Scientific Publications by FDA Staff

Rapid Commun Mass Spectrom 1992 May;6(5):331-8

Methane chemical ionization of pesticides by ion-trap technology: Spectral characteristics and data precision

Cairns T, Chiu KS, Siegmund E

Examination of the methane chemical ionization (CI) spectra produced in an ion trap under automatic reaction control has revealed a strong concentration dependence phenomenon even at trace levels (ppm). The spectra produced during the elution profile of various pesticides via capillary gas-chromatographic introduction have indicated a large percentage of an electron ionization (EI) spectral component superimposed on the CI spectrum. This duplicity of spectral character can be an important asset for confirmation of presence and it does not present a problem of obtaining acceptable precision and accuracy on quantification of pesticide residues. Identification of residues using the standard spectral library databased derived from other sources might require careful scrutiny before acceptance.