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DETERMINATION OF ETHYL CARBAMATE IN COMMERCIAL PROTEIN BASED CONDIMENT SAUCES BY GAS CHROMATOGRAPHY‐MASS SPECTROMETRY

1988; Wiley; Volume: 9; Issue: 3 Linguagem: Inglês

10.1111/j.1745-4565.1988.tb00518.x

1745-4565

Thomas G. Hartman, Robert T. Rosen,

Fermentation and Sensory Analysis

ABSTRACT Commercially obtained protein based condiments, including soy sauces, were analyzed for the presence of ethyl carbamate (urethane) using combined gas chromatography‐mass spectrometry (GC‐MS). Samples were spiked with 100 parts‐per‐billion (ppb) of t ‐butyl carbamate internal standard, extracted with methylene chloride and concentrated prior to GC‐MS analysis. For quantitation, the ratio of the pseudomolecular ions produced during isobutane chemical ionization (CI) at m/z 90 (ethyl carbamate) and m/z 118 ( t ‐butyl carbamate) were monitored by mass chromatography. Response factors for ethyl carbamate versus the internal standard were determined in both the electron ionization (EI) and chemical ionization modes. The CI mode was used for quantitation as it was more sensitive and interference free. Samples testing positive by CI‐MS were subsequently scanned by EI‐MS for confirmation of identity as the CI spectra did not contain fragment ions necessary for adequate specificity. This method proved simple and reliable with detection limits less than 1 ppb. Limits of confirmation were 10 ppb. The recovery of internal standard was 86.7%± 5.6%. Only fermented products were found to contain ethyl carbamate.