The determination of aqueous fluoride by flow injection analysis (FIA) with a helium microwave-induced plasma (He-MIP) is described. This system operates at 500 W and utilizes a modified TM010 resonator cavity with a demountable plasma torch. Both direct nebulization and FIA in conjunction with ultrasonic nebulization (USN) were investigated. FIA was found to be the most reliable method because extended nebulization of aqueous fluoride was found to cause memory effects. Detection limits for aqueous fluoride of 35 and 4 ppm were observed for FIA and direct USN, respectively. The interference effects of pH and selected elements were also studied.

No abstract