Positive and negative chemical ionization mass spectra of some aromatic chlorinated pesticides

Dougherty, Ralph C.; Roberts, Jane D.; Biros, Francis J.

doi:10.1021/ac60351a054

Cited by 71 publications

(38 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…C ertain gaseous molecules are known to undergo anion attachment under negative-ion-generating atmospheric pressure or vacuum chemical ionization (APCI) conditions [1][2][3][4]. One of the gaseous anions found in the plasma of discharge ion sources under negative-ion-generating conditions is the superoxide radical-anion, O 2 -• [5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Hassan

Pinto

Weisbecker

et al. 2015

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Abstract. Carboxamides bearing an N-H functionality are known to undergo deprotonation under negative-ion-generating mass spectrometric conditions. Herein, we report that N-H bearing carboxamides with acidities lower than that of the hydroperoxyl radical (HO-O ], respectively. For somewhat acidic carboxamides, the association between the two entities is weak. Thus, upon mildest collisional activation, the adduct dissociates to eject the superoxide anion. Superoxide-adduct formation results are useful for structure determination purposes because carboxamides devoid of a N-H functionality undergo neither deprotonation nor adduct formation under HePI conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Hassan

Pinto

Weisbecker

et al. 2015

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…Dougherty has reported on the methane and isobutane negative ion CI Spectra of polycyclic chlorinated insecticides ( 13) and aromatic chlorinated pesticides (14) and has also discussed the utility of C1 as a CI reagent ion (15). Use of C1 and in an atmosph .ric CI source for the analysis of barbituates (16), chlorinated…”

mentioning

confidence: 99%

Chemical Ionization Mass Spectrometry of Nitroaromatic Vapors.

Collins¹,

Hunt²

1979

View full text Add to dashboard Cite

“…Ionization of the substrate in the source then occurs, either through ion-molecule reactions or by reaction with the low energy secondary electrons that are present in the gaseous plasma. (1)(2)(3)(4). These features make NCI mass spectra particularly attractive as a tool for looking for unknown organochlorine residues NCI mass spectra are analogous to gas chromatography with an electron capture detector.…”

mentioning

confidence: 99%

“…There are four major ion-forming reactions in NGI mass spectra with methylene chloride as the reagent gas (1-4, 7, 8 (2,7), [3] deprotonation (7), and [4] oxygen chloride exchange (8).…”

mentioning

confidence: 99%

“…When a major chlorine-containing isotope cluster is observed in the NCI spectrum of a mixture, we estimate the number of chlorines by isotope abundance and then search available files for polychloro compounds whose molecular weight is related to the mass of the first ion of the cluster as [1] exact, [2] minus 35 daltons, [3] plus one dalton, and [4] plus 19 daltons, respectively. The identity of the compound can then be confirmed by examining the NCI spectra and gas chromatography mass spectra of the unknown and an authentic sample.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Screening by negative chemical ionization mass spectrometry for environmental contamination with toxic residues: Application to human urines.

Dougherty¹,

Piotrowska²

1976

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

A screening procedure based on solvent extraction with minimal clean up followed by examination with negative chemical ionization mass spectrometry has been developed for organochlorine residues and related compounds with masses greater than 130 daltons. The procedure has been made quantitative for analysis.of pentachlorophenol residues. A limited survey of human urines indicated extensive contamination of the subjects, studied at parts per billion and higher levels, with pentachlorophenol, 2,4,5-trichlorophenoxy acetic acid, other polychlorophenoxy acids, and numerous unknown compounds. In an attempt to define the source of the contamination, the screening procedure was applied to samples of environmental substrates. The results suggest the food chain as one significant source of the contamination. A preliminary study of organochlorine compounds in human seminal fluid showed pentachlorophenol and other organochlorine residues in every sample, a result which suggests that this area may merit additional monitoring.This report describes an analytical method designed to detect any unknown member of a broad class of toxic compounds in environmental substrates. There are roughly 900 toxic chemicals registered for use as pesticides in the United States. The number of toxic metabolites and the number of toxic chemicals that have industrial uses increase the number of potential environmental hazards to several thousand. The problem of surveying the food chain, water supplies, and other environmental substrates for contamination by many or all of these molecules is impossibly large if a specific procedure is required for each of the compounds. It should be economically possible to screen selected substrates for contamination if the procedure would reliably detect any member of a broad chemical class of toxic substances. Our work has thus far concentrated on polychloroorganic residues (1-4); however, the general approach developed for organic polychlorides should be directly applicable to other classes of less persistent toxic substances, e.g., phosphate derivatives. These methods are analogous to the use of chemical ionization mass spectrometry in rapid screening of crude extracts of biofluids for basic drugs in overdose cases (5).Chemical ionization (6) and negative chemical ionization (NCI) (7) mass spectrometry are carried out with the source region of the mass spectrometer operating at a pressure of ca 1 torr (130 Pa). This relatively high pressure is supplied by a reagent gas that receives the bulk of the primary ionization from a-source of high energy electrons. Ionization of the substrate in the source then occurs, either through ion-molecule reactions or by reaction with the low energy secondary electrons that are present in the gaseous plasma. (1-4). These features make NCI mass spectra particularly attractive as a tool for looking for unknown organochlorine residues NCI mass spectra are analogous to gas chromatography with an electron capture detector. Negative chemical ionization offers the advantage...

show abstract

Positive and negative chemical ionization mass spectra of some aromatic chlorinated pesticides

Abstract: Positive and negative isobutane chemical ionization mass spectra appear to offer several advantages over electron impact mass spectra for the analysis of aromatic chlorinated pesticides. The techniques are truly complementary and 58 .

Cited by 71 publications

References 27 publications

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Chemical Ionization Mass Spectrometry of Nitroaromatic Vapors.

Screening by negative chemical ionization mass spectrometry for environmental contamination with toxic residues: Application to human urines.

Contact Info

Product

Resources

About

Positive and negative chemical ionization mass spectra of some aromatic chlorinated pesticides

Abstract: Positive and negative isobutane chemical ionization mass spectra appear to offer several advantages over electron impact mass spectra for the analysis of aromatic chlorinated pesticides. The techniques are truly complementary and 58 .

Cited by 71 publications

References 27 publications

Competitive Deprotonation and Superoxide [O2-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Competitive Deprotonation and Superoxide [O2-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Chemical Ionization Mass Spectrometry of Nitroaromatic Vapors.

Screening by negative chemical ionization mass spectrometry for environmental contamination with toxic residues: Application to human urines.

Contact Info

Product

Resources

About

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

Competitive Deprotonation and Superoxide [O₂^-•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions