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

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Classification: Biological fluid -> blood -> whole

Citations 41

"Determination Of Urea With An Ammonia Gas-sensitive Semiconductor Device In Combination With Urease"
Anal. Chim. Acta 1984 Volume 163, Issue 1 Pages 143-149
F. Winquist, A. Spetz and I. Lundström, B. Danielsson

Abstract: An Ir - Pd metal oxide semiconductor capacitor and urease were used in two systems. One comprised essentially a column of immobilized urease in a flow injection system. Urea was determined in whole blood and serum (after 500-fold dilution) by this method; the serum values were in reasonably good agreement with those obtained by a spectrophotometric method, the coefficient of variation (n = 10) for 4.5 mM urea in whole blood was 4.6%, and recoveries of additions of 0.5 to 2 mM urea to whole blood ranged from 85 to 106%. The second system was an enzyme probe based on urease enclosed between a dialysis membrane and a gas-permeable membrane. The dialysis membrane formed part of a flow-cell through which the buffered sample was pumped, and the capacitor was mounted 0.1 mm from the other membrane. Up to 5 mM urea could be determined. For the first method, the limit of detection was 0.2 µM-urea, and the calibration graph was rectilinear up to 50 µM, for 150 µL portions of the diluted samples. For the second method, the calibration graph was non-rectilinear, and the limit of detection was 0.01 mM.
Urea Electrode Dialysis Method comparison Immobilized enzyme Reactor

"Heterogeneous Samples In Flow Injection Systems. 1. Whole Blood"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 115-122
Jeffrey J. Harrow and Jirí Janata

Abstract: Errors in the direct analysis of heterogeneous samples by non-steady state flow methods are associated with undefined dilution and dispersion. The problem is examined theoretically and confirmed experimentally by determinations of pH and pCO2 in whole blood. Micro-bubbles attached to the surface of a micro-electrode or CHEMFET detector can also substantially reduce the precision of the results.
Carbon dioxide pH Electrode Field effect transistor Dispersion Precision Interferences Theory General Steady state Viscosity

"Heterogeneous Samples In Flow Injection Systems. 2. Standard Addition"
Anal. Chim. Acta 1985 Volume 174, Issue 1 Pages 123-132
Jeffrey J. Harrow and Jirí Janata

Abstract: The effect of undefined dispersion in flow injection analysis of heterogeneous samples can be eliminated by the method of standard additions, a significant improvement over the direct calibration method. Because flow injection analysis is a precise dilution method, the initial free volume of the sample (e.g., total volume minus haematocrit, for whole blood) must be known in order to produce accurate results for such samples. The Gran plot technique is adapted for use in flow injection analysis and it is shown that the dispersion, D, can be obtained from these experiments. In homogeneous samples, flow injection analysis with standard additions provides a means of determination which does not assume a constant dispersion and which can be used with both linear and logarithmic detectors. It is thus a robust method, which is not affected by changes in dispersion, such as those caused by bubbles or viscosity.
Potassium Potentiometry Dispersion Standard additions calibration Theory Viscosity

"Flow Injection And Microwave-oven Sample Decomposition For Determination Of Copper, Zinc And Iron In Whole Blood By Atomic Absorption Spectrometry"
Anal. Chim. Acta 1986 Volume 179, Issue 1 Pages 351-357
M. Burguera and J. L. Burguera, O. M. Alarcón

Abstract: The sample and 0.3 M HCl - 0.4 M HNO3 reagent are injected in parallel into the flow injection system and mixed, and the sample is mineralized on passage through a microwave oven (2.45 MHz) to the nebulizer of an AAS detection system. The mean recoveries are 103.0 and 103.2% with coefficient of variation of 2.0% for added amounts of 0.5 and 1.0 mg L-1 of Cu, respectively; 101.5 and 101.1%, and 4.0 and 3.2% for 8 and 16 mg L-1 of Zn, respectively, and 102.8 and 101.8%, and 2.0 and 2.2% for 0.2 and 0.6 g L-1 of Fe, respectively. There is good agreement with the results obtained by conventional spectrophotometry.
Copper Zinc Iron Clinical analysis Spectrophotometry Microwave Method comparison

"Automated Determination Of Cadmium And Lead In Whole Blood By Computerized Flow Potentiometric Stripping With Carbon Fiber Electrodes"
Anal. Chim. Acta 1987 Volume 193, Issue 1 Pages 71-79
Lena Almestrand, Daniel Jagner and Lars Renman

Abstract: A sample pretreatment involving only the dilution (1 + 19) of two 0.2-0.4 mL sample aliquots with 0.5 M hydrochloric acid, with a standard addition to one of the aliquots, precedes the injection of each sample. The computer-controlled flow system used automatically executes a pre-programmed number of cycles on each sample pair before presenting the final result. Each cycle, which has a duration of 80 or 135 s for lead(II) and cadmium(II), respectively, involves the display of the derivative stripping signal on a printer/plotter and integration of the stripping peaks generated. For lead(II), striping is done in 0.5 M hydrochloric acid, which eliminates interferences from copper, though at the cost of a relatively high stripping rate, compared to the 5 M calcium chloride used for cadmium(II). The flow cell consists of a silver chloride-lined silver tube which acts as both reference and counter electrode, and a disposable carbon-fiber working electrode mounted in a PVC tube, which normally will operate for 50-200 cycles. The method was verified for whole blood reference standards and by comparison with results obtained by atomic absorption spectrometry.
Lead Electrode Potentiometric stripping analysis Automation Computer

"Enzymic Determination Of Urea In Undiluted Whole Blood By Flow Injection Analysis Using An Ammonia Ion-selective Electrode"
Anal. Chim. Acta 1988 Volume 209, Issue 1-2 Pages 239-248
Bo A. Petersson

Abstract: A sample was injected into a carrier stream of buffer (4 mM KCl, 86 mM NaCl, 60 mM HEPES and 0.55 g L-1 Na2EDTA) at 0.125 mL min-1. Urea was detected with an electrode comprising an immobilized urease membrane placed over the membrane of an NH4+ ion-selective electrode. Response was rectilinear from 1 to 40 mM urea. In the determination of urea in whole blood, the coefficient of variation (n = 10) was 1.1% and results agreed well with those obtained by an established method. Interference from K+ was reduced to 3% by adjusting the K concentration. of the carrier stream and the aqueous calibration solution to 4.0 mM.
Urea Electrode Potentiometry Closed loop Immobilized enzyme Interferences

