How to Read a COA: Peptide Purity, Identity and Lot Checks
Reading a certificate of analysis (COA) for a peptide comes down to three checks, done in sequence. Start with the lot number, which has to be exactly the same on the report as on your vial label. Next comes the mass spectrometry result, where the observed mass ought to line up with the expected molecular weight of the sequence, confirming identity. Last is HPLC, which states purity as the main peak's portion of the total peak area, ideally with the chromatogram included. Without all three, the report cannot describe the contents of your vial. The rest of the page, including appearance and method details, simply backs up those answers.
Buy Peptides Backed by a Certificate of Analysis
Think of a COA as the testing record for a single production lot. It sets out the tests performed, the specification each one needed to hit and the outcome. Since it covers just one lot, it tells you nothing about earlier or later batches, and that is why a general "product COA" carrying no lot reference is of little value. Laboratories format their reports differently, yet a report worth trusting will include the following.
- The compound name, along with its sequence or structure.
- A batch or lot number and the date of testing.
- HPLC purity expressed as a percentage, together with the chromatogram.
- Mass spectrometry data, meaning the observed mass, the expected mass and the spectrum itself.
- Appearance, such as white lyophilised powder, or blue powder in the case of copper peptides.
- Method notes covering things like column type, mobile phase and detection wavelength.
- The testing laboratory's name plus an authorisation line.
Order Pure Peptides by Reading the HPLC Result
In high-performance liquid chromatography, the dissolved sample is forced through a packed column, typically reverse-phase C18, with a gradient of water and acetonitrile. Every component exits the column at its own retention time, and a UV detector tuned to roughly 214 to 220 nm, the range where peptide bonds absorb, records each as a peak. Purity equals the area of the main peak divided by the combined area of every peak. So a 98.7% figure tells you that 98.7% of the material absorbing UV light was the target peptide.
Reading the Chromatogram Peak by Peak
- A single tall, narrow main peak. When the main peak looks broad or split, aggregation or weak separation may be the cause.
- Minor peaks on each side. Synthetic peptides normally show these, and they come from truncated chains, oxidised forms or deletion sequences that lost a residue. What matters is how large they are in total.
- A peak table that reconciles. The integrated peak areas should match the headline purity number.
- Several peaks for a blend. A mixed product like the Wolverine Blend ought to show a main peak for each component instead of one dominant peak.
Limits of an HPLC Purity Figure
Purity is expressed as a ratio, not a mass. Salts, water and counter-ions like trifluoroacetate or acetate hardly show up at 214 nm, so they leave the figure unchanged. Net peptide content, meaning the share of the vial's weight that is genuinely peptide, needs its own test, and plenty of reports skip it. On top of that, HPLC alone cannot prove identity, since an extremely pure batch of the wrong peptide would still produce a single clean peak.
Shop With Confidence Using Mass Spec Identity Data
In mass spectrometry the sample is ionised and its mass-to-charge ratio (m/z) is measured. Set the observed mass against the theoretical molecular weight of the sequence listed on the report. With small peptides, a match within roughly 1 Da is standard. New readers often trip over three points.
- Extra protons. Electrospray measures the molecule with protons attached. BPC-157, which should come in close to 1,419.5 Da, shows up as [M+H]+ at around 1,420.5 or as [M+2H]2+ at around 710.8.
- Several charge states. Bigger peptides like sermorelin (about 3,357.9 Da) usually produce [M+3H]3+ at about 1,120.3 and [M+4H]4+ at about 840.5, and software deconvolutes them into a single mass.
- Monoisotopic against average mass. Catalogues list average molecular weight, while high-resolution instruments sometimes give the monoisotopic mass, which is a little lower.
Reference Molecular Weights for Peptides in Our Range
These are average molecular weights rounded to one decimal place, useful for a quick check of the identity section on any report.
