Purification of xylenol orange by preparative paper chromatography, and examination of its zirconium complex

Abstract

Preparative paper chromatography is proposed as a suitable method for purification of Xylenol Orange (XO). The last three dissociation constants of pure XO have been determined with the aid of the program SPEKTFOT, the values found being p K 9 = 12.34; p K 8 = 10.66; p K 7 = 6.69 (0.1 M KNO 3, 20 ± 0.5°). The complexation of zirconium with the purified reagent has been studied and the co-existence of ML and M 2 L complexes proved by use of the program DALSFEK. The following conditional stability constants of the complexes and their molar absorptivities were computed: log β' ml 4.58; log β' M 2L 11.59; ϵ ML 2.00 × 10 4; ϵ M 2L 9.40× 10 4 l.mole −1.cm −1 at 550 nm.