Interlaboratory Comparison for the Determination of Five Residual Organochlorine Pesticides in Ginseng Root Samples by Gas Chromatography

An interlaboratory comparison study for the determination of 5 residual organochlorine pesticides (hexachlorobenzene and 4 hexachlorocyclohexane isomers) in ginseng root was performed. This program [Asia Pacific Laboratory Accreditation Cooperation (APLAC) T049] was the first of its kind for an herbal matrix and involved the participation of 70 laboratories from 26 countries worldwide. Consensus mean values were computed statistically from the reported results, which were eventually used to assess the performance of individual laboratories in terms of the z-scores. The distribution of analytical data was found to be widespread, with standard deviation ranging from 43.9 to 55.9%, and the result patterns obtained were similar to those residue pesticide programs using other matrixes. Although the estimation of measurement uncertainty is a crucial requirement for all quantitative tests for laboratories that meet the requirements of International Organization for Standardization/International Electrotechnical Commisssion (ISO/IEC) 17025, some laboratories in this program had difficulties and showed unfamiliarity with respect to that quality criterion. It was recommended that laboratories review and rectify the situation promptly so that they would have a better understanding of measurement uncertainty or the test service provided.