extended anal. times for small samples, high ion transmission and its overall ease-of-use provide important practical advantages for polypeptide covalent microanalysis. We have constructed a modified nanoES ion source that is highly durable and user-friendly, and potentially allows for full auto-sampling operation. The injection adaptable Fine Ionization Source ('JaFIS') can be operated at flow rates of 10^-100 nL per min and with sensitivities in the 25 fmol peptide per µL range. The ion spray needles usually last for days, allowing for standards and multiple samples to be analyzed consecutively under similar conditions. In this configuration, quality controlled needles can also be saved and reused, providing for more consistent and reproducible day-to-day operating conditions. JaFIS-ES also permits sample recovery should any failure occur during anal.
Mass spectrometry

"An Automated Electro-osmotic Sample Introduction/separation Interface For Automated Electro-osmotic Flow Flow Injection Mass Spectrometry, Infusion Mass Spectrometry And Capillary Electrochromatography Mass Spectrometry"
Rapid Commun. Mass Spectrom. 1998 Volume 12, Issue 14 Pages 947-954
Stephen J. Lane *, Michael G. Tucker

Abstract: A novel automated electro-osmotic flow (EOF) sample introduction and separation interface has been designed, developed and successfully coupled to an electrospray mass spectrometer. The system consists of a small-footprint automated capillary electrochromatography (CEC) injection and separation interface that has an integrated auto sampler and connects to the outside world via a proprietary controller for automated CEC/MS, EOF infusion and flow injection analysis (EOFFIA). The system utilizes a previously described CEC/MS/MS micro-electrospray interface that allows optimization of the spray conditions. Short CEC columns or open capillaries are immobilized in a hollow stainless steel needle that is located in a pincher bar through which injection and running high voltage is applied. The needle assembly is easily removed for ease of column installation and changeover. At the heart of the automated system is a microprocessor-based controller which allows both manual and automated control via a 12-way key pad. The controller provides automatic indexing of a 10 position sample carousel, control of kV supply so that injection and running voltages can be set independently for full flexibility and mass spectrometer synchronizing signals. The design, although currently on a Finnigan TSQ 7000, has been made flexible in both mech. and electronic design to be easily adaptable to other mass spectrometers. Examples of all functions of the system are presented here including rapid flow injection and controllable infusion experiments Simple mixtures could be separated by CEC/MS with great efficiency and sensitivity in a short time. An example of multiple automated anal. runs performed continuously over a period of 10 h are described. We believe this is the first report of a custom built CEC system with an integrated CEC/MS/MS interface that obviates the need for an expensive and unsuitable converted commercial CE system for sample introduction while allowing for a useful degree of automation. This system addresses many of the robustness and redn.-to-practice problems of CEC/MS and will catalyze the development of CEC/MS and allow the systematic optimization and evaluation of the technique.
Mass spectrometry

"Coupled Chromatography In Pesticide Residue Analysis"
Sci. Total Environ. 1993 Volume 132, Issue 2-3 Pages 105-114
Piet van Zoonen

Abstract: An overview is given of the applicability of coupled chromatographic systems in pesticide residue analysis. These systems can be based on liquid chromatography (LC) coupled to itself (LC-LC) or to GC (LC-GC) or on GC-GC combinations. The main advantage of coupled chromatographic techniques is the enhancement of both sensitivity and selectivity combined with a high potential for automation. However, in pesticide residue analysis too high a selectivity may prove to be a drawback, since it limits the scope of the analytical procedure. In order to circumvent this problem with the application of capillary GC, which is a highly selective end-method, the coupling of capillary GC to flow injection techniques and low resolution LC techniques (such as gel permeation chromatography and separation on solid phase cartridges) can be of great importance. The advantages and drawbacks of coupled chromatographic and flow injection techniques coupled to capillary GC are discussed in relation to the analysis of pesticide residues in environmental and biological samples.
Pesticides Environmental Biological GC

"Sample Introduction System For ICP-MS"
Shitsuryo Bunseki Kagaku 1988 Volume 36, Issue 6 Pages 273-285
Shimamura, T.

