Cross-section

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

160 recordsmedian 99.17 %spec 98.5 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	67	30min	High	99.34	+0.00	99.34	ADEQUATE
PeptideMeter	31	28min	High	99.25	-0.05	99.30	ADEQUATE
Medutest	20	25min	Unit	99.09	+0.08	99.01	ADEQUATE
VendorInvestigate	17	32min	High	98.85	-0.11	98.96	ADEQUATE
Nordanalyt	15	35min	High	99.17	+0.02	99.15	ADEQUATE
Kestrel	10	15min	Unit	98.91	+0.24	98.67	ADEQUATE

Figure. Semax 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.