Cross-section

Melanotan II 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 Melanotan II, with a class minimum gradient of 22 min, the method is a live explanation.

186 recordsmedian 99.24 %spec 98.5 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	89	30min	High	99.31	+0.00	99.31	ADEQUATE
PeptideMeter	35	28min	High	99.23	-0.05	99.28	ADEQUATE
Medutest	21	25min	Unit	99.21	+0.08	99.13	ADEQUATE
VendorInvestigate	21	32min	High	98.73	-0.11	98.84	ADEQUATE
Kestrel	12	15min	Unit	99.80	+0.24	99.56	BELOW CLASS MINIMUM
Nordanalyt	8	35min	High	99.19	+0.02	99.17	ADEQUATE

Figure. Melanotan II 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.