METHOD OF SEPARATELY DETERMINING RESORCINOL AND 2,4- DINITRORESORCINOL IN PRESENCE OF 4-NITROSORESORCINOL

摘要

FIELD: analytical methods.;SUBSTANCE: invention is directed to controlling treated waste waters from varnish-and-paint industry enterprises and discloses a method of separately determining resorcinol and 2,4-dinitroresorcinol involving potentiometric titration in dimethylformamide medium, determination being carried out in aqueous sample preliminarily acidified to pH 2-3 and treated with acetone in presence of ammonium sulfate as salting-out agent in amount 36.5-40.0% of the weight of sample. Organic layer containing resorcinol and 2,4-dinitroresorcinol is then separated, diluted with dimethylformamide at volume ratio 1:5, and titrated with solution of potassium hydroxide in isopropyl alcohol. Content of each of resorcinols is calculated from differential titration curves in according to formula: C = C_o100/R wherein C and Co are concentrations of resorcinols in initial aqueous sample and in extract, respectively, mg/dm³, and R degree of recovery of resorcinols in acetone/water-salt solution, %.;EFFECT: enabled selective determination of resorcinol and 2,4-dinitroresorcinol, reduced detection limits (extraction concentration operation), and expanded application area.;2 tbl, 12 ex