What is the detection limit of target copy number per chamber for qPCR on the Biomark HD system? Is there a Ct cutoff?
The Biomark system can theoretically detect one copy per chamber, with a Ct value of 27−28 equating to single-copy. However, this can vary based on a variety of experimental factors. The most optimal Ct range for the Biomark system is ~6−25. With Ct <6, it is possible that the concentration of template is too high and the reaction has become saturated, and therefore that the Ct called can be inaccurate. At Ct >25, the number of copies per chamber is getting lower, and therefore the reliability of the Ct value is less robust. The standard deviations will be larger at Ct >25 and will vary depending on the assay efficiency.