Category: Analytical Methods

How pore size, C18, C8, C4 and phenyl ligands and the acid additive shape a peptide HPLC separation, and why column choice changes purity figures.

How saturation, competition, fluorescence polarization and SPR binding assays differ, and what to check before trusting a peptide affinity value.

How solid-phase peptide synthesis builds a chain one residue at a time, why yield compounds with length, and where deletion sequences come from.

Bioburden, sterility and endotoxin are three separate microbiological tests. See what each one measures and why an HPLC purity report covers none of them.

How chromatogram peak integration shapes a peptide purity figure: shoulders, drop-line versus valley-to-valley splits, and baseline placement.

Why some peptides aggregate in solution: sequence features, nucleation, concentration and pH, and what aggregation hides from an HPLC purity result.

How cell line choice shapes peptide assay results: authentication, mycoplasma, receptor expression, species differences and culture conditions.

What HPLC system suitability checks before a peptide sample is run, why a degraded column can inflate purity, and how to read suitability data.

Forced degradation explained: how deliberate acid, base, oxidant, heat and light stress proves an HPLC method is stability-indicating for peptides.

What HPLC carryover is, why peptides are prone to it, how blanks and wash choice expose it, and how it can make a purity result look worse.