Cross-section

IGF-1 DES (1-3) 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 IGF-1 DES (1-3), with a class minimum gradient of 15 min, the method is a live explanation.

15 recordsmedian 99.12 %spec 95.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	7 n=7	30min	High	98.51	+0.00	98.51	ADEQUATE
Medutest	4 n=4	25min	Unit	99.52	+0.08	99.44	ADEQUATE
PeptideMeter	3 n=3	28min	High	99.67	-0.05	99.72	ADEQUATE
Nordanalyt	1 n=1	35min	High	98.22	+0.02	—	ADEQUATE
VendorInvestigate	0	32min	High	—	-0.11	—	ADEQUATE
Kestrel	0	15min	Unit	—	+0.24	—	ADEQUATE

Figure. IGF-1 DES (1-3) 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.