EN ISO 787-19:1995

General methods of test for pigments - Part 19: Determination of water-soluble nitrates (Salicyclic acid method) (ISO 787-19:1974) EN ISO 787-19:1995

Publication date:   Dec 22, 2003

Scope

This document specifies a spectrophotometric method. The principle of the method consists in that the nitrate present in the extract of the sample is used to nitrate salicylic acid in sulphuric acid medium. The nitro-compound formed is of an intense yellow colour in alkaline solution and the colour is measured spectrophotometrically at a wavelength of 410 nm. ISO 787/13 specifies a method using Nessler's reagent. The two methods may not necessarily give the same result; work is being carried out to compare the two methods.