Showing papers on "Atmospheric-pressure chemical ionization published in 1997"
TL;DR: A sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer that is applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke.
Abstract: We describe a sensitive and specific method for measuring cotinine in serum by HPLC coupled to an atmospheric pressure chemical ionization tandem mass spectrometer. This method can analyze 100 samples/day on a routine basis, and its limit of detection of 50 ng/L makes it applicable to the analysis of samples from nonsmokers potentially exposed to environmental tobacco smoke. Analytical accuracy has been demonstrated from the analysis of NIST cotinine standards and from comparative analyses by both the current method and gas chromatography/high-resolution mass spectrometry. Precision has been examined through the repetitive analysis of a series of bench and blind QC materials. This method has been applied to the analysis of cotinine in serum samples collected as part of the Third National Health and Nutrition Examination Survey (NHANES III).
316 citations
TL;DR: A survey of the acylglycerol components of a range of vegetable oils (blackcurrant, blue poppy seed, evening primrose, extra virgin olive, hazelnut, maize and rapeseed) carried out using HPLC/APCI-MS is reported in this article.
Abstract: High performance liquid chromatography in conjunction with atmospheric pressure chemical ionization mass spectrometry (HPLC/APCI-MS) enables the positional isomers of individual triacylglycerols in mixtures to be identified. Application of HPLC/APCI-MS to the analysis of soybean oil allowed thirty nine triacylglycerols and seven diacylglycerols to be positively identified. The compounds present were quantified and the distribution of fatty acids in the ‚-position calculated. This distribution compared favourably with that obtained using a more conventional regiospecific lipase degradation of the oil. A survey of the acylglycerol components of a range of vegetable oils (blackcurrant, blue poppy seed, evening primrose, extra virgin olive, hazelnut, maize and rapeseed) carried out using HPLC/APCI-MS is reported. © 1997 by John Wiley & Sons, Ltd.
184 citations
TL;DR: This group has recently expanded the use of quantitative LC/MS/MS into the area of discovering new substances as potential drug candidates and screened over 400 compounds in two different target classes in a period of 24 weeks.
Abstract: Liquid chromatography, combined with tandem mass spectrometry (LC/MS/MS) has been rapidly embraced by the pharmaceutical industry as the definitive method for the determination of drug levels in biological fluids obtained from pharmacokinetic and toxicological studies. This technique has proved to be reliable, accurate and precise for the determination of drugs and related substances (e.g. metabolites and isotope-labeled compounds) in support of preclinical and clinical studies. Our group has recently expanded the use of quantitative LC/MS/MS into the area of discovering new substances as potential drug candidates. When used as an accurate mass detector, triple quadrupole instruments have the ability to simultaneously and specifically detect minute quantities of closely-related drug substances in the extracts of biological fluids. Analytical procedures have been developed and validated that simultaneously determine plasma concentrations of up to 12 drug candidates over a concentration range of 1–1000 ng mL−1 in single analytical occasions. This approach is used to support drug discovery by rapidly providing pharmacokinetic data to a wide range of compounds following either the administration of multiple compounds to single animals, or by increasing the speed and efficiency of analyzing samples following the administration of single compounds to multiple animals. Currently, we have screened over 400 compounds in two different target classes in a period of 24 weeks. A standard operating procedure defining the acceptability of quality control data obtained during such screening experiments is described. © 1997 John Wiley & Sons, Ltd.
154 citations
TL;DR: In this article, the best sensitivity and the lowest detection limit for all three groups were obtained by using a mobile phase consisting of methanol and 1%-2% acetic acid in water.
144 citations
TL;DR: Target compound analyses of river water allowed the confirmation of the presence of herbicides such as diuron, simazine, atrazine and terbutylazine at sub-microgram/l levels.
113 citations
TL;DR: The method appeared very selective and may be used for the routine determination of opiates in body fluids of heroin abusers and patients treated with opiates.
109 citations
103 citations
TL;DR: A simple and selective method for the determination of anandamide (arachidonoylethanolamide) and its analogs with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) was developed and was applied to their determination in rat brain and peripheral tissues.
