Category: Analytical Methods

How to read isotope patterns in peptide mass spectra: charge from line spacing, monoisotopic versus apex peaks, sulfur at M+2 and adducts.

What makes two analytical methods truly orthogonal for peptide identity, which common pairings share a blind spot, and how to match methods to risk.

Fmoc vs Boc solid-phase peptide synthesis compared: how each protection strategy works and the impurity signatures, like +222 Da, that each leaves.

How peptide mapping works: protease choice, sequence coverage, missed cleavages and digestion artifacts, and what a map can and cannot confirm.

How resin type, loading and linker choice in solid-phase peptide synthesis shape C-terminal identity and the impurity profile a buyer sees.

Why two peptides at 98% HPLC purity are not equally pure: UV response factors, 214 vs 280 nm detection, and what area percent can support.

How a peptide lyophilization cycle works: freezing, primary drying and secondary drying, why cakes collapse, and why residual moisture is the key output.

What MTT, resazurin and other cell viability assays really measure, where they mislead in peptide research, and the controls that fix it.

What makes a peptide specification meaningful: attribute, method and limit, where acceptance criteria come from, and five questions to ask of any spec.

Standard deviation, standard error or confidence interval? What each error bar means, why n matters, and how to read lab figures correctly.