Gravimetric · calibrated analytical balance · Included in core · $250

Does a "10 mg" vial hold 10 mg?

The simplest test and the one most often skipped. We weigh the sealed vial, empty it, weigh it again, and report the difference against the label. Short-filled vials are among the most common failures in the registry.

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GRAVIMETRIC · VL-2026-[00404a]10.2 mg · 102%

Gross

1215.4

Tare (empty vial)

1205.2

Contents

10.2

mg · 102% of label

Balance BAL-01 · calibrated 2026-09-30 · readability 0.01 mg

Illustrative readout — real lot spectra replace this when the registry opens.

How it works

01
Weigh gross
The intact vial with cap and contents is weighed on a balance readable to 0.01 mg, calibrated on a recorded schedule.
02
Open and transfer
Contents are dissolved out for the other tests; the vial is dried.
03
Weigh tare
The empty vial, cap and stopper are weighed. Contents = gross − tare.
04
Compare with the label
Reported as milligrams found and as a percentage of the label claim.

What the result means — and what it doesn't

Contents is the mass of everything that was in the vial: peptide, its counter-ion, and any residual moisture or bulking agent. It answers "did I get the amount I paid for". At least 90% of the label is one of the seal's four checks. It is not the mass of pure peptide; combine it with purity to get close, and note that a 10 mg fill of 98% pure peptide-TFA still weighs 10 mg.

We will not say: "10 mg of active peptide" from a weight alone.

Why another lab might report a different number

Lyophilized powder is hygroscopic; a vial opened in humid air gains weight in minutes. We weigh sealed.
Balance class and calibration state. Ours are on the result.
Whether the lab reports contents (what we do) or net peptide content (needs amino-acid analysis or quantitative UV).

That's why every result here prints the method and the limit next to the number. The full science article on why tests vary.

Methods described are Vialidate's own and are published so results can be compared with other laboratories' on equal terms. Nothing on this page is medical advice. ISO 17025 accreditation in progress.