Quality of Epitalon peptide: how to interpret the COA, the purity of the HPLC and the results of mass spectrometry?

The evaluation of the quality of Epitalon requires much more than checking the percentage purity stated on the label. Even a result of 99% HPLC does not explain all the properties of the material. To properly characterize the sample, its chemical identity, chromatographic purity, actual peptide content, impurities, chemical form, and documentation of the specific batch must be evaluated separately. Depending on the type of study, the stability and microbiological quality may also be important.[1–5]

Epitalon, also known as Epithalon and Epithalone, is a synthetic tetrapeptide with the sequence Ala-Glu-Asp-Gly (AEDG). In scientific research, correctly identifying this molecule is essential because experiments performed with improper or poorly characterized material can lead to results that are difficult to reproduce.

A scientific review published in 2025 indicates that despite the extensive literature on Epitalon biology, its physicochemical and structural characteristics remain relatively limited. Meanwhile, a 2015 study showed that the presence of AEDG in unauthorized preparations can be verified using liquid chromatography combined with mass spectrometry.[1,2]

In this context, terms such as „Epitalon COA”, „Epitalon purity”, „Epitalon HPLC” and „third-party tested Epitalon” take on particular importance. A document labeled with an analysis certificate can provide valuable information, but only if it is possible to determine which sample was tested, by what methods, in which laboratory and whether the report actually concerns the evaluated batch.

How is the quality of Epitalon peptide evaluated?

The reliable evaluation of Epitalon is based on several independent, mutually complementary studies. Each of them answers a different question regarding the sample, therefore a single result should not be considered as a complete confirmation of quality.[2–6]

The primary step is identity verification. It is necessary to determine whether the tested substance actually corresponds to the Ala-Glu-Asp-Gly tetrapeptide. Subsequently, it is possible to determine what proportion of the detected components constitutes the main peptide, what impurities are present, and how much AEDG is actually present in the sample.

The chemical composition of the material is also important. The presence of acetate, trifluoroacetate, or other counterions can affect the overall composition and mass of the sample. For this reason, the mass of the powder is not always equivalent to the mass of the peptide itself.

In practice, quality analysis should cover the following issues:

• Confirmation of a sequence or chemical structure consistent with AEDG.
• Indication of chromatographic purity.
• Characteristics of pollutants formed during synthesis and degradation.
• Determination of the actual content of the peptide.
• Identification of chemical species and anti-ions.
• Correlation of analytical results with the party number.
• Assessment of stability under specific conditions.
• Performing additional microbiological tests if the assumptions of the experiment require it.

McCarthy and colleagues described a multi-method approach to the characterization of synthetic peptide reference materials. This includes chromatography, mass spectrometry, NMR, and appropriate quantitative techniques that allow for the independent evaluation of identity, purity, and content. [3]

It is important to distinguish between chemical and microbiological quality. The HPLC result is not proof of sterility, and the consistency of the molecular mass does not confirm the absence of endotoxins.

What information should the Epitalon analysis certificate present?

Certificate of analysis, abbreviated as COA Certificate of Analysis, A report is a document that presents the results of research on a specific material or batch. Its reliability depends on the identity of the sample, the methods used, and the extent of documented measurements. [3–6]

The document should primarily clearly indicate which compound is being analyzed. In the case of Epitalon, the designations Epitalon, Epithalon, Ala-Glu-Asp-Gly or AEDG are useful. The catalog name alone may not be sufficient for proper chemical identification.

The batch number is equally important. It should correspond to the designation found on the vial or its packaging. Without such a link, it is not possible to determine whether the results presented relate to the material currently being evaluated.

The value-added COA may contain:

• the name of the compound and the amino acid sequence;
• serial number or batch number;
• the date of manufacture, the sampling or the analysis;
• information about the chemical form and the counterion;
• HPLC or UHPLC purity result;
• chromatogram showing the breakdown of the components;
• MS or LC-MS result confirming the identity;
• the expected and measured molecular mass;
• the result of the quantitative determination of AEDG;
• data regarding water, solvents and anti-ions, if they are indicated;
• storage conditions;
• the name of the laboratory, the report identifier and the method of its authentication.

