Lab Notes
Plain-language notes on how research peptides are analyzed, made and stored. Start with how to read a certificate of analysis, then see what HPLC and mass spectrometry can and cannot show, why a powder is never all peptide, and why dry material is kept cold, dark and dry.
Reading a certificate
- How to read a certificate of analysisA walkthrough of a drawn example certificate, line by line. It shows how to check who issued a report and whether it belongs to the lot in your hands, what a method can and cannot tell you, and what a certificate leaves out.
- HPLC and how to read a chromatogramHow reversed-phase HPLC separates a sample, and how to read the chromatogram it produces. It covers retention time, peak area, area-percent purity and its limits, with a clean and an impure example trace side by side.
- Mass spectrometry: identity, not purityMass spectrometry measures the mass of molecules. This page explains electrospray ionization, the mass-to-charge ratio, multiply charged ions and deconvolution with invented worked numbers, and why a correct mass confirms identity but not purity.
Quality and chemistry
- Purity, net content, net peptide content and salt formsThree numbers, three different questions. This page separates HPLC purity, net content and net peptide content, explains how counterions and water add to a powder’s mass, and works through invented arithmetic showing why a purity of 99% by HPLC does not mean the powder is 99% peptide.
- How peptides are madeMost synthetic peptides are built one amino acid at a time on a solid resin. This page walks through Fmoc solid-phase peptide synthesis, from deprotection and coupling to cleavage and purification by preparative HPLC, and shows with simple arithmetic why some impurities are unavoidable.
Handling science
- Why research peptides ship as a powderResearch peptides are supplied as a freeze-dried powder because water drives several of the reactions that slowly change them. This page explains lyophilization step by step: freezing, sublimation under vacuum, secondary drying, the cake and residual moisture.
- Storage science for lyophilized materialDry peptide material changes slowly, and three things set the pace: temperature, light and moisture. This page explains the chemistry behind each, from reaction rates to photo-oxidation to water uptake and condensation, and why the rule is cold, dark and dry.
Reference
The examples on these pages are invented, and no page names a product.