METHOD OF DETERMINING 4-AMINOBENZOIC ACID IN AQUEOUS SOLUTIONS Russian patent published in 2004 - IPC

FIELD: analytical methods.

SUBSTANCE: invention is meant for use for controlling quality of untreated and treated waste waters from enterprises engaged in production of synthetic dyes and pharmaceutical preparations. Determination of 4-aminobenzoic acid comprises sampling 100 cm³ waste water, liquid extraction and concentration of acid in presence of 23% Li₂SO₄ as salting-out agent followed by analyzing extract through titration method with alcohol KOH solution and calculating weight of acid using formula: m = 0.01CVMR, where C is concentration of KOH titrant in ethyl alcohol, mole/dm³; V volume of titrant reacted in titration, cm³; M molar mass of acid equivalent, g/mole; and R is degree of recovery of acid in single extraction step, %. According to invention, sample is preliminarily acidified to pH 2, extractant utilized is mixture of isobutyl alcohol, acetone, and ethyl acetate in amounts 2-5, 5-10, and 2-5 cm³, respectively, and analysis of extract involves potentiometric titration with glass indicator electrode.

EFFECT: simplified analytical procedure, improved selectivity and accuracy of analysis.

1 dwg, 1 tbl, 10 ex