"Determination Of Lead In Whole Blood With A Simple Flow Injection System And Computerized Stripping Potentiometry"
Anal. Chim. Acta 1988 Volume 209, Issue 1-2 Pages 339-343
L. Almestrand, M. Betti, Chi Hua, D. Jagner and L. Renman

Abstract: The sample was diluted 20-fold with 0.5 M HCl containing 40 µg L-1 of Cd(II) as internal standard and 100 mg L-1 of Hg(II). The solution (1.1 ml) was injected into the carrier stream of 0.5 M HCl and 100 mg L-1 of Hg(II) (for plating) in aqueous 25% ethanol. Seven cycles were carried out at the Hg-plated carbon-fiber electrode comprising electrolysis at -1.7 V vs. Ag - AgCl for 15 s followed by stripping. The response was rectilinear up to 1000 µg L-1 of Pb(II); the coefficient of variation were between 1.1 and 12% (n = 10). The results for reference samples agreed with certified values with coefficient of variation for 335 µg L-1 (n = 8) and 691 µg L-1 (n = 12) of 11 and 3.5%, respectively. With this system 24 samples per hour could be analyzed.
Lead Clinical analysis Electrode Potentiometric stripping analysis Potentiometry Computer Reference material

"Conducting Organic Salt Amperometric Glucose Sensor In Continuous-flow Monitoring Using A Wall-jet Cell"
Anal. Chim. Acta 1990 Volume 229, Issue 1 Pages 83-91
Hari Gunasingham and Chin-Huat Tan

Abstract: A paste was prepared by mixing tetrathiafulvalene - 7,7,8,8-tetracyanoquinodimethane complex salt with 10% of Nujol (with or without added graphite) and packed into the well of an electrode consisting of a PTFE holder and a graphite disc. The paste was successively covered with glucose oxidase, bovine serum albumin - glutaraldehyde (4:1) and a 0.03 µm-pore polycarbonate membrane. The electrode was used with a large-volume wall-jet cell, a graphite counter-electrode and Ag - AgCl reference electrode in an automated system for (i) flow injection or (ii) steady-state analysis. At 0.2 V a rectilinear response was observed for up to 60 mM glucose (I) by method (i) or 30 mM by method (ii). Results obtained by method (ii) were more consistent than those by method (i). For determination of 5.5 to 11 mM I in whole blood at 0.15 V and 0.5 mL min-1, results by method (ii) were lower than those by method (i) and were in better agreement with results obtained with use of a Haemo-glutotest 20-800R (Boehringer Mannheim) test strip.
Glucose Amperometry Electrode Electrode Sensor Complexation Method comparison

"Effect Of Whole Blood And Plasma On The Permeability Of Glucose Through Different Cellulose And Cellulose Acetate Membranes"
Anal. Chim. Acta 1990 Volume 231, Issue 2 Pages 165-173
Lars Risinger, Thomas Buch-Rasmussen, Gillis Johansson

Abstract: The transfer of glucose (I) from whole blood, plasma and aqueous standards through different membranes for use in biosensors was carried out with use of a flow injection system (diagram given) incorporating a flow-through dialysis cell that contained the membrane being studied. Detection was with use of a glucose dehydrogenase enzyme reactor and a graphite electrode at 0 mV vs. Ag - AgCl. The membranes studied were: cellulose acetate; Spectra/por 4 (mol. wt. cut off = 12,000 to 14,000; Spectrum Medical Industries, Los Angeles, CA); Spectra/por 6 (mol. wt cut off = 1,000) and cellulose acetate Cuprophan (mol. wt cut off = 5,000). Theoretical models are proposed for the effect of plasma viscosity and haematocrit on glucose transfer rate. Lower membrane permeability resulted in less dependence on haematocrit and smaller differences between results in aqueous solution, plasma and whole blood.
Glucose Sensor Cellulose acetate Membrane Viscosity Dialysis

"Spectrophotometric Determination Of Ethanol In Blood Using A Flow Injection System With An Immobilized Enzyme (alcohol Dehydrogenase) Reactor Coupled To An Online Dialyser"
Anal. Chim. Acta 1990 Volume 231, Issue 1 Pages 115-119
Gabrielle Maeder, Jean-Luc Veuthey, Michel Pelletier and Werner Haerdi

Abstract: Whole blood (110 µL) which was not pre-treated was introduced into the carrier stream of sodium pyrophosphate decahydrate - semicarbazide hydrochloride - glycine - NaCl - NAD+ - water (pH 9.0) by means of a rotary valve. The mixture was passed at 650 µL min-1 to a dialyser comprising a Cuprophan membrane between two Plexiglas plates, then to a controlled-pore glass enzyme reactor with a nylon filter fabric (mesh size 100 µm) at each end, kept at 25°C. The absorbance of NADH was measured at 340 nm. The calibration graph was rectilinear from 3 to 40 µg mL-1 of ethanol, corresponding to 0.3 to 4.0 g of ethanol per 1000 g of whole blood prior to dilution. The results agreed with those from direct-injection GC.
Ethanol Spectrophotometry Dialysis Immobilized enzyme pH Membrane Filter Nylon Controlled pore glass Calibration Enzyme Method comparison

"Comparative Study Of First-generation, Second-generation And Third-generation Amperometric Glucose Enzyme Electrodes In Continuous-flow Analysis Of Undiluted Whole-blood"
Anal. Chim. Acta 1990 Volume 234, Issue 2 Pages 321-330
Hari Gunasingham and Chin-Huat Tan, Tar-Choon Aw

