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
Email: schalk@unf.edu
Website: @unf

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Journal of Mass Spectrometry

  • Publisher: Wiley
  • FAD Code: JMSY
  • CODEN: JMSPFJ
  • ISSN: 1076-5174
  • Abbreviation: J. Mass Spectrom.
  • DOI Prefix: 10.1002/jms
  • Language: English
  • Comments: Fulltext from 1968 V1

Citations 16

"Chiral Analysis By Mass Spectrometry Using The Kinetic Method In Flow Systems"
J. Mass Spectrom. 2006 Volume 41, Issue 4 Pages 499-506
Karel Lemr *, Václav Ranc, Petr Fryák, Petr Bedná, Juraj evík

Abstract: Chiral analysis is an important task of analytical chemistry. Besides separation techniques, mass spectrometry can be applied in this field. One mass spectrometric approach is based on Cooks' kinetic method. The method was successfully applied in a static system in which the concentration of the analyte as well as the chiral selector solution was constant during the experiment. The application of the kinetic method in dynamic systems (changing concentration of analyte) is presented. Such systems allow the speeding up of the analytical process (flow injection analysis (FIA)) or the use of the kinetic method for chiral detection after liquid chromatographic separation. The influence of the concentration of the components of the chiral selector solution as well as its flow rate on the recognition of enantiomers was evaluated. A new procedure for correction for the differences between ratio of enantiomers in the liquid phase and their observed ratio in the gas phase is also described. A significant improvement in accuracy using this procedure was achieved. Applicability of the method was demonstrated in the analysis of amino acids using FIA as well as HPLC/MS. After an achiral separation of leucine and isoleucine, chiral mass spectrometric detection was successfully used for enantiomeric recognition.

"Analysis Of 10B Antitumoral Compounds By Means Of Flow-injection Into ESI-MS/MS"
J. Mass Spectrom. 2005 Volume 40, Issue 12 Pages 1546-1549
F. Basilico, W. Sauerwein, F. Pozzi, A. Wittig, R. Moss, P. L. Mauri*

Abstract: Boron neutron capture therapy (BNCT) is a promising binary treatment for cancer. BNCT is based on the ability of the nonradioactive isotope 10B to capture, with a very high probability, thermal neutrons. This nuclear reaction results in two particles (an α and a lithium nucleus). The particles have a high biological effectiveness, which is limited in tissue to approximately the diameter of one cell. If the reaction can be limited to a tumor cell, the physical characteristic opens up the possibility to selectively destroy cancer cells, while sparing the surrounding healthy tissue. Quality control of 10B-containing compounds and their distribution at present are very important, and different analytical methods have been developed, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS), electron energy loss spectrometry (EELS), prompt gamma analysis and inductively coupled plasma-optical emission spectrometry (ICP-OES). These methods allow the analyzes of 10B, but it is not possible to characterize the specific molecular compounds containing 10B. For this reason, we propose a fast and quantitative method that permits the determination of closo-undecahydro-1-mercaptododecaborate (BSH) and 10boron-phenylalanine (BPA) and their eventual metabolites. In particular, 10B-containing compounds are detected by means of flow-injection electrospray tandem mass spectrometry (FI/ESI-MS/MS). This approach allows the identification of Boron compounds, BSH and BPA, using tandem mass spectrometry, and quantitative analysis is also possible (c.v. ±4.7%; n = 5; linear range 10^-10 000 ng/ml). Furthermore, 10B-containing compounds were detected in actual biological sample (urine and plasma, diluted 10 000- and 1000-fold, respectively) injecting a small volume (1 µL) of diluted samples.

"Borate-nucleotide Complex Formation Depends On Charge And Phosphorylation State"
J. Mass Spectrom. 2004 Volume 39, Issue 7 Pages 743-751
Danny H. Kim, Kym F. Faull, Andrew J. Norris, Curtis D. Eckhert

