Usefulness of Gas Chromatography/Negative Ion Chemical Ionization Mass Spectrometry for Detection of an Organophosphate Pesticide in a Victim

1986 ◽  
Vol 26 (4) ◽  
pp. 263-269 ◽  
Author(s):  
H. Hattori ◽  
O. Suzuki ◽  
M. Asano

A case is described of a 51-year old male found dead outdoors with froth around his mouth. The presence of aromatic smelling stomach contents suggested the presence of a toxic chemical. The blood, urine and stomach contents, after extraction with organic solvents, were subject to analysis by gas chromatography (GC)/mass spectrometry (MS) in the positive electron impact (EI) mode. The mass spectra showed peaks at m/z 320, 274 and 246. Negative chemical ionization (CI)/GC/MS was also carried out. The negative CI mass spectra of the chemical showed a large anion at m/z 157, which strongly suggested a dimethylphosphorodithioate group of an organophosphate. Therefore, we looked for a dimethylphosphorodiothioate commercially obtainable in Japan, which had a molecular weight of 320 or more. We finally identified the chemical in question as phenthoate (PAP). The present report demonstrates that GC/MS using negative CI in combination with positive EI is extremely useful in the identification of unknown compounds and in this case enabled the identification of the organophosphate pesticide (PAP). The high sensitivity of detection of organophosphates by negative CI/GC/MS was also demonstrated.

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Hsiu-Chuan Yen ◽  
Hsing-Ju Wei ◽  
Ting-Wei Chen

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.


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