Gas Chromatography of Various Phenyl N-Methylcarbamates

Postcolumn addition of buffer for thermospray liquid chromatography/mass spectrometry identification of pesticides

“…The pesticides are thermally labile which prevents direct analysis by gas chromatography. Spectrometric methods lack specificity or sensitivity (3)(4)(5). Although high-performance liquid chromatography (HPLC) is ideally suited for carbamate separation, mass spectrometry is appropriate for their detection.…”

Reaction gas chromatographic analysis of pesticides. I. On-column transesterification of N-methylcarbamates by methanol

“…for the gas chromatographic analysis of Nmethylcarbamate pesticides have been developed which employ gas chromatography of the intact carbamate (Riva and Carisano, 1969;Strother, 1968; Zielinski and Fishbein, 1965a,b,c) or gas chromatography of a derivative of the carbamate (Bowman and Beroza, 1967; Crosby and Bowers, 1968; Tilden and Van Middelem, 1970). Generally the derivative is designed to make the carbamate sensitive to detection by either the electron capture detector (Crosby and Bowers, 1968; Tilden and Van Middelem, 1970) or the flame photometric detector (Bowman and Beroza, 1967).…”

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A method is described for the on-column transesterification of iV-methylcarbamate pesticides to methyl A-methylcarbamate, chromatography on Porapak P, and detection by RÍ^SO» pellet alkali flame ionization detector. Reproducible high yields were obtained for transesterification with methanol.Distinguishing gas chromatographic peaks were also obtained when an N-methylcarbamate pesticide was injected in ethanol, 1-propanol, and n-butanol.

Proceduresfor the gas chromatographic analysis of Nmethylcarbamate pesticides have been developed which employ gas chromatography of the intact carbamate (Riva and Carisano, 1969;Strother, 1968; Zielinski and Fishbein, 1965a,b,c) or gas chromatography of a derivative of the carbamate (Bowman and Beroza, 1967; Crosby and Bowers, 1968; Tilden and Van Middelem, 1970). Generally the derivative is designed to make the carbamate sensitive to detection by either the electron capture detector (Crosby and Bowers, 1968; Tilden and Van Middelem, 1970) or the flame photometric detector (Bowman and Beroza, 1967).Carbamates have been used by the polyurethane industry to provide a blocked, capped, or disguised isocyanate which, upon heating to temperatures in the 150°to 200°C range, would split to produce the isocyanate (Saunders and Frisch, 1967) RNHCOOR' -4 RNCO + R'OH This type of decomposition is predominant when R' is an aryl group, which is the case for nearly all carbamate pesticides.

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Pesticide residues

“…Strother (219) presented data on the GLC behavior of various phenyl Ar-methylcarbamates and their phenolic moieties on polar, nonpolar, and mixed columns.…”