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 modifica tion of silica gels was studied, and procedures for determining fluoride an d chloride ions by solid-phase spectrophotometry and test methods were deve loped. 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 asse ssed. 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 de termining 20-200 mg/L chloride ions. The determination of fluoride and chlo ride ions is based on exchange complexation reactions proceeding in the sys tems immobilized Xylenol Orange-zirconium(IV) and immobilized diphenylcarba zone-mercury(II), respectively. Performance characteristics of the develope d procedures were estimated. The procedures were verified by determining ha lide ions in Narzan mineral water.