The percent recovery of the carbamates for different food samples is shown in Table 3. It was found that aldicarb, carbofuran, ethiofencarb and methomyl showed good recoveries from the food stuffs, while the recovery for benzimidazolyl compound, especially of benomyl was relatively poor. Relatively poor recovery of benomyl might have been due to partial hydrolysis of benomyl to carbendazim (i.e. methyl-2-
benzimidazole carbamate). Inference is further supported from the observation that a 24 h aged sample of benomyl (80 mg/L in HPLC grade acetonitrile) showed a small satellite peak at ca. 57 min retention time in addition to parent benomyl peak with relative area ca. 3% of the parent (Fig. 3). Recoveries of thiophanate ethyl and thiophanate methyl were high (>90%). The recoveries from grains were higher than that
from apple and fenugreek leaves. Lower recovery from apple and fenugreek leaves appears to arose from absorption and entrapment of the carbamates in the meshed up matrix upon standing.