Spectral Matrix
Definition
A mathematical correction factor that decouples the overlapping emission spectra of the fluorescent dyes used in a multiplex STR kit. Must be computed fresh for each capillary array.
- Field
- STR typing, capillary electrophoresis
- Function
- Decouples overlapping fluorescent dye emission spectra
- Applies to
- Multiplex STR kits
- Recalculation need
- Fresh for each capillary array
Common questions
What happens if the spectral matrix is outdated or wrong for a run?+
Dye colours bleed into each other's channels, which can produce spurious peaks called pull-up artefacts that mimic extra alleles and complicate profile interpretation.
Why can't one spectral matrix be reused indefinitely across instruments?+
Capillary arrays and detection optics age and vary slightly between installations, so a matrix calibrated on one array can drift out of accuracy on another and must be recalibrated using a matrix standard.
Related terms
- Allelic Ladder
- A multi-allele reference standard containing the full range of known alleles at each STR locus in the panel, co-injected with samples to...
- Capillary Electrophoresis (CE)
- A separation technique that resolves DNA fragments by size through a polymer-filled glass capillary under an applied electric field. Single-base resolution is...
- Drop-in
- Sporadic appearance of a low-level peak not reproducibly present in re-amplifications, typically caused by trace contamination. Distinguished from genuine minor-contributor alleles by...
- Drop-Out
- Failure of a genuine allele to amplify above the analytical threshold, typically due to low or degraded template. Creates apparent homozygosity at...
- GeneMapper ID-X
- Applied Biosystems analysis software for STR genotyping. Current-generation tool used in the majority of US, UK, and Australian forensic DNA laboratories.
- OSIRIS
- Open-source STR analysis software developed by NIST (US National Institute of Standards and Technology), used as an independent or supplementary analysis tool...
- Pull-Up (Bleed-Through)
- A spectral artefact where a tall peak in one dye channel generates a spurious smaller peak in an adjacent dye channel at...
- Stochastic Threshold (ST)
- A validated minimum peak height below which allele calls are considered uncertain due to stochastic amplification effects. Profiles with peaks between the...
- Stutter Peak
- A PCR artefact appearing one repeat unit below (and occasionally above) a genuine allele peak, caused by polymerase slippage. Typically 5-15% of...