A multinational joint project on the evaluation of residual pesticide analysis in tea in the Asia Pacific region

This paper presents the results of a multinational joint proficiency testing (PT) programme on four pesticide residues (cypermethrin, α-endosulfan, β-endosulphan and bifenthrin) in two tea samples. The objectives were to evaluate the performance and to improve the testing capability of field laboratories in the Asia Pacific region for analysis of pesticide residues in tea. A total of 42 laboratories registered for the programme and 32 laboratories from 12 economies returned the results to the organizers. The assigned values of the pesticides were agreed to be the respective weighted mean determined by the three metrology institutes - the National Measurement Institute, Australia (NMIA), the National Institute of Metrology, China (NIM) and the Government Laboratory, Hong Kong (GLHK) in an Asia Pacific Metrology Programme (APMP) pilot study programme (APMP.QM-P15) using the same test materials. The performance of participating laboratories was expressed using the numerical indicators of z-scores and En-scores. Amongst the reported data, only 35.3% and 35.0% achieved satisfactory z-scores (|z| ≤ 2) and En-scores (|En| ≤ 1) respectively. Only two laboratories achieved satisfactory z-scores and En-scores for all the analytes. The results demonstrated that the performance of the majority of the laboratories participating in this study on the analysis of pesticide residues in tea was not satisfactory, and more capability building is required for further improvement.

► A proficiency testing programme on residual pesticides in tea was reported. ► Reference values were used for performance assessment. ► Participants were found to have difficulties in the analysis of residual pesticides. ► Training is required to improve the measurement capabilities.