Quantifying the measurement uncertainty of the nopaline synthase terminator in mixed samples of genetically modified rice using a bottom-up approach.

In this study, we report a method to estimate the measurement uncertainty (MU) when testing genetically modified organisms (GMOs) using a bottom-up approach. The repeatability of the test, the linear calibration, the purity of the reference DNA, weighing, the determination of the DNA concentration, and transferring precise volumes with a liquid with pipette were considered MU sources within the real-time quantitative PCR assay of the nopaline synthase terminator. The terminator’s concentration in a mixed sample with an expanded MU was 11.25 ± 1.6%, indicating that 14.2% of the concentration gave an estimated expanded MU. The largest MU originated from pipetting errors and the smallest MU originated from the purity of the reference DNA. Compared with the other sources, the MU from the purity of the reference DNA was negligible. We recommend that the MU be determined when testing food and feed products because of the importance in providing analytical data for GMO threshold compliance decisions. In practice, estimating the MU using the bottom-up approach is suitable for the routine detection of GMOs in a sample in a single testing laboratory. [ABSTRACT FROM AUTHOR]