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.

97 recordsmedian 99.22 %spec 99.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	48	30min	High	99.19	+0.00	99.19	ADEQUATE
Medutest	14	25min	Unit	99.62	+0.08	99.54	ADEQUATE
Nordanalyt	14	35min	High	99.21	+0.02	99.19	ADEQUATE
PeptideMeter	11	28min	High	99.32	-0.05	99.37	ADEQUATE
VendorInvestigate	6 n=6	32min	High	98.78	-0.11	98.89	ADEQUATE
Kestrel	4 n=4	15min	Unit	99.50	+0.24	99.27	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.