Abstract: Flow injection analysis with electrospray ionization mass spectrometry was used to investigate borate-nucleotide complex formation. Solutions containing 100 ?M nucleotide and 500 ?M boric acid in water-acetonitrile-triethylamine (50:50:0.2, v/v/v; pH 10.3) showed that borate complexation with nicotinamide nucleotides was significantly influenced by the charge on the nicotinamide group and the number of phosphate groups on the adenine ribose. Borate binding decreased in the order of NAD+, NADH, NADP+ and NADPH. To investigate the relationship between complex formation and phosphorylation, association constants (KA) of borate-adenine (AMP, ADP, ATP), -guanine (GMP, GDP, GTP), -cytidine (CMP, CDP, CTP) and -uridine (UMP, UDP, UTP) complexes were compared. The results showed that the number of nucleotide phosphate groups was inversely proportional to the relative abundance of the borate complexes, with the KA of borate-nucleotide complex decreasing in the order mono-, di- and tri-phosphates (AMP ? GMP ? CMP ? UMP > ADP ? GDP ? CDP ? UDP > GTP > ATP ? CTP ? UTP). At pH 7.4, using ammonium bicarbonate buffer, only borate-NAD+ complex was observed. This indicates that the borate-NAD+ complex may be the most physiologically relevant of those studied.

"Exact Mass Measurement On An Electrospray Ionization Time-of-flight Mass Spectrometer: Error Distribution And Selective Averaging"
J. Mass Spectrom. 2003 Volume 38, Issue 10 Pages 1043-1053
Jiejun Wu, Heather McAllister

Abstract: An automated, accurate and reliable way of acquiring and processing flow injection data for exact mass measurement using a bench-top electrospray ionization time-of-flight (ESI-TOF) mass spectrometer is described. Using Visual Basic programs, individual scans were selected objectively with restrictions on ion counts per second for both the compound of interest and the mass reference peaks. The selected 'good scans' were then subjected to two different data-processing schemes ('combine-then-center' and 'center-then-average'), and the results were compared at various ion count limit settings. It was found that, in general, the average of mass values from individual scans is more accurate than the centroid mass value of the combined (same) scans. In order to acquire a large number of good scans in one injection (to increase the sampling size for statistically valid averaging), an on-line dilution chamber was added to slow down the typically rapid mass chromatographic peak decay in flow-injection analysis. This simple addition worked well in automation without the need for manual sample dilution. In addition, by dissolving the reference compound directly into the mobile phase, manual syringe filling can be eliminated. Twenty-seven samples were analyzed with the new acquisition and process routines in positive electrospray ionization mode. For the best method found, the percentage of samples with RMS error less than 5 ppm was 100% with repetitive injection data (6 injections per sample), and 95% with single injection data. Afterwards, 31 other test samples were run (with MW ranging from 310 to 3493 Da, 21 samples in ESI+ and 10 in ESI- mode) and processed with similar parameters and 100% of them were mass-calculated to RMS error less than 5 ppm also.

"Open-access Liquid Chromatography/mass Spectrometry In A Drug Discovery Environment"
J. Mass Spectrom. 2002 Volume 37, Issue 9 Pages 889-896
Larry M. Mallis, Ani B. Sarkahian, John M. Kulishoff Jr, William L. Watts Jr

Abstract: The use of open-access mass spectrometry to monitor synthetic chemistry reactions, and also the integrity and purity of new chemical entities, has been a part of the medicinal chemists tool-box for more than 5 years. Originally in our group at Wyeth Research there were two open-access methods available to the chemists, flow injection analysis (FIA) and liquid chromatography/mass spectrometry (LC/MS). The FIA method was similar to3 min long, while the LC/MS method was similar to20 min long (including an 8 min gradient). Within the first 2 years, the total number of open-access analyzes increased by similar to125%. It is interesting, however, that the number of LC/MS analyzes increased by more than 285%. This is attributed to the fact that the chemists began using the LC/MS data to monitor reactions and also to check final product integrity and purity. In addition, the number of chemists performing parallel synthesis reactions has increased; thus, individual chemists can produce sample sets of up to 100 vials. This paper describes the implementation of new methodology, which accommodates the need for much faster run times and also the ability to acquire alternating positive and negative ion spectra within the same run. In addition, the instrument has been configured to e-mail the resulting processed data report to the submitting chemist. Several methods have been developed, including structure elucidation using in-source collision-induced dissociation (CID) and night-time analysis. The LC/MS methods for this system are described herein and are applicable to both industrial and academic synthetic chemistry optimization efforts.
Synthesis

"Operation Of An Academic Open Access Mass Spectrometry Facility With Particular Reference To The Analysis Of Synthetic Compounds"
J. Mass Spectrom. 2002 Volume 37, Issue 8 Pages 777-785
John Greaves

