Why low cross-contamination matters
In multiplex sequencing workflows, contamination from co-synthesized index primers can contribute to read misassignment and reduced confidence in downstream analysis.
NGSgrade Oligos 2.0 are specifically engineered to minimize these risks and help ensure maximum sequencing accuracy.
The cross-contamination rate of 0.01 – 0.05% was determined by sequencing representative sets of Unique Dual Index (UDI) primer pairs using Illumina instruments at Eurofins Genomics’ European NGS sequencing facility. The rate given represents the typical total percentage of read pairs not matching the expected UDI combinations for a set of 96 UDI primer pairs. The corresponding Application Note shows a cross-contamination rate of 0.0014% for a set of 14 UDI primer pairs.
Please note that the total cross-contamination rate (percentage of incorrectly assigned read pairs) is influenced by the total amount of UDI primer pairs analysed in parallel. The more UDI primers are analysed, the higher the total cross-contamination can get, as more unexpected index combinations can be attributed.
In all cases, the actual cross-contamination of primers would be even lower as stated above. This is because the association of reads with other unexpected UDI primer pairs is a result of primer cross-contamination and index hopping during sequencing. Discriminating between these causes is not possible in this analysis setup.
Please note that Eurofins Genomics does not determine the cross-contamination rate for each individual set of NGS oligonucleotides produced and shipped.
| |
Total cross-contamination rate per UDI set (% total read pairs not matching the expected UDI combinations |
Lowest measured cross-contamination per UDI combination |
Reference |
| Eurofins Genomics NGSgrade Oligos 2.0 |
Typically 0.01 - 0.05% |
0.00446% |
Set of 96 UDI primer pairs |
| Eurofins Genomics NGSgrade Oligos 2.0 |
0.0014% (see application note) |
0.00045% |
Set of 14 UDI primer pairs |
| Other supplier |
0.0208% (see application note) |
0.00767% |
Set of 14 UDI primer pairs |