Analytical fundamentals
Purity versus net peptide content, HPLC and mass spectrometry, reading a certificate of analysis, endotoxin, lyophilisation, storage and stability, counter-ions.
- Counter-ions in synthetic peptides: trifluoroacetate and acetate
Where trifluoroacetate comes from in synthesis and purification, how much of a lyophilised solid it can account for, what the literature reports about its effect in cell-based assays, and what exchange to acetate changes.
reviewed 2026-09-22
- Endotoxin testing: what the figure on a certificate means
Bacterial endotoxin, the three LAL formats and the recombinant factor C alternative, how endotoxin units are defined against a reference standard, and why interference testing is part of the result.
reviewed 2026-09-22
- HPLC and mass spectrometry explained
How reversed-phase separation, ultraviolet detection at 214, 220 and 280 nm, and electrospray or MALDI ionisation combine to produce a purity figure and an intact mass, and what that mass cannot settle.
reviewed 2026-09-22
- Lyophilisation: what freeze-drying does to a peptide
Freezing, primary and secondary drying, the structure of the cake and the collapse temperature that limits it, residual moisture and its measurement by Karl Fischer titration, and the limits of what drying achieves.
reviewed 2026-09-22
- Our methodology: what is tested, and what is published
The tests run on every released lot, how release and quarantine decisions are made, and the rule that governs which identity figures appear on this site and which are shown as unverified.
reviewed 2026-09-22
- Purity and net peptide content: two different numbers
Chromatographic purity describes the composition of what a column detects; net peptide content describes how much of a vial's mass is peptide. A sample can be high in one and low in the other.
reviewed 2026-09-22
- Reading a certificate of analysis
What each field on a peptide certificate means, which questions it answers, which it does not, and how a certificate is tied to the specific lot of material in front of a researcher.
reviewed 2026-09-22
- Solid-phase peptide synthesis and where impurities come from
How the Merrifield cycle assembles a peptide chain, how the Fmoc and Boc strategies differ, and which characteristic impurity each stage of a synthesis leaves behind in the crude material.
reviewed 2026-09-22
- Storage and stability of synthetic peptides
What the published literature reports about how lyophilised peptides and peptide solutions degrade, which residues are vulnerable, and the storage conditions used in analytical and assay work.
reviewed 2026-09-22
- Third-party testing and laboratory accreditation
What accreditation to ISO/IEC 17025 covers, why a scope of accreditation is the operative document, what method validation involves, and what an independent test result does and does not establish.
reviewed 2026-09-22