Spectrophotometric determination of Ga~(3+) and In~(3+)with 4-(2-pyridylazo)-resorcinol

An effective spectrophotometric determination of Ga(3+) and In(3+) with 4-(2-pyridylazo)-resorcinol (PAR) has been studied. PAR and Ga(3+) can form a hyacinth complex in the range of pH 5.5 to 6.5. Beer's law is obeyed over the concentration range from 0 to 5.0 μg·mL(-1) at 505 nm against reagent blank.The apparent molar absorptivity and Sandell's sensitivity of Ga(3+) are 1.4×104 L·mol(-1)·cm(-1) and 0.0050 mg·cm(-1) respectively.The similar color complex of In(3+) with PAR is formed in the range of pH 6.0 to 6.5.Beer's law is obeyed over the concentration range from 0 to 4.6 μg·mL(-1) at 505 nm.The apparent molar absorptivity and Sandell's sensitivity of In(3+) are 1.37×104 L·mol(-1)·cm(-1) and 0.0084 mg·cm(-1)respectively.The spectrophotometric determination of these metal ions with PAR is largely affected by the amount of PAR added and the acidity in the aqueous.