BACKGROUNDFor the determination of P₂O₅ in complete silicate analysis of uranium-producing ore by alkali fusion-phosphovanoclonolybeate spectrophotometry with wavelength of 420nm, iron (Fe) was detected simultaneously, because Fe as the co-existing element complexed with ammonium vanadium molybdate and showed the same yellow with phosphovanoclonolybeate. Iron produced positive interference on the results of P₂O₅.

OBJECTIVESTo correct the interference of Fe on the determination of P₂O₅.

METHODSTaking Fe₂O₃ as the assessment amount of Fe in complete silicate analysis, when detection wavelength was changed from 400nm to 480nm, the effects of different amounts of Fe₂O₃ (0.00 to 0.70mg/mL) on the absorption value of P₂O₅ with content of 0.20g/mL, 2.00g/mL and 8.00g/mL were investigated, respectively.

RESULTS(1) It was found that when the detection wavelength of P₂O₅ was changed from 420nm to 450nm, the positive interference produced by Fe₂O₃ on the analysis results of P₂O₅ was corrected. Moreover, the contents of Fe₂O₃ and P₂O₅ in the sample was within the calibration range at the correction wavelength of 450nm when taking national standard materials GBW04117-GBW04122 of uranium-producing ore as verification samples. (2) When P₂O₅ in national standard material of uranium-producing rocks, basalts and argillaceous limestone was analyzed at 450nm, the results were within the error range. The method precision (RSD) was between 1.1% and 15.7%, which met requirements of analyzing P₂O₅ in other samples with a similar matrix such as silicate and uranium ores.

CONCLUSIONSThe corrected method is simple and easy to operate. It provides a supplementary method for accurate spectrophotometric determination of P₂O₅ during complete silicate analysis in uranium-producing ore.