Fumigant contamination during large-scale food sampling for analysis

Incurred fumigants were determined from twenty-two food items before and after routine large-scale preparation of samples to see if these or similar kinds of chemicals were entering the samples during the preparation. This preparation includes making the samples table ready before compositing them for analysis. The following five fumigant residues were determined by gas chromatography (GC): carbon disulfide (CS₂), carbon tetrachloride (CCl₄), chloroform (CHCl₃), methyl chloroform (CH₃CCl₃), and tetrachloroethylene (or perchloroethylene, PCE). The number of residues determined from each sample ranged from none to four. The amounts determined varied significantly between the before and after portions from several samples. Four samples gained at least one new residue during the preparation. Six lost most of the residues determined from the original before portions, and 12 contained essentially the same residues before and after the preparation, although the amounts varied between the two portions. In samples where the variant residues were detected in both portions, five showed a tenfold or greater increase of CHCl₃ or CCl₄ and two showed a ten-fold or lesser decrease of CH₃CCl₃ or PCE in the after portions.