KAPA Adapters undergo extensive qPCR- and sequencing-based functional and QC testing to confirm:
- optimal library construction efficiency
- minimal levels of adapter-dimer formation
- nominal levels of barcode cross-contamination
Please refer to the KAPA Single-Indexed and Dual-Indexed Adapter Technical Data Sheets for information about barcode sequences, pooling, kit configurations, formulation, and dilution for different KAPA DNA and RNA library preparation kits and inputs.
Library construction efficiency and adapter-dimer formatin are assessed in a low-input library construction workflow. The conversion rate achieved in the assay indicates library construction efficiency. This is calculated by measuring the yield of adapter-ligated library (before any amplification) by qPCR (using the KAPA Library Quantification Kit), and expressing this as a % of input DNA. To assess adapter-dimer formation, a modified library construction protocol— designed to measure adapter dimer with high sensitivity—is used.
Barcode cross-contamination is assessed by sequencing. Each adapter is ligated to a unique, synthetic insert of known sequence, using a standard library construction protocol. These constructs pooled and sequenced on a MiSeq. For every barcode, the number of reads (in the range of 115,000 – 500,000) associated with each insert is counted, and the total % correct inserts calculated. Contamination of any barcode with any other single barcode is guaranteed to be <0.25%. The total level of contamination for any barcode is typically in the range of 0.1 – 0.5%. This assay is unable to distinguish between chemical cross-contamination and adapter “cross-talk”, and measures the total number of incorrect inserts resulting from both phenomena.