Development of Cannabis Proficiency Test Sample for Pesticide Residue and Heavy Metal Analysis

Abstract

         Since 2019, the medicinal cannabis policy has been established, the value chains related to cannabis plantation, distribution and product development have then been dramatically increasing. For the quality and safety of medical product' concerns, pesticide residues and heavy metals are highly recommended parameters for cannabis raw material analysis. To monitor and enhance the competency of DMSc network laboratories, the Department of Medical Sciences, a reference laboratory for medical services and public health has planned for setting the cannabis proficiency testing. Therefore, this study focused on the development of a cannabis proficiency test (PT) sample. The dried cannabis containing incurred pesticide residues and heavy metals provided by the Office of the Narcotics Control Board was prepared, packed and tested for its homogeneity. The result showed that the candidate PT sample was sufficiently homogeneous, the average concentration and standard deviation determined by using GC-ECD/FPD for chlorpyrifos and cypermethrin were in the range of 85.6 ± 3.5 and 32,520 ± 1,625 μg/kg, respectively. That of cadmium analyzed by using ICP-MS was 344 ± 18 μg/kg. In addition, temperature effects during transportation for 3-day at uncontrolled temperature and 2-month at -10°C storage were carried out. Chlorpyrifos, cypermethrin and cadmium concentrations still remained at the level of 89.6 ± 3.4, 33,753 ± 2,619 and 321 ± 11 μg/kg, respectively. As a result of statistical analysis, it indicated that those analytes in the prepared PT sample were satisfactorily homogeneous and stable. It could be concluded that the prepared sample was successfully developed as a potential PT sample with sufficiently homogeneous and stable properties following ISO 13528: 2015 and suitably used for the laboratory evaluation of pesticide residues and heavy metals.