Certificate of Analysis is a laboratory document detailing the analysis that has been performed on one single batch of peptide and its test results. It allows checking if the product corresponds to the label in terms of purity and identity; however, it does not confirm safety or efficacy on its own. Buyers tend to stop after seeing a "99% purity" line. The following guide describes every point and possible misconceptions.
Why peptide quality needs checking
Peptide synthesis involves adding amino acids one after the other. During each addition, there is always some error in the form of missing amino acid, duplicated amino acid, or an incorrect amino acid. The product is therefore a blend that consists of the desired peptide along with impurities and is purified before it is lyophilized into a powder.
It is because of this reason that two vials carrying the same label might actually be different from each other. FDA-approved peptide drugs are manufactured following strict regulations and regulation, but products labeled "research peptides" usually do not.
The anatomy of a COA
The following are the parts of a typical COA. Verify that they all are there.
1. Product and batch identification
Search for the following information: the name of the peptide, the amino acid sequence, the molecular formula, the molecular weight, the batch (or lot) number, and the date of testing. The batch number is the key point here. The certificate of analysis should be relevant to your particular batch only, not just the name of the product.
2. Appearance
"This is typically 'white lyophilized powder.'" This is a basic test. Any change in color or consistency can indicate degradation or contamination, although a normal appearance does not confirm purity.
3. HPLC purity
In HPLC, the components of the substance are separated. The instrument will give a plot called the chromatogram, which is a line with peaks. The peaks represent various compounds.
The reported purity is the ratio of the area of the principal peak to the total area of all peaks. If the principal peak makes up 98.5% of the total area, then the reported purity will be 98.5%.
Things to look out for:
- The actual chromatogram is important to have rather than the number only. The figure without the chromatogram cannot be validated.
- Also consider the peaks in the chromatogram. A dominant peak with multiple other peaks indicates the presence of more impurities than the stated percentage.
- Method is important. Reliable articles mention the column used, solvent system, and detection wavelength (peptides are normally detected at 214-220 nm).
- Purity is a relative concept and not an absolute one. Substances which do not absorb the detection wavelength will not appear in the purity percentage.
4. Mass spectrometry (identity)
Mass spectrometry (MS) is an analytical method for determining the mass of the molecular ions in the sample. This answer the question "Is the primary compound the correct molecule?" The report must include the theoretical (predicted) mass and the experimental mass, which should be close.
Peptides are found in the spectrum of mass with multiple charges. Thus, the peaks shown in the print out will differ from the molecular weight. The reader should observe the calculation and experimental values clearly stated. MS verifies identity. MS does not check purity, and HPLC does not verify identity. An authentic COA should include both.
5. Net peptide content
It's probably the most ignored information, and the one which allows figuring out what is inside the vial.
Freeze-dried peptide powder is not entirely a peptide itself. It also consists of some water and counterions, for example, trifluoroacetate (TFA) or acetate. The net peptide content is the weight percent of the powder which is a real peptide. This figure is always less than 100% and may be around 70-90% or so, depending on the particular case.
Content and purity are two different things. For example, one can get 99% pure material by HPLC and have only 80% of peptide in terms of weight. So, if the vial says "5 mg" but doesn't specify the content, one cannot really know how many milligrams of the peptide is inside. A certificate of analysis including net peptide content is more informative than the one without it.
6. Water content and counterion
In some analyses, water content (usually determined via Karl Fisher analysis) and the identity of the counter ion are given. This helps substantiate the total content, proving that the material was well-characterized in the lab. Identity of the counter ion may also be important regarding tolerability.
7. Endotoxin and sterility testing
Two types of test are important if a peptide is going to be injected:
Endotoxin: bacterial cell wall components that can result in fever and inflammation even without the presence of viable bacteria.
Sterility: freedom from living microorganisms.
COAs for research peptides do not always provide results for these types of tests. The purity certificate for the powder form of a peptide does not mean that the peptide is sterile. If the results of the tests are not provided, it means that they have not been performed.
8. Residual solvents
Some reports also contain remaining chemicals from the production process. Their nonexistence is not an alarming feature in relation to research products; however, their existence denotes a more thorough analysis.
What a COA cannot tell you
COA does not prove the following:
- Peptide safety or effectiveness in humans
- Legal use of the product for any purpose in your country
- That the vial in your hands is from the same batch used in testing, unless the batch numbers match
- The independence of the lab, in case of self-reporting by the seller
- Proper storage and transportation of the product after testing
A COA is evidence about a sample at one point in time. It is not an approval.
Red flags that suggest an unreliable COA
- Absence of a batch number or an incongruent batch number
- No chromatogram or spectrum; just a typed-out percentage
- An unknown lab that is unapproachable or does not have a known address
- Reuse of the same report on different batches or products
- Round figures or a claim of 100 percent purity
- An absence of a test date or one much earlier than production
- A file with signs of editing, like inconsistent fonts and pasted logos
- Hesitancy to provide data when asked
How to verify a COA
- Check that the batch number from the certificate matches the one on the vial.
- Contact the lab by using the contact information available to you separately, not just on the report, and get confirmation of its authenticity.
- Use independent third-party labs wherever possible. ISO/IEC 17025 accreditation means that the lab has achieved an internationally recognized standard of competence in testing.
- If all that's presented is the summary data, request the actual raw chromatogram and mass spectrum data.
- Check the similarity between batches. Small differences between batches are expected. Matching reports are fishy.
- See what information is absent, including net peptide content, endotoxin, and sterility in injectables.
COA versus pharmaceutical quality
Pharmaceutical peptides are produced using GMP and are tested against specifications, which include sterility, endotoxin, and dosage consistency tests. Research COA, even if high quality, is not comparable to the above. The mere presence of COA does not turn a product into a medicine.
Frequently asked questions
What is a good purity percentage?
Most research peptides have purity levels of 95 percent or more through HPLC. In some applications, even higher purity levels are required. The number alone means nothing without the corresponding chromatogram and total amount of peptide.
Is a 99% pure peptide 99% peptide by weight?
No. Purity is the percentage of material in the sample related to the peptide. Net peptide amount is the peptide amount relative to the weight of the powder.
Does a COA prove a product is safe to inject?
It doesn’t. Safety is based on sterility, endotoxins, dosage, the patient, and the clinical setting; most COAs do not test for these.
Can COAs be faked?
It does. That is why you check the batch number and ask for the raw data from the laboratory.
Who should I ask for advice about a peptide product?
An experienced physician or pharmacist, preferably prior to any application inside the body.
Key takeaways
- The COA is a lab report that is batch specific, and the batch number should correspond to yours.
- Purity is verified using HPLC and identity by mass spectrometry; you need both.
- Peptide content gives the percentage of peptide within the powder.
- Endotoxin/sterility data are usually not available but are important for injectable peptides.
- A COA eliminates uncertainty but doesn't ensure safety.
Medical disclaimer: This article is for educational purposes only and is not medical advice. It does not recommend or endorse any product. Consult a qualified healthcare professional before using any peptide.