SAMPLE BARCODE IN MULTIPLEX SAMPLE SEQUENCING

Methods and systems for sample contamination detection are disclosed. In particular, sample barcodes are utilized, wherein each sample barcode is assigned to a sample and ligated to fragments from the sample. The sample barcodes are used in conjunction with indices from sequencing libraries to accurately assign sequence reads to samples during multiplex sequencing. Molecule identifiers may also be utilized to aid in de-duping of sequence reads to precisely identify original NA fragments from a sample. Accordingly, in one or more embodiments, a sequencing method includes isolating DNA fragments in a sample, ligating the DNA fragments with unique molecule identifiers (UMIs), performing an amplification process resulting in amplicons, ligating a sample barcode onto the amplicons, and performing amplicon sequencing. The analytics system looks to whether indices are matched and whether a sample barcode matches to the pair of indices when identifying single-index or double-index hopping events.