Comparison of Ion Chromatography and Barium Sulfate Spectrophotometry for Sulfate Determination in Water

Objectives  To compare the similarities and differences of ion chromatography and barium sulfate spectrophotometry for the determination of sulfate in water.

Methods  Analyzing and comparing the scope of application, sample volume, analyzing time, linear range, recoveries, precision, detection limits of ion chromatography and barium chromate spectrophotometry in the determination of sulfate in water.

Results  The recoveries of sulfate in 4 standardized synthetic water samples ( < 10.0 mg/L) detected by ion chromatography and barium chromate spectrophotometry were 86.5~93.1% and 99.7%~101.0%, respectively. The Results of 20 water samples (>10.0 mg/L) measured by these two Methods were tested by paired t test, and no significant difference was observed (t=1.395, P < 0.05). The detection limit, detectable limit, linear range, recovery and RSD of sulfate detected by ion chromatography were 0.0028 mg/L, 0.1 mg/L, 0.1~300 mg/L, 90.0%~100.2% and 0.3%~0.8%, respectively; and the detection limit, detectable limit, linear range, recovery and RSD of barium sulfate detected by spectrophotometry were 1.68 mg/L, 5 mg/L, 5~200 mg/L, 97.2%~100.4% and 0.4%~2.2%, respectively. Experimental Results showed that the accuracy of barium chromate spectrophotometry was lower than ion chromatography when the concentration of sulfate in water was low ( < 10.0 mg/L); while the concentration of sulfate in water was more than 10.0 mg/L, better accuracy could be achieved by using both methods. The analyzing time, linear range, detection limit and precision of sulfate in water samples detected by ion chromatography were superior to barium chromate spectrophotometry.

Conclusions  The accuracy of ion chromatography was better than barium sulfate spectrophotometry in the determination of low concentrations of sulfate in water ( < 10.0 mg/L), a better accuracy could be got by both Methods while the concentration of sulfate in water was more than 10 mg/L.The method of ion chromatography is simple and fast in the detection of a variety of anions, and more suitable for the detection of a large number of samples.