A spectrophotometric study of the complexation equilibria and the determination of nickel(II) with 4-(2-pyridylazo)resorcinol, 4-(2-thiazolylazo)resorcinol, and 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol

The complexation equilibria of Ni(II) with 4-(2-pyridylazo)resorcinol (PAR) and 4-(2-thiazolylazo)resorcinol (TAR) in 30 vol.% ethanol and with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (BrPADAP) in 10 vol.% ethanol containing 0·1% BRIJ-35 tenside were studied spectrophotometrically. The absorbance data were processed by the SPEFO 8, HALTAFALL SPEFO and SQUAD-G programs. The working procedures for the determination of Ni(II) with the reagents in pure solutions were optimized and statistically evaluated, and PAR was applied to the determination of Ni(II) in drinking water.