Abstract: A review is presented, with 14 references, of several methods of sample introduction in ICP-MS, including aqueous solution, flow injection, organic solvent, laser ablation and electrothermal vaporization methods.
Mass spectrometry

"Interfacing HPLC And Cold Vapor AA With Online Preconcentration For Mercury Speciation"
Spectrosc. Lett. 1991 Volume 24, Issue 5 Pages 681-697
J. C. Gaston Wu

Abstract: A quartz reaction vessel is designed and constructed to interface HPLC and cold-vapor AA for mercury speciation in aqueous samples. Inorganic mercury, methyl mercuric and ethyl mercuric compounds can be separated effectively within 10 minutes. An on-line pre-concentration unit is used to reduce the limit of detection (LOD) before the sample is introduced into the reversed-phase HPLC. Without pre-concentration, the detection limits for the three mercury species are 0.094, 0.085 and 0.124 ppm, respectively. Limits of detection are reduced to 0.78, 0.78 and 0.42 ppm, with the use of pre-concentration technique. The feasibility of this method is tested by analyzing mercury compounds in synthetic tap and river water samples.
Mercury River Water HPLC Spectrophotometry

"Sensitive Quantitation Of Chromium-DNA Adducts By Inductively Coupled Plasma Mass Spectrometry With A Direct Injection High-efficiency Nebulizer"
Toxicol. Sci. 1998 Volume 46, Issue 2 Pages 260-265
Jatinder Singha, John A. McLean, Daryl E. Pritchard, Akbar Montaser, and Steven R. Patierno

Abstract: A novel method is described for the sensitive detection of Cr-DNA adducts. Cr-DNA adducts were determined in 1 µg DNA from normal human lung fibroblasts exposed to sodium chromate using microscale flow injection analysis with a direct injection high-efficiency nebulizer and inductively coupled plasma mass spectrometry detection. The frequency of Cr-DNA adducts increased in a dose-dependent sigmoidal manner, indicating satn. and toxicity. The low detection limits (on the order of parts per trillion) allows the detection of as few as 2 Cr adducts per 10,000 bases, which, coupled with the small DNA sample requirement, makes this technique suitable for measuring metal-DNA adducts as biomarkers of exposure to toxic and carcinogenic metals such as Cr, in cultured cells, animals, and humans. (c) 1998 Society of Toxicology.
Chromium, adducts, DNA Lung Mass spectrometry

"Thermospray Sample Introduction For Atomic Spectrometry"
Trends Anal. Chem. 1987 Volume 6, Issue 7 Pages 171-175
John A. Koropchak and Daniel H. Winn

Abstract: The use of thermospray aerosol production for sample introduction in atomic spectrometry is reviewed. Application to injection into ICP in continuous or flow injection mode is described and illustrated. The principles behind improvements in detection limits by this method are explained. Thermospray nebulizers have been used in HPLC - ICP-AES. (14 references).
Spectrophotometry

"Interfacing Of Flow Injection Pre-treatment Systems With Capillary Electrophoresis"
Trends Anal. Chem. 1998 Volume 17, Issue 1 Pages 34-41
Petr Kuban and Bo Karlberg*

Abstract: This article reviews the interfacing of flow injection analysis (FIA) with capillary electrophoresis (CE). Various sample pre-treatment procedures such as dialysis and gas diffusion can be fully automated as can the application of the electrokinetic injection principle for introduction of the treated sample into the CE system using a specially designed interface. The practical applicability of the FIA-CE technique has been demonstrated by the determination of small anions in, for instance, water, juice and milk samples. Sample throughput rates can reach 170/h and the repeatability is typically 2% (RSD).
Anions Water Fruit Cow Electrophoresis Sample preparation

"The Combination Of Flow Injection With Electrophoresis Using Capillaries And Chips"
Electrophoresis 2004 Volume 25, Issue 23-24 Pages 3962-3969
Xingguo Chen, Liuyin Fan, Zhide Hu

Abstract: The combined flow injection capillary electrophoresis (FI-CE) system that integrates the essential favorable merits of FI and CE, can significantly expand the application scope of CE by exploring the various on-line sample pretreatments and pre-concentration of FI. The principle behind this technique, some innovative designs of the split-flow interface, as well as novel applications to a variety of analytical problems, are reviewed and discussed. Some salient features and unique advantages of this technique are outlined.

