Purity vs quantity

Two independent claims that are routinely conflated: purity describes the quality of the compound present, quantity describes how much of it there is — and a certificate can establish one without the other.

A 99% purity figure and a 10 mg label answer different questions, and neither implies the other. Purity — normally chromatographic peak area — describes what fraction of the detected material is the intended compound. Quantity is a mass claim about how much material is in the vial. A powder can be extremely pure in small quantity, or plentiful and impure, and a certificate reporting only purity has said nothing about fill mass.

The gap between the two is wider than it first appears, because the label mass is gross powder weight. Residual water and counterion count toward the grams but not toward the peptide, so even a truthful label overstates peptide content unless net peptide content was measured. Chromatographic purity, being a ratio of peak areas, is indifferent to fill mass entirely.

Reading a certificate carefully therefore means holding three numbers apart: the purity percentage, the labelled fill mass, and — where reported — the net peptide content that connects them. Treating any one of them as a proxy for the others is the most common way a COA gets over-read.

For research purposes only. Not for human consumption, diagnosis, treatment, or prevention of any condition. Nothing on this page is medical advice.