Study on the Chromogenic Reaction of Dibromo-p-methyl-chromosulfonazo with Strontium and Its Analytical Application

The chromogenic reaction of dibromo-methyl-chromosulfonazo with strontium has been studied in this paper. In 0.72 mol·L~(-1) HCl medium , the reagent reacts with strontium to form a 2∶1 blue complex, having an absorption maximum at 633 nm with a molar absorptivity of 7.7×10~4 L·mol~(-1)·cm~(-1).Beer's law is obeyed in the range 0～30 μg of strontium in 25 mL of solution. It is found that dibromo-p-methyl-chromosulfonazo is a highly sensitive and selective chromogenic reagent in comparison with other reagents when determining strontium. The method has been applied to the determination of strontium in aluminium alloy with satisfactory results.