How to match a certificate of analysis to the batch you receive

It is written for the person who opens the parcel: a laboratory technician, a stores clerk at a distributor, or the owner of a small brand receiving a first run. No chemistry beyond reading a number off a page is needed. No use instructions are given, and nothing in the procedure involves opening a vial.

What a lot number is and where it appears

A lot number, sometimes called a batch number, is the identifier a manufacturer assigns to one production run of one product at one fill. Everything made in that run shares the number; nothing made in another run does. It is the thread that ties a certificate to a container, and it is the one field on a certificate that cannot be copied from a template, because it is assigned when the batch is made. In the Pepti public library each record carries a lot alias in a fixed pattern, so that two fills of the same compound are visibly different lots.

The lot number appears in four places, and the receiving procedure below checks all four.

• On the certificate. Usually near the top, next to the product name and the fill.
• On the vial label. Vials carry the product name, the fill and the lot number. A label without a lot number is a label for a product, not for a batch.
• On the outer container. For raw powder, the sealed container carries the product, the weight and the lot. For vials, the kit box or inner carton repeats the lot.
• On the dispatch note or packing list. The paperwork in the parcel lists each line with its lot number and quantity.

Why four positions and not one

If all four agree, the certificate describes the material. If any one disagrees, you do not yet know which lot you have, and the certificate is evidence of nothing until the disagreement is explained. Checking four positions takes a minute, and it is the minute that makes every later question answerable from the file rather than from memory.

The fields on a certificate of analysis

A batch certificate for research peptide raw material is a one-page document. The fields below are the ones on the Pepti template and on most others; the order varies, the content should not.

The three dates

The dates should be in order: manufacturing, then test, then retest. On the public Pepti records the retest date falls about two years after the manufacturing date. A test date before the manufacturing date, or a retest date already past when the parcel arrives, is a question to raise before the material goes into stock. None of the dates is a day on which the material stops being what it is; the retest date is a prompt to re-examine, as the storage and retest guide explains.

Reading the HPLC result and the MS result

The two analytical results on the certificate answer two different questions. Reading one as if it answered the other is a common misreading, and it is the reason a certificate with only one of the two is incomplete.

The HPLC result: how much of the material is one thing

High-performance liquid chromatography separates the dissolved sample into peaks over time. The purity figure is the area of the main peak as a percentage of the total area of all peaks detected.

What it proves: the material is predominantly one substance, and the proportion of other detectable substances is small. What it does not prove: that the one substance is the compound you ordered. A clean sample of the wrong peptide also gives a single peak. It also says nothing about anything the detector does not see, including water, counter-ion and inorganic salts, which is why chromatographic purity and net peptide content are different numbers.

The MS result: whether that one thing is the right thing

Mass spectrometry measures the mass of the molecule. The certificate reports an observed molecular weight, which you compare with the calculated weight for the CAS number. For BPC-157 the calculated weight is 1419.5 g/mol, and the public records report observed values of 1418.5 Da and 1420.51 Da. For TB-500 the figure is 889.0 g/mol; a result near 4,963 g/mol would mean full-length thymosin β4, which is a different substance.

What it proves: the main component has the mass of the compound named, so the purity figure is a purity figure for the right substance. What neither result proves is listed below, and none of it is reported on a public summary unless the certificate prints a separate line for it. The Pepti summaries do not.

• Fill mass. The certificate states the nominal fill; it does not weigh your vial.
• Sterility. Not examined unless a sterility result is printed.
• Endotoxin. Not examined unless an endotoxin result is printed.
• Water content. Not examined unless a Karl Fischer or loss-on-drying result is printed.
• Net peptide content. Not reported unless an amino acid analysis or nitrogen result is printed; the gross weight includes counter-ion and water.

How a public COA library helps

A certificate that arrives in the parcel can be compared with the container in the parcel. A certificate published before the parcel ships can also be compared with the quotation and with every other record for the same product. That wider comparison is what a public library adds.

Pepti publishes batch records in its own public COA library, and each compound page on this site mirrors them in a batch table. Each record is one lot at one fill and links to a PDF summary with the purity result, the molecular-weight result and the three dates. The library can be searched by product name, so the record for the lot named on your quotation can be opened before you pay and again when the parcel arrives. The records also show the range a production has reported: the five public BPC-157 records report purity between 98.73% and 99.72%, and the three public TB-500 records report between 99.1% and 99.6%. Those are results for specific lots, not a specification for future lots.

A public record also makes a mismatch visible to someone other than you and the supplier. If the lot number on your container is not in the library and the certificate you were sent claims to be a Pepti record, the library settles the question.

Published lots and unpublished lots

A lot that has been published is documented by the public record. A lot that has not been published yet, for example a new production batch made for your order, is documented on the same template and document availability is confirmed per lot on the quotation. The receiving procedure is the same; the only difference is that the comparison against the library is made later or not at all. Ask at quotation stage whether the lot will be published.

