Simultaneous Determination of Fluoride and Chloride in Phosphorus Rock by Steam Distillation-Ion Chromatography

An ion chromatographic method for simultaneous determination of fluoride and chloride in phosphoˉrus rock using steam distillation for sample pretreatment was developed.The HPLC(Shimadzu LC-10A)was converted into a suppressor ion chromatograph by using the YSA-8column(China made)for separation and the DZS self-electric suppressor for suppression.The eluent was a mixture of4.3mmol/L Na 2 CO 3 and6.0mmol/L NaHCO 3.After dissolving the sample with sulfuric acid,the fluoride and chloride were separated from the matrices by steam distillation.The distillate,after passing through the0.45μm filter membrane,was used for analysis.Under optimal conditions,the correlation coefficients of the calibration curves for fluoˉride and chloride were0.9996and0.9994,respectively and the detection limits(S/N=3)were2mg/kg and3mg/kg,respectively.The relative standard deviations for fluoride and chloride were2.1%-2.6%and2.5%-3.8%,respectively and the recoveries were93%-104%,and95%-98%,respectively.The method has been applied to the determination of fluoride and chloride in phosphorus rock samples with satisfactory results.