What Purity Actually Means: Impurities, Certificates and Specifications

A purity percentage is a statement about one chromatogram, one detector and one day, not about the contents of the bottle. This hub maps impurity thresholds, response factors, specifications and reference materials.
Identity and Purity: A Complete Guide to Analytical Methods for Small Molecules

Every analytical technique answers one question well and is blind to several others. This hub maps HPLC, GC-MS, NMR, MS, FTIR, XRPD and Karl Fischer titration onto the questions they can actually settle – and explains why regulators expect orthogonal evidence.