Beginner Guide

Most of the vocabulary on this store comes from analytical chemistry rather than from retail, which makes a first order harder than it needs to be. This page explains the paperwork that arrives with a vial, what the numbers on it actually measure, and the abbreviations used across the site.

The certificate of analysis

A certificate of analysis — a COA — is the record of the tests run on one specific batch of material before it was given a label. It is the single most useful document on this site, and the one worth learning to read.

The important property of a COA is how narrow it is. It describes the batch it names and nothing else. A report for one lot says nothing about a different lot of the same compound, even if the compound, the vial size and the supplier are identical. Every batch is assayed on its own.

Match the lot before you read the numbers

The lot code printed on your vial selects its own report. Before reading a single value, check that the lot on the report is the lot on the glass in front of you. A report that does not match the vial is not evidence about that vial.

The rows you will see

• Purity (HPLC) — the share of the peptide material present that is the target compound, measured by high-performance liquid chromatography, usually read at 220 nm. Reported as a percentage against a specification of at least 99.0%.
• Identity (LC–MS) — mass spectrometry confirming that the molecule present has the molecular mass the compound should have. Reported as “Conforms”, alongside the observed mass.
• Peptide content — the share of what is physically in the vial that is peptide, as opposed to counter-ions, residual water and salts left behind by manufacturing. Reported against a specification of at least 80%.
• Appearance — a visual description of the dried cake, so you can compare it against what you receive.
• Water content (Karl Fischer) — residual moisture left after freeze-drying. Moisture is what degrades a dried peptide over time, so a low figure matters for storage life.
• Bacterial endotoxin — a contamination test.
• Acetate content — residue from purification.
• Tested date and testing laboratory — when the work was done and who did it.
• Report identifier, issue date and overall status — whether the lot passed every specification on the sheet.

Purity and fill accuracy are not the same measurement

These two get conflated constantly, and they answer completely different questions.

Purity is a ratio

Purity asks: of the peptide material that is present, what fraction is the compound named on the label? It is measured by separating everything in the sample by HPLC and comparing peak areas. It is a relative figure. A purity result says nothing about how much material is in the vial — a nearly empty vial and a correctly filled one can both report the same purity, because purity is blind to quantity.

Fill accuracy is a quantity

Fill accuracy asks the other question: does the vial actually contain the mass printed on the label? Two things bear on it. Peptide content tells you what share of the powder in the vial is peptide rather than salt and water, so a vial can be correctly filled by weight and still hold less peptide than the number on the label implies. Net fill weight is the physical amount of material dispensed into the vial during filling.

What “lyophilised” means

Lyophilisation is freeze-drying. The material is frozen and then held under vacuum so the water sublimes away without ever passing through a liquid phase, leaving a dry cake or powder behind. Peptides in solution degrade; dried, they are stable enough to sit on a shelf and to survive a parcel at ambient temperature. That is why vials ship dry.

The cake itself varies in appearance. It can be a compact disc at the bottom of the vial, a loose powder, or a thin film smeared up the inside of the glass. All three are normal and none of them indicates a problem — the cake shifts in transit. A lyophilised vial has to be reconstituted with a suitable diluent before it can be used in the lab; see Storage & Handling for how that is done.

How lot numbers work

Every batch produced gets its own lot code, printed on the vial label. Ours look like PL-2602-BPC10: the PL prefix, a four-digit batch code, then the compound abbreviation and the vial size.

The lot code is the key to everything else:

• It selects the certificate of analysis for that batch.
• It travels with your order — it appears on cart lines and on the order confirmation, so the paperwork matches the glass.
• It identifies the material in your own records, which is what makes a result reproducible later.

Two vials of the same compound at the same size, bought months apart, will normally carry different lot codes and have different reports. That is expected. Record the lot alongside your results rather than recording only the compound name.

Glossary

• COA — certificate of analysis. The test record for one lot.
• HPLC — high-performance liquid chromatography. The separation technique used to measure purity.
• LC–MS / MS — liquid chromatography–mass spectrometry. Confirms identity by measuring molecular mass.
• Lot (also batch) — one production run, tested and released as a unit, with its own code and its own report.
• RUO — research use only. Supplied for laboratory research, not for human or veterinary use. See the Research Use Policy.
• Lyophilised (also lyophilized) — freeze-dried to a stable solid.
• Reconstitution — dissolving the dried cake in a diluent to return it to solution.
• Bacteriostatic water — sterile water containing a preservative, used as the diluent for reconstitution. Sold here as a separate item because a lyophilised vial cannot be reconstituted without one.
• Peptide content — the proportion of the vial contents that is peptide rather than counter-ion, salt or residual water.
• KF — Karl Fischer titration, the method used to measure residual water content.
• Spec — the acceptance limit a result has to meet for the lot to be released.
• mg — milligram. The labelled mass of peptide in a vial; it is the vial size, not a quantity to use.
• Vial — the sealed glass container the material is supplied in. One vial is one unit of stock.

Where to go next

• Storage & Handling — keeping a vial stable, and reconstituting it with sterile technique.
• Research Use Policy — what these products are supplied for, and what they are not.
• Track an Order — dispatch, tracking and what to do if a parcel goes missing.
• Browse the catalogue — organised by research goal rather than by acronym.