Verify the Batch You Received
Every Celtek research peptide batch is assigned a lot number and supported by analytical documentation for that specific material.
Use this page to locate the Certificate of Analysis or test report associated with your peptide and lot number.
Current analytical testing may include:
- HPLC analysis
- Mass spectrometry
- Reported chromatographic purity
- Expected and observed molecular mass
- Lot-specific documentation
The important part is the connection between the physical product and the report:
Peptide → Lot Number → Test Report
A COA for a different batch should not automatically be treated as evidence for the material currently being supplied.
Find Your Test Report
I would put the actual searchable COA library immediately here.
Search by Peptide or Lot Number
[Search field]
Placeholder:
Enter peptide name or lot number
Then a table or card grid like:
| Peptide | Lot Number | HPLC Purity | Identity | Report Date | Documents |
|---|---|---|---|---|---|
| Retatrutide | RET-XXXX | 99.X% | MS Verified | Date | View COA |
| Compound | LOT-XXXX | 99.X% | MS Verified | Date | View COA |
I would make the lot number prominent. Researchers should not have to open five PDFs to figure out which one applies to their vial.
If several lots exist, keep the older reports available under an Archived Lots section rather than replacing them.
Where to Find Your Lot Number
The lot number is the identifier that connects a product to its analytical documentation.
Depending on your packaging, it may appear on:
- the peptide vial
- product label
- outer packaging
- packing documentation
- order records.
Match that number to the corresponding report on this page.
For example:
Product: Example Peptide
Lot: CP-260901-A
The report you review should identify the same lot.
What Is a Certificate of Analysis?
A Certificate of Analysis, commonly abbreviated COA, summarizes analytical information for a specific batch of material.
A useful peptide COA may contain information such as:
- peptide name
- lot or batch number
- molecular formula
- theoretical molecular weight
- analytical method
- HPLC result
- chromatographic purity
- mass spectrometry result
- observed molecular mass
- testing date
- laboratory information
- associated chromatogram or spectrum.
The exact format may vary between laboratories and analytical methods.
The purpose is not simply to display a certificate.
The purpose is to provide enough information for a researcher to understand what was tested, which batch was tested, and what the analytical results actually show.
Why Lot-Specific Testing Matters
Suppose Celtek receives two batches of the same peptide several months apart.
The peptide name may be identical.
The analytical results are not automatically identical.
Each batch may differ slightly in:
- chromatographic purity
- peptide-related impurities
- water content
- counterion content
- residual material
- physical characteristics.
That is why a report from one batch should not simply be reused forever as evidence for every future batch.
Celtek’s testing system is intended to preserve the relationship between the report and the material being distributed.
HPLC Purity Testing
High-performance liquid chromatography, or HPLC, is one of the primary methods used to characterize peptide purity.
In a typical reversed-phase HPLC analysis, the compounds in a sample are separated as they pass through a chromatography column.
The detector records the separated material as peaks.
The intended peptide generally produces the dominant peak.
Smaller peaks may represent peptide-related impurities or other detectable substances.
The relative area of the main peak can then be used to calculate chromatographic purity.
For example:
Reported HPLC purity: 99.3%
generally means that approximately 99.3% of the integrated detected peak area under the analytical conditions was assigned to the primary peptide peak.
It does not necessarily mean that 99.3% of the total physical weight of the vial is peptide.
That is an important distinction.
Mass Spectrometry and Peptide Identity
Mass spectrometry provides different information from HPLC.
The technique measures ions according to their mass-to-charge ratio.
For peptide characterization, the analytical result can be compared with the theoretical molecular mass calculated from the intended sequence.
Agreement between expected and observed mass provides evidence supporting the identity of the peptide.
This is why Celtek uses HPLC and mass spectrometry as complementary analytical tools.
Conceptually:
HPLC asks:
How chromatographically clean does the sample appear?
Mass spectrometry asks:
Does the observed molecular mass support the expected identity?
A purity result alone does not fully answer the identity question.
Purity and Identity Are Not the Same Thing
Consider a sample that produces one dominant HPLC peak representing 99.5% of detected peak area.
That may indicate very high chromatographic purity.
But the chromatogram alone does not establish that the dominant compound is definitely the intended peptide sequence.
A sample can theoretically be:
high purity + wrong identity
or:
correct identity + lower purity.
That is why the two measurements should be reviewed separately.
For a deeper explanation, see:
Peptide Identity vs. Purity: Why They Are Not the Same Thing
How to Read an HPLC Chromatogram
A typical peptide HPLC report includes a graph containing one or more peaks.
Several pieces of information may appear:
Retention Time
Retention time indicates how long a detected compound took to pass through the chromatography system.
Peak Area
The analytical software calculates the area under each detected peak.
Area Percentage
The relative areas of the peaks may then be used to calculate reported chromatographic purity.
A simplified example might look like:
| Peak | Retention Time | Area % |
|---|---|---|
| Minor Peak 1 | 8.42 min | 0.22% |
| Main Peptide Peak | 9.17 min | 99.41% |
| Minor Peak 2 | 10.03 min | 0.37% |
Under those analytical conditions, the main peak would account for approximately:
99.41% of integrated peak area.
Researchers should remember that chromatography results depend on the analytical conditions being used.
How to Read a Peptide Mass Spectrum
Mass spectra can look more complicated because peptides often appear as ions carrying more than one electrical charge.