The scope of the required tests depends on the laboratory application. Not every research material requires the full set of tests provided for pharmaceutical active substances. However, unperformed measurements should not be treated as automatically correct.

For example, a COA presenting only chromatographic purity does not confirm that the vial labeled as 10 mg actually contains 10 mg of AEDG. Similarly, a proper LC-MS result can confirm the presence of the appropriate peptide, but it is not sufficient to fully assess all impurities.

The separation of these parameters is in accordance with ICH Q2(R2) guidelines, which distinguish between identification procedures, quantitative determinations, purity tests and analyses of impurities. [6]

What does the purity of Epitalon determined by the HPLC method mean?

HPLC, or high performance liquid chromatography, enables the separation of sample components based on differences in their interactions with the chromatographic system. The method allows to assess whether one component dominates in the sample and whether other detectable substances are present. [3–5]

In the analysis of synthetic peptides, RP-PLHPLC is often used. During the test, the sample passes through a column, and its components move at different speeds. The detector registers them as pixels with a specific retention time.

Dominant peaks may indicate high chromatographic homogeneity of the material. Smaller peaks may correspond to byproducts of synthesis, incomplete sequences, modified peptides, or degradation products.

However, this does not mean that every pixel was unequivocally identified.

How to interpret the result of 99% HPLC?

A purity result of 99% HPLC most often means that the main peak corresponds to approximately 99% of the integrated surface of the detected peaks under the conditions of the given method.

It should not be automatically interpreted as information that 99% of the powder mass is Epitalon.

Several limitations affect the interpretation:

• Individual compounds can generate signals of varying intensity.
• Some pollutants can co-exist with the main peptide.
• The selected wavelength may not provide adequate detection of all components.
• Water, salts and some solvents may not be included in the calculation of the pixel area.
• Chromatographic conditions can affect the resolution and the way the signal is integrated.

Therefore, chromatographic purity does not have to correspond to purity expressed as a mass fraction.

The significance of the precise characterization of contaminants is illustrated by the study of synthetic human peptide C. Li and colleagues identified more than 65 contaminants associated with the peptide in the reference material using liquid chromatography and high-resolution mass spectrometry.[5]

This example shows why the ability of the applied method to distinguish AEDG from similar molecules is important when evaluating Epitalon.

HPLC therefore provides information about the chromatographic behavior of the sample and detectable impurities. It does not constitute independent evidence of the complete chemical identity or the exact content of the peptide.

How does mass spectrometry help confirm Epitalon's identity?

Mass spectrometry, or MS, analyses ions based on their mass to charge ratio. This allows the properties of the compound under study to be compared with the expected values for the AEDG tetrapeptide.[2–5]

Unlike HPLC, whose primary function is to separate components, MS primarily provides information about their molecular properties.

In Epitalon’s analysis, LC-MS techniques, which combine chromatographic separation with mass measurement, are particularly useful. This approach was used by Vanhee and colleagues in a study identifying AEDG in unauthorized preparations. [2]

High-resolution mass spectrometry can reveal small differences in molecular masses. Tandem mass spectrometry, referred to as MS/MS, provides additional structural information based on the fragmentation of peptide ions.

This is important when examining impurities that may differ from the proper peptide by only a slight modification.

Such differences may result from:

• omission of one of the remaining amino acids;
• introduction of an incorrect amino acid;
• oxidation;
• deamination;
• cyclization;
• structural restructuring;
• changes in the final group;
• other reactions occurring during synthesis or storage.

Does mass consistency mean full confirmation of the structure?

Not always. Two different molecules can have the same or very similar mass. Some isomers and sequence variants may therefore require additional characterization.

In such situations, MS/MS, comparison with the reference material, chromatographic analysis, NMR or other methods independent of the basic mass measurement may be useful.

McCarthy and colleagues point out that isobaric amino acids, chiral configuration, and other structural properties that cannot be resolved solely on the basis of a simple mass spectrum may require special attention [3].

