A documented lot is only as good as the check it gets on arrival. This guide is a receiving checklist in the order the work happens at the bench: carton and packing list, lot codes, the certificate field by field, the HPLC and MS results, the comparison with public records, the optional independent test, and what to record and whom to tell if something does not match.
Most of the check can be prepared before delivery. Have the confirmed specification sheet to hand, because every field on the certificate is read against it. Calculate the theoretical molecular weight of the sequence if you did not do it when ordering. Know the lot code, which the sales desk sends with the tracking reference. And know what the baseline document set is, so you notice if a piece is missing rather than assuming it was never included.
The baseline set for every lot from this desk is in the panel. Anything beyond it was written into the specification; if it is not on the sheet, it was not ordered.
Batch Certificate of Analysis One per lot, with lot code, product or sequence, fill, dates, HPLC purity result, MS identity result and conclusion.
Lot-coded vial label Neutral or your approved artwork, carrying the same lot code as the certificate.
Packing list Kits, vials per kit, cartons, courier reference.
Confirmed specification sheet Sent at order confirmation; the reference for every check below.
Open the outer carton and check its condition and the cold-chain packing: the insulated liner and the ice packs should be present. Count the kits against the packing list and the kit count on the specification, and open one kit to confirm it holds 10 vials. Note the lot code on the outer carton; you will read it again in the next step. If the kit count is short, photograph the open carton and the packing list before anything is moved, and tell the sales desk the same day with the courier reference.
Do not sign a delivery note that says "received in good condition" until the count is done. A count after signature is still a count, but a count before is evidence.
The lot code ties the vial to the paperwork, so read it in three places and make sure they are the same: the vial label, the kit carton, and the certificate. If the order has several lines, each line has its own lot code and its own certificate; match each certificate to its line. For a private-label order the lot-code position on the label is the one marked on the approved proof, so you know where to look.
| Where | Read | If it does not match |
|---|---|---|
| Vial label | Lot code, product or sequence name, fill | Stop. Photograph the label and the certificate side by side and raise it with the sales desk before using any vial. |
| Kit carton | Lot code, kit count | Open every kit and read every vial label; a mixed shipment must be sorted by lot before anything else. |
| Certificate | Lot code, product, fill | Ask for the certificate issued for the lot code on the vials. Do not read a certificate for a different lot as evidence for these vials. |
With the lot code confirmed, read the certificate against the specification sheet one field at a time. The point is not to admire it but to find any field that disagrees with what was ordered.
| Certificate field | Compare with | Pass |
|---|---|---|
| Product or sequence name | Specification field one | Same name, same sequence if printed |
| Fill per vial | Specification field three | Same nominal fill |
| Lot code | Vial label and carton | Identical in all three places |
| Manufacturing date | Order timeline | Within the period between confirmation and shipment |
| Test date | Manufacturing date | On or after manufacturing, before shipment |
| Retest date | Manufacturing date | Later than manufacturing; note it in the order file |
| HPLC purity result | Specification field two | At or above the purity target |
| MS identity result | Your calculated theoretical molecular weight | Observed value matches within the instrument tolerance |
| Conclusion | All of the above | States that the lot meets the specification |
A certificate that passes every row is evidence that the lot was made to the sheet and measured. A certificate missing a row, or with a row that disagrees, is a question for the sales desk, and it is better asked the day the carton arrives than a month later.
The HPLC purity result is the area of the main peak as a percentage of all peak areas in the analytical run. Read it against the purity target on the specification: at or above the target is a pass. Then put it in context. Published HPLC purity across Pepti's public COA library of catalogue lots falls between 98.4% and 99.8% as of this page's review date; a catalogue lot well outside that range deserves a question, and a custom lot is judged against its own target, which may differ.
Remember what the number does not say. It does not measure how much peptide is in the vial, so it cannot confirm the fill; it does not count water, salts or counter-ions, which do not absorb at the detection wavelength; and it does not identify the main peak, which is the MS result's job. If measured fill was written into the specification, there is a separate line for it on the certificate; if it was not, do not read the purity figure as if it were one.
If you have the chromatogram as well as the figure, look at it: a single dominant peak with minor peaks well separated from it is the expected picture for a purified lot. Shoulders on the main peak or a cluster of close minor peaks are worth a question even when the percentage passes.
