LOD/LOQ

Real Time PCR

We base all our DNA analyses on the Real-Time PCR method. Real-Time PCR is by far the most sensitive GMO testing method and the only one recognised by the EU. The method is so sensitive that it can detect a single copy of DNA. High quality is very important and of course includes a strong focus on avoiding false negative as well as false positive results.

All our analyses are based on two independent sub-samples. In parallel positive controls, both the reference gene and GM target are analysed in order to ensure that the desired limit of detection (LOD) is reached. This information can be used to determine the LOD in each sample analysed, which can be as low as 0.01% GM gene copies relative to the number of haploid genome copies analysed. The qualitative analysis generates a report stating DETECTED or NOT DETECTED with the actual LOD of the sample.

We are also accredited for quantification of GMO. Quantification includes three  Real-Time PCR tests of each of the two DNA sub-samples and the results are correlated to a standard curve. We can quantify the amount of GMO down to 0.05% GM gene copies of the haploid genome.
 

Precision

The standard deviation (square root of the variance) is the most common measure of precision. If many data points are close to the mean, the standard deviation is small, while if many data points are far from the mean, the standard deviation is large.
In the event of a PCR analysis being 100% efficient, there is one CT (cycle threshold) between the mean of a two-fold dilution. The greater the standard deviation, the lower the ability to distinguish between two-fold dilutions. To be able to quantify a two-fold dilution in more than 95% of cases, the standard deviation has to be ≤ 0.250. For more information on CT values please visit the web-page of Applied Biosystems