89 citations
TL;DR: In this article, an automated on-line immunosorbent phase extraction method was developed and validated for the analysis of triazine and phenylurea herbicides in environmental matrixes such as sediments and natural waters.
Abstract: A new automated on-line immunosorbent phase extraction method was developed and validated for the analysis of triazine and phenylurea herbicides in environmental matrixes such as sediments and natural waters. This method is a first application and consists of trace analyte extraction using an immunosorbent columncontaining either anti-atrazine or anti-chlortoluron antibodiescombined with a liquid chromatograph by use of an on-line sample preparation system coupled directly to an atmospheric pressure chemical ionization/mass spectrometer in positive mode of operation. After the percolation of 20 mL of water through the immunosorbent columns, high recoveries of extraction were obtained for all the compounds with the exception of deisopropylatrazine and diflubenzuron. Calibration curves were linear in the range between 0.01 and 0.2 μg/L in groundwater. The limits of detection ranged from 0.001 to 0.005 μg/L, indicating good sensitivity achieved by both types of immunosorbents. Environmental sediment samples ...
84 citations
TL;DR: An automated method for trace level determination of 19 priority phenols in water samples has been developed using on-line liquid/solid extraction followed by liquid chromatography/mass spectrometry (LC/MS) with atmospheric pressure chemical ionization (APCI) and ion spray (ISP) interfaces in the negative ionisation (NI) mode as discussed by the authors.
Abstract: An automated method for trace level determination of 19 priority phenols in water samples has been developed using on-line liquid/solid extraction followed by liquid chromatography/mass spectrometry (LC/MS) with atmospheric pressure chemical ionization (APCI) and ion spray (ISP) interfaces in the negative ionization (NI) mode. Sixteen phenols were determined by LC/APCI-MS with high sensitivity. Three compounds were not detected by APCI-MS: phenol, 4-methylphenol, and 2,4-dimethylphenol could only be determined by ISP-MS using a porous graphitic carbon column with 100% of methanol as eluent. [M − H]- ion was the base peak using either LC/APCI-MS or LC/ISP-MS. Limits of detection ranging from 5 to 0.1 μg/L and 0.1−25 ng/L were found when 50−100 mL of river water was processed in full-scan and time-scheduled SIM modes, respectively. The proposed analytical method was validated by participating in various interlaboratory exercises distributed by Aquachek (WRC, Medmenham, U.K.), using groundwater samples cont...
83 citations
TL;DR: This approach considerably reduces the number of animals needed to screen drug candidates and its power is illustrated by determination of the pharmacokinetics of 10 substances after their simultaneous administration to dogs.
Book•
31 Dec 1997
TL;DR: In this article, the authors present a survey of atmospheric pressure ionization techniques and their application in the field of field desorption and field ionization, including Thermospray Ionization Matrix Assisted Laser Desorption Ionization.
Abstract: Introduction Atmospheric Pressure Ionization Techniques - Electrospray Ionization and Atmospheric Pressure Chemical Ionization Electron Impact and Chemical Ionization Fast Atom/Ion Bombardment Ionization, Continuous Flow Fast Atom/Ion Bombardment Ionization Field Desorption and Field Ionization Thermospray Ionization Matrix Assisted Laser Desorption Ionization Appendices Subject Index.
TL;DR: The utility of utilizing two different methods coupled with APCI-MS for the quantification and identification of ceramides in biological samples is demonstrated.
Abstract: Ceramides are intermediates in the biosynthesis of membrane sphingolipids. These biomolecules are also important as second messengers in signal transduction pathways controlling cell growth. We have developed two reversed-phase high pressure liquid chromatography (RPHPLC) techniques for identification and quantification of ceramides from mammalian cells. One method was based on atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) detection of ceramides and had the advantage of requiring minimal sample preparation, yielding significant structural information, and affording high sensitivity. The second method relied on perbenzoylation of the ceramides and detection at 230 nm. The predominant ceramides detected in the human leukemic HL-60 cell were N-(palmitoyl)-sphingosine, N-(nervonyl)-sphingosine, and N-(lignoceroyl)-sphingosine. When selected ion monitoring was used with RPHPLC/APCI-MS, approximately 2.2 pmol N-(palmitoyl)-sphingosine and 1.7 pmol N-(nervonyl)-sphingosine were observed in an extract from 40,000 HL-60 cells. Perbenzoylation with benzoyl chloride permitted RPHPLC separation and 230 nm UV absorbance detection of the trisbenzoyl derivatives of sphingosine, N-(palmitoyl)-sphingosine, N-(nervonyl)-sphingosine, and N-(lignoceroyl)-sphingosine in the HL-60 cells. These results demonstrate the utility of utilizing two different methods coupled with APCI-MS for the quantification and identification of ceramides in biological samples.