Mass spectrometry is therefore a strong element in confirming the identity of Epitalon, but it does not replace the tests for purity, content and microbiological quality.

Why are the identity, purity, and content of Epitalon three different parameters?

Identity indicates the relationship between the sample and the target component. Purity describes the proportion of the target component relative to the detected impurities, while content determines the actual amount of the peptide. These parameters require separate interpretation and appropriately selected analytical methods. [3–6]

One can imagine a sample whose chromatogram contains one dominant peak. If the peak corresponds to another peptide, the material may show high chromatographic purity, but it may not be Epitalon.

The reverse situation is also possible. The sample can be analyzed for AEDG using MS, although it contains significant amounts of other substances.

The third issue concerns the quantity. Even a properly identified and chromatographically pure peptide may be present in a vial in a quantity different from that declared.

The separation of these parameters is particularly important when comparing the different chemical forms of Epitalon.

Samples of identical nominal mass may contain different amounts of AEDG if they differ in the content of anti-ions or water.

Does 99% HPLC mean 9.9 mg of Epitalon in a 10 mg vial?

No. The result of 99% HPLC does not allow one to independently determine that the vial labeled as 10 mg contains exactly 9.9 mg of AEDG. Such calculation assumes that the total mass of the material is correct and that the percentage of the chromatographic surface corresponds to the mass fraction of the peptide. None of these assumptions automatically follows from the chromatogram.[3,5]

The result of the chromatographic analysis may represent the relative proportion of the main peak in the detector signal. However, it does not necessarily take into account water, solvents, anti-ions, and other components of the sample.

To determine the actual content, appropriate quantitative determination is required, for example a calibrated chromatographic method, qNMR or other validated approach.

In the case of reference materials, mass balance methods and measurements that take into account different categories of pollutants are also used.

For this reason, terms such as Epitalon 10 mg, Epitalon 50 mg or Epitalon 100 mg refer to the declared amount of material. Confirmation of this value is a separate analytical task.

How to check the conformity of the batch number with the laboratory report?

Party verification involves determining whether the analytical results actually pertain to the material being evaluated. The batch number on the vial should correspond to the identifier indicated in the supplier documentation, the COA, and the laboratory report.

The term „examined by an independent laboratory” is not sufficient if the origin of the sample cannot be determined.

An independent laboratory can mitigate certain conflicts of interest, but the mere execution of an analysis by an external entity does not guarantee the correctness of every procedure.

The most important thing is the ability to trace the following relationship:

Flask or packaging → batch number → batch documentation → COA → analytical report.

The report should include data allowing to determine when the sample was received, when the test was performed, what methods were used and what results were obtained.

It is also worth checking whether the document has an individual number and whether the laboratory allows for the authenticity of the document to be confirmed.

Why is the test date important?

Peptides can change during storage. The result obtained directly after production describes the condition of the sample at the time of analysis, but does not necessarily confirm its properties after a longer period.

Stability requires separate data covering the appropriate conditions and observation period.

Similarly, analysis of a single vial does not automatically prove the homogeneity of all vials belonging to a batch.

In formal peptide quality systems of reference materials, identity, homogeneity, stability, and assigned content constitute separate elements of the characterization. [3]

Does the independent COA guarantee the quality of Epitalon?

No. An authentic certificate issued by an independent laboratory can increase the credibility of the documentation, but its conclusions only apply to the tested sample and the analyses actually performed.

If the laboratory performed HPLC and LC-MS, the report can confirm the specified chromatographic purity and the consistency of the molecular properties with the AEDG.

However, this does not mean an automatic confirmation of all the other characteristics.

Such a report does not necessarily prove that:

• all vials from the batch have the same content;
• the material is sterile;
• does not contain endotoxins;
• the nominal amount of the peptide is correct;
• the sample remained stable after the analysis was performed;
• the water and solvent content was determined;
• the participation of anti-ions is known;
• Later batches have the same quality profile.

The calculation should always correspond to the range of measurements performed.

