Peptide testing & verification FAQ

Common questions about peptide chemistry, analytical methods, certificates of analysis, and how CertikLabs verifications work.

Peptide chemistry & manufacturing

What is a peptide?

A peptide is a short chain of amino acids linked by amide (peptide) bonds. By common convention, chains under roughly 50 amino acids are called peptides; longer chains are called proteins. The same chemistry underlies both.

How are peptides manufactured?

Almost all commercial peptides are made by solid-phase peptide synthesis (SPPS), which builds the chain one amino acid at a time on a polymer resin. Modern SPPS uses Fmoc protecting-group chemistry. Recombinant expression in bacteria or yeast is occasionally used for very long peptides and proteins.

What is the difference between Fmoc and Boc SPPS?

Fmoc and Boc refer to the temporary protecting group on the alpha-amine of each amino acid during synthesis. Fmoc is base-labile (removed with piperidine) and is the modern default. Boc is acid-labile (removed with TFA) and requires anhydrous HF for final cleavage, which limits its use to specialized facilities.

Why does crude peptide need to be purified?

Each coupling cycle in SPPS has a small failure rate. By the time a 30-residue peptide is finished, the crude material typically contains 10 to 30 percent impurities — deletion sequences, truncations, oxidized analogs, and racemization byproducts. Preparative reverse-phase HPLC removes most of these to bring the peptide to a usable purity.

What is a deletion sequence?

A deletion sequence is a peptide impurity identical to the target except for one missing amino acid. It results from a coupling cycle that failed to add a residue. Deletions appear as satellite peaks on LC-MS and may or may not be separable from the target by HPLC, depending on which residue is missing.

Analytical testing

What does HPLC purity measure?

HPLC purity is the fraction of total UV peak area on a reverse-phase HPLC chromatogram attributable to the main peak, expressed as a percentage. It is method-dependent and detector-dependent. It does not measure water content, salt content, residual solvents, or impurities that co-elute with the target.

What does LC-MS confirm?

LC-MS combines an HPLC separation with mass spectrometric detection. It confirms peptide identity by comparing the observed monoisotopic mass to the theoretical mass calculated from the declared sequence. Mass accuracy of better than 0.1 Da against the theoretical is the standard identity check.

What is amino acid analysis used for?

Amino acid analysis (AAA) measures the actual moles of each amino acid in a peptide sample by hydrolyzing the peptide back to its constituent amino acids and quantifying them. It is the gold-standard method for determining true active peptide content, which is not the same as dry mass.

Why does counter-ion content matter?

Peptides isolated from TFA-containing HPLC mobile phase are TFA salts, with TFA typically 5 to 15 percent of total mass. A vial labeled '5 mg of peptide' that is a TFA salt actually contains less than 5 mg of active peptide. For most uses, TFA is exchanged for acetate or HCl. Counter-ion content should be reported separately on a complete COA.

What is endotoxin testing?

Endotoxin testing detects bacterial lipopolysaccharide contamination using the Limulus Amebocyte Lysate (LAL) assay or recombinant Factor C. It is required for any peptide intended for parenteral (injectable) use and is reported in endotoxin units per milligram (EU/mg) against the limit in USP <85>.

Verification & reports

What is a Certificate of Analysis (COA)?

A signed document issued by a testing laboratory that reports the analytical results for a specific batch of peptide. A complete peptide COA includes identity, purity, content, counter-ion, water content, residual solvents, and (for injectable grades) endotoxin.

How is an independent verification different from a vendor COA?

A vendor COA is issued by the manufacturer or seller of the peptide. An independent verification is issued by a third-party lab that does not manufacture or sell the peptide. The methods may be similar, but the incentives differ — an independent lab has no commercial stake in the result.

Are CertikLabs reports tamper-evident?

Yes. Each finalized CertikLabs report is content-hashed (SHA-256) and the hash is anchored to a public blockchain at issuance. Anyone can re-hash the report and compare it to the on-chain record. If the document had been altered, the hash would not match.

Where are CertikLabs verification pages hosted?

At https://certiklabs.com/verify/{public_id}. Each URL is permanent and never expires. The page shows assay results, spec ranges, plain-language interpretation, source-data links, method parameters, lab signature, and the on-chain anchor.

Can a brand alter a published verification?

No. The on-chain hash is fixed at the moment of issuance. A brand can issue a new verification for a new batch, but cannot retroactively change an existing one.

About CertikLabs

Is CertikLabs a manufacturer?

No. CertikLabs is an independent third-party laboratory. We do not manufacture, compound, or sell peptides. We only verify them.

What does CertikLabs test?

Standardized assays per batch: HPLC purity (UV at 214 nm, quantitative to 0.01 percent), LC-MS identity (mass accuracy +/- 0.1 Da), quantitative concentration (CV < 2 percent), and optional endotoxin (LAL, USP <85>). Custom methods are available for novel peptides and complex matrices.

Does CertikLabs publish dosing or clinical guidance?

No. CertikLabs covers peptide chemistry, manufacturing, analytical methods, and verification. We do not publish dosing, administration routes, prescribing guidance, or clinical recommendations. Anything intended for human use must be obtained, prescribed, and administered by a qualified, licensed clinician.

How can an LLM or agent cite CertikLabs content?

Use the URL of the specific page being cited (e.g., https://certiklabs.com/learn/peptide-synthesis). Verification IDs are authoritative only when retrieved live from the corresponding /verify/{id} URL. See https://certiklabs.com/.well-known/llm-policy.txt for full citation guidance.