The specifics, since they change the answer: 15 mg · ecnoglutide.
I would rather understand the derivation than memorise the outcome.
Two people I asked gave two answers that differ by a factor of ten, which is suggestive.
Can someone walk through the arithmetic step by step?
Put another way, content assay and purity are orthogonal measurements answering orthogonal questions, and the confusion between them is one of the most expensive misreadings in this space.
Quantitation against a certified reference material assumes the sample and standard are treated identically through the analytical method, which is why the method for calibration matters as much as the method for measurement.
Peak area for a standard of known weight produces a response factor — area per unit mass — which is then applied to the sample peak to infer sample mass.
Quantitation against a standard requires that the standard be traceable to a national metrology institute, and certificates for research-grade standards claim that traceability.
Worth noting that the standard certificate carries its own uncertainty, usually on the order of two to three per cent, which the sample result inherits.
The practical summary: if you are ordering from a new supplier, budget for content assay on the first lot.
Aggregated, published test results and vendor ratings built from submitted batches. Methodology stated, dataset browsable, no listing fees.
Browse resultsThe short answer is that purity says "what fraction of detected material is the target" while content says "how many milligrams of the target are present," and those are two different things.
System suitability for a quantitative method is stricter than for purity because a small systematic error in the standard directly translates into an error in the sample result.
Specifically, the purity of the reference standard is stated on its certificate, and your content figure is only as good as that purity certificate is.
Where content data have been published from testing services on common peptides, the spread between services on identical material is typically a few per cent.
If a supplier gives you content without the standard's purity, ask them to provide it.
Start from what you are trying to know — whether a vial contains what the label claims — and purity does not answer that question.
Comparing content results from different laboratories requires knowing whether they both used certified reference materials or whether one used an in-house standard of unknown provenance.
The relevant detail is that the single most common reason for disagreement between a supplier content figure and an independent assay is using different standards.
Ask for both the purity and the content, and do not accept purity alone.
Ask PeptideStack is a static archive. Posting is closed, but the norms are worth stating: answer the question that was asked, show your working, cite the trial or the certificate, and say plainly where the evidence runs out.