Two suppliers send you a COA. Both look real. But only one matches the vial you hold. How can you tell? A COA is your proof of quality. Check it before the peptide goes into your lab work.
Sichuan Pengting Technology Co., Ltd. has sold peptide raw materials since 2021. Its buyers are in North America, Europe and Asia. It makes only peptide raw materials. The facts about the company here come from its website. This page shows eight warning signs. It also gives simple checks to run before you pay.
The main peptide COA red flags are a wrong or missing batch number, a purity number with no test method, no HPLC graph or MS trace, one COA used for many batches, no lab name, and a missing or changed date of testing.
What Is a Peptide COA Meant to Prove?
A certificate of analysis is a report on one batch of peptide. It shows how pure the peptide is. It shows if it is the right peptide. It also shows the quality. The maker or a test lab writes it. It must name one lot number. A plain template used for many shipments is not a real COA.
Peptides can break down while they are made. They can end up shorter than planned. They can pick up impurities. A COA shows what is in each batch. So you do not have to just trust the seller.
What a COA Should Include
| COA Element | What It Confirms | Typical Method |
| Purity percentage | Target peptide vs. impurities | HPLC |
| Identity confirmation | Molecule matches the stated sequence | Mass spectrometry (MS) |
| Batch/lot number | Link to a specific production run | Internal batch records |
| Appearance and solubility | Basic physical consistency | Visual inspection |
| Testing lab and date | Who tested it and when | Lab accreditation records |
For a full guide, see How to Read a Peptide COA.
8 Peptide COA Red Flags That Stop a Deal
Most troubles are in the little things. The issue is seldom the purity number. One flag = stop and inquire. Two or more, go away.
Batch Number Mismatch With the Label
The batch number can be missing. Or it might be different from the tag. Then you can’t track the product.” Fix it before you use it. Request the supplier to identify the correct lot in writing.
A Purity Figure With No Method Named
A purity number without a method is an assertion. A straightforward ‘99%’ means zilch. Real measurement, if the number names HPLC or MS.
Missing Chromatogram or Mass Spec Trace
“Give me the HPLC graph or the mass spec trace. If you don’t receive either of these, be wary. A summary page does not tell you how the test was done. Ask for the whole graph.
A Reused COA Shared Across Many Batches
Each manufacturing run will have its unique COA. A huge red flag is the same file for two lots. So is the same file for two order dates. Compare two files side-by-side.
No Testing Lab Named on the Document
You should know which laboratory executed the test. A lab name lacking is a concern. And a missing accreditation reference is included. Then no one is behind the result.”
A Test Date That Is Missing or Altered
All COA need a date of testing. The numerals have been changed, which usually means someone altered the file. Needs a response to a date later than the ship date
Molecular Weight That Does Not Match
The observed mass should be consistent with the mass anticipated for the sequence. It is a minor gap, that’s normal. If you see a disparity of only a few tenths of a percent, you should speak to your supplier. Do it before you tackle the batch.
Signs the File Was Edited From a Template
Watch for irregular typefaces. Search for boxes that have been moved or for copy-paste markings. A tidy arrangement is no proof. Verify the info.
Red Flags at a Glance
| Red Flag | Why It Matters | What to Ask For |
| Lot number conflict | Breaks the link between paper and product | Written confirmation of the correct lot |
| Purity with no method | Cannot be checked | Method name and the HPLC trace |
| No chromatogram or MS trace | Test steps stay hidden | The full graph files |
| Shared COA | Results may belong to another lot | A COA for your lot and the previous lot |
| No lab named | No one owns the result | Lab name and accreditation reference |
| Missing or changed date | Hints at editing | The original dated file |
| Mass gap | The molecule may be wrong | Measured and expected mass, with tolerance |
| Template look | The file may be copied | Raw data straight from the lab |
Are Purity and Identity the Same Test?
No. Purity shows how clean the sample is. Identity shows if it is the peptide you ordered. A sample can be 99% pure by HPLC and still have the wrong sequence. That can happen when no one tests identity.
What HPLC Shows That a Number Cannot
Purity is often determined by HPLC with UV detection. Look for one big peak. That peak is the peptide you are seeking. The little peaks represent contaminants or fragments of short peptides. Every little peak should have its own importance.
For most research-grade material, ≥95% is a strong result.
Why Mass Spectrometry Data Confirms Identity
MS measures the weight of the sample. It compares the mass to the anticipated mass. A match means the molecule is correct. Good purchasers also search for these fields:
- Water content (Karl Fischer titration)
- Counter-ion content (ion chromatography)
- Storage conditions
- The test standard used
An Example Using Alarelin Acetate
Alarelin (acetate), CAS No. 79561-22-1 is listed by Pengting. It is a white powder of 99% purity. Its molecular formula is C56H78N16O12. It has a molecular weight of 1167.33.
Check the mass on the MS report against 1167.33. What is the value on the lab? Some MS reports display ions, not just the mass.
It is an acetate salt. The salt gives it weight. So the concentration of counter-ions influences the amount of actual peptide in every gram.
