KPV — analytical characterisation
Chromatographic conditions, identity, related substances, presentation, reconstitution and in-use stability.
§6Analytical characterisation
§6.1Chromatographic conditions
- Column
- C18 with an aqueous-compatible or polar-embedded phase; a 342 Da tripeptide has almost no reverse-phase retention on a conventional method
- Mobile phase and gradient
- A: 0.1 % trifluoroacetic acid in water; B: acetonitrile. Gradient 0–15 % B over 15 min, or a hydrophilic-interaction method as an alternative
- Detection
- UV 214 nm only; no aromatic residue
- Retention
- Essentially at the void on a conventional C18 method. This is the extreme case of the retention problem affecting small polar peptides, and purity determination requires either a specialised phase or an orthogonal separation mode
§6.2Identity by mass spectrometry
[M+H]⁺ at m/z 343.2. At this mass a nominal-resolution instrument is entirely adequate for identity.[3]
§6.3Related substances and degradation
Table 7. Related substances recorded for KPV, with the process or storage route that generates each and its analytical signature.
| Related substance | Origin | Analytical signature |
|---|---|---|
| Sequence-scrambled tripeptides (VPK, PKV and others) | Coupling errors | Isobaric — indistinguishable by mass and, on a poorly retaining method, indistinguishable chromatographically. This is a genuine analytical difficulty for very short peptides and requires either a resolving method or amino-acid sequencing |
| Diketopiperazine of Lys-Pro | Cyclisation | −18 Da; the Xaa-Pro motif is specifically prone to diketopiperazine formation and this is the characteristic degradant |
| Free amino acids | Hydrolysis | Very early elution; requires a method capable of resolving the void region |
| Counter-ion | Purification | Enormous in proportional terms — one trifluoroacetate on a 342 Da peptide is 25 % of the mass. Peptide content for small basic peptides is routinely in the 70s as a percentage, which is normal and must be stated |
Degradation routes
- Diketopiperazine formation at the Lys-Pro bond
- Peptide-bond hydrolysis
- No oxidation-sensitive residues
§7Presentation, reconstitution and storage
§7.1Presentation and reconstitution
- Presentation
- Lyophilised powder; oral capsules; topical preparations
- Reconstitution
- A 10 mg vial with 2.0 mL gives 5 mg/mL; 500 µg is then 0.10 mL, that is 10 units on a U-100 syringe.
- Storage, lyophilised
- −20 °C, desiccated
- Storage, reconstituted
- 2–8 °C
- In-use period
- No supported claim
For peptides below about 500 Da the counter-ion fraction dominates the mass balance. A certificate for KPV reporting 99 % purity and no peptide content figure has communicated very little about what is in the vial.
§7.2In-use stability
Applicable standards: CEI-MS-01 · CEI-MS-02 · CEI-MS-03 · CEI-MS-04 · CEI-MS-05 · CEI-MS-06. The full series is at methodological standards.
Working calculators: reconstitution and insulin-unit conversion · purity against peptide content · certificate minimum-data checker.
References cited on this page
References are numbered in order of first citation in this document. Each superscript in the text links to its entry below.
- United States Pharmacopeial Convention. General Chapter ⟨1225⟩ Validation of Compendial Procedures. United States Pharmacopeia — National Formulary (USP–NF) 2024;USP 2024 Issue 1. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q2(R2) Validation of Analytical Procedures. ICH Harmonised Guideline 2023;Step 4 version, 1 November 2023. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q6B Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products. ICH Harmonised Tripartite Guideline 1999;Step 4 version. identifier not held by the Institute
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH Q1A(R2) Stability Testing of New Drug Substances and Products. ICH Harmonised Tripartite Guideline 2003;Step 4 version. identifier not held by the Institute
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharmaceutical Research 2010;27(4):544–575. doi:10.1007/s11095-009-0045-6 · PMID 20143256
Identifiers are reproduced only where the Institute holds them. Where a digital object identifier or PubMed identifier is not shown, the Institute has recorded the journal and year and has not constructed an identifier.