Journal of the Serbian Chemical Society 2003 Volume 68, Issue 1, Pages: 65-73
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Spectrophotometric determination of phosphorus in coal and coal ash using bismuth-phosphomobybdate complex
Mihajlović Ranđel P., Ignjatović Nataša R., Todorović Marija R., Holclajtner-Antunović Ivanka D., Kaljević Vesna M.
A modified spectrophotometric method using the bismuth phosphomolybdate complex for the determination of phosphorus in coal and coal ash is suggested. Bismuth together with phosphate and molybdate forms a very stable complex in acid medium which turns blue ("molibdenum blue") by reduction with ascorbic acid. The apparent molar absorptivity of PBiMo is 1.66x104 dm3 mol-1cm-1 at 720 nm and 2.10x104 dm3 mol-1cm-1 at 670 nm isobutyl methyl ketone (MIBK). Interference caused by the ions present are within the tolerance limits (±2 %). Beer’s law is obeyed in the for concentration range to 0.6 μg/mL (aqueous solution) and to 1.2 μg/mL P (MIBK). The sensitivity of the proposed method is 0.0078 μg/mL (aqueous solution) and 0.0066 μg/mL (MIBK).
Keywords: spectrophotomery, phosphorus determination, coal, coal ash, bismuth phosphomolybdate complex.