[Determination of trace nickel in coal gangue by catalytic fading spectrophotometry].

In KH2PO4-Na2B4O7 (pH = 6.3) buffered solution the trace Ni(II) can strongly catalyze the fading reaction of carmine. Time and temperature can influence the reaction, and the reaction stops at the low temperature. Based on this study, a catalysis spectrophotometric method for determining trace Ni(II) is developed. The results show that the detection limits of the method is 2.5 x 10(-11) g.mL-1 for Ni(II) and Beer's law is obeyed for Ni(II) in the range of 0-1.2 micrograms.50 mL-1. Combined with solvent extraction spearation, the method has been applied to the determination of trace Ni in coal gangue with satisfactory results.