Therefore, stating that a specific sample showed high HPLC purity and mass consistent with the AEDG is more precise than a general declaration that the product has been completely verified in terms of quality.

What warning signs may be present in Epitalon documentation?

The most important problems concern the lack of identification, incomplete results, and overly broad interpretations of limited research.

Documents that lack the batch number, the date of analysis, the laboratory's identification, or information about the method used may raise doubts.

Similarly, a declaration of purity without a chromatogram and without an explanation of the method of calculating the percentage value does not allow for a detailed assessment.

Other signals that require explanation include:

• inconsistency of the batch number between the vial and the report;
• identical images of chromatograms presented for different batches;
• absence of wills or results confirming identity;
• ambiguous names and peptide sequences;
• sterility declarations based solely on HPLC;
• no results despite the indication of the names of the analytical methods;
• there is no possibility to determine who issued the report;
• claims of full quality based on one parameter.

A single incomplete piece of information does not automatically mean that the material is defective. However, it may limit the possibility of independent verification.

It is also worth checking whether the documentation actually describes Ala-Glu-Asp-Gly. If a different sequence or structural modification appears, it is necessary to explain why the material is identified as Epitalon.[1]

What impurities can be present in synthetic Epitalon?

Contaminants of synthetic peptides can originate from the production process, purification, formulation, or subsequent degradation. Not all of them belong to the same chemical category and not all of them can be identified using a single method. [3–5]

The synthesis of peptides involves the gradual formation of bonds between amino acids. The incomplete course of the reaction can lead to the formation of shorter sequences or other by-products.

Improper amino acid residues, residues of protective groups, modified end-groups of the molecule, and products of metabolic processes occurring during storage are also possible.

Potential degradation processes include oxidation, hydrolysis, cyclization, and structural rearrangement.

Sharma and colleagues describe the use of various chromatographic techniques and mass spectrometry to study impurities, degradation, and aggregation of synthetic peptides. The choice of methods depends on the structure of the compound being studied.[4]

Can the AEDG sequence affect stability?

Yes. The amino acid sequence is important for the potential chemical reactions occurring in the peptide.

The Asp-Gly fragment occurs in Epitalon. In the broader chemical literature, it has been described that certain motifs containing aspartyl residues can participate in rearrangement or degradation reactions under appropriate conditions.[2]

This does not mean that every sample of Epitalon undergoes such changes to an important extent.

It does, however, indicate that stability cannot be determined solely based on the nominal sequence. Results of studies conducted under specific conditions are necessary.

The quality assessment should therefore take into account both the condition of the material after production and the possibility of changes during the declared storage period.

How do anti-inflammatory agents affect the interpretation of the quality of Epitalon?

Przeciwjon is a component associated with the charged form of a peptide. In synthetic materials, it can be present, among other things, in the form of acetate and trifluoroacetate, abbreviated as TFA.

The presence of anti-ion affects the overall chemical composition and mass of the sample.

Peptides are often purified in an acidic environment, therefore ions derived from the reagents used may remain in the final material. It is also possible to perform an exchange of counterions.

The 2025 review of Epitalon discusses the various chemical forms of this compound and the limitations of the available physicochemical characterization.[1]

If the document only mentions „Epitalon 10 mg”, but does not explain the basis for the labeling, there may be ambiguity.

The value can refer to the total mass of the material, the mass of a specific salt, or the amount expressed as the equivalent of a free peptide.

In experiments requiring precise molar concentration, this difference may be significant for interpreting the results.

Therefore, the chemical composition, chromatographic purity, and the content of AEDG must be considered separately.

How can we interpret HPLC and MS together?

The most useful interpretation of the basic analytical results occurs when chromatography and mass spectrometry provide consistent information.[2–5]

The HPLC shows whether the sample contains the dominant chromatographic component. MS helps determine whether this component corresponds to the expected peptide.

This approach is referred to as orthogonal analysis because the methods used measure different properties of the sample.

The study by Vanhee and colleagues shows the value of combining chromatography and mass spectrometry in the identification of Epitalon.[2]

However, it should be remembered that even the compliance of both methods does not replace quantitative determination, stability testing or microbiological analyses.