Storage should be included in the COA. Listing claims -20℃ for a lengthy period. It reads 2℃ to 8℃ for short-term.
For more on this test, see Peptide Purity by HPLC.
In-House QC or Third-Party Testing?
The COA is from the manufacturer’s own QC lab or a third-party contract lab. A reputable provider will tell you which.
A second test is done by an independent lab. But only if the lab is legit. Look it up. Make sure that it’s on. Make sure it performs the test it says it does.
It matters less who executed the test than how transparent the provider is about it.
Lot Traceability From Paper to Package
Traceability only works if the vial lot number matches the COA. Lot 10 should resemble lot one. Place two COAs side by side.
What to Compare Between Two COAs
- Both refer to the same test procedure.
- The major summit is in the same site
- No fresh peaks of impurity arise
- Lot numbers follow the same trend
If a new peak appears, ask why. Keep your own batch records on file. For shelf-life data, see Peptide Stability Testing (ICH Guidelines).
How Do You Check a COA Before You Pay?
Match the lot number, check both test methods, and ask for raw data if something looks off. Follow these five steps:
- Compare the batch number on the COA to the label on the box.
- Make sure the COA includes a purity method (HPLC) and an identity method (MS).
- Search for the specified testing lab. See whether it is running.
- The observed molecular weight was compared with the predicted value.
- If something is unclear ask for the HPLC graph or the mass spec trace
A QR code on a vial does not prove a COA is real. It only opens a file. The lot number in that file must still match the label.
Questions Worth Asking the Supplier
- Who produced this batch? Who owns the test data?
- Can I view any samples before I place my order?
- Can I do a modest trial order to test against the COA?
If a supplier will not talk about test methods or lab names, slow down. For more checks, read How to Choose a Peptide Manufacturer and Peptide Manufacturer vs Supplier.
What Does Pengting Put Behind Each Batch?
Pengting sends a full set of papers with every batch. Here is what the company says about itself.
Factory Scale and a Focus on Peptides
- Founded in 2021. Located in Leshan, Sichuan, China
- Only makes peptide raw materials
- A cooperative manufacturing base of 6,500 m²
- 5+ PhD R&D engineers
- Over 100 raw materials from research to industrial manufacture
Certifications Stated in Plain Terms
- Holds ISO 9001
- Has its manufacturing partner follow GMP requirements
- Says it is not yet cGMP certified or has a US FDA DMF
- Only sells to verified business customers
- Peptides are for research use only
Delivery Cycle and Paperwork per Batch
Every shipment is accompanied by a COA, an HPLC chromatogram, an MS report, and an MSDS. Each set is associated with certain manufacturing runs. Pengting also claims all its raw ingredients are traceable. Trial orders begin at 1g per product.
- Delivery cycle: 15 to 30 days
- Europe and America: 15 to 20 days
- Southeast Asia: 7 to 10 days
- Urgent orders: shipped within 72 hours
Learn more about Pengting or see the Custom Peptide category.
FAQs
What are peptide COA red flags?
Warning indications of a peptide COA include an inability to track or trust the COA. Here are the most important ones.
- Any discrepancy between the label and the batch number or no number at all
- Absence of MS data, graph, or test technique
- Using the same file for several batches, without having a lab name, or an updated date
How can you tell if a COA is fake?
You can tell by looking at the numbers, not the appearance. Verify the lab name, test procedures, and batch number.
- Find any indications that the file was altered.
- Request the original HPLC graph or MS data from a different vendor.
Should a COA include an HPLC chromatogram?
Indeed, a certificate of analysis (COA) ought to include or refer to an HPLC chromatogram. On its own, a purity figure reveals nothing about the testing procedure.
- Get the whole graph by requesting it.
- Keep an eye out for a minor peak in addition to the main peak.
Is a COA batch specific?
An authentic certificate of analysis (COA) is batch-specific, which is correct. A genuine one is good for a single manufacturing run and lot number.
- Test results, not assertions in general, are shown.
- Your shipment should be compatible with its lot number.
What purity is good on a peptide COA?
For the majority of research-grade materials, an HPLC purity result of 95% or more is considered strong. Unless the test method is specified, the numerical value is meaningless.
- Typically, HPLC along with UV detection is used.
- Purity is not a substitute for MS’s identification test.
What should you do if a COA is incomplete?
Prior to accepting the batch, inquire with the supplier about the missing pieces. You can’t verify quality with a thin COA.
- Please include the technique, lab name, or lot number that is missing.
- Obtain the raw data if you see that the file is looking thin.
Conclusion
An excellent COA is pure and identifiable. It is linked to the product via the lot number. It mentions a lab you might try. It also provides a date.
If any of these are missing, the file isn’t performing its job. Even if it appears nice, that’s true. Run the five tests on every new COA, even if it’s from a known source. It takes minutes to learn these peptide COA red flags. It can save a whole project.
Business buyers can send a sequence and an amount to Sichuan Pengting Technology Co., Ltd. to ask for lot-specific COA samples and a quote. The company shares sample papers before you order. It also says plainly which certificates it holds and which it does not.
