Efficient delivery of metrological services by institutes through accuracy-based proficiency testing programme on additives in food sauce for laboratories in the Southeast Asian region

This paper describes a collaborative effort by five metrology institutes to organise a proficiency testing (PT) programme which aims to evaluate the performance and improve the measurement capabilities of food testing laboratories on additives in food sauce in the Association of Southeast Asian Nations (ASEAN). It was the first joint PT programme organised by the metrology institutes under the auspice of the ASEAN Reference Material Network (ARMN). Five common additives, namely: benzoic acid, sorbic acid, methyl paraben, n-propyl paraben and saccharin in tomato sauce, were chosen as the measurands of the PT programme. Thirty-nine laboratories from five economies participated in this PT programme through the ARMN network. Metrologically traceable assigned values used for performance evaluation of the additives were jointly determined by three metrology institutes using isotope dilution mass spectrometry (IDMS). Issues discussed in the paper include determination of assigned values, performance evaluation, participating laboratories’ analytical methods and evaluation of measurement uncertainties. The overall performance of participating laboratories was considered to be satisfactory as 88 % of the participating laboratories achieved satisfactory z-scores (or z’-scores). The joint ARMN accuracy-based PT programme enables a broader understanding of the comparability of measurement capabilities of the food testing laboratories, which play an important role in supporting trade-related industries among the close trading economies in the Southeast Asian region.