Spectrophotometric Determination of Gallium(III) with 4-(2-Pyridylazo)-resorcinol and Nitron

The formation and liquid-liquid extraction of ion-association complex between gallium(III) - 4-(2-pyridylazo)-resorcinol (PAR) - 1,4-diphenyl-3-(phenylamino)-1H-1,2,4-triazole (nitron, Nt), water and chloroform were studied. The optimum conditions for gallium(III) extraction as an ion-association complex, (NtH)(+)[Ga3+(PAR)(2)](-), were found: pH, concentration of the reagents and shaking time. The following key constants were calculated: constant of extraction (logK(ex) = 6.28 +/- 0.07), constant of association (log beta = 4.98 +/- 0.05), constant of distribution (logK(D) = 1.30 +/- 0.02) and recovery factor (R / % = 95.17 +/- 0.02). Beer's law is obeyed for Ga(III) concentration up to 0.8 mu g cm(-3) with apparent molar absorptivity of (10.3 +/- 0.4) x 10(4) dm(-3) mol(-1) cm(-1) at lambda(max) = 510 nm. Some additional characteristics, such as limit of detection (LOD = 0.072 mu g cm(-3)), limit of quantification (LOQ = 0.24 mu g cm(-3)) and Sandell's sensitivity (SS = 0.000675 ng cm(-2)) were estimated as well.