Aliquots of the standard solutions of each of the above mentioned
pesticides were diluted 20 times (40 mg/L) and 10 mL of this solution
was sprayed over 5 g of exactly weighed grains in a 20 mL graduated
test tubes. The mixture was then shaken mechanically for 10 min and
was left for 24 h. Afterward the pesticides were extracted 5 times,
each using 10 mL portions of acetonitrile. The extracts were combined
and evaporated to dryness under vacuum at 40 °C and the
dry mass were dissolved in 10 mL of acetonitrile, filtered and injected
into HPLC for analysis. The procedure was repeated with 20 mg/L,
10 mg/L, 8 mg/L and 4 mg/L carbamate solutions after appropriate
dilution of the stock solution. Five replicates of each recovery experiment
were carried out and the average values were reported. Recoveries
were calculated as a ratio of the peak areas of the analyte to the
standard sample of corresponding concentration.