Abstract: Open access mass spectrometry now provides the opportunity to move this spectroscopic method to the beginning of the analytical chain, a place formerly the exclusive province of NMR and TLC. To date this transition has been occurring in industrial settings but there has been less change in the academic environment. This paper provides one blueprint for setting up such a facility, primarily in support of organic synthesis but also for the use of biological scientists. The open access format used at UCI utilizes four instruments: an ESI-TOFMS system used in the flow injection mode, two GC/MS systems (one in EI and one in CI) and a MALDI-TOFMS system. The first three instruments have autosamplers and open access software whereas the MALDI system has a fully automated plate handling interface. This level of automation allows access to the instruments by a user community of more than 100 users, day or night. The decisions made in setting up these instruments were based on a keep it simple philosophy, given the fact that the primary type of data of interest is the molecular mass of the analyte and that data are required for a very wide range of structures.

"Crossing The Phase Boundary To Study, Protein Dynamics And Function: Combination Of Amide Hydrogen Exchange In Solution And Ion Fragmentation In The Gas Phase"
J. Mass Spectrom. 2002 Volume 37, Issue 6 Pages 557-565
Igor A. Kaltashov, Stephen J. Eyles

Abstract: Protein dynamics are the key to understanding their behavior. The static protein structure alone in most cases is insufficient to describe the vast array of complex functions they perform in vivo. Until recently there were relatively few techniques available to investigate the dynamic nature of these proteins. Mass spectrometry has recently emerged as a powerful biophysical method, capable of providing both structural and dynamic information. By utilizing the labile nature of amide hydrogens as a marker of the backbone dynamics in solution, combined with gas-phase dissociation techniques, we now have a high-resolution tool to locate these exchanging hydrogens within the sequence of the protein and to probe the functional importance of its structural elements. In this paper we describe several applications of these methodologies to illustrate the importance of dynamics to the biological functions of proteins.

"Environmental Applications Of Membrane Introduction Mass Spectrometry"
J. Mass Spectrom. 2002 Volume 37, Issue 5 Pages 457-476
Raimo A. Ketola, Tapio Kotiaho, Mary E. Cisper, Todd M. Allen

Abstract: The purpose of this review is to highlight the versatility of membrane introduction mass spectrometry (MIMS) in environmental applications, summarize the measurements of environmental volatile organic compounds (VOCs) accomplished using MIMS, present developments in the detection of semi-volatile organic compounds (SVOCs) and forecast possible future directions of MIMS in environmental applications.

"Electrospray Ionization Of Alkali And Alkaline Earth Metal Species. Electrochemical Oxidation And PH Effects"
J. Mass Spectrom. 2000 Volume 35, Issue 8 Pages 981-989
Andrew R. S. Ross, Michael G. Ikonomou, Kristin J. Orians

Abstract: The utility of electrospray ionization mass spectrometry (ESI-MS) for characterizing dissolved metal species has generated considerable interest in the use of this technique for metal speciation, However, the development of accurate speciation methods based on ESI-R;IS requires a detailed understanding of the mechanisms by which dissolved metal species are ionized during electrospray. We report how the analysis of alkali and alkaline earth metal species pro,ides new information about some of the processes that affect electrospray ion yield. Selected metal ions and organic ligands were combined in 50:50 water-acetonitrile buffered with acetic acid or ammonium acetate and analyzed by flow injection ESI-MS using mild electrospray conditions. Species formed by alkali metal ions with thiol and oxygen-donating ligands were detected in acidic and neutral pH solutions. Electrochemical oxidation of N,N-diethyldithiocarbamate and glutathione during electrospray was indicated by detection of the corresponding disulfides as protonated or alkali metal species, The extent of ligand oxidation depended on solution pH and the dissociation constant of the thiol group, Tandem mass spectrometric experiments suggested that radical cations such as [NaL](+.) (where L = N,N -diethyldithiocarbamate) can be generated by in-source fragmentation of disulfide species. Greater complexation of alkali metals at neutral pH tvas indicated by a corresponding decrease in the relative abundance of the free metal ion, The number of alkali metal ions bound by glutathione and phthalic acid also increased with increasing pH, in accordance with thermodynamic equilibrium theory. Alkaline earth metal species were detected only in acidic solutions, the absence of 8-hydroxyquinoline complexes being attributed to their relative instability and subsequent dissociation during electrospray, Hence, accurate speciation by ESI-MS depends on experimental conditions and the intrinsic properties of each analyte, Copyright
Stoichiometry

