A multinational joint project on the evaluation of residual pesticide analysis in tea in the Asia Pacific region Disni Dayarathna a , Champika Thirimanna a , Azeez Mubarak a , Lindsey Mackay b , Jill Rogerson b , Hua Tang c , Jie Feng c , Della W.M. Sin d , Yiu-chung Wong d, ⁎ a Industrial Technology Institute, Sri Lanka b National Measurement Institute, Australia c National Institute of Metrology, China d Government Laboratory, Hong Kong, China abstract article info Article history: Received 26 July 2012 Received in revised form 26 October 2012 Accepted 29 October 2012 Keywords: Tea Pesticides Cypermethrin α-Endosulphan β-Endosulphan Bifenthrin Proficiency testing Assigned values 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 Govern- ment 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 E n -scores. Amongst the reported data, only 35.3% and 35.0% achieved satisfactory z-scores (|z| ≤2) and E n -scores (|E n | ≤1) respectively. Only two laboratories achieved satisfactory z-scores and E n -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. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Tea drinking has a long history and remains a popular social event in many countries around the globe. Tea contains antioxidant-rich natural substances such as catechins, proanthocyanidins and poly- phenolic compounds (Luximon-Ramma et al., 2005). The common evergreen shrub, Camellia sinensis L. is the essential species used to produce black, green and Oolong tea. Production of these three main tea types is solely depending on fermentation treatment (Wan, Li, & Zhang, 2008). The majority of the tea producing countries are located in Asia where China, India, and Sri Lanka are amongst the key global stakeholders. The volumes of tea exported from Asia are projected to reach more than 800,000 tonnes in 2017 (Hicks, 2009), and the tea industry has made a significant contribution to the econ- omy of some Southeast Asian countries like India, Indonesia and Sri Lanka. Similar to other modern cultivation processes, pesticides have been applied to tea plants for pest control before harvesting to increase production yield. As a result, various residual pesticides are often detected in raw tea and tea products (Chen, Cao, & Liu, 2011; Huang et al., 2009). Analysis of the presence of residual pesticides in crops and foods is therefore vital for quality control, environmental monitoring, public health protection, legislative enforcement as well as building stronger brand images. Accurate quantification of pesticide residues, however, is not al- ways easy. There are a large number of possible pesticides and their concentrations in agricultural and food matrices are generally low (Jin, Xie, Guo, & Pang, 2012; Sinha, Rao, & Vasudev, 2012). To achieve a reliable measurement system, implementation of the use of sensi- tive and calibrated analytical instruments, efficient extraction proce- dures, well trained staff and other requirements as specified in the ISO/IEC 17025 is necessary. This is always a challenge not only to lab- oratories in the developing nations but also to well-equipped labora- tories in the developed nations. Having observed the problems of pesticide analysis over the past few years in the region, the Develop- ing Economies Committee (DEC) of APMP proposed a PT programme on pesticide residues in tea during a workshop held in Jakarta in 2008. The objectives of the programme were to set up a technical platform for a critical evaluation of the testing capability and, if possible with a view for further improvement, to identify the specific difficulties ex- perienced by the participating field laboratories in the analysis under test. The programme was an international joint effort by Food Research International 53 (2013) 931–937 ⁎ Corresponding author. Tel.: +852 27624042; fax: +852 21941147. E-mail address: ycwong@govtlab.gov.hk (Y. Wong). 0963-9969/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodres.2012.10.039 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres