How to Read Peptide Lab Reports (COA)

Why COAs Matter for Peptide Research

The peptide market includes suppliers ranging from pharmaceutical manufacturers to small synthesis labs with varying quality control standards. A Certificate of Analysis (COA) is your primary tool for verifying that a peptide product is what it claims to be. Without a valid COA, you have no way to confirm identity, purity, or safety of a research peptide.

Key Tests in a Peptide COA

HPLC Purity Analysis

High-Performance Liquid Chromatography (HPLC) is the gold standard for assessing peptide purity. The peptide sample is dissolved and run through a chromatographic column that separates it from impurities based on chemical properties. The result is displayed as a chromatogram showing the main peak (your peptide) and any additional peaks (impurities).

What to look for on an HPLC report:

• Purity percentage -- Should be 98% or higher for research use. This is calculated as (main peak area / total peak area) x 100.
• Retention time -- The time at which the main peak appears. Should match the expected value for the specific peptide.
• Peak shape -- The main peak should be sharp and symmetrical. Broad, asymmetric, or split peaks suggest impurities co-eluting with the peptide.
• Impurity peaks -- Small peaks at other retention times represent impurities. Their identity and quantity should be noted.

Mass Spectrometry (MS)

Mass spectrometry confirms the molecular identity of the peptide by measuring its molecular weight. The observed mass must match the theoretical mass calculated from the amino acid sequence.

What to look for:

• Observed molecular weight -- Should match the theoretical MW within instrument tolerance (typically plus or minus 0.1-1.0 Da depending on the instrument)
• m/z peaks -- The mass spectrum shows peaks at different mass-to-charge ratios. The main peaks should correspond to known charge states of the target peptide.
• Absence of unexpected masses -- Peaks at masses significantly different from expected may indicate contamination with other peptides or degradation products.

Amino Acid Analysis (AAA)

Amino acid analysis hydrolyzes the peptide and quantifies each amino acid present. This verifies that the correct amino acids are present in the correct ratios. It also provides the actual peptide content (as opposed to total powder weight, which includes salts and moisture).

Endotoxin Testing (LAL Test)

The Limulus Amebocyte Lysate (LAL) test detects bacterial endotoxins. Injectable peptides should be below 5 EU/mg (endotoxin units per milligram). High endotoxin levels can cause fever, inflammation, and in severe cases, septic shock. Not all vendors test for endotoxins, but it is an important quality indicator for injectable products.

Sterility Testing

Some premium suppliers include sterility testing, confirming no viable microorganisms are present. This is especially important for peptides intended for injection. Standard tests involve incubating samples in growth media to check for bacterial or fungal growth.

Red Flags in COAs

• No batch number -- Every COA should have a unique batch/lot number matching your product
• Internal testing only -- COAs from the vendor's own lab without third-party verification are less reliable
• Purity below 95% -- Indicates poor synthesis or purification
• Mass discrepancy -- If observed MW does not match theoretical MW, the peptide may be misidentified
• No chromatogram included -- A purity percentage without the actual HPLC chromatogram is incomplete
• Generic or templated appearance -- COAs that look identical across different products may be fabricated

How to Verify a COA

1. Check that the batch number matches your product label
2. Verify the testing laboratory is a real, reputable analytical lab
3. Confirm the observed MW matches the published MW for your peptide
4. Ensure purity is 98%+ with a clean HPLC chromatogram
5. For injectable products, check for endotoxin testing results
6. Cross-reference the COA date with your order date (should be recent)

Connecting COAs to the Peptide Calculator

The COA tells you the actual peptide content per vial (which may differ from the label claim due to salt content and moisture). For example, a vial labeled "5 mg BPC-157" might contain 5 mg of total powder but only 4.2 mg of actual peptide (the rest being counterions and moisture). If the COA provides net peptide content, use that figure in the Peptide Calculator Plus for the most accurate dosing.