What cannot be inferred from the COA of Epitalon?

The analysis certificate documents specific results regarding the material. It does not automatically confirm biological efficacy, clinical safety, sterility, suitability for human administration, or regulatory status.

It is possible to obtain high chromatographic purity and proper chemical identification for a substance whose safety of use in humans remains insufficiently known.

Similarly, the results of biological experiments concerning a particular peptide do not guarantee that another, poorly characterized batch will correspond to the material used in these studies.

A 2025 review indicates that despite numerous publications concerning Epitalon, there are still limitations in the knowledge about its mechanisms, long-term safety, and physicochemical properties.[1]

In turn, the analytical identification of AEDG in unauthorized preparations does not imply confirmation of their efficacy or safety.[2]

Quality documentation therefore supports the proper characterization and reproducibility of experiments, but does not replace clinical studies.

What studies answer the most important questions about the quality of Epitalon?

The table shows why the general term „Epitalon quality” encompasses many independent characteristics.

Frequently asked questions about COA, HPLC and the purity of Epitalon

What does the Epitalon COA mean?

The COA for Epitalon means a certificate of analysis documenting the results of testing on a specific sample or batch of peptide. The document may contain information about identity, chromatographic purity, content, and other quality parameters. Its value, however, depends on the completeness of the data and the ability to link the report to the physical material. The „COA” itself does not confirm that each vial has been tested or that all possible analyses have been performed.

Is 99% purity of HPLC sufficient to confirm the quality of Epitalon?

No. The result of 99% HPLC primarily indicates the contribution of the main peak in the chromatographic signal obtained by a specific method. It does not independently confirm the identity of the AEDG, the actual peptide content, sterility, or stability. To obtain a more complete picture, the chromatography should be combined with an identification method such as MS or LC-MS, and with the appropriate quantitative tests and additional tests required for the given experiment.

Does mass spectrometry confirm that the sample contains Epitalon?

Mass spectrometry can provide strong evidence confirming the presence of an AEDG-compliant molecule. High-resolution measurements and analysis of MS/MS fragmentation are particularly valuable, providing additional structural information. However, mass alone does not always allow all isomers or sequence variants to be distinguished. In more complex cases, a chromatographic comparison, NMR, or the use of a reference material may be necessary.[3]

Which method is more important for Epitalon: HPLC or MS?

HPLC and MS perform different functions, therefore they should not be considered as alternative methods. HPLC is mainly used to separate components and evaluate chromatographic purity, whereas MS supports molecular identification and analysis of impurities. A sample may have one dominant peak and yet contain an incorrect peptide. It may also contain an appropriate AEDG along with numerous impurities. The combined use of both techniques reduces these ambiguities.

Does the COA confirm that the vial of Epitalon 10 mg actually contains 10 mg?

Only when the document contains the appropriate quantitative result of the content determination is it meaningful. The value of 10 mg on the label is a nominal declaration, whereas the result of 99% HPLC usually describes the relative surface area of the chromatographic peak. Therefore, it is not possible to automatically multiply these values and consider the result to be the actual mass of the AEDG. Accurate determination may require taking into account water, anti-ions, residual solvents, and other components of the sample.

Does the batch number on the COA have to match the number on the vial?

The consistency of batch numbers is a fundamental element of traceability. An analytical report regarding another batch can provide information about previous material, but does not constitute direct confirmation of the quality of the current sample. The most useful documentation allows the vial label to be linked to production records, the analysis certificate, and the laboratory report. This allows determining which material was actually tested.

What does the term „Epitalon tested by an independent laboratory” mean?

It usually means that the analysis was performed by an external entity against the manufacturer or supplier. However, the term itself does not indicate which tests were performed or whether the report concerns the correct batch. The scientific value of such a study depends on the laboratory, the sample, the methods, the date of the analysis, and the actual results. Organizational independence does not replace an appropriate methodology.

Does HPLC allow the detection of all Epitalon impurities?

