Cross-section

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

42 recordsmedian 97.75 %spec 92.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	22	30min	High	97.75	+0.00	97.75	ADEQUATE
PeptideMeter	6 n=6	28min	High	97.54	-0.05	97.59	ADEQUATE
Kestrel	5 n=5	15min	Unit	98.04	+0.24	97.80	ADEQUATE
Medutest	4 n=4	25min	Unit	98.19	+0.08	98.11	ADEQUATE
Nordanalyt	4 n=4	35min	High	96.83	+0.02	96.81	ADEQUATE
VendorInvestigate	1 n=1	32min	High	97.41	-0.11	—	ADEQUATE

Figure. PEG-MGF 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.