How to read a peptide Certificate of Analysis (COA)

A Certificate of Analysis (COA) is the third-party laboratory report that documents what's in your specific batch of medication. Every PeptideRx prescription ships with a lot number that traces back to a published Eagle Analytical Services COA. This guide walks every field on a real Eagle COA and explains what the numbers actually mean: sterility methods, USP <85> endotoxin limits, USP <621> potency assays, lot numbers, and BUDs.

6 min read · Updated May 6, 2026

Medically reviewed by Dr. Jonathan Snipes, MD (NPI 1821250077). Last reviewed May 6, 2026.

Why a COA matters

A Certificate of Analysis (COA) is the test report that proves a specific batch of medication actually contains what the label says and is free of contamination. For compounded peptides, this is not optional documentation. It is the difference between a regulated medication you can verify and an unverified powder from a research vendor.

Optimal Balance Pharmacy contracts Eagle Analytical Services, an FDA-registered, A2LA ISO 17025-accredited independent laboratory in Houston, Texas, to test every compounded batch before release. Every test report is published on the corresponding product page and on /quality.

Header fields: lot, sample, dates

The top of an Eagle COA always lists four key fields you can cross-reference against your shipment label:

  • Submission #. Eagle’s internal ID for the batch, formatted ETX-YYMMDD-NNNN. Used as the primary key when you search the published reports.
  • Sample Name. The full product name including active ingredient, strength, and volume. For example, “ Tirzepatide/Cyanocobalamin 6mg/0.5mg/ml (2mL) T6” describes a 2 mL vial at 6 mg/mL tirzepatide plus 0.5 mg/mL B-12.
  • Lot #. The pharmacy’s manufacturing lot identifier, printed on every vial label. Match this against the label on your specific vial.
  • Date Received. When Eagle Analytical received the sample. The Date Completed for each test (under the test sections) is when that test result was finalized.

Sterility test (ScanRDI or Celsis)

Sterility verifies the batch contains no viable microorganisms. Eagle uses two validated rapid-detection platforms:

  • ScanRDI Sterility Test. A rapid solid-phase cytometry method that detects any viable cells in the sample. Eagle holds international patents on the ScanRDI Oil Method (U.S. 2019, Canada 2021, Australia 2022). Result line shows either Pass or the specific contamination identified.
  • Celsis Sterility Test. An ATP-detection platform with a Day 7 readout. Result line shows Day 7 Result: Pass when no microbial growth is detected.

Either method satisfies USP sterility standards. Eagle assigns the method based on the product type and the established validation for that compound.

Bacterial endotoxin test (USP <85>)

USP General Chapter <85> is the standard for measuring bacterial endotoxin contamination in injectable products. Endotoxins are fragments of bacterial cell walls that survive sterilization and trigger fever or shock if injected. Every batch is tested.

The endotoxin section of the COA lists three numbers:

  • Numerical Value. The measured endotoxin concentration in EU/mL (endotoxin units per milliliter). Most PeptideRx batches test at <2 EU/mL.
  • Endotoxin Limit. The regulatory ceiling for this product type. Typical limits are 375 to 450 EU/mL for small-volume parenteral products. The limit varies by product because it depends on the maximum dose volume the patient can safely receive.
  • Result. Pass if the numerical value is below the limit. Fail if it is at or above the limit. PeptideRx publishes every result; failures (none to date) would also be published.

Potency test (USP <621>)

Some batches receive an additional Potency assay under USP <621>. This test confirms the active ingredient is present at the labeled concentration. The Potency section lists:

  • Measured Concentration. The actual concentration of active ingredient as measured (e.g., 6.07 mg/mL for a vial labeled 6 mg/mL).
  • Potency. The percentage of the labeled concentration. 100 percent is exact match. The conventional USP <621> passing range is 90 to 110 percent.
  • Method. The chromatographic method used (HPLC with various detection types, depending on the active).

Potency tests are not run on every batch because Optimal Balance Pharmacy validates compounding procedures separately. When a potency result is published, it confirms the specific batch met USP concentration standards.

How to verify your specific vial

Three steps:

  1. Look at the printed label on your vial. Find the lot number (a 6-digit numeric code, sometimes followed by a hyphen and a sequence number).
  2. Open the matching product page (e.g., Tirzepatide/B12) or the central /quality page.
  3. Find the row with your lot number and click through to the PDF COA. Confirm the sample name on the PDF matches the active ingredient and strength on your vial label, and that all test results show Pass.

Bottom line

A Certificate of Analysis is not a marketing document. It is a third-party test report that proves a specific batch of medication met sterility, endotoxin, and (where tested) potency standards before it shipped. PeptideRx publishes the COA for every batch dispensed by Optimal Balance Pharmacy. You can match the lot on your vial against the published report in under a minute. None are withheld.

See every published COA

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Frequently asked questions

What does "USP <85>" mean on a peptide COA?
USP General Chapter <85> is the United States Pharmacopeia standard for measuring bacterial endotoxin contamination in injectable products. Every batch result includes a numerical value in EU/mL (endotoxin units per milliliter) and a regulatory limit. A "Pass" result means the sample is below the limit. PeptideRx batches typically test at less than 2 EU/mL against limits of 375 to 400 EU/mL.
What is the difference between ScanRDI and Celsis sterility tests?
ScanRDI and Celsis are both rapid microbial detection methods used to verify sterility. ScanRDI scans for any viable microorganism in the sample and reports a Pass when no contaminating organisms are detected. Celsis is an alternative validated platform that uses ATP detection to identify microbial growth. Eagle Analytical Services uses both methods depending on the batch and product type. Pass results from either method satisfy USP sterility requirements.
How do I verify my specific lot against a published COA?
Every PeptideRx vial label has a lot number printed on it (for example, 032526-23). The matching COA is published on the relevant product page and on the /quality central page. Find the report whose lot number matches your label and compare the lot, sample name, and manufacturing date. The result fields (Sterility, Endotoxin, Potency) tell you what was tested and whether it passed. Reports remain on file for the full Beyond Use Date period and longer.
What does "Pass" mean in the Result column?
A "Pass" result means the batch met the regulatory limit for the test in question. For sterility, Pass means no viable organisms were detected. For endotoxin (USP <85>), Pass means the measured endotoxin value (in EU/mL) is below the regulatory limit for that product type. For potency (USP <621>), Pass conventionally means the measured concentration is between 90 and 110 percent of the labeled active concentration.
Are these COAs from independent testing?
Yes. Eagle Analytical Services is a third-party FDA-registered, A2LA ISO 17025-accredited independent laboratory that contracts with Optimal Balance Pharmacy to test every batch. Eagle has no commercial interest in any specific batch result. Reports are submitted under Eagle's own laboratory accreditation, not under Optimal Balance's pharmacy license.