"Modification Of Capillaries Coupled To Micro-flow Nebulizers: A New Strategy For On-line Interference Removal In Inductively Coupled Plasma Mass Spectrometry"
J. Mass Spectrom. 2000 Volume 35, Issue 7 Pages 891-896
Hans-Gerd Riepe, Milagros Gómez, Carmen Cámara*, Jörg Bettmer

Abstract: The application of interference removal within modified silica capillaries for the introduction of liquid samples by a micro-flow nebulizer into an inductively coupled plasma quadrupole mass spectrometer is described using the example of 103Rh and its mass interferences resulting from 63Cu (ArCu+), 87Rb (RbO+), 87Sr (SrO+) and 206Pb (Pb2+). A strong cation exchanger was covalently bound to the capillary surface and its ability to interact with cations in aqueous solution was investigated. At pH 7.0 the interfering elements can be selectively adsorbed within the capillaries without hampering the elution of Rh. The capillaries are easily regenerated by flushing with 10^-3 M hydrochloric acid in order to exchange retained cations for protons. Calibrations show no significant difference between the absence and presence of interfering elements, so the detection limit for Rh of 6.0 ng L-1 (3) is not influenced by adding up to a 100-fold excess of interferents. The method developed is compared with a mathematical correction model for inductively coupled plasma mass spectrometry using the example of Rh determination in particulate car exhaust fumes and the results obtained are discussed.

"Quantitative Determination Of SC-68328 In Dog Plasma Using Flow Injection And Tandem Mass Spectrometry"
J. Mass Spectrom. 2000 Volume 35, Issue 3 Pages 354-360
Ji Y. Zhang, Douglas M. Fast, Grant L. Schoenhard, Vinod K. Arora, Frank J. Belas, Ian A. Blair

Abstract: A flow injection/tandem mass spectrometric assay was developed to quantitate SC-68328 in dog plasma using its stable isotopic analog [C-13(4)]SC-68328 as an internal standard (IS), Since SC-68328, a manganese-based superoxide dismutase mimetic, is very unstable, very polar and adheres to silica-based high-performance liquid chromatographic columns, the analyte and IS were derivatized to their bis-isothiocyanate forms followed by a liquid-liquid extraction with methylene chloride and analyzed using positive Ion electrospray mass spectrometric detection. SC-68328 was quantitated using the peak-height ratio of SC-68328 to its IS using MS/MS in the multiple reaction monitoring mode. The loner Limit of quantitation of the assay was 0.25 µg mL-1 SC-68328 in dog plasma with an inter-day precision of 11.8% and an accuracy of 113% (n = 12). Acceptable precision and accuracy were also obtained for concentrations in the calibration curve range (0.25-10 µg mL-1 SC-68328 in dog plasma), Copyright

"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 Supported liquid membrane Interface Optimization Silicone membrane

"Identification Of Carbamates By Particle Beam/mass Spectrometry"
J. Mass Spectrom. 1997 Volume 32, Issue 1 Pages 43-54
Jaroslav Slobodník, Maria E. Jager, Sacha J. F. Hoekstra-Oussoren, Maarten Honing, Ben L. M. van Baar*, Udo A. Th. Brinkman

Abstract: The possibility of analyzing 33 carbamate pesticides and 14 of their transformation products was investigated utilizing flow injection particle beam/mass spectrometry (PBMS) with electron impact (EI) ionization and ammonia and methane positive and negative chemical ionization (CI). Optimum operating conditions of the interface and mass spectrometer in each mode were determined, with special attention given to spectrum quality; variables investigated included ion source temperature and ion source pressure in CI experiments. Ammonia, as a reagent gas, provided less fragmentation and better quantitative results than methane. The CI response was generally higher with positive ion detection (PCI) than with negative ion detection (NCI), but NCI was found to be highly selective for compounds such as aminocarb, asulam and thiophanate-methyl. As regards analyte detectability, EI performed best for most compounds, with the spectra providing relevant structure information. The response of more polar degradation products is generally larger by 2-3 orders of magnitude compared with the parent compounds. When analyzing real samples, the combined use of CI for molecular mass determination and EI for structure elucidation is required. The spectral information from this study and additional chromatographic data were used for the determination of low- and sub µg L-1 levels of the test carbamates in surface water.
Carbamates Surface Mass spectrometry