Abstract: First-, second- and third-generation amperometric glucose enzyme electrodes were compared under flow injection and steady-state conditions for the monitoring of undiluted whole blood. Measurements were made in a large volume wall-jet cell (illustrated) with a four-way manual injection value, a sample loop of 25 µL or 200 µL for flow injection and steady-state modes, respectively, and a graphite counter electrode vs. Ag - AgCl. Use of first-generation electrodes, based on H2O2 detection at a Pt electrode, was limited by their instability. Second-generation electrodes in which re-oxidation of glucose oxidase occurs by a mediator are more suitable for blood analysis however the choice of mediator is important. With regard to the rectilinearity and stability, tetrathiafulvalene achieves better results than dimethyl ferrocene. Third-generatin electrodes based on tetrathiafulvaleine - teracyanoquinodimethane where direct oxidation of glucose oxidase occurs, were also useful, but display lower stability and a smaller dynamic range than second-generation devices. The calibration graphs for first, second and third-generation electrodes were rectilinear up to 10, 35 and 25 mM for steady-state analysis and 25, 80 and 60 mM for flow injection analysis, respectively.
Glucose Amperometry Electrode Electrode Electrode Enzyme Calibration Apparatus Detector

"Direct Vapor Generation Fourier Transform Infrared Spectrometric Determination Of Ethanol In Blood"
Anal. Chim. Acta 1996 Volume 336, Issue 1-3 Pages 123-129
Amparo Pérez-Ponce, Salvador Garrigues and Miguel de la Guardia*

Abstract: A new procedure is proposed for a direct determination of ethanol in plasma and whole blood. The method is based on the injection of a discrete sample volume of 10 l into an electrically heated Pyrex glass reactor in which, at a temperature of 90°C, the ethanol is volatilized and introduced by means of a N2 carrier flow inside a long-path infrared gas cell and the corresponding flow analysis recording registered as a function of time. The measurement of the area of the flow injection recording, obtained from the absorbance of the transient signal in the range 1150-950 cm-1, allows the direct quantification of ethanol upto 2 g l-1, with a limit of detection of 0.020 g L-1 and coefficient of variation between 0.3 and 1.9% for three replicate analyzes of the same sample. The analysis frequency of the method is 40 h-1, and it can be applied to a single drop of finger blood.
Ethanol Spectrophotometry Gas phase detection Heated reaction Volatile generation

"Determination Of Lead In Blood By Hydrodynamic Voltammetry In A Flow Injection System With Wall-jet Detector"
Talanta 1998 Volume 45, Issue 4 Pages 703-711
S. Jaenicke*, R. M. Sabarathinam, B. Fleet and H. Gunasingham

Abstract: We describe an automated electrochemical method, using flow injection analysis with a wall-jet detector. Lead is released from its binding site in the blood by ion exchange and quantified by stripping voltammetry with a mercury film electrode (MFE). The method allows for the detection of 0.05 ppm Pb2+ with an accuracy of about 10%. Electrode poisoning by proteins from the blood can be effectively suppressed when a MFE modified with a Nafion-membrane coating is used. Such modified electrodes can be activated in the solution without further treatment, and used for more than 100 analyzes before they have to be replaced. A solid matrix MFE with a Nafion-membrane and all necessary chemicals for mercury film formation and lead release has been developed. Such electrodes are discussed as disposable electrodes for a portable blood lead detector. Lead is one of the most widely distributed toxic heavy metals in the environment. It is a cumulative poison, affecting the brain and nervous system. The threshold between the normal lead level and the level where physiological effects become manifest is relatively narrow. It is therefore desirable to screen exposed populations in order to identify the danger in time. The lead concentration in the blood is a measure to the total amount of lead in the body. A fast, accurate and cheap method for the determination of lead in blood is therefore needed. The conventional method used to determine lead in blood is atomic absorption. Electrochemical methods like stripping voltammetry combine high analytical sensitivity with relatively low cost for the equipment; however, electrode preparation is critical for the success of an analysis, and highly skilled personnel are needed. We describe an automated electrochemical method, using flow injection analysis with a wall-jet detector. Lead is released from its binding site in the blood by ion exchange and quantified by stripping voltammetry with a mercury film electrode (MFE). The method allows for the detection of 0.05 ppm Pb2+ with an accuracy of about 10%. Electrode poisoning by proteins from the blood can be effectively suppressed when a MFE modified with a Nafion-membrane coating is used. Such modified electrodes can be activated in the solution without further treatment, and used for more than 100 analyzes before they have to be replaced. A solid matrix MFE with a Nafion-membrane and all necessary chemicals for mercury film formation and lead release has been developed. Such electrodes are discussed as disposable electrodes for a portable blood lead detector.
Lead Voltammetry Electrode Ion exchange Electrode Electrode Method comparison

"Carbon Paste-tetrathiafulvalene Amperometric Enzyme Electrode Forthe Determination Of Glucose In Flowing Systems"
Analyst 1990 Volume 115, Issue 1 Pages 35-39
Hari Gunasingham and Chin-Huat Tan

Abstract: The development of a carbon paste-tetrathiafulvalene amperometric enzyme electrode for the determination of glucose in flowing streams is described. The enzyme electrode is operated in a flow-through detector based on the wall-jet configuration under flow injection (FI) and steady-state (SS) conditions. Under FI conditions, high precision (0.6%) and sample throughput (120 samples h-1) are possible. Moreover no pre-conditioning of the electrode is required. The flow system is suitable for the determination of glucose in whole blood without sample dilution. With proper orientation of the jet with respect to the enzyme electrode, high accuracy can be obtained under SS conditions. The electrode was prepared by placing a graphite disc (3 mm diameter x 2 mm thick) into a PTFE holder leaving a well 1 mm deep into which was packed carbon paste containing tetrathiafulvalene (20%) in Nujol. The polished paste surface was coated with glucose oxidase and dried, covered with 2.5 µL of bovine serum albumin (5%) and glutaraldehyde (2.5%) and a polycarbonate membrane. Glucose was determined directly in whole blood by flow injection and steady-state methods in a large volume wall-jet cell vs. Ag - AgCl using 25 or 250 µL samples, respectively. No electrode pre-conditioning was necessary. Flow injection gave high precision and sample throughput (120 samples h-1); high accuracy can be attained for steady-state conditions with careful jet orientation.
Glucose Electrode Amperometry Enzyme Detector

"Flow Injection Online Coprecipitation Preconcentration For Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 2 Pages 439-446
Zhaolun Fang and Liping Dong

