Why Should a Peptide COA Include the Chromatogram, Not Just a Purity Number?

Paul Bakhtiar, MBA | Published October 15, 2026

Short answer. The chromatogram is the primary record the purity number came from. Without it, no one can check how the peaks were integrated, whether early or late peaks were excluded, what wavelength and gradient were used, or whether the trace belongs to the stated lot. A number typed into a template is an assertion; a chromatogram with a sample ID, date and method header is evidence.

What this means for your clinic. Make the chromatogram and its integration table a condition of accepting a certificate, written into your supplier file, and file the trace with the certificate for every lot. When a supplier sends a summary page alone, ask for the trace before the lot leaves quarantine, and record the request and the answer.

What does a chromatogram actually show?

A chromatogram is the instrument’s own record of the run. Time runs along the bottom, detector signal up the side, and each substance that left the column appears as a peak at its retention time. Under the trace sits the integration table: one row per peak, with retention time, area, height and area percent. Above it sits a header with the sample ID, the injection date and time, the instrument, the method name and usually the analyst.

Everything a purity number claims is visible there. The main peak’s share of the total area is the purity. The small peaks are the impurity profile. The flat stretches between peaks are the baseline the software drew, and the shape of the main peak, symmetric or trailing a shoulder, shows how well the method separated what was in the sample. USP <621>, the general chapter on chromatography, is where those terms are defined: retention time, resolution, tailing factor and the system suitability tests that show the system was working that day.

A certificate of analysis that includes the trace lets you check all of that. One that includes only the number asks you to take the laboratory’s word for every choice made along the way. That is the line the clinic’s guide to verifying peptides draws between an assertion and evidence.

Which integration choices inflate a purity number?

Integration is where judgment enters. The same raw data can produce different purity figures depending on decisions that never appear on a summary page.

Choice	How it raises the number	What to look for on the trace
Baseline placement	A baseline drawn high under the small peaks shrinks their area and enlarges the main peak’s share	Baselines that cut through the foot of small peaks
Integration start	Integration set to begin late excludes early impurities along with the solvent front	Peaks before the integration start line
Run length	A run stopped early leaves late-eluting impurities on the column, out of the denominator	A trace that ends soon after the main peak, with no wash step
Minimum peak area	A high threshold drops small peaks from the table entirely	Visible bumps with no row in the table
Shoulder handling	A shoulder merged into the main peak is counted as product	A main peak that is asymmetric or has a step on one side
Wavelength	A wavelength that some impurities do not absorb at makes them disappear	A method header showing 254 or 280 nm rather than 210 to 220 nm

None of these is necessarily wrong. Each is a decision that should be visible, and on a chromatogram it is. FDA’s 2018 guidance on data integrity and compliance with drug CGMP gives the example directly: a dynamic chromatography record lets a user change the baseline and reprocess the data so that peaks appear smaller or larger. That is why the electronic record, with its metadata and audit trail, counts as the complete record and a printed trace as a static copy. A number typed into a template is neither.

How do you match the trace to the certificate and the lot?

A trace proves something only if it belongs to the lot in front of you. Five fields tie it down.

Sample ID. The identifier on the chromatogram header should appear on the certificate’s summary page and in the laboratory’s own records.

Lot number. The lot on the header should match the certificate and the vial label.

Injection date and time. The run should fall on or before the certificate’s test date, never after the report date.

Method. The column, gradient and wavelength in the header should match the method statement on the certificate.

Analyst and reviewer. The initials of the person who ran the test and of a second person who reviewed it should appear, with dates.

If the header is cropped off the image a supplier sends, ask for the full page. A trace with no header is a picture of a peak. It could belong to any lot, any product or any laboratory.

Why is the trace part of the laboratory record?

The US drug manufacturing regulation is explicit. 21 CFR 211.194(a)(4) requires a laboratory record to include a complete record of all data secured in the course of each test, including all graphs, charts and spectra from laboratory instrumentation, properly identified to show the specific material and lot tested. The same section calls for the initials or signature of the person who performed each test and the date, and for a second person’s review of the original records for accuracy and completeness. Part 211 binds drug manufacturers; it is cited here as the benchmark a legitimate supplier meets, not as an obligation on a clinic.

The point for your clinic is what that implies about the document you receive. If the laboratory kept the trace, as the benchmark requires, sending it costs nothing. A supplier that will not send it is either not keeping it or choosing not to show it, and either answer belongs in the supplier file.

How do you read the EV-01 trace?

The independent laboratory’s report for lot IGF1A122925 (EV-01) carries the chromatogram, the integration table and a mass spectrum on one document, with a main peak of 99.80%. Start at the header and confirm the sample ID, lot and run date. Then read the integration table from top to bottom: the main peak’s area percent should be the purity on the summary page, and the remaining rows should account for the rest.

Then look at the trace itself for what the table cannot tell you: where the baseline was drawn, whether integration starts after the solvent front, whether the run continued long enough after the main peak, and whether the main peak has a shoulder. Finally, note the wavelength in the method line. That reading takes two or three minutes and turns a number into a document you have checked.

How Helios does it

Under the Helios verification standard, step 2 requires a lot-specific certificate before shipment: the manufacturer’s certificate plus an independent laboratory report for the exact lot, carrying the panel the standard specifies, which lists purity with the chromatogram rather than a purity figure alone. The record this step produces is the certificate set, and Helios Consultants LLC applies the requirement lot by lot. Under step 6, the lot is held in quarantine until steps 2 to 5 pass. The full sequence is in how Helios verifies every lot. If you want help setting this up in your clinic, book a consultation.

Sources

USP <621> Chromatography, adoption notice. USP. https://www.usp.org/harmonization-standards/pdg/excipients/chromatography

FDA, Data Integrity and Compliance With Drug CGMP: Questions and Answers, Guidance for Industry (2018). https://www.fda.gov/media/119267/download

21 CFR 211.194, Laboratory records. eCFR. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-C/part-211/subpart-J/section-211.194

Educational content for licensed professionals. Not legal or medical advice. No product is offered for sale on this page.