Determination of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in hair using gas chromatography/tandem mass spectrometry in negative ion chemical ionization mode

2007 ◽  
Vol 21 (7) ◽  
pp. 1339-1342 ◽  
Author(s):  
Jin Young Kim ◽  
Moon Kyo In
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Carboxylic Acid ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Negative Ion Chemical Ionization ◽  
Ionization Mode

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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