Abstract: A flow injection pre-concentration system was synchronously coupled to an electrothermal AAS instrument for the determination of Cd and Ni in whole blood. Samples (1 ml) were digested with HNO3 - HClO4 (5:1) at 170°C to near dryness and the residue was mixed with Fe(II) solution (10 g l-1) and 1% sulfosalicylic acid solution The solution was injected into the flow injection system and mixed with a stream (0.4 mL min-1) of aqueous 0.25% hexamethyleneammonium - hexamethylenedithiocarbamate (I). Cadmium and Ni were co-precipitated with the Fe(II) - I complex on the walls of a PTFE knotted reactor. The resulting precipitate was dissolved in isobutylmethylketone before introduction on to the platform of a graphite furnace carried by a stream of I. Electrothermal AAS was carried out in parallel with the pre-concentration. of the next sample. The detection limits were 3 and 2 ng L-1 for Cd and Ni, respectively, with coefficient of variation of 5.9 and 6.0% for 20 ng L-1 and 1.5 µg L-1 of Cd and Ni, respectively. A flow injection online co-precipitation system has been synchronously coupled to an electrothermal atomic absorption spectrometric system for the determination of trace amounts of heavy metals in whole blood digests. Cadmium and nickel in the digest were co-precipitated with the iron(II)-hexamethylenedithiocarbamate (HMDTC) complex on the walls of a knotted reactor without using a filter. The ppt. was dissolved in 60 µL of iso-Bu Me ketone and stored in a poly(tetrafluoroethylene) tube before introduction onto the platform of a graphite furnace carried by a stream of HMDTC reagent. Electrothermal atomic absorption spectrometric determination of the analyte was performed in parallel with the pre-concentration. of the next sample. Enrichment factors of 16 and 8 were obtained for cadmium and nickel, respectively, using 20 and 40 s ppt. collection times, at a sample flow-rate of 3 mL min-1 for cadmium and 2 mL min-1 for nickel. The detection limits (3s) were 0.003 and 0.02 µg L-1 for cadmium and nickel, respectively, and the precisions were 5.9% relative standard deviation (RSD) at the 0.02 µg L-1 level for cadmium, and 6.0% RSD at the 1.5 µg L-1 level for nickel. Recoveries of cadmium and nickel in blood digests were 103 and 106%, respectively
Cadmium Nickel Sample preparation Spectrophotometry Preconcentration Coprecipitation Knotted reactor Organic solvent

"In Vivo Sample Uptake And Online Measurements Of Cobalt In Whole Blood By Microwave-assisted Mineralization And Flow Injection Electrothermal Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 5 Pages 343-347
M. Burguera, J. L. Burguera, C. Rondón, C. Rivas, P. Carrero, M. Gallignani and M. R. Brunetto

Abstract: Blood was pumped directly from the subject to a time-based solenoid injector (details given) which is automatically controlled to inject the sample-HNO3-EDTA (coagulant) mixture into the carrier stream. The mixture was carried down to the microwave-oven and a 20 µL portion of the mineralized sample was deposited on the graphite tube platform and mixed with 10 µL magnesium nitrate solution. The furnace ashing and atomization temperature program (details given) was followed and the Co absorbance was measured at 324.8 nm by AAS. The calibration graph was linear up to 50 µg/l Co and the detection limit was 0.3 µg/l. RSD (n = 10) were 2.6 and 3.1%, respectively, for a Co standard solution and a Whole Blood certified reference material, at 5 µg/l Co. The method was applied to the analysis of Co in two blood reference materials and the results agreed well with certified values.
Cobalt Spectrophotometry Sample preparation Microwave Online digestion Reference material In vivo monitoring

"Determination Of Creatinine By An Ammonia-sensitive Semiconductor Structure And Immobilized Enzymes"
Anal. Chem. 1986 Volume 58, Issue 1 Pages 145-148
Fredrik Winquist, Ingemar Lundstroem, and Bengt Danielsson

Abstract: The determination is described of creatinine in biological samples, by using an enzymatic flow injection system (diagram presented). A 25-fold dilution was used for whole blood and plasma and a 1000-fold dilution for urine. An NH3-sensitive Ir - metal oxide semiconductor sensor was developed to detect the NH3 produced by immobilized creatinine deiminase. Endogenous NH3 was removed by the action of immobilized glutamate dehydrogenase. The sensitivity for 85 µL aliquots was 0.2 µM-creatinine and the calibration graph was rectilinear for up to 30 µM. The results correlated well with those obtained by conventional spectrophotometry. The recoveries ranged from 93 to 105% and the only significant interferences were from low-mol.-wt. amines.
Creatinine Electrode Interferences Immobilized enzyme Method comparison

"Voltammetric-enzymatic Determination Of Ethanol In Whole Blood By Flow Injection Analysis"
Fresenius J. Anal. Chem. 1987 Volume 327, Issue 5-6 Pages 552-554
A. Fernández, M. D. Luque de Castro and M. Valcárcel

Abstract: Two automated enzymatic methods are described. The ethanol is oxidized by NAD+ in the presence of alcohol dehydrogenase. The NADH formed is measured directly at +0.8 V vs. a silver - AgCl electrode or indirectly via a coupled reaction involving 2,6-dichlorophenolindophenol as redox mediator in the presence of dihydrolipoamide dehydrogenase, with measurement at +0.07 V vs. silver - AgCl. A pyrophosphate buffer solution of pH 9 is the flow injection carrier stream and working and auxiliary electrodes of vitreous carbon were used. The coupling method is the more sensitive, with rectilinear response in the range 0.5 to 30.0 µg mL-1 of ethanol, a coefficient of variation of 4.1% and an analysis rate of 30 samples h-1.
Ethanol Electrode Voltammetry Enzyme

"Flow Injection Determination Of Ethanol In Whole Blood Using Immobilized Enzymes"
Microchem. J. 1987 Volume 36, Issue 3 Pages 316-322
J. Ruz, M. D. Luque de Castro and M. Valcárcel

Abstract: Blood was subjected to normal or stopped-flow flow injection analysis by mixing with NAD+ and semicarbazide solution or 2,6-dichlorophenolindophenol, and the mixture was passed through immobilized alcohol dehydrogenase and dihydrolipoamide reductase (NAD+) with fluorimetric detection at 460 nm (excitation at 340 nm) or amperometric detection at 800 mV. The calibration graphs were rectilinear for 0.1 to 30.0 mL-1 of ethanol and the coefficient of variation were 0.64 to 1.45%.
Ethanol Fluorescence Immobilized enzyme Stopped-flow

