Abstract: In this study, the low-level presence of genetically modified (GM) soybean event GTS-40-3-2 was quantitatively detected and the measurement uncertainty was estimated. Within 95% confidence interval, the quantitative method developed using real-time polymerase chain reaction (PCR) and digital PCR could stably detect 0.01% GTS-40-3-2 content with acceptable cost and uncomplicated operation, while the digital PCR method could quantify 0.1% GTS-40-3-2 content accurately, and the quantitative error did not exceed 50% even at GTS-40-3-2 content as low as 0.05%. The sources of uncertainty in quantitative digital PCR analysis were analyzed, and the calculation formula for uncertainty was derived from calculation models in analytical chemistry. Furthermore, GTS-40-3-2 was used for laboratory verification. The expanded uncertainty in quantitative analysis of 0.1% and 0.05% GTS-40-3-2 contents was calculated as 23.56% and 107.29% (k = 2), respectively.

Key words: genetically modified organism; low-level presence; digital polymerase chain reaction; quantitation