Determination of sulfate in natural and residual waters by turbidimetric flow-injection analysis.
A turbidimetric flow-injection system was developed for the determination of sulfate in natural and residual water samples, with no previous treatment, using spectrophotometric detection. The precipitating agent, 7.0% (w/v) barium chloride solution prepared in 0.10% (w/v) polyvinyl alcohol, was added by using the merging-zones approach. A 100 mg/L sulfate solution in 0.07M nitric acid was mixed with the sample before it entered the injection loop to improve the detection limit, provide in-line pH adjustment, and prevent the interference of some anionic species. The relative standard deviations of the results were between 1.4 and 3.0% and were in agreement with results obtained by the reference method. Samples within a linear concentration range of 10-120 mg SO4(2-)/L can be analyzed at a rate of 40/h. The detection limit is 5 mg SO4(2-)/L.
Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal.
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Rangel
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D017022:Flow Injection Analysis / Q000592:standards; D005618:Fresh Water / Q000032:analysis; D007202:Indicators and Reagents; D007220:Industrial Waste / Q000032:analysis; D009391:Nephelometry and Turbidimetry; D012015:Reference Standards; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013431:Sulfates / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D007202:Indicators and Reagents; D007220:Industrial Waste; D012996:Solutions; D013431:Sulfates; D014874:Water Pollutants, Chemical