Indirect inductively coupled plasma atomic emission determination of fluoride in water samples by flow injection...

An indirect determination of fluoride in water by inductively coupled plasma atomic emission spectrometry combined with flow injection coupled with solvent extraction is reported in this paper. A manifold for rapid determination of fluoride has been designed that uses a single coil for complex formation and extraction. The method involves the formation of lanthanum/alizarin complexone/fluoride complex and its extraction into hexanol containing N,N-diethylaniline. The concentration of fluoride is determined indirectly by introduction of the organic layer into the plasma and measurement of the emission intensity of the La II 333.75-nm line. The optimum experimental conditions for the determination are described. A coiled groove phase separator fitted with a grid and PTFE porous membrane was used in this work. The sampling rate was 36 samples per hour and the calibration graphs were linear from 0.03 to 1.3 micrograms/mL. The relative standard deviation found was 2.16% for 200 microL of 1 microgram/mL of fluoride. The method is selective and has been applied satisfactorily to the determination of fluoride in water samples.