I spent 2:11 a.m. arguing with the thermocycler because our strongest peak came from a contaminant on the evidence bag, not the blood swab. Anyone else have a swab that testifies louder than the suspect thanks to one rogue skin cell?
Been there; when the “bag testifies louder than the swab,” I log it as the source and request a re-collection with fresh packaging. At 2 a.m., the thermocycler starts doing stand-up with a gavel — was that bag ever reopened downstream, even briefly?
And i’d add a packaging-control swab to the batch and compare profiles so you can document the bag as the source; if you suspect carryover, enable UNG to wipe old amplicons before that 2 a.m. séance. @vthoma18 is right on re-collection, but if that’s not possible, re-extract and set a stricter low-template threshold to see if the suspect alleles hold up.
I log a separate ‘bag seal/cut-edge’ control and it’s nailed the loud profile more than once while the swab was clean; just make sure LIMS doesn’t auto-merge it with the item, @davidson64. You noticing it cluster by bag lot or shift?
After the ‘2:11 a.m.’ thermocycler debate, I screenshot the readout and open a contamination incident; @olivia7606 caps night runs.