"High-sampling-rate Automated Continuous-flow Fluorimetric Technique For Analysis Of Nanogram Levels Of Histamine In Biological Samples"
Anal. Biochem. 1983 Volume 133, Issue 1 Pages 16-29
B. Lebel

Abstract: The method is based on that of Shore et al. (J. Pharmacol. Exp. Ther., 1959, 127, 182), automated to allow 60 analyzes in 1 h. Flow schemes, one with and the other without dialysis, are presented. Histamine is caused to react with phthalaldehyde, and the fluorescence of the product is measured at 450 nm (excitation at 360 nm); peak heights and baseline corrections are calculated by a computerized system. The limit of detection is 25 pg, and the rectilinear calibration range is 0 to 5 µg mL-1 of histamine. The method has been applied to whole blood, tissues and cell cultures.
Histamine Fluorescence Dialysis

"Improved Blood Compatibility At A Glucose Enzyme Electrode Used For Extracorporeal Monitoring"
Anal. Lett. 1986 Volume 19, Issue 3&4 Pages 461-478
Hanning, I.;Vadgama, P.M.;Covington, A.K.;Alberti, K.G.M.M.

Abstract: For the continuous monitoring of glucose concentration. in blood a Clark oxygen electrode with a platinum working electrode (20 µm) and a silver - AgCl reference electrode (E 5046 Radiometer, Copenhagen) was connected to a Radiometer PHM 72b acid - base analyzer.. The O-permeable membrane of the Clark electrode was changed to a Cuprophan 100 PM membrane (Enka AG, Wuppertal, W. Germany). Enzyme membranes were prepared by cross-linking glucose oxidase to bovine serum albumin, and were retained behind the Cuprophan membrane. A diagram of the continuous-flow system for extracorporeal monitoring is shown. The detection limit for glucose was 0.02M. The use of silane-treated membranes improved sensitivity and prevented the coating of the electrode membrane with blood constituents.
Glucose Electrode Electrode

"Continuous-flow Determination Of Blood Alcohol Using Biamperometric Monitoring Of Enzymatic Reaction"
Anal. Lett. 1987 Volume 20, Issue 7 Pages 1099-1113
Attiyat, A.S.;Christian, G.D.

Abstract: A three-channel flow system was used, the first channel pumping NAD+ and dihydrolipoamide dehydrogenase(I), the second alcohol dehydrogenase(II) and K3Fe(CN)6 and the third diluted blood samples, all at the same flow rate. The three channels merged at a single point, thence passing through a flow cell containing two open-tubular carbon electrodes, with a potential difference of 200 mV. In the presence of ethanol and II, NAD+ was reduced to NADH; this was oxidized back to NAD+ by Fe(CN)63- in the presence of I. The Fe(CN)64- formed was detected at the electrodes. Blood samples were initially diluted 100-fold with 0.1 M Tris buffer (pH 8.5). The detection limit was 0.15 µg mL-1 of ethanol in blood and coefficient of variation were 4%. On eleven samples, correlation with a GC method was good (r = 0.98).
Ethanol Biamperometry Electrode Method comparison

"Determination Of Urea In Undiluted Blood Samples By Flow Injection Analysis Using Optosensing"
Anal. Lett. 1987 Volume 20, Issue 12 Pages 1977-1994
Petersson, B.A.;Andersen, H.B.;Hansen, E.H.

Abstract: The flow injection manifold is described and illustrated. It incorporates a hydrophobic gas-permeable membrane and a hydrophilic membrane between which is contained a gel of covalently immobilized urease. The carrier solution is 0.1 M Tris buffer (pH 9.2). The NH3 generated enzymatically is detected by absorbance at 635 nm of an acceptor solution containing 0.04% of bromothymol blue in aqueous 24% ethanol (pH 6.2 to 6.3) that flows past the gas-permeable membrane. The calibration graph is rectilinear up to 6 mM urea; the standard deviation was <2% (n = 160). Variation in pH (of physiological magnitude) did not affect the analysis. The activity of the membrane sandwich remained constant for 7 days of operation.
Urea Spectrophotometry Gas diffusion Immobilized enzyme Hydrophilic membrane Optosensing

"Evaluation Of An Enzymic Method For Determination Of Glucose In Whole Blood Using Flow Injection Analysis With Detection By Chemiluminescence"
Anal. Lett. 1989 Volume 22, Issue 1 Pages 83-100
Petersson, B.A.

Abstract: A flow injection manifold is described and illustrated that comprises an injection valve and detection and dialysis units. Particulate matter in samples was removed by a dialysis system containing a cellulose nitrate membrane. Glucose oxidase was immobilized on spherical glass beads (75 to 125 µm diameter; pore size 0.7 µm), which were then packed into a PVC column. The H2O2 formed was detected from the chemiluminescence produced by its reaction with alkaline 1 mM luminol in the presence of K3Fe(CN)6. The optimum reaction conditions used were as previously described (Ibid., 1986, 19, 649). A home-built luminometer with two photodiodes directly facing the flow channel of the flow-through cell was used. The calibration graph was rectilinear for 0.1 to 41 mM glucose, the sampling rate was 95 h-1, and the coefficient of variation was 1.5%. The system cannot be applied satisfactorily to blood owing to sensitivity of the response to the haematocrit level. A further problem is that the pressure drop over the enzyme reactor increases with time, thereby reducing the rate of glucose transfer across the dialysis membrane.
Glucose Chemiluminescence Dialysis Glass beads Photodiode Detector Apparatus

"Cyclic Enzymatic Determination Of L-lactate By Differential PH Measurement"
Anal. Lett. 1995 Volume 28, Issue 14 Pages 2475-2490
Compagnone, D.;Mosca, A.;Palleschi, G.