TL;DR: A case study of a patient admitted, with suspected primary hyperaldosteronism, on the basis of a high radioimmunoassay (RIA) aldosterone concentration is presented, suggesting that RIA was unreliable, causing unnecessary patient discomfort and a costly 6-day hospital stay.
TL;DR: The optimum LC-ES-MS and LC-APCI-MS conditions thus determined were used for a quantitative analysis of some phenolic compounds in spiked tap water and sea water samples.
TL;DR: In this article, a high performance liquid chromatographic/atmospheric pressure chemical ionization mass spectrometric (APCI-MS) method was developed for the determination of 10 pesticides.
Abstract: A high performance liquid chromatographic/atmospheric pressure chemical ionization mass spectrometric (APCI-MS) method has been developed for the determination of 10 pesticides. Initial comparison was made between the two atmospheric pressure ionization techniques, APCI and electrospray. Optimum separation of the compounds was obtained using a Hypersil carbamate column with a 0.05M ammonium acetate/acetonitrile isocratic elution at a flow rate of 0.5 mL/min. A positive/negative ionization mode switch was operated during each acquisition enabling the determination of 8 of the compounds in the positive ionization mode and 2 of the compounds in the negative ionization mode. The method was applied to the determination of all 10 compounds in extracts of strawberries and plums. Limits of detection were both compound and matrix dependent and ranged from 0.002–0.025 ng/μL in solvent-based standards and 0.003–0.05 ng/μL in matrix-matched standards (equivalent to 0.002–0.033 mg/kg in the crop). Where set, current Codex Alimentarius Commission and UK Maximum Residue Levels are clearly met by the sensitivity achieved by this method. © 1997 Crown Copyright
TL;DR: Full-scan mass spectra of drugs examined by means of APCI with collision induced dissociation (APCID) contained protonated molecular ions (M+H)+ and fragments typical for particular drugs.
Abstract: Amphetamine (A), methamphetamine (MA), methylene dioxyamphetamine (MDA), methylenedioxyethylamphelamine (MDE), and methylenedioxymethamphetamine (MDMA), as well as eight other sympathomimetic amines (benzyl-1-phenylethylamine, ephedrine, fenfluramine, norfenfluramine, phentermine, phenylethylamine, phenylpropanolamine, and propylhexedrine), were extracted from serum or urine with ether, derivatized with phenylisothiocyanate, and subjected to high-performance liquid chromatographic (HPLC) examination in isocratic mode. Two detection arts were applied: atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and UV-spectrometry as diode array detection (DAD) or single wavelength at 250 nm. The derivatives were well-separated and showed good chromatographic behavior. Full-scan mass spectra of drugs examined by means of APCI with collision induced dissociation (APCID) contained protonated molecular ions (M+H)+ and fragments typical for particular drugs. APCID-liquid chromatography-mass spectrometry (LC-MS) appeared very selective for differentiation of all drugs involved. The quantitation with APCID was performed using selected ion monitoring (SIM) of (M+H)+ ions and selected fragments of drugs involved and their deuterated analogues. The limits of detection ranged from 0.001 mg/L (MA, MDMA, and MDE) to 0.005 mg/L (A and MDA). In HPLC-DAD, the spectra of MDMA and MDE were practically identical with maxima of 236-240 nm. Other amphetamines showed slightly different spectra with maxima of 245-250 nm. The limits of detection in UV detection amounted to 0.01-0.03 mg/L (single wavelength detector at 250 nm) or 0.05-0.1 mg/L (DAD).
