Nachweis von Organophosphorinsecticiden durch Gas-Chromatographie-Massenspektrometrie

Stan, Hans‐Jürgen; Abraham, B.; Jung, Johannes; Kellert, M.; Steinland, K.

doi:10.1007/bf00634498

Cited by 40 publications

(8 citation statements)

References 7 publications

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“…2 and 3. The spectra coincided well with the data of malathion in the literature [5]. Thus, we measured the spectra of the authentic malathion in the negative CI and positive EI and CI modes as shown in Fig.…”

Section: Resultssupporting

confidence: 86%

Detection of malathion in a victim by gas chromatography/negative ion chemical ionization mass spectrometry

1985

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Summary.We experienced an autopsy case in which a 53-year-old woman committed suicide by ingesting allegedly a certain agricultural chemical. The blood and stomach contents, after extraction with acetonitrile and chloroform, were subjected to analysis by gas chromatography (GC)/negative ion chemical ionization (CI) mass spectrometry (MS). By total ion monitoring in the negative CI mode, a large peak appeared. The mass spectrum of the peak showed a strong anion at m/z 157, suggesting the presence of an organophosphorus pesticide. By measuring its spectrum in the positive electron impact (EI) mode, it was identified as malathion. The selected ion monitoring in the negative CI mode showed that the malathion peak was not interfered with by any impurities, and its background was very low. The sensitivity in the negative CI mode was about 5-10 times higher than that in the positive EI mode. Our data show that the GC/negative ion CI MS is useful for both screening and sensitive quantitation of organophosphorus pesticides.Key words: Malathion, mass spectrometry -Organophosphorus pesticide, malathion -Mass spectrometry, negative ion Zusammenfassung. Eine 53 Jahre alte Frau beging Selbstmord dutch Einnahme eines Schfidlingsbekfimpfungsmittels. Blut und Mageninhalt wurden mit Acetonitril und Chloroform extrahiert und mittels Gaschromatographie (GC)-negativer chemischer Ionisierung (CI)-Massenspektrometrie (MS) untersucht. Im negativen Ionenstrom-Diagramm trat ein groger Peak auf, das Massenspektrum zeigte ein m/z 157, was auf die Anwesenheit eines Organophosphat-Insektizids hinweist. Durch Untersuchung des Spektrums im positiven Ionenstrom-Diagramm wurde es als Malathion identifiziert. Im negativen Ionenstrom-Diagramm war der Malathion-Peak ohne Verunreinigungen darstellbar und zeigte nut einen geringftigigen Untergrund. Die Empfindlichkeit bei der Methode der negativen Ionisierung ist ca. 5-10fach hOher als bei positiver Ionisierung. Die Ergebnisse zeigen, dab GC in Ver-

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Section: Resultssupporting

confidence: 86%

Detection of malathion in a victim by gas chromatography/negative ion chemical ionization mass spectrometry

1985

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“…The electron impact mass spectra of the synthetic organophosphates agree with that reported by Stan et al (30). It has been suggested that the m/z 109 ionic species observed for both dimethyl and diethyl phosphates is not a homologous fragment for the two dialkyl p-nitrophenyl phosphates, but rather a different ion with the same m/z (30). The data we present suggest two different 109 fragments for each of the individual dimethyl and diethyl analogues: the separate phosphorus-containing species (30) as well as a homologous ion derived from the aromatic portion of the dialkyl p-nitrophenyl phosphates.…”

Section: Discussionmentioning

confidence: 99%

Species specificity in the chemical mechanisms of organophosphorus anticholinesterase activity

Wallace¹,

Kemp

1991

Chem. Res. Toxicol.