"Separation And Determination Of Four Active Anthraquinones In Chinese Herbal Preparations By Flow Injection-capillary Electrophoresis"
Electrophoresis 2005 Volume 26, Issue 15 Pages 2999-3006
Lihong Liu, Liuyin Fan, Hongli Chen, Xingguo Chen, Professor, Zhide Hu

Abstract: A simple, rapid, and accurate method for the separation and determination of physcion, chrysophanol, aloe-emodin, and emodin in Rhubarb, Juemingzi, and Chinese herbal preparations was developed by combination of flow injection-capillary zone electrophoresis for the first time. The analysis was carried out using an unmodified fused-silica capillary (75 mm x 50 m ID x 375 m OD, effective separation length of 48 mm) and direct ultraviolet detection at 254 nm. By a series of optimization, the sample solvent consisted of NaOH (100 mmol/L) and ACN (1:1 v/v), and a running buffer composed of 15 mmol/L sodium borate - 12.5 mmol/L sodium dihydrogen phosphate - 42% v/v ACN (pH 10.1) was applied for the separation of the four anthraquinones. The separation was rapid and highly reproducible, with complete resolution of all four compounds within 6 min. The sample throughput rate could reach up to 12 per h. The repeatability (defined as relative standard deviation) was 4.45, 4.44, 4.34, 0.61% with peak height evaluation and 1.62, 0.89, 2.49, 2.19% with peak area evaluation for physcion, chrysophanol, aloe-emodin, and emodin, respectively.
Physcion Chrysophanol Aloe-emodin Emodin Chinese Spectrophotometry Electrophoresis

"Separation And Determination Of Sulfonamides In Pharmaceutical Preparations By A Microfluidic Capillary Electrophoresis System With A Continuous Sample Introduction Interface"
J. Sep. Sci. 2003 Volume 26, Issue 15-16 Pages 1376-1382
Liu Yin Fan, Hong Li Chen, Xing Guo Chen *, Zhi De Hu

Abstract: A simple, rapid microfluidic capillary electrophoresis system with a continuous sample introduction interface is described in the present paper. The interface with an H-channel structure was produced using a non-lithographic approach. The H-channel structure fixed on a planar plastic base utilized a horizontal 6.5-centimeter-long separation capillary with two vertical sidearm tubes on each end that served as inlet and outlet flow-through electrode reservoirs. The inlet reservoir also functioned as interface for coupling to the FI system. The performance of the system was demonstrated in the separation and determination of trimethoprim (TMP), sulfadiazine (SDZ), and sulfamethoxazole (SMZ) with UV detection at 214 nm, achieving baseline separation within 2.5 min. The sample throughput rate can reach up to 30 samples h-1. The repeatability (defined as relative standard deviation, RSD) was 2.23%, 1.19%, 2.64% with peak height evaluation and 2.43%, 1.46%, 3.58% for peak area evaluation, respectively. The limits of detection (S/N = 3) were 0.17 g/mL, 1.05 g/mL, and 1.28 g/mL for TMP, SDZ, and SMZ, respectively. This technique has been applied to the analysis of two commercial pharmaceutical preparations containing TMP, SDZ, and SMZ for the first time and has achieved satisfactory results.
Sulfoamides Trimethoprim Sulfadiazine Sulfamethoxazole Pharmaceutical Spectrophotometry Electrophoresis

"Flow Injection Analysis NMR (FIA-NMR): A Novel Flow NMR Technique That Complements LC-NMR And Direct Injection NMR (DI-NMR)"
Magn. Reson. Chem. 2003 Volume 41, Issue 7 Pages 509-516
Paul A. Keifer

Abstract: Details of a new flow NMR technique, flow injection analysis NMR (FIA-NMR), are presented for the first time. This method blends some aspects of both liquid chromatography-NMR and direct injection NMR, and complements both. FIA-NMR is shown to be useful as an analytical technique, especially for repetitive analyzes, and may also prove useful in the analysis of combinatorial chemistry libraries. The feasibility of FIA-NMR is demonstrated by the quantitative analysis of an over-the-counter pharmaceutical.
Caffeine Pharmaceutical Nuclear magnetic resonance