scholarly journals Negative-Ion Chemical Ionization Gas Chromatography–Mass Spectrometry Assay for Enantioselective Measurement of Amphetamines in Oral Fluid: Application to a Controlled Study with MDMA and Driving Under the Influence Cases

2007 ◽  
Vol 53 (4) ◽  
pp. 702-710 ◽  
Author(s):  
Frank T Peters ◽  
Nele Samyn ◽  
Thomas Kraemer ◽  
Wim J Riedel ◽  
Hans H Maurer
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Chemical Ionization ◽  
Oral Fluid ◽  
Plasma Concentrations ◽  
Driving Under The Influence ◽  
Negative Ion ◽  
Gas Chromatography Mass Spectrometry ◽  
Controlled Study ◽  
Negative Ion Chemical Ionization

Abstract Background: Enantioselective analysis of amphetamine (AM), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) helps interpret toxicological results. Methods have been described for various matrices, but so far not for oral fluid, a matrix of increasing importance in testing for drugs of abuse, especially in the context of driving under the influence of drugs (DUID). Methods: After dilution with 200 μL carbonate buffer (pH 9), oral fluid samples (10–50 μL) were derivatized with S-heptafluorobutyrylprolyl chloride. The resulting diastereomers were extracted into 100 μL of cyclohexane, separated by gas chromatography (HP-5MS column), and detected by mass spectrometry in the negative-ion chemical ionization mode (GC-NICI-MS). The method was validated and applied to samples from a controlled study with MDMA and from authentic DUID cases. Results: The derivatized AM, MA, MDA, MDMA, and MDEA enantiomers were well separated from each other. The method was linear from 5–250 μg/L per enantiomer of MDA and from 25–1250 μg/L per enantiomer of AM, MA, MDMA, and MDEA. With the exception of MDEA, analytical recoveries, repeatability, and intermediate precision were within required limits. The analyte concentrations and enantiomer ratios in the application samples correlated only weakly with corresponding published plasma data. Conclusions: This sensitive, reliable, and fast GC-NICI-MS assay enantioselectively measures AM, MA, MDA, and MDMA in oral fluid samples. Prediction of plasma concentrations and enantiomer ratios from respective oral fluid data is not possible.

scholarly journals Analytical Variables Affecting Analysis of F2-Isoprostanes and F4-Neuroprostanes in Human Cerebrospinal Fluid by Gas Chromatography/Mass Spectrometry

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Hsiu-Chuan Yen ◽  
Hsing-Ju Wei ◽  
Ting-Wei Chen
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Cerebrospinal Fluid ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Gas Chromatography Mass Spectrometry ◽  
Ionization Mass ◽  
Negative Ion Chemical Ionization ◽  
Gold Marker

F2-isoprostanes (F2-IsoPs) are a gold marker of lipid peroxidationin vivo, whereas F4-neuroprostanes (F4-NPs) measured in cerebrospinal fluid (CSF) or brain tissue selectively indicate neuronal oxidative damage. Gas chromatography/negative-ion chemical-ionization mass spectrometry (GC/NICI-MS) is the most sensitive and robust method for quantifying these compounds, which is essential for CSF samples because abundance of these compounds in CSF is very low. The present study revealed potential interferences on the analysis of F2-IsoPs and F4-NPs in CSF by GC/NICI-MS due to the use of improper analytical methods that have been employed in the literature. First, simultaneous quantification of F2-IsoPs and F4-NPs in CSF samples processed for F4-NPs analysis could cause poor chromatographic separation and falsely higher F2-IsoPs values for CSF samples with high levels of F2-IsoPs and F4-NPs. Second, retention of unknown substances in GC columns from CSF samples during F4-NPs analysis and from plasma samples during F2-IsoPs analysis might interfere with F4-NPs analysis of subsequent runs, which could be solved by holding columns at a high temperature for a period of time after data acquisition. Therefore, these special issues should be taken into consideration when performing analysis of F2-IsoPs and F4-NPs in CSF to avoid misleading results.

Irace Level Detection of Chlorinated Paraffins in Biological and Environmental Samples, Using Gas Chromatography/Mass Spectrometry with Negative-Ion Chemical Ionization

1985 ◽  
Vol 68 (3) ◽  
pp. 427-430
Author(s):  
Peter P Schmid ◽  
Markus D Muller
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Environmental Samples ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry ◽  
Biological And Environmental Samples ◽  
Chlorinated Paraffins ◽  
Negative Ion Chemical Ionization

Abstract A method is described for detection of chlorinated paraffins (CPs) in biological and environmental samples. Sample preparation includes sulfuric acid treatment followed by adsorption chromatography on ilumina, which yields the CPs in one fraction that is almost free of interfering material. Using gas chromatography/mass spectrometry j with negative-ion chemical ionization, the limit of detection is 5 ng (corresponding to the lower ppb range). CP levels of 30 ppm, 200 ppb, ' and 5 ppb were found in sewage sludge, human fat, and sediment, respectively.

scholarly journals Comparison of Gas Chromatography-Mass Spectrometry and Gas Chromatography-Tandem Mass Spectrometry with Electron Ionization and Negative-Ion Chemical Ionization for Analyses of Pesticides at Trace Levels in Atmospheric Samples

2008 ◽  
Vol 3 ◽  
pp. ACI.S1005 ◽  
Author(s):  
Renata Raina ◽  
Patricia Hall
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Tandem Mass Spectrometry ◽  
Chemical Ionization ◽  
Detection Limits ◽  
Negative Ion ◽  
Gas Chromatography Mass Spectrometry ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Negative Ion Chemical Ionization

A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (OPs) and pre-emergent herbicides used in the Canadian prairies (triallate, trifluralin, ethalfluralin). The developed GC-EI/SIM, GC-NCI/SIM, and GC-NCI/SRM are suitable for the determination of pesticides in air sample extracts at concentrations <100 pg µL-1 (< 100 pg m-3 in air). No one method could be used to analyze the range of pre-emergent herbicides, OPs, and OCs investigated. In general GC-NCI/SIM provided the lowest method detection limits (MDLs commonly 2.5-10 pg µL-1) along with best confirmation (<25% RSD of ion ratio), while GC-NCI/SRM is recommended for use where added selectivity or confirmation is required (such as parathion-ethyl, tokuthion, carbofenothion). GC-EI/SRM at concentration < 100 pg µL-1 was not suitable for most pesticides. GC-EI/SIM was more prone to interference issues than NCI methods, but gave good sensitivity (MDLs 1-10 pg µL-1) for pesticides with poor NCI response (OPs: sulfotep, phorate, aspon, ethion, and OCs: alachlor, aldrin, perthane, and DDE, DDD, DDT).

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