The MS result reports the observed molecular weight of the main species. Compare it with the theoretical molecular weight you calculated from the sequence on the specification, including the termini and any modifications, because a free acid and an amide differ by a fixed mass and an acetylated N-terminus adds another. A match within the instrument's tolerance is a pass and is the single strongest piece of evidence that the vial contains the sequence ordered.
If the observed value is off by a mass that corresponds to a missing residue, an unremoved protecting group, an oxidation or a different salt form, that is a specific question to put to the sales desk, with both numbers. MS does not confirm residue order, so a pass here is a pass on mass, not a sequence verification; if your project needs sequence confirmation beyond mass, that was a document to specify at the RFQ.
Three dates matter. The manufacturing date should fall within the order timeline, between confirmation and shipment. The test date should be on or after the manufacturing date and before shipment, because the lot cannot be tested before it exists, and its certificate cannot be issued after it leaves. The retest date is the date after which the factory recommends re-examining the lot before use; record it in the order file and plan around it. A certificate whose dates fall outside the order timeline was not issued for this order, whatever the lot code says, and is a question for the sales desk.
For catalogue compounds there is a third point of comparison beyond the specification and the vial: the public COA library at peptioem.com/coa, where Pepti publishes certificates for catalogue lots by product, fill and lot code. Open the record for the same product and fill as your lot and compare: the same certificate fields in the same format; the same kind of HPLC and MS results; and a purity result for your lot that sits in the published range rather than far outside it. The comparison does not replace the checks above, but it tells you that your certificate looks like the factory's other certificates for that product, which is what a genuine lot certificate should do.
Custom-sequence lots do not appear in the library, because the sequence is yours. For those the comparison is with the specification and, on a repeat, with the previous lot's certificate.
Independent testing is optional and welcome. Send vials from the lot to a laboratory of your choosing for analytical HPLC and MS, and read the result against the lot certificate. Expect the MS mass to agree. Expect the HPLC purity to be close but not necessarily identical, because a different column, gradient or detection wavelength legitimately changes the percentage by a small amount; a material disagreement is one that would change the pass or fail against the specification. Keep the independent report with the certificate in the order file. If the two disagree materially, send both to the sales desk with the lot code; confirmed quality issues on a lot are handled under the order terms.
Pepti does not name specific laboratories on this site. Choose one that reports its method alongside the result, so the comparison with the certificate can account for method differences.
Keep one file per lot. It is what a repeat order starts from, what an auditor or a collaborator asks for, and what settles any later question about which lot was used for which work. The panel lists its contents. The file is more useful if it also records who did the receiving check and when.
Order file for one lot
Mismatches fall into three kinds, and each has a different first move.
In every case, the lot code is the first thing to quote and the specification sheet is the reference. A clear message with both gets a clear answer.
A complete, passing document set tells you that the lot was made to the specification, that the main species has the mass of the ordered sequence, that the lot meets its purity target by HPLC, and that the vial in hand belongs to that lot. It does not tell you the measured fill unless fill was specified and tested, does not tell you the water or salt content, does not tell you the microbial status, and does not establish suitability for any use. Those limits are the same for every research-peptide certificate from any supplier; a document set that claims more than its measurements support is a reason for caution, not reassurance.
Scope statement
Pepti does not present itself as a cGMP drug-substance (API) manufacturer or CDMO and does not publish a GMP certificate or DMF. Peptides on this site are supplied for research use by qualified B2B buyers. For research use only. Not for human or veterinary use.
The kit count against the packing list, before signing for the delivery, then the lot code in three places: vial label, kit carton and certificate. Everything else follows from a confirmed lot code.
Calculate the theoretical molecular weight from the sequence on your specification, including termini and modifications, and compare it with the observed value on the certificate. A match within instrument tolerance is a pass on mass.
At or above the target on your specification. For context, published HPLC purity across Pepti's public COA library is 98.4%–99.8% as of this page's review date. A custom lot is judged against its own target.
It is optional and welcome. Expect the MS mass to agree and the HPLC purity to be close, with small method-related differences. Keep the report in the order file and send material disagreements to the sales desk with the lot code.
Do not use the vials. Photograph the vial label beside the certificate and ask the sales desk for the certificate issued for the lot code on the vials. A certificate for another lot is not evidence for these vials.
No. HPLC purity does not measure quantity. If measured fill matters, it must be written into the specification so it is tested and reported as its own line on the certificate.
Open WhatsApp with a pre-filled Pepti-RFQ message, or email the same details. A quote needs the compound or sequence, fill per vial, vial count, labelling and the document set you require.