· Blenders International · Water Science
How is blending water tested? The methods behind every number on a certificate of analysis
A blending-water specification is a list of limits. A certificate of analysis is a list of claims that those limits were met. Between the two sits a set of standardised analytical methods — conductivity by a three-stage pharmacopoeial test, organic carbon by oxidation, trace ions by ICP-MS and ion chromatography, organisms by culture, and taste by a trained panel — each with its own blind spots. Here is what actually measures what, why two honest certificates can disagree, and the questions that separate an audited supplier from a confident one.