No. HPLC detects components that can be separated and quantified under the conditions of the method used. Some impurities may co-elute, show a weak detector response, or not be properly quantified in a given system. Water, specific solvents, metals, endotoxins, and microbiological impurities require other techniques. Therefore, the chromatographic purity result describes only a specific range of the sample’s properties.

Does the high purity of Epitalon mean that the material is sterile?

No. Chemical purity and sterility relate to other characteristics of the material. A sample may exhibit high chromatographic purity while having no microbiological test results. HPLC and MS are not tests of sterility or endotoxin markers. If such parameters are required for a specific research application, separate, appropriately selected tests are necessary.

Does one HPLC peak confirm the complete purity of Epitalon?

No. A single dominant peak may indicate that the sample is chromatographically homogeneous under the applied conditions, but does not preclude the presence of undetected or unresolved substances. It also does not confirm that the main component has the correct AEDG sequence. Interpretation depends on the resolution of the method, detector, sample preparation, and integration principles. Additional identification analysis and characterization of impurities allow for a better assessment of the result.

Does the correct molecular mass mean the correct AEDG sequence?

Mass consistency supports identification, but does not always resolve all structural issues. However, various compounds can have identical or very similar masses, and some changes in sequence and spatial configuration are not unequivocally detected in basic MS measurements. In such situations, mass fragmentation/MS, comparison with a reference material, chromatography, or NMR can be helpful. The scope of confirmation should correspond to the methods actually used.

Can the content of anti-ion matter change the interpretation of the Epitalon mass?

Yes. Octane, trifluorooctane, and other reagents may constitute part of the total mass of the material. This means that two samples described with the same value in milligrams do not necessarily contain the same number of AEDG molecules. The difference is particularly important in quantitative analyses requiring precise molecular concentration. Therefore, the documentation should explain whether the declared mass refers to the free peptide, the specified salt, or another basis for the designation.

Can the COA confirm the stability of Epitalon throughout the storage period?

A single COA usually describes the state of the sample on a specific day and is not sufficient evidence of long-term stability. During storage, degradation reactions can occur depending on temperature, humidity, pH, and other conditions. Verification of stability requires stability studies covering appropriate time points and methods to detect qualitative changes. The initial HPLC or MS result does not replace such data.

Does the report from one vial confirm the quality of the entire batch of Epitalon?

Not automatically. Analysis of a single sample provides direct information about the material that was actually tested. To claim that the entire batch is compliant requires an appropriate sampling plan, homogeneity data, and a process control system. Without such documentation, it cannot be assumed that each vial has identical content, purity, and contaminant profile. The result of a single analysis must therefore be interpreted in accordance with the representativeness of the sample.

Does the verified purity of Epitalon confirm its safety or effectiveness?

No. Chemical quality studies and clinical trials address different questions. HPLC, MS, and quantitative determinations can confirm specific material properties, but they do not prove that the substance is safe for human use or effective in treating any disease. Such conclusions require separate pharmacological, toxicological, and clinical studies. A reliable COA supports the identification and reproducibility of experiments, not the confirmation of therapeutic use.

Limitations of the Epitalon quality assessment

One of the main limitations is the lack of a uniform, universally accepted meaning for the term „Epitalon of the research class”. Different suppliers and laboratories may use different specifications, scope of tests, and acceptance criteria.

The mere labeling of the material as intended for research does not therefore constitute proof of compliance with a specific quality standard.

Another limitation results from the dependence of chromatographic results on the method used. The type of column, the composition of the mobile phase, the gradient, temperature, detector, and integration rules can all influence the resulting chromatogram and the calculated purity. Therefore, procedures should be appropriately characterized or validated according to their intended use.[4,6]

The third problem concerns time. The certificate confirming quality on the day of testing does not prove that the material retains the same properties after transport, temperature changes, or multiple months of storage.

The fourth limitation is the representativeness of the sample. Without data on sample collection and batch uniformity, it is not possible to draw full conclusions about all the packages.

The fifth issue concerns microbiological quality. The results of the HPLC and MS tests do not confirm sterility or the absence of endotoxins, therefore such properties require separate testing when they are relevant to the experiment.

