Only high-purity DNA samples which are free of residual salts, proteins, detergents or other contaminants should be used as input material. Library preparation can be conducted using 1 – 1000 ng of DNA. Fluorometric methods (such as the Qubit assay, Invitrogen) are recommended to accurately determine DNA concentration, especially when using <100 ng of DNA as input. DNA samples should be resuspended in molecular biology grade water, a low EDTA concentration Tris-HCl buffer (such as 0.1 mM EDTA TE buffer) or a 10 mM Tris-HCl pH 8.0 saline buffer (such as QIAGEN Buffer EB or equivalent). If DNA samples are kept in a high EDTA concentration buffer (such as 1x TE), DNA needs to be purified using a commercially available kit or DNA Purification Beads (such as Target Pure™ NGS clean-up beads or equivalent) and resuspended in one of the above-mentioned buffers.