METHOD OF DETERMINING 2,4-DICHLOROBENZOIC ACID IN AQUEOUS SOLUTIONS Russian patent published in 2004 - IPC

FIELD: analytical methods. SUBSTANCE: method, which may be used for monitoring of process and treated waste waters from synthetic dye, polymer material, and pesticide production enterprises, comprises preliminary liquid-liquid extraction and concentration of acid followed by analysis of extract. Water-saturated ethyl acetate in amount 5-10 cm³ is used as extractant and extract is analyzed by turbidimetric titration technique in 2-cm cuvette at wavelength 440-490 nm using KOH in ethanol as titrant. Mass of 2,4-dichlorobenzoic acid is calculated by formula m = 0.01C*V*M*R wherein C represents concentration of sodium hydroxide in ethanol, mole/dm³; V volume of sodium hydroxide/ethanol titrant consumed for titration, cm³; M molecular mass of acid equivalent, g/mole; R percentage of isolation of acid in a single extraction, %; and R = 100D/(D+r), where D is coefficient of distribution of 2,4-dichlorobenzoic acid in water/ethyl acetate system (D=215) and r is ratio of equilibrium volumes of aqueous and organic phases. EFFECT: increased accuracy and sensitivity of analysis and simplified analytic procedure. 1 dwg, 2 tbl, 9 ex