Cross-section

Tirzepatide 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 Tirzepatide, with a class minimum gradient of 25 min, the method is a live explanation.

750 recordsmedian 98.55 %spec 97.0 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	352	30min	High	98.58	+0.00	98.58	ADEQUATE
PeptideMeter	146	28min	High	98.41	-0.05	98.45	ADEQUATE
Medutest	89	25min	Unit	98.48	+0.08	98.40	ADEQUATE
Nordanalyt	63	35min	High	98.69	+0.02	98.67	ADEQUATE
VendorInvestigate	60	32min	High	98.41	-0.11	98.52	ADEQUATE
Kestrel	40	15min	Unit	99.09	+0.24	98.85	BELOW CLASS MINIMUM

Figure. Tirzepatide 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.