Anatomy of a chromatographic peak
Retention time (where it elutes), peak height, peak width at half-height, and peak area together describe a peak. Purity = main peak area ÷ total integrated area, in the elution window of interest.
Common impurities and what they look like
Front-shoulder: deletion sequence (a residue short). Rear-shoulder: oxidation product or diastereomer. Late-eluting hump: hydrophobic aggregate. Multiple small peaks before main: synthesis precursors.
Pass/fail judgment
≥99% main peak is our release threshold. Borderline batches (98.5–99%) are re-tested; below 98.5% is rejected. We never blend batches to hit a number.
Frequently asked questions
Should baseline be flat?+
Reasonably flat between peaks; a gentle drift is normal during a solvent gradient.