A receiving procedure, step by step

This takes about fifteen minutes per line and is done before the material goes into cold storage. Do it with the dispatch note, the certificate and a camera to hand.

• Step one: photograph the parcel as received. Outer packing, cold-chain packing, any temperature indicator and the seal, before anything is opened.
• Step two: read the dispatch note. Match each line to your order: product, format, fill or grams, quantity, lot number.
• Step three: read the outer container or kit box. Confirm the product, the fill or weight and the lot number against the dispatch note.
• Step four: read a vial label, or the powder container label. Confirm the lot number. For a kit, check that every vial carries the same lot and fill, and count the vials.
• Step five: open the certificate. Confirm product, CAS number, lot number and fill match the label. Confirm the three dates are in order and the retest date is in the future.
• Step six: read the results. Confirm an HPLC purity result and an MS molecular-weight result are both present, that the molecular weight is close to the calculated value for the CAS number, and that the purity figure sits in the range the public records for that product report.
• Step seven: compare with the public record. Open the library, find the lot, and confirm the published PDF matches the certificate in the parcel field for field.
• Step eight: weigh what you can weigh. Gross weight of a sealed powder container against the dispatch note; for vials, a count and a look at whether each cake resembles the others. This is a plausibility check, not an assay.
• Step nine: log it. Lot, receipt date, retest date, storage location, and where the certificate is filed. Then put the material away cold.

What the procedure does not do

You are not confirming purity or identity yourself; you are confirming that the documents agree with each other and with the container. Analytical confirmation is an outside laboratory's job, covered below.

What to do on a mismatch

A mismatch is any disagreement between certificate, label, container and dispatch note, or between the certificate and the public record. Handle it against the record, not from memory.

• Stop and photograph. The label, the certificate field, the container and the dispatch note, each showing the disputed value.
• Open nothing further. A sealed container can be returned or re-documented; an opened one is harder to argue about.
• Write to the supplier with the lot number in the subject line. State which field disagrees, quote both values, attach the photographs.
• Ask for one of three outcomes. A corrected certificate for the lot you hold, if the error is on the paper; a replacement from the lot on the certificate, if the error is in the parcel; or a written explanation you can file, if the discrepancy is cosmetic, for example a trade name on the label and a sequence name on the certificate.
• Quarantine the material until the outcome is in writing. Mark the shelf position so no one else takes it.
• Record the outcome in the same log entry as the receipt, with the date the question was closed.

Differences that are not mismatches

Some differences are expected. The observed molecular weight on the MS line differs from the calculated value by a small amount, as the BPC-157 figures above show. A trade name on the label and a sequence name on the certificate can refer to the same substance; the CAS number settles it. Two records with the same product name and different fills are two lots, not an error. What is never expected is a lot number that appears nowhere else, or a certificate with no MS line at all.

When to send a portion to an outside laboratory

The certificate is the manufacturer's result. An outside laboratory's result is yours. The cost is yours too, so the question is when the second result earns its cost. These are the situations in which it usually does.

• When qualifying a supplier for the first time, so your own result and the certificate can be filed together as the baseline for later lots.
• When you distribute to others and your customers will ask what you did beyond reading the paperwork.
• When the material will go into a labelled run under your own name.
• When the lot is not in the public library and you have only the certificate in the parcel.
• When the retest date has passed on material still in stock.
• When a mismatch has been resolved on paper and you want to close the file with a measurement.

What to ask the laboratory for

Ask for HPLC purity by the same kind of method the certificate used, and for a mass-spectrometry identity result, so the two reports can be read side by side. Give the laboratory the lot number and a copy of the certificate so its report cites the same lot. If your work needs fill mass, water content or net peptide content, ask for those separately; they are not what the certificate reports and the laboratory will need to know. Keep an unopened unit from the same lot as a retained sample.

A record-keeping template

One row per lot received. Keep it in whatever system you already use; the columns matter, not the software.

What Pepti publishes, and what is not claimed

Pepti manufactures in Guangzhou and publishes batch records in its own public COA library. Each record is one lot at one fill; each reports an HPLC chromatographic purity result and a molecular-weight result from mass spectrometry, with the manufacturing date, the test date and the retest date, and each links to a PDF summary. The quotation from this site names the lot where stock is allocated so that the record can be read before payment. The quality page and order photographs show what the paperwork and packing look like.

What is not claimed: the public records do not report sterility, endotoxin, water content, residual solvent or net peptide content, and this guide has not suggested that they do. No certificate or registration is claimed on this site. Matching a certificate to a batch confirms that the paperwork and the container agree; it does not confirm anything about what the compound does, and no page here describes that. For the choice between formats, see vials versus raw powder; for comparing supplier paperwork before you order, see comparing quotations.