Abstract: An electrochemical procedure for the analysis of L-lactate based on the lactate dehydrogenase/lactate oxidase reaction cycle has been developed and applied in whole blood and wine. The reaction of lactate with lactate oxidase produces pyruvate, which is the substrate, at physiological pH, of the enzyme lactate dehydrogenase. This enzyme, in the presence of NADH, converts pyruvate to lactate consuming H+. An automated software controlled differential pH meter was used for H+ detection and the Delta pH measured was correlated to the lactate concentration present in the sample. (24 References)
l-Lactate Electrode Potentiometry Immobilized enzyme Indirect

"Amperometric Biosensors Based On NAD(P)-dependent Dehydrogenase Enzymes"
Electroanalysis 1997 Volume 9, Issue 3 Pages 191-202
Maria Jes&uacute;s Lobo, Arturo J. Miranda, Paulino Tu&ntilde;&oacute;n

Abstract: This review deals with the use of pyridine-nucleotide dependent dehydrogenase enzymes in amperometric biosensor design. The electrochemistry of the nicotinamide coenzymes, their mechanism and the challenges associated with their direct oxidation on solid electrodes are discussed. In addition, a survey of the different solutions proposed in the literature for addressing these problems and some of their applications are presented. 175 References
Amperometry Sensor Electrode Immobilized enzyme Review

"Fast Determination Of Whole Blood Glucose With A Calorimetric Micro-biosensor"
Sens. Actuat. B 1993 Volume 15, Issue 1-3 Pages 141-144
Bin Xie, Ulrika Hedberg, Michael Mecklenburg and Bengt Danielsson

Abstract: A calorimetric flow injection sensor was used to provide rapid determination of whole-blood glucose without pre-treatment. Glucose oxidase was immobilized together with catalase on controlled-pore glass beads in a micro-column (1.5 cm x 0.6 mm i.d.). When the sample was reduced in volume from 20 to 1 µL the linear range for glucose was increased from 0.5-2.5 mM to 0.5-20 mM. Results correlated well with those obtained with a Reflolux-S blood glucose analyzer.. The RSD (n = 100) was 3.7%. The sensor could be used for at least one month if stored at 4°C. The measurement period was 40 s and the device could be used to analyze 90 samples per hour.
Glucose Calorimetry Sensor Controlled pore glass

"Ion-selective Field-effect Transistors: Principles And Applications In Clinical Chemistry And Biology"
Anal. Proc. 1982 Volume 19, Issue 2 Pages 65-68
J. Janata

Abstract: The principles of operation of ion-selective field effect transistors (ISFET) have been recently reviewed.l For the purpose of this paper it suffices to realise that an ISFET is a device in which the ion-selective membrane is integrated with the solid-state pre-amplifier. A schematic diagram of this sensor is shown in Fig. 1 (a). A cross-section of the ISFET chip is shown in Fig. l(b) together with a schematic diagram of the whole package in Fig. l(c)....
Calcium pH Potassium Clinical analysis Field effect transistor Review

"Analysis Of Penicillins In Biological Material By Reversed-phase Liquid Chromatography And Post-column Derivatization"
Acta Pharm. Suec. 1979 Volume 16, Issue 3 Pages 187-214
Westerlund D, Carlqvist J, Theodorsen A.

Abstract: The procedure comprises injection of the biological fluid or homogenate after protein precipitation, separation by reversed phase liquid chromatography (LiChrosorb RP 8), post-column derivatization with air-segmentation and finally detection of the UV-absorbance at 310 nm. The derivatization involves formation of the mercuric mercaptide of penicillenic acid and is specific for penicillins with an intact ring system. The conditions for liquid chromatography and derivatization are optimized for the determination of ampicillin [69-53-4] and mecillinam [32887-01-7], but the method is general and may be adapted to any penicillin [1406-05-9] or cephalosporin [11111-12-9]. The influence of pH and MeOH content of mobile phase was systematically studied. By the injection of 100 mL plasma, ampicillin and mecillinam can be quant. determined at 100 ng/mL with a precision of 8%, but the sensitivity increases in direct proportion to the injected volume up to 2 mL. The method was applied to determinations in plasma, whole blood, urine and lymph.
Penicillins HPLC Spectrophotometry Post-column derivatization Optimization

"Flow Injection Analysis With Membrane Separation. Determination Of Ammonia In Blood And Urine"
Bunseki Kagaku 1984 Volume 33, Issue 10 Pages 505-509
Aoki, T.;Uemura, S.;Munemori, M.

Abstract: The sample, made alkaline with 1 M NaOH, was injected into the outer tube of a separation unit (shown diagrammatically), which comprised an inner micro-porous PTFE tube containing phthalaldehyde - 2-mercaptoethanol reagent, and an outer tube containing water. Ammonia permeated into the inner tube and the reaction product flowed into a flow cell for fluorimetric determination at 486 nm (370-nm excitation). Calibration graphs were rectilinear for 1 µM to ~1 mM NH3. Various compounds commonly found in blood and urine did not interfere. Recovery of NH3 was 95 to 108, 104 to 110 and 97 to 101% from whole blood, plasma and urine, respectively.
Ammonia Clinical analysis Fluorescence Gas diffusion Interferences Teflon membrane

"Clinical Evaluation Of Amperometric Enzyme Electrodes In Continuous-flow Analysis For Glucose In Undiluted Whole Blood"
Clin. Chem. 1990 Volume 36, Issue 9 Pages 1657-1661
H Gunasingham, CH Tan and TC Aw

Abstract: We have evaluated the carbon-paste enzyme/wall-jet electrode in continuous-flow analysis for glucose in undiluted whole blood. Responses of the electrode to protein-based and aqueous samples under wall-jet configuration are described. Imprecision in the flow injection mode was less than 2% for glucose values in the usual analytical range (1-25 mmol/L). The dynamic range for glucose was from 0.03 to 45 mmol/L, with about 100% recovery of added substrate. The performance of the electrode (y) in flow injection and steady-state modes was compared with a colorimetric method (x; Kodak Ektachem XR700), yielding linear-regression equations of y = 1.152x + 0.295 and y = 0.979x + 0.500, respectively. Among the anticoagulants, blood preservatives, and interfering substances investigated, only ascorbic acid gave a significant positive bias. The electrode exhibited good stability for analyzes of undiluted whole-blood samples.
Glucose Amperometry Electrode Electrode Electrode Clinical analysis Interferences Method comparison

