Sampling for Genetically Modified Organisms Content Analysisin Agricultural Products: From Analytical Sample to Test Portion

Abstract

Objective: At present, Sampling standards and regulations for genetically modified organisms (GMO) are commonly based on theoretical calculations or computer simulations, and there is a lack of field data to validate these simulations. In view of this situation, we sampled agricultural products for GMO content analysis, and investigated the influence of various factors on the accuracy of the results. We have prepared a three-part series and in this part focused on the process from analytical sample to test portions. Method: Using non-transgenic maize as matrix, 12 lines of transgenic maize were used to produce standard analytical samples. After systematic sampling, the GMO contents of these samples were randomly tested, and their single relative standard deviations (RSD) were calculated as a measure of total RSD (single analysis) per sample. Results: By comparing the RSDs of various sampling methods, it was found that the results of 12 strains were basically consistent, and the data of MON810 were listed as a representative. The parameters affecting the standard deviation included the content ( a AS ), particle size ( d AS ), test portion mass ( M TP ) and the number of increments ( n IT ). Total analytical RSD could be reduced by decreasing particle size, and increasing test portion mass or the number of increments. Based on current laboratory testing conditions and current used kits, for high content analytical sample(>0.01%), more than 2 duplicate test portions with at least -100mesh particle size and 200mg mass were recommended. Conclusion: Based on the results, the recommended values of particle size, test portion mass and the number of increments for the process from analytical sample to test portions were given. These factors were independent on species or strains of the product, so the results were suitable to all species and strains, provided that the solid particles could be crushed to required particle size.