FAQ: What is the best way to quantify my NEBNext UltraExpress™ DNA libraries?

Libraries can be loaded on TapeStation using HSD1000 ScreenTape or a similar fragment analysis instrument for library quantification. However, for high-input DNA using the recommended PCR cycle number, there will be a second peak beyond the upper marker resulting from amplification in the non-linear amplification phase during late PCR cycles. Although the molecules generated during the non-linear amplification phase are sequencible to generate high-quality data, their different migration speed on ScreenTape causes inaccurate quantification of the library concentration. In this case, we recommend measuring library concentration on NanoDrop or Lunatic using 400 bp or the expected library size to convert the concentration values to nanomolar. For more information, please refer to the product manual.