For example, a peptide may appear as:
- [M+H]+
- [M+2H]²+
- [M+3H]³+
- or additional charge states.
As a result, the largest number printed on a spectrum is not necessarily the peptide’s full molecular weight.
Analytical software or the testing laboratory can use the observed charge states to determine the corresponding molecular mass.
The key comparison on the report is usually:
Expected molecular mass
versus
Observed molecular mass
If those values agree within the expected analytical tolerance, the data provide evidence supporting molecular identity.
What Does 99%+ Purity Mean?
When Celtek lists a peptide as 99%+ purity, the claim should refer to the applicable chromatographic result for the current batch.
It should not be interpreted as a universal statement about every possible measurement of purity.
In particular, HPLC purity is not necessarily the same as:
- peptide content by total vial mass
- sterility
- endotoxin level
- absence of residual solvents
- absence of every possible chemical contaminant
- pharmaceutical-grade release testing.
Those are separate analytical questions.
HPLC Purity vs. Peptide Content
This distinction is especially important with lyophilized peptides.
Imagine a vial containing a lyophilized peptide preparation with:
99.2% HPLC purity.
That percentage describes the relative chromatographic components detected by the HPLC method.
The physical lyophilized material may also contain:
- water
- counterions
- salts
- other non-peptide material.
Therefore:
99.2% HPLC purity
does not necessarily mean:
99.2% of the physical powder weight is peptide.
Researchers who require quantitative peptide content should distinguish that measurement from chromatographic purity.
Why We Publish the Underlying Reports
A simple claim such as:
99% pure
requires the researcher to trust the supplier.
A report containing the analytical results gives the researcher more information to evaluate.
Whenever practical, Celtek makes the associated analytical documentation available so researchers can review:
- the applicable lot
- the method
- the chromatographic result
- the molecular mass result
- the underlying analytical data.
This does not eliminate every limitation of testing.
But it makes the basis for a quality claim more transparent.
What These Reports Do Not Establish
A peptide test report should be interpreted according to the tests actually performed.
Routine HPLC and mass spectrometry do not automatically establish:
- sterility
- bacterial endotoxin levels
- absence of microorganisms
- absence of every possible contaminant
- suitability for injection
- safety in humans
- safety in animals
- therapeutic effectiveness
- FDA approval.
Those conclusions require different forms of testing, manufacturing controls, clinical research, or regulatory review.
Celtek research peptides are intended for laboratory research purposes and are not supplied as pharmaceutical products.
Independent Laboratory Testing
Celtek uses third-party laboratories to provide independent analytical characterization of current research peptide batches.
Independent testing creates separation between the organization supplying the material and the organization generating the analytical result.
But the phrase third-party tested should never replace the actual report.
Researchers should still ask:
- Which batch was tested?
- Which method was used?
- What was measured?
- What result was obtained?
- Does that batch match my material?
Those questions are more informative than the phrase alone.
When Was the Batch Tested?
Where available, test reports should identify the analysis or report date.
This can help researchers understand when a particular batch was evaluated.
Older reports may remain available for historical reference after a new lot becomes the currently supplied batch.
I would visually mark the database:
CURRENT LOT
and
ARCHIVED LOT
That makes the page much easier to use.
Archived Test Reports
Celtek should retain historical reports when practical.
An archived report may still be useful to researchers who previously received material from an older lot.
But archived results should be clearly separated from reports for the batch currently being distributed.
I would structure this section as:
Current Lots
Current products currently shipping.
Archived Lots
Earlier analytical reports retained for reference.
That is much cleaner than deleting the old COA whenever inventory changes.
Custom Peptide Testing
Custom peptide synthesis projects may also include analytical documentation.
Standard custom peptide characterization may include:
- HPLC analysis
- mass spectrometry
- synthesis information
- requested purity specification.
Additional testing may be available depending on project requirements.
Custom synthesis projects can differ substantially in sequence, modification, quantity, and analytical requirements, so specifications are established during project review.
Learn more:
Custom Peptide Synthesis
Questions About an Analytical Report?
If you believe:
- your vial lot does not match the listed report
- a test report is missing
- the molecular mass requires clarification
- you cannot locate your lot
- analytical documentation appears inconsistent
contact Celtek before relying on the report.
Include:
Peptide name
Lot number
Order number, if applicable
and describe the question.
That makes it easier to locate the correct batch documentation.
Understanding Peptide Analysis
Researchers who want a deeper explanation of the analytical techniques used in peptide characterization can explore our research guides:
How Peptide Purity Is Measured
HPLC, LC-MS, purity percentages, and their limitations.
Understanding HPLC Testing for Peptides
How chromatography works and how HPLC reports are interpreted.
HPLC vs. LC-MS in Peptide Analysis
What each analytical method can and cannot tell you.
Peptide Identity vs. Purity
Why a clean chromatogram is not by itself proof of molecular identity.
Peptide Concentration Explained
The difference between mass, volume, concentration, and analytical purity.
This is a perfect place to internally link the foundation articles we’ve already written.
View Current Certificates of Analysis
Use the database above to locate the analytical report associated with your peptide and lot number.
If your lot is not listed, contact Celtek for assistance locating the applicable documentation.
For Research Use Only. Not for human or veterinary use. Not for diagnostic or therapeutic use.