of the Quant-iT PicoGreen dsDNA reagent, also describe this influence of ssDNA and RNA on the fluorimetric measurement. RNA also competes against the DNA for the binding sites of the magnetic beads. Therefore, we suggest to include an additional RNA digestion step using RNase A to correct the proportionality between DNA yield and Cq value, especially for soya bean samples. Underlined by our results, we can state that using a proteinase K application followed by a centrifugation at high speed ([16,0009g ) is sufficient for a thorough sample preparation prior to automated DNA extraction. However, this could be improved by an RNase A digestion step. The results also demonstrate the applicability of the automated DNA extraction for the detection of low-level presence of gm DNA in seed samples, as even traces of gm DNA (0.033 % gm content) are detected. As a result of our development and optimisation process, a new DNA extraction kit (Maxwell 16 FFS Nucleic Acid Extraction System, Custom, Promega GmbH, Germany) for the Maxwell 16 instrument was introduced. This new kit can be used for high-throughput extraction of DNA from seed samples, is suitable for the detection of low levels of gm contaminations and can be adopted for DNA extraction from food and feed samples.
Acknowledgments The authors would like to thank Ingo Engels for his preliminary work. Promega GmbH is particularly acknowledged for providing Maxwell 16 AS1290 kits.