Cross-section

Epitalon 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 Epitalon, with a class minimum gradient of 15 min, the method is a live explanation.

37 recordsmedian 98.63 %spec 99.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	14	30min	High	98.64	+0.00	98.64	ADEQUATE
Medutest	9	25min	Unit	98.68	+0.08	98.60	ADEQUATE
PeptideMeter	8	28min	High	99.43	-0.05	99.48	ADEQUATE
VendorInvestigate	5 n=5	32min	High	98.22	-0.11	98.33	ADEQUATE
Nordanalyt	1 n=1	35min	High	98.55	+0.02	—	ADEQUATE
Kestrel	0	15min	Unit	—	+0.24	—	ADEQUATE

Figure. Epitalon 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.