Development and Validation of a Spectrophotometric Method to Measure Sulfate Concentrations in Mine Water without Interference |
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Authors: | Arup Roy Bidus Kanti Das Jayanta Bhattacharya |
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Affiliation: | (1) Department of Mining Engineering, Indian Institute of Technology, Kharagpur, 721302, India; |
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Abstract: | Sulfate concentrations are determined in mine water by gravimetric, titrimetric, colorimetric, turbidometric, ion chromatographic,
inductively coupled plasma absorption spectrophotometric, and other methods. Accurate sulfate measurement of mine water can
be difficult due to interfering groups, cations, and anions, mainly arsenate (AsO4
3−) and phosphate (PO4
3−). In this paper, a simple and effective spectrophotometric method is described for the determination of sulfate in mine water.
When the SO4
2− reacts with barium chloranilate at pH 4.5 in aqueous ethyl alcohol solution, it releases acid-chloranilate, which shows maximum
absorption at 350 nm and obeys Beer’s law over the concentration range of 10–1,000 mg/L. Results show that the proposed method
was significantly more accurate than a conventional method. Absorbance was found to increase linearly with increasing concentration
of sulfate, which is corroborated by the calculated correlation coefficient value of 0.999 (n = 7). The slope and intercept
of the equation of the regression line were 0.00091 and 0.00778, respectively. The limit of detection and limit of quantification
were found to be 0.03861 and 0.06774 mg/L, respectively. The validity of the described procedure was assessed. Statistical
analysis of the result indicated high accuracy and good precision. The proposed method was successfully applied in mine water
without interference from common groups like AsO4
3− and PO4
3−. The relative standard deviations of the proposed method ranged from 0.03 to 0.26%, with recoveries of 99.79–101.57%. |
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