Indicator tubes and indicator powders for determining fluoride and chloride ions

Noncovalent immobilization of Arsenazo I, Alizarin Red, Xylenol Orange, and diphenylcarbazone by incorporation into silicic acid xerogels and modification of silica gels was studied, and procedures for determining fluoride and chloride ions by solid-phase spectrophotometry and test methods were developed. Reactions of immobilized reagents with aluminum(III), zirconium(IV), and mercury(II) were studied. The possibility of using immobilized reagent-metal ion-halide ion systems for the determination of halide ions was assessed. Indicator powders were proposed for determining 0.5-10 mg/L fluoride ions and 1-30 mg/L chloride ions, and indicator tubes were developed for determining 20-200 mg/L chloride ions. The determination of fluoride and chloride ions is based on exchange complexation reactions proceeding in the systems immobilized Xylenol Orange-zirconium(IV) and immobilized diphenylcarbazone-mercury(II), respectively. Performance characteristics of the developed procedures were estimated. The procedures were verified by determining halide ions in Narzan mineral water.