[Quality control examination on testing pesticides residues in food for agencies in charge of food safety risk monitoring and inspection].

Objective: To find out the proficiency of professionals in monitoring and inspection agencies on the determination of pesticides residue in food, and to improve the accuracy and comparability of testing results.

Methods: Three sets of quality control samples with the same matrix but different in concentrations of pesticides were prepared; one of blind quality control samples contained chlorpyrifos, methyl parathion, methyl pirimiphos, fenitrothion or triazophos and bifenthrin was dispatched to each inspection agency. Criteria for testing results were evaluated by Z scores: [Z] = < or = 2 for satisfactory; 2 < [Z] < 3 for uncertainty and [Z] > or = 3 for unsatisfactory.

Results: The results of all quality control blind samples delivered to 162 agencies were submitted back on time. The qualitative and quantitative qualification rate for chlorpyrifos was 99.4% and 93.8%, for parathion-methyl was 96.3% and 94.9%, for bifenthrin was 95.7% and 89.7%, for fenitrothion was 92.0% and 89.6%, for triazophos was 100% and 91.9%, respectively.

Conclusion: The general proficiency on tested pesticide residues in food was relatively good for monitoring and inspection agencies. The agency who got unsatisfied results has recognized the problems in the process of testing; the cause of uncertainty and unsatisfactory results were found; and effective corrections were conducted to ensure the accuracy of data in the future.