TL;DR: The most widely used liquid chromatography/mass spectrometry interfaces for carotenoid analysis are electrospray and atmospheric pressure chemical ionization (APCI) as discussed by the authors.
Abstract: The sensitivity, specificity and selectivity of liquid chromatography/mass spectrometry (LC/MS) and LC-tandem mass spectrometry (LC/MS/MS) make these essential tools for the characterization and identifkation of carotenoids. LC/MS analysis is particularly important for studies of carotenoids obtained from natural sources, since these compounds are usually present in trace quantities and are often contaminated with biological matrices. To date, five LC/MS techniques have been used for carotenoid analysis including 1) moving belt; 2) particle beam; 3) continuous- flow fast atom bombardment; 4) electrospray; and 5) atmospheric pressure chemical ionization (APCI). Among these LC/MS interfaces, electrospray and APCI are probably the easiest to use and are rapidly becoming the most widely available. These techniques provide comparable sensitivity (at the low pmol level) and produce abundant molecular ions. Whereas electrospray forms primarily molecular ions showing little fragmentation, APCI produces molecular ions and/or protonated or deprotonated molecules depending upon the mobile phase conditions. In addition, APCI produces abundant fragment ions, especially for xanthophylls. Although any of these LC/MS techniques may be combined with tandem mass spectrometry, the majority of LC/MS/MS effort to date has involved the use of continuous-flow fast atom bombardment.
TL;DR: In this article, the literature is reviewed with regard to packed column supercritical fluid chromatography (SFC) coupled directly with mass spectrometry (MS) using either analytical scale or microbore columns that have typically been used for liquid chromatography analysis.
TL;DR: In this article, the retention of five phenylurea herbicides (chlorotoluron, isoproturon, diuron, linuron and diflubenzuron) was evaluated by solid-phase extraction with an automated sample preparation (ASPEC) system using anti-isopropuron immunosorbents.
TL;DR: In this study, cooked meats containing incurred HAAs as well as control (microwave) meat, were spiked with four labeled HAA internal standards and extracted using a liquid/liquid cleanup procedure to provide accurate data on the consumption of HAAs in the diet for use in human cancer risk assessment.
Abstract: Heterocyclic aromatic amines (HAAs) are formed in cooked meats through pyrolysis reactions of different amino acids in the presence or absence of creatine/creatinine and sugars. HAAs are mutagens, colon/mammary gland carcinogens in rodents, and are suspected in the etiology of human cancers. In this study, cooked meats containing incurred HAAs as well as control (microwave) meat, were spiked with four labeled HAA internal standards (MeIQx, IQ, AAC and PhIP) and extracted using a liquid/liquid cleanup procedure. Isotope dilution measurements were made using on-line liquid chromatography atmosphere pressure chemical ionization tandem mass spectrometry with multiple reaction monitoring to provide the sensitivity and specificity needed for trace analysis in these complex matrices. The procedure was validated using control meat spiked with the four native HAAs at 0-50 ppb. The levels of HAAs found in cooked meats ranged from non-detectable (limit of detection 0.1-1.0 ppb) in microwave-cooked hamburger to 226 ppb PhIP and 104 ppb AAC in well-done grilled chicken. This methodology has the potential to provide accurate data on the consumption of HAAs in the diet for use in human cancer risk assessment.
TL;DR: Liquid chromatography/mass spectrometry (LC/MS), using ESI, APCI, or FAB as an ionization method, is currently the preferred method for the analysis of low- to high-molecular-weight substances in uremic blood.
