Every lot we sell ships with an independent certificate of analysis, and every one of those certificates is published on this site before the product goes on sale. That is easy to say and easy to imitate. What is harder — and what actually protects a researcher — is knowing how to read the document you are handed.
Purity is a percentage of peak area, not a guarantee
High-performance liquid chromatography separates the compounds in a sample by how strongly they interact with a stationary phase. What comes out is a chromatogram: a series of peaks, each one a compound, each with an area proportional to how much of it is present.
A purity figure of 99.4% means the target peptide accounts for 99.4% of the total peak area detected. The remaining 0.6% is process-related material — truncated sequences, deletion peptides, residual reagents. It does not mean the vial is 99.4% peptide by mass; water and counter-ions are not part of that calculation. Anyone who tells you a purity number is a mass fraction has either misread the report or is hoping you will.
Identity is the test most buyers skip
Purity tells you the sample is clean. It does not tell you the sample is what the label says. A vial of an entirely different peptide, synthesised well, will return an excellent purity figure.
Mass spectrometry closes that gap. The instrument measures the molecular weight of the compound and compares it against the theoretical weight of the declared sequence. A match within tolerance is a positive identification. This is the single most important line on a certificate, and it is the one most often left off cheaper reports.
Fill weight is where the quiet failures live
A vial labelled 10 mg should contain 10 mg. Under-filling is invisible to the buyer, costs the supplier nothing in reputation until someone checks, and directly changes every concentration calculation downstream.
We ask the lab to weigh the lyophilised contents against label claim on every lot and we publish the result whether it flatters us or not. Our target is greater than 90% of label across the lot.
What a certificate cannot do
A certificate describes the material in the vial. It is not a statement that a compound is safe, effective, or suitable for any application in a living organism. Nothing on a lab report — ours or anyone’s — changes the fact that these products are supplied strictly for in vitro laboratory research.
Checking ours
Every report linked from our certificates page opens on Janoshik Analytical’s own verification domain. We do not host the PDFs and we cannot edit them. If the numbers on our product pages ever disagreed with the numbers on theirs, theirs would be the record.