| Peptide | Chain length | Expected MW (Da) |
|---|---|---|
| KPV | 3 amino acids | 342.4 |
| Epitalon | 4 amino acids | 390.4 |
| SS-31 | 4 residues, amidated | 639.8 |
| Ipamorelin | 5 residues, amidated | 711.9 |
| Selank | 7 amino acids | 751.9 |
| Semax | 7 amino acids | 813.9 |
| DSIP | 9 amino acids | 848.8 |
| BPC-157 | 15 amino acids | 1,419.5 |
| AOD-9604 | 16 amino acids | 1,815.1 |
| Thymosin Alpha-1 | 28 amino acids, acetylated | 3,108.3 |
| Sermorelin | 29 amino acids, amidated | 3,357.9 |
| CJC-1295 No DAC | 29 amino acids, amidated | 3,367.9 |
| Tesamorelin | 44 amino acids, N-terminally modified | 5,135.9 |
Two items need extra care. Because TB-500 is a synthetic fragment of thymosin beta-4, its report should name the precise sequence tested, and the expected mass has to correspond to that fragment, not to the complete protein. GHK-Cu is a copper complex whose copper may detach during ionisation, meaning the spectrum can display the free GHK tripeptide at roughly 340.4 Da rather than the full complex.
Buy the Right Vial by Matching the COA Lot Number
A lot number is what links a piece of paper to the actual vial on your bench. Read the number on the label, locate it on the report and check the two one character at a time. NovaPep sends every lot to an independent laboratory for purity and identity testing, and the lot on each certificate is the lot on the vial label. You can find the reports by product in our COA library. After that, look at the test date, because a report dated years before your lot could have existed is not about your stock.
Shop Smart and Spot Peptide COA Warning Signs
- A missing lot number, or one that is nowhere on the vial.
- A headline purity percentage without any chromatogram.
- Mass spectrometry simply marked "conforms", with neither an observed mass nor a spectrum.
- An expected molecular weight that is wrong for the sequence named.
- Different products sharing chromatograms that match right down to the tiniest impurity peak.
- Inconsistent fonts, fuzzy numbers or a cropped screenshot in place of a complete report.
- A testing laboratory that cannot be identified.
- Purity of precisely 99.99% on every product and every lot.
Having read a great many of these reports, our view is simple. A genuine, lot-matched certificate showing 98.4% with the full trace attached beats a flawless 99.9% on a document that carries no lot number. One describes what your vial holds, and the other describes nothing at all.
Read the Report, Then Order Lab-Tested Peptides Online in Australia
Review the certificate before you order rather than afterwards. If a lot you have received is not listed yet, send the product name and lot number to order@novapepaus.com. Once the paperwork is in order, the next step is covered in our peptide reconstitution guide. Everything we sell is strictly for laboratory research and never for veterinary or human use.
Certificates in our COA library are organised by lot, which means you can review the report for BPC-157, retatrutide or GHK-Cu before you spend a cent. For every batch, an independent lab performs HPLC for purity and mass spectrometry for identity, the very two checks explained above. Browse the lab-tested peptides range online, test the figures against the warning signs listed earlier, order the compound you need, and when it arrives, match the lot on the vial label to its report.
How to Read a COA: Peptide Purity, Identity and Lot Checks FAQ
What purity level should research peptides have?
Synthetic research peptides are usually specified at 98% HPLC purity or above, and a lot of batches come back above 99%. That number only means something when the chromatogram is included and the lot number matches the vial you hold. For quantitative studies, keep in mind that HPLC purity differs from net peptide content, since salts, water and counter-ions are invisible in the UV trace.
How do HPLC and mass spec differ on a peptide COA?
HPLC reports purity, in other words what share of the UV-absorbing material in the sample is the target peptide. Mass spectrometry confirms identity by weighing the molecule and checking it against the expected molecular weight. A sound report includes both, because a sample might be very pure yet be the wrong compound, or be the correct compound with substantial impurities.
Why doesn't the mass on my peptide COA exactly equal the molecular weight?
Minor differences are normal. Electrospray attaches protons, so the reported value may be the [M+H]+ ion roughly 1 Da higher, or a multiply charged ion at a fraction of the full mass. High-resolution instruments can also report monoisotopic mass, which falls a little under the average molecular weight listed in catalogues. Once both are allowed for, a match within about 1 Da is typical for small peptides.
How can I confirm a COA belongs to my peptide vial?
Locate the lot number on the vial label and check it against the certificate's lot number one character at a time. The two have to be identical. Next, make sure the test date makes sense for that lot. NovaPep files reports by product in its COA library, and if your lot is missing, email us the product name and lot number.
How can I buy peptides online in Australia with a matching COA?
NovaPep sells research peptides online from stock held in Australia, and before anything goes on sale, each batch goes to a third-party lab that checks its HPLC purity and its mass. Certificates are kept in our COA library and filed by lot number, so you can read the report before you buy and check it against the label once the vial arrives. Every product is sold for laboratory research only.