Cross-section

Dihexa by laboratory

The same compound measured by different laboratories on different gradients. Where the medians differ, the question is whether the material differed or the method did — and for Dihexa, with a class minimum gradient of 15 min, the method is a live explanation.

35 recordsmedian 99.84 %spec 98.5 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	12	30min	High	99.89	+0.00	99.89	ADEQUATE
Medutest	8	25min	Unit	99.91	+0.08	99.83	ADEQUATE
VendorInvestigate	6 n=6	32min	High	99.44	-0.11	99.55	ADEQUATE
Nordanalyt	4 n=4	35min	High	99.92	+0.02	99.90	ADEQUATE
Kestrel	4 n=4	15min	Unit	99.93	+0.24	99.69	ADEQUATE
PeptideMeter	1 n=1	28min	High	99.35	-0.05	—	ADEQUATE

Figure. Dihexa purity by contributing laboratory. Any offset between rows has two possible sources — a real difference in the material each laboratory happened to receive, and the laboratory's own bias — and this figure cannot separate them. The paired analysis that can is on inter-lab agreement.