Library quantification results. A. Reproducibility of UT-PCR assays. Twelve 454 libraries were assayed with six to eight replicates by both UT-digital PCR and UT-quantitative PCR. UT-quantitative PCR was calibrated using a library quantified by digital PCR. The CV for dPCR is significantly lower than that for qPCR. B. Accurate digital PCR quantification of 454 libraries from trace quantities of input E. coli genomic or amplicon DNA. E. coli shotgun and amplicon DNA were first quantified by mass-based methods and the indicated amounts (0.5 to 35 ng) used for library preparation. The input quantity and yield are correlated with R2 = 0.88. The library yield was assessed based on replicate UT-digital PCR quantification. Useful numbers of library molecules were recovered in all cases.