Abstract: This article reviews the literature on the mass spectrometry (MS) that has been used in the research of uremic toxins. Gas chromatography/mass spectrometry (GC/MS) has been most often used for the analysis of low-molecular-weight compounds in uremic blood such as organic acids, phenols, and polyols. However, it cannot be used for the analysis of middle- to high-molecular-weight substances or for involatile compounds. The development of fast atom bombardment (FAB) and liquid secondary ion mass spectrometry (LSIMS) has made possible the analysis of middle-molecules and involatile low-molecular-weight substances such as peptides and nucleosides. The development of atmospheric pressure chemical ionization (APCI) has also lead to the analysis of involatile low-molecular-weight substances. The recent advances in ionization methods, such as electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI), have permitted the MS analysis of high-molecular-weight substances such as β2-microglobulin, a major component of dialysis amyloid. Liquid chromatography/mass spectrometry (LC/MS), using ESI, APCI, or FAB as an ionization method, is currently the preferred method for the analysis of low- to high-molecular-weight substances in uremic blood. ESI-LC/MS and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOFMS) are useful for elucidating the structure of post-translationally modified proteins obtained from the blood and tissues of uremic patients. Post-translational modification such as the formation of advanced glycation end-products and carbamoylation is enhanced in uremic patients, and is considered to be responsible for some uremic symptoms. Laser microprobe MS is unique in its capability for the two-dimensional detection of atoms such as aluminum in a tissue section obtained from uremic patients. This review focuses on the mainstream research for discovering uremic toxins, specific uremic toxins identified or quantified using MS, and the MS analysis of post-translationally modified proteins in uremia. These studies have provided ample evidence that MS has played an important role in the search for uremic toxins. © 1998 John Wiley & Sons, Inc., Mass Spec Rev 16, 307–332, 1997
TL;DR: In this article, a method for the characterization of complex mixtures of organic contaminants present in various industrial effluents is proposed, which consists of setting up a methodology based on solid phase extraction (SPE) using an Automated Sample Preparation with Extraction Columns system (ASPEC XL) and Lichrolut EN sorbent material.
Abstract: Contaminated industrial effluents often contain a variety of organic pollutants which are difficult to analyse by standard GC-MS methods since this technique often misses the more polar or non-volatile fraction of these organic compounds. In the present work a method for the characterization of complex mixtures of organic contaminants present in various industrial effluents is proposed. The protocol consists of setting-up a methodology based on solid phase extraction (SPE) using an Automated Sample Preparation with Extraction Columns system (ASPEC XL) and Lichrolut EN sorbent material for preconcentrating 300-500 ml of water volumes spiked with a variety of pollutants: phenolic compounds, benzophenone, isothiocyanate-cyclohexane, ethylbenzoate, 1 -methyl-2-pyrrolidinone, 2-methylbenzenesulphonamide, benzidines, acridine, 1,1,3,3-tetramethyl-2-thiourea, 2,2-dimethyl-1,3-propanediol, phosphates, phthalates and non-ionic detergents characterized by LC-MS using atmospheric pressure chemical ionization in the positive and negative ion modes. The developed protocol permitted unequivocal identification of target analytes such as pentachlorophenol, tributyl pbosphate, 4-nonylphenol, dibutylphthalate, dimethylphthalate, bis(2-ethylhexyl)phthalate, isothiocyanate-cydohexane, ethylbenzoate, 2-methylbenzene-sulphonamide, tetramethyl-thiourea, 2,2-dimethyl-1,3-propanediol and 1-methyl-2-pyrrolidinone at concentration levels varying from 0.16 to 54.4 μg l -1 .
TL;DR: In this paper, a matrix-assisted laser desorption/ionization and electrospray ionization are combined with chromatographic separations, and a series of mass spectra are acquired for each fraction of the distribution.
Abstract: Recent advances in soft ionization techniques for mass spectrometry of polymeric materials make it possible to determine the mass of intact molecular ions exceeding 1 × 10 6 Da. Developments in high resolution mass spectrometers have additionally led to impressive advances in our ability to characterize polymers. The entire molecular mass distribution of a polymer sample can be accurately measured. From the molecular mass, the molecular formulae and information regarding polymer composition and end-groups can be deduced. The two techniques which have received the most attention are matrix-assisted laser desorption/ionization and electrospray ionization. In recent work, these techniques have been combined with chromatographic separations, and a series of mass spectra are acquired for each fraction of the distribution. This simplifies the analysis by reducing the number of components present in each mass spectrum, and additionally improves quantitation.
TL;DR: In this paper, a solvent vapor-saturated nitrogen purge in an electrospray ionization source is demonstrated as a highly selective method for synthesizing clusters consisting of a transition-meta...
Abstract: Incorporation of a solvent vapor-saturated nitrogen purge in an electrospray ionization source is demonstrated as a highly selective method for synthesizing clusters consisting of a transition-meta...
