Cross-section

GHRP-2 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 GHRP-2, with a class minimum gradient of 15 min, the method is a live explanation.

110 recordsmedian 99.28 %spec 99.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	49	30min	High	99.48	+0.00	99.48	ADEQUATE
PeptideMeter	20	28min	High	99.21	-0.05	99.26	ADEQUATE
Medutest	16	25min	Unit	99.28	+0.08	99.20	ADEQUATE
VendorInvestigate	11	32min	High	98.80	-0.11	98.91	ADEQUATE
Nordanalyt	8	35min	High	99.43	+0.02	99.41	ADEQUATE
Kestrel	6 n=6	15min	Unit	99.75	+0.24	99.52	ADEQUATE

Figure. GHRP-2 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.