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Structure-activity relationships reveal that the two principal determinants of anticholinesterase activity for various organophosphorus insecticides are steric hindrance and the electrophilic strength of the phosphorus atom. The objective of the present investigation was to distinguish between the molecular properties governing species-related differences in organophosphorus sensitivity by comparing the physical-chemical relationships for the inhibition of brain acetylcholinesterase isolated from rats, chickens, or rainbow trout. A homologous series of five dialkyl p-nitrophenyl phosphates consisting of methyl through n-butyl and isopropyl were synthesized and characterized both chemically and biologically. Structure-activity correlations revealed that whereas steric hindrance is the principal factor governing inhibitory potency for rats and hens, the electrophilicity of the phosphorus atom is the principal determinant of anticholinesterase activity in trout. The inductive effect of successive methylene substitutions on the phosphoryl group is reflected by 13C and 31P NMR spectroscopy which correlates with anticholinesterase activity in trout, but not in rats or hens. The results provide the first indication for species-related differences in the molecular regulation of anticholinesterase activity, suggesting that the trout enzyme possesses a relatively weak nucleophilic center within a dimensionally restricted esteratic subsite. Species-specific distinctions in the molecular properties governing anticholinesterase activity provide novel design strategies for improving the selectivity of toxic organophosphorus insecticides.

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“…An ion of mlz 125 is among the most abundant fragment ions (Figure 2; Table 1) formed by electron ionization of dimethyl 4-chlorophenyl thiophosphate (an analog of the pesticide Methyl parathion) [23].…”

Section: Phosphorus-containing Fragment Ionmentioning

confidence: 99%

“…The first step involves isomerization of the molecular ion to a dis tonic ion i. The molecular ions of organophosphorus compounds are known to isomerize to thermodynamically more stable distonic structures after ionization in tandem mass spectrometers [16,23]. Isomerization of the molecular ion is followed by radical addition to the aromatic ring to form the interrnedi-Estimated Ion KE.…”

Section: Phosphorus-containing Fragment Ionmentioning

confidence: 99%

“…The fragmentation behavior of the protonated molecules of some of the thiophosphates was also studied because much of the literature on analytical applications of mass spectrometry detail studies of protonated molecules rather than of molecular ions [3][4][5]23 (Table 1). This finding indicates that the fragment ion of mrz 125 is not aromatic; it has a structure similar to that of the reference ion of mlz 125 generated from trimethyl thiophosphate (Figure 6c; Scheme IIId).…”

Section: Protonated Moleculesmentioning

confidence: 99%

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Multiple-stage mass spectrometry in structural characterization of organophosphorus compounds

Zeller

Farrell

Kenttämaa

et al. 1993

J. Am. Soc. Mass Spectrom.

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Multiple-stage mass spectrometry involving consecutive collision-activated dissociation reactions was used to examine the structures of fragment ions commonly formed on electron ionization of organophosphorus esters. The compounds studied include several aryl thiophosphates, some of which are analogs of common pesticides. Energy-resolved collisionactivated dissociation experiments allow the dissociation of the molecular ions of these compounds in such a manner that only a few fragment ions dominate the spectrum. An abundant fragment ion of m/z 109, formed from all of the compounds studied, can have at least four different stable structures: (CH3O)2PO(+), CH3CH2OP(O)OH(+), CH2 =CHOP(H)(OH)2 (+), and (CH2O)2P(H)OH(+). The structure of the fragment ion of m/z 109 was found to reflect the phosphorus-containing part of the compounds studied. Another abundant fragment ion obtained for all the aryl esters studied is structurally characteristic of the aromatic moiety of the molecule. This fragment ion is the result of a complex rearrangement involving transfer of an alkylene group to the aromatic ring from the phosphoruscontaining part of the molecular ion. The utility of these fragment ions in the structural characterization of unknown organophosphorus esters is discussed.

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Nachweis von Organophosphorinsecticiden durch Gas-Chromatographie-Massenspektrometrie

Cited by 40 publications

References 7 publications

Detection of malathion in a victim by gas chromatography/negative ion chemical ionization mass spectrometry

Detection of malathion in a victim by gas chromatography/negative ion chemical ionization mass spectrometry

Species specificity in the chemical mechanisms of organophosphorus anticholinesterase activity

Multiple-stage mass spectrometry in structural characterization of organophosphorus compounds

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