The sixth limitation is related to structural identification. Even a correct mass may not resolve all isomeric, stereochemical, and sequential differences. In some cases, more detailed orthogonal methods are needed.[3]

Additionally, a review from 2025 indicates limited physicochemical characteristics of Epitalon compared to its biological literature. This emphasizes the importance of clear analytical documentation when comparing materials used in different experiments.[1]

Applications

The quality of Epitalon is a multidimensional concept. It cannot be reliably determined based on a single percentage value, a chromatogram, or a general assurance of the performance of laboratory tests.

HPLC enables the evaluation of chromatographic purity and the detection of specific impurities. Mass spectrometry supports the identification of AEDG and the characterization of its molecular forms. Both methods provide complementary information, but they do not replace appropriate quantitative determination.

If the actual content of Epitalon in the vial is important, a separate confirmation of the amount of peptide is necessary. When interpreting, the anti-antibodies, water and other components of the material must also be taken into account.

A reliable analysis certificate should present specific results, identify the laboratory and allow the report to be linked to the appropriate batch. Chromatograms, mass spectra, serial numbers, and clearly described methods allow for a much more accurate assessment of what has actually been confirmed.

The key remains the distinction between analytical quality and clinical evidence. Even a well-characterized Epitalon does not therefore become a substance with proven safety and therapeutic efficacy.

Disclaimer

The article is purely educational and informational in nature. It concerns analytical methods and quality control of materials used in laboratory studies. It does not constitute medical advice, purchase recommendations, instructions for preparing or administering Epitalon, nor an encouragement to use it in humans.

Confirmation of the identity, purity, or content of a peptide does not imply confirmation of its clinical safety, efficacy, sterility, or suitability for medical applications. The scope of required quality tests should correspond to the specific laboratory application and the appropriate institutional and regulatory requirements.

References

[1] Araj, S. K., Brzezik, J., Mądra-Gackowska, K., & Szeleszczuk, Ł. (2025). Overview of Epitalon—Highly bioactive pineal tetrapeptide with promising properties. International Journal of Molecular Sciences, 26(6), 2691.
https://doi.org/10.3390/ijms26062691

[2] Vanhee, C., Moens, G., Van Hoeck, E., Deconinck, E., & De Beer, J. O. (2015). Identification of the small research tetra peptide Epitalon, assumed to be a potential treatment for cancer, old age and Retinitis Pigmentosa in two illegal pharmaceutical preparations. Drug Testing and Analysis, 7(3), 259–264.
https://doi.org/10.1002/dta.1771

[3] McCarthy, D., Han, Y., Carrick, K., Schmidt, D., Workman, W., Matejtschuk, P., Duru, C., & Atouf, F. (2023). Reference standards to support quality of synthetic peptide therapeutics. Pharmaceutical Research, 40(6), 1317–1328.
https://doi.org/10.1007/s11095-023-03493-1

[4] Sharma, N., Kukreja, D., Giri, T., Kumar, S., & Shah, R. P. (2022). Characterization of synthetic pharmaceutical peptides using chromatography principles and method development. Journal of Separation Science, 45(13), 2200–2216.
https://doi.org/10.1002/jssc.202101034

[5] Li, M., Josephs, R. D., Daireaux, A., Choteau, T., Westwood, S., Wielgosz, R. I., & Li, H. (2018). Identification and accurate quantification of structurally related peptide impurities in synthetic human C-peptide by liquid chromatography–high resolution mass spectrometry. Analytical and Bioanalytical Chemistry, 410(20), 5059–5070.
https://doi.org/10.1007/s00216-018-1155-y

[6] International Council for Harmonisation. (2024). ICH Q2(R2): Validation of Analytical Procedures. Current guideline for validation of analytical methods used for purposes including identity, assay, purity and impurity testing.
https://www.ema.europa.eu/en/ich-q2r2-validation-analytical-procedures-scientific-guideline

U.S. FDA version:
https://www.fda.gov/media/161201/download