"Urea And Lactate Determined In 1-mu-L Whole-blood Samples With A Miniaturized Thermal Biosensor"
Clin. Chem. 1994 Volume 40, Issue 12 Pages 2282-2287
Bin Xie,' Ulrika Harborn, Michael Mecklenburg, and Bengt Danielsson

Abstract: A miniaturized flow injection thermal biosensor was developed for the determination of urea and L-lactate in undiluted blood in 1 µL samples. The sensor employed a small enzyme column constructed of stainless steel tubing and microbead thermistors. Urease and lactate oxidase/catalase were separately immobilized onto controlled-pore glass beads, which, in turn, were charged into the enzyme column. With a flow rate of 70 µL/min, linear analytical ranges from 0.2 to at least 50 mmol/L and 0.2 to 14 mmol/L were obtained for urea and lactate, respectively. The relative standard deviations (CVs) for measurements of analyte in buffer were 0.91% for urea and 1.84% for lactate. For urea in whole blood, the CV for 50 determinations was 4.1%. Contrived samples containing various concentrations of urea and L-lactate in whole blood were determined with this sensor and with a spectrophotometric method. Comparisons of the results gave correlation coefficients of 0.989 and 0.984 for 30 blood urea and 30 blood lactate assays in concentrations ranging from 4 to 20.9 mmol/L and from 1.7 to 12.7 mmol/L, respectively.
Urea Lactate Sensor Thermistor Clinical analysis Method comparison Immobilized enzyme Column Controlled pore glass

"Electrochemical Dehydrogenase-based Homogeneous Assays In Whole Blood"
Clin. Chem. 1995 Volume 41, Issue 4 Pages 591-598
Jlaiou Yao, H. Brian Halsall, William R. Heineman, and Sarah H. Jenkins

Abstract: An electrochemical method was developed for the determination of NADH in whole blood using dehydrogenase-based assays in a flow injection system. The Emit theophylline (I) EIA (Syva Co., San Jose, CA, USA) and the hexokinase glucose (II) assay (Sigma) were used as models. NADH was oxidized by an electron-transfer coupling reagent, 2,6-dichloroindophenol (III), and the reduced form of III was measured amperometrically by flow injection analysis (details given). Detection was with a glassy C working electrode held at 200 mV vs. an Ag/AgCl reference electrode; a stainless-steel auxiliary electrode was used. Results, including calibration data, detection limits, RSD and recoveries are presented. Results agreed well with those obtained by reference methods. An electrochemical method has been developed for determining NADH in whole blood for dehydrogenase-based assays by flow injection analysis. NADH generated by dehydrogenase is oxidized by an electron-transfer coupling reagent, 2,6-dichloroindophenol (DCIP). The reduced form of DCIP (DCIPH2) is measured amperometrically by flow injection analysis. Endogenous interferents were inhibited by p-hydroxymercuribenzoate. Electrode fouling by proteins was not observed under assay conditions. The Emit theophylline enzyme immunoassay and the hexokinase glucose assay were used as models. For the glucose assay, the intraassay CVs were 15% at 0.31 g/L and 3.5% at 1.82 g/L. Recoveries of glucose from whole blood (compared with that for aqueous standards) were 109%, 97.9%, and 101% at 0.050, 2.00, and 5.00 g/L glucose, respectively, and 104%, 101%, and 102% for theophylline at concentrations of 5.0 (low), 16.4 (medium), and 30.2 (high) mg/L, respectively, with corresponding precisions of 12%, 9.5%, and 8.8%. Both assays correlated well with results by reference methods. These studies demonstrate that this method can measure NADH in whole blood without prior separation and that it is potentially applicable to other dehydrogenase-based assays in whole blood.
Glucose Nicotinamide adenine dinucleotide reduced Amperometry Electrode Clinical analysis Method comparison Interferences

"Rapid Determination Of Ammonia In Whole Blood And Plasma Using Flow Injection Analysis"
Clin. Chim. Acta 1982 Volume 119, Issue 1-2 Pages 7-14
Gunilla Svensson* and Torbj&ouml;rn Anf&auml;lt

Abstract: A flow injection method for the determination of ammonia in whole blood and plasma is described. The method utilizes diffusion of ammonia into a stream of a pH-sensitive indicator, which is monitored by a photometer. A volume of 90 µL is needed and the result is obtained within 1 min. Ammonia concentrations increase during storage due to deamination. It is proposed to use plasma samples, which could be stored frozen at -20°C without significant change.
Ammonia Clinical analysis Spectrophotometry Gas diffusion

"An Oxygen-based Enzyme Electrode For Whole Blood Lactate Measurement Under Continuous-flow Conditions"
Clin. Chim. Acta 1986 Volume 155, Issue 3 Pages 295-308
Mark R. Weaver and Pankaj M. Vadgama

Abstract: The enzyme electrode was prepared by immobilizing lactate 2-monooxygenase from Mycobacterium smegmatis on a Millipore ultra-filtration membrane which was applied to the gas-permeable membrane of an O sensor (Radiometer E5046 pO2 electrode). The electrode was housed in a measuring chamber (Radiometer D616) for continuous-flow analysis and an AutoAnalyzer II proportioning pump was used to construct a flow system designed to achieve a blood dilution of 1:40. Response was rectilinear up to 0.8 mM. Results for serum and plasma correlated well with those by a routine fluorimetric method (r = 0.959 and 0.952, respectively). This system permits reagentless continuous in vivo extracorporeal lactate monitoring.
Lactate Clinical analysis Electrode Method comparison Millipore

"Determination Of Cadmium In Human Blood Using A Flow Injection Graphite-furnace AAS System With Online Preconcentration By Dithizone (DTZ) Coprecipitation"
Fenxi Shiyanshi 1992 Volume 11, Issue 6 Pages 5-9
Dong, L.P.;Fang, Z.L.