TL;DR: A solid-phase extraction clean-up procedure was performed prior the LC-MS analysis due to the complexity of the sample and the compounds Glu-P-1, Harman, Norharman and A alpha C were identified in the samples at ppb levels and successfully confirmed using in-source fragmentation.
Patent•
31 Jan 1997TL;DR: In this paper, a cylindrical lens which extends along the side walls of the atmospheric pressure ionization chamber has been configured to be semitransparent for viewing into the chamber.
Abstract: Improvements have been made to the Electrospray and Atmospheric Pressure Chemical Ionization source chambers interfaced to mass spectrometers to simplify source performance optimization and source operation and to improve system sensitivity. The atmospheric pressure ion source procedure for optimizing performance has been simplified by adding windows along the sides of the atmospheric pressure ionization chamber allowing direct viewing of the Electrospray and Atmospheric pressure ion sources during operation. A cylindrical lens which extends along the side walls of the atmospheric pressure chamber has been configured to be semitransparent for viewing into the chamber. This cylindrical shaped side lens is electrically isolated from the Electrospray liquid introduction needle and Electrospray chamber endplate. Improved Electrospray mass spectrometer system sensitivity can be achieved when operating the cylindrical lens with a higher potential difference between it and the Electrospray liquid introduction needle than is set between the needle and the endplate.
TL;DR: In this article, the potential and limitations of these hyphenated analytical techniques are discussed using heterocyclic aromatic amines, fumonisins, acylated glycoconjugates and regioisomeric fatty acid hydroperoxides as examples.
Abstract: The development of techniques utilizing atmospheric pressure ionization, namely atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), has pioneered the coupling of liquid chromatography (HPLC) with mass spectrometry in recent years. Both ESI and APCI generate ions from polar and labile biomaterials with remarkable ease and efficiency. In particular, the use of HPLC with tandem mass spectrometry (MS-MS) opens further dimensions in the field of bioorganic analysis. Thus, HPLC-MS-MS provides the tools for direct elucidation of the structure and variety of polar natural compounds in complex matrices. In order to develop efficient and straightforward strategies for the analysis of polar natural products, the potential and the limitations of these hyphenated analytical techniques are discussed using heterocyclic aromatic amines, fumonisins, acylated glycoconjugates and regioisomeric fatty acid hydroperoxides as examples.
Patent•
26 Jun 1997TL;DR: In this paper, a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer is presented. But the interface is limited to the case where the separation buffer or solvent is a light absorbing component.
Abstract: The present invention provides a laser-induced vaporization and ionization interface for directly coupling microscale separation processes to a mass spectrometer. Vaporization and ionization of the separated analytes are facilitated by the addition of a light-absorbing component to the separation buffer or solvent.
TL;DR: In this article, a reversed-phase high-performance liquid chromatography (HPLC) coupled with atmospheric pressure chemical ionization mass spectrometry (APCI) was used to determine the molecular species compositions of triacylglycerols in complex natural mixtures.
Abstract: Triacylglycerols of oils rich in α- and/or γ-linolenic acids were analyzed by reversed-phase high-performance liquid chromatography (HPLC) coupled with atmospheric pressure chemical ionization mass spectrometry [(APCI)MS] The (APCI)MS spectra of most triacylglycerols exhibited [M + H]+ and [M - RCOO]+ ions, which defined the molecular weight and the molecular association of fatty acyl residues, respectively Reversed-phase HPLC resulted in, at least, partial separation of triacylglycerols containing α- and/or γ-linolenic acid moieties Molecules containing α-linolenic acid residues exhibited a relatively weaker retention by the stationary phase than the corresponding molecules containing γ-linolenic acid residues Good separation of triacylglycerols of cloudberry seed oil, evening primrose oil, borage oil, and black-currant seed oil was achieved The molecular species identification of separated components was based on the (APCI)MS data as well as on the elution properties of triacylglycerols on reversed-phase HPLC This study demonstrated the efficiency of HPLC-(APCI)MS in determining the molecular species compositions of triacylglycerols in complex natural mixtures Good quality mass spectra could be extracted even from minor chromatographic peaks representing 02% or less of the total triacylglycerols