We recommend to store the library pool (undenatured) at 4oC – 8oC to prevent freeze/thaw cycles. The libraries are stable for at least 4 months when stored in the refrigerator. Please ensure that the plate or tubes are closed properly to avoid evaporation. Before starting the NGS run, we recommend to (re-)measure the library concentration by qPCR for accuracy. It is also recommended to check the library integrity after long-term storage on an agarose gel. In case the libraries have (partially) degraded, the fragment size will be smaller and the library concentration will be lower.