Abstract: Sample (1 ml) was placed in a PTFE crucible, treated with 6 mL of HNO3 - HClO4 (10:1) and heated at 170°C to near dryness. The residue was transferred into a 15 mL polyethylene tube with hot water, mixed with 1 drop of 1% thiosalicylic acid, the solution was adjusted to pH 2 to 3 with sodium acetate saturated solution and treated dropwise with 2% ascorbic acid until the red color disappeared. After addition of 3 drops of 2% ascorbic acid, the solution was diluted to 10 mL with water. The solution was used for online pre-concentration. by DTZ co-precipitation and flow injection graphite - furnace AAS (flow diagram and procedure program given). Detection limit was 3 µg mL-1 of Cd with coefficient of variation (n = 7) of 2.6%. The results obtained compared well with certified values.
Cadmium Sample preparation Spectrophotometry Coprecipitation Preconcentration Reference material Dithizone

"Continuous-flow Quantification Of Total Mercury In Whole Blood, Plasma, Erythrocytes And Urine By Inductively Coupled Plasma Atomic-emission Spectroscopy"
J. Anal. Toxicol. 1992 Volume 16, Issue 2 Pages 99-101
Buneaux F, Buisine A, Bourdon S, Bourdon R.

Abstract: For the determination of Hg, blood and urine underwent sample preparation (details given), before dilution with aqueous NH3 buffer and reduction by sodium borohydride at pH 9.5. The reduced mixture was analyzed by ICP-AES; the test material sample was not nebulized into the torch, but the Hg vapor was collected in a reactor vial and swept into the plasma by the carrier gas (Ar) using a glass apparatus (described). An oxidative mineralization was not required. Optimization of the experimental conditions is discussed. The separation of liquid and gaseous phases decreased background noise and increased the sensitivity of the method; the detection limit was 4 µg l-1. The coefficient of variation (n = 9) was 9% for 35 µg L-1 of Hg. Recoveries were quantitative. The method can be used for routine determinations but it is recommended that a specific standardization is first performed. Mercury determination in blood and urine can be performed by inductively coupled plasma atomic emission spectroscopy after dilution in an ammonia buffer and reduction by sodium borohydride. The proposed method does not need an oxidative mineralization. The sample is not nebulized into the torch, but the mercury vapor, after collection in a reactor vial, is swept into the plasma by the argon carrier gas using the described glass app.
Mercury Spectrophotometry Optimization Volatile generation Phase separator Volatile generation

"Determination Of Mercury In Urine And Whole Blood By Flow Injection Analysis-cold Vapor Atomic Absorption Spectrometry"
J. Flow Injection Anal. 1992 Volume 9, Issue 1 Pages 13-19

Abstract: A flow injection cold vapor atomic absorption spectrometric method for the determination of mercury in urine and whole blood was devised. The calibration graph is linear up to 25 µg/L with a detection limit of 0.1 µg/L (0.1 mg of mercury). The relative standard deviation varied between 1.4 and 1.7%. The values obtained by this method were in good agreement with the certified values. The mean urine and blood contents of 128 unexposed human subjects were 1.0 and 2.5 µg/L, respectively.
Mercury Spectrophotometry Reference material

"Effect Of Surfactants And Of Ultrasonic Mixing In The Determination Of Calcium, Magnesium, Copper And Zinc In Whole Blood By Flow Injection Flame Atomic Absorption Spectrometry"
J. Trace Elem. Med. Biol. 1995 Volume 9, Issue 1 Pages 49-54
Rondon CE, Burguera M, Burguera JL, Brunetto MR, Carrero P

Abstract: The behavior of five non-ionic surfactants of different chain lengths was studied in relation to the improvement in sensitivity that their use affords as a sample pre-treatment procedure for the determination of calcium, magnesium, copper and zinc in real samples by flow injection flame atomic absorption spectrometry. The results show that the sensitivity changed with surfactant concentration, length of the hydrophobic chain and ultrasonic agitation time. Higher outputs were obtained with Triton X-100, which is the surfactant with the shortest chain length. In this case, the sensitivity of the atomic absorption signal increased 2.2, 2.2, 2.3 and 2.5-fold for aqueous solutions of calcium, magnesium, copper and zinc, respectively. The data also showed that ultrasonic agitation of the sample probe considerably improved the sensitivity, regardless of the element under evaluation. A relative precision between 0.6 and 3.3% was achieved with a smaller sample consumption than by the conventional atomic absorption method. The results obtained from the proposed sample pre-treatment procedure for the analysis of the elements under study were in good agreement with those obtained by microwave-assisted mineralization and flow injection AAS (for zinc and copper) and flame AAS (for calcium and magnesium).
Calcium Magnesium Copper Zinc Sample preparation Spectrophotometry Surfactant Triton X Optical fiber Method comparison

"Portable System For Simultaneous Measurements Of Blood Electrolytes"
Proc. Eur. Dial. Transplant Assoc. 1980 Volume 17, Issue 1 Pages 179-185
J Harrow, J Janata, R L Stephen, W J Kolff

Abstract: Miniature, rugged Chemfet sensors have been developed by coating field-effect transistors with ion-sensitive membranes. These sensors have been combined with a flow injection analysis manifold to demonstrate feasibility of a small portable system capable of simultaneous determinations in 10 seconds of hydrogen, potassium and calcium ion activities in 20 µL samples of whole blood, serum or dialysate.
Electrolytes Calcium Potassium pH Field effect transistor Potentiometry Portable

"Segmental Flow Injection Analysis, A Hybrid Technique Of Segmented Continuous-flow Analysis And Flow Injection Analysis"
Trends Anal. Chem. 1998 Volume 17, Issue 7 Pages 411-417
Zheng-liang Zhi

Abstract: A review with 26 references. The use of a segmental flow injection analysis (SFIA) system, a hybrid of segmented continuous-flow anal. (SCFA) and flow injection analysis (FIA) that integrates the essential favorable merits of FIA and SCFA, can significantly expand the application scope of flow anal. techniques by facilitating determinations with relatively slow reactions and/or requiring reaction at elevated temps. The higher dispersion with longer residence times inherent in flow injection systems can be feasibly and efficiently improved by adopting the SFIA technique. The principle behind this technique, some innovative designs of the devices for SFIA sampling and segmentation, and for bubble removing, as well as novel applications to a variety of anal. problems, are reviewed and discussed. Some salient features and unique advantages of this technique are outlined.
Electrochemical analysis Spectrophotometry Segmented flow Review Debubbler Theory