"High-performance Liquid Chromatography/continuous-flow Liquid Secondary Ion Mass Spectrometry Of Flavonoid Glycosides In Leguminous Plant Extracts"
J. Mass Spectrom. 1996 Volume 31, Issue 5 Pages 472-485
Lloyd W. Sumner*, Nancy L. Paiva, Richard A. Dixon, Paul W. Geno

Abstract: A method for the identification of flavonoid glycosides utilizing continuous-flow liquid secondary ion mass spectrometry (CF-LSIMS) is presented. Minimum detectable quantities (MDQs) were determined for three model flavonoid glycosides (rutin, naringin and esculin) by both positive ion direct insertion probe (DIP)-LSIMS (1.6 nmol, 1.7 nmol and 730 pmol, respectively) and positive ion CF-LSIMS (330 pmol, 340 pmol and 290 pmol, respectively). Optimization of CF-LSIMS instrumental parameters was performed using the model compound rutin. Parameters optimized included mobile phase composition, glycerol concentration, mobile phase flow rate, ion source temperature, acceleration lens potential (amplitude and polarity) and Cs+ primary ion energy. Final instrumental optimization yielded an MDQ of 1.0 ng (1.6 pmol) for rutin by flow-injection CF-LSIMS. The optimization parameters were utilized in the identification of flavonoid glucosides in alfalfa (Medicago sativaL) and chickpea (Cicer arietinum) extracts by high-performance liquid chromatography/CF-LSIMS. The results support the controversial identification of a major extract component as formononetin-7-O-glucoside-6-malonate as opposed to afrormosin-7-O-glucoside-6-malonate.
Glycosides, flavonoid Plant HPLC Mass spectrometry

"Evaluation Of Flow Injection Sample To Standard Addition Method For The Inductively Coupled Plasma Mass Spectrometric Determination Of Aluminum In Biological Tissues"
J. Mass Spectrom. 1996 Volume 31, Issue 4 Pages 427-432
A. G. Coedo*, M. T. Dorado, J. Ruiz, M. Escudero, J. C. Rubio

Abstract: Tissues were minced, dried and powdered. Portions (0.5 g) were oxidized with 4 mL HNO3 in a microwave apparatus, with a 7-step heating programme. The solution was evaporated almost to dryness, mixed with a solution containing 1 µg Sc(III) (internal standard to compensate for plasma and ion signal instability) and diluted to 25 mL with 0.1% HNO3. Portions (0.5 ml) of this solution were injected into the carrier (2.8 ml/min) containing an Al(III) standard of 20 ng/ml and 40 ng/nl of Sc(III) in 0.1% HNO3 and this was followed by the injection of 0.5 mL of a digestion blank. The injection valve was located a few cm away from the cross-flow nebulizer and the ions 27Al and 45Sc were measured. The sample concentration then corresponded to the difference between the signals for the sample (maximum) and the blank (minimum). The method has the advantages of requiring less sample, being quicker and minimizing salt deposition on the sample and skimmer cones. Results for reference materials were similar to those obtained by conventional standard additions. Recovery of 0.5-10 ppm Al(III) was close to 100%. The detection limit was 10 ppb.
Aluminum(III) Biological tissue Mass spectrometry Sample preparation Calibration Reference material Standard additions calibration

"High-sensitivity Liquid Chromatography-combustion Isotope Ratio Mass Spectrometry Of Fat-soluble Vitamins"
J. Mass Spectrom. 1995 Volume 30, Issue 3 Pages 466-472
Richard J. Caimi, J. Thomas Brenna*

Abstract: The sensitivity of high-precision liquid chromatography/combustion isotope ratio mass spectrometry (LC/C-IRMS) was improved by more than two orders of magnitude by modifications which permit optimization of flows. The lower limits for high precision are about 3 g of analyte on-column for flow injection and LC modes. Pneumatic aerosol spray coating was implemented and compared with simple dip coating. The signal enhancement for aerosol compared with dip coating is up fourfold at higher levels but drops to less than twofold at lower levels, while the dynamic range is extended at higher levels by fourfold at high sample load levels. LC separations for underivatized tocopherols, retinyl acetate and ergocalciferol are demonstrated with precision and accuracy of about 13C < 2.5% for replicates. This work demonstrates sensitivity useful for a wide range of LC analyzes and extends high-precision LC/C-IRMS to the determination of several fat-soluble vitamins.