茜素红退色动力学光度法测定痕量钴

Catalytic kinetic spectrophotometric determination of trace amounts of cobalt by alizarin red fading

在pH8．0的NH3·H2O-NH4Cl介质中，以聚氧乙烯醚-200（PED-200）为活化剂，Co（Ⅱ）催化溴酸钾氧化茜素红退色，建立了动力学光度法测定痕量Co（Ⅱ）的新方法。方法检出限为2．0×10^-7g／L，线性范围0．01～0．21μg／50mL，最大相对标准偏差为2．3％，用于湖水及生产排水的测定，结果满意，加标回收率在96．0％～105．0％之间。

A rapid, simple and sensitive kinetic photometry method is presented for the determinations of cobalt （Ⅱ）. The method is based on the oxidation fading of alizarin red by KBrO3 and activation of the polyethylene glycol-200 （PEG-200） and catalysis of cobalt （Ⅱ） in a medium of NH3·H2O-NH4Cl. The reactions can be monitored spectrophotometrically by measuring the absorbance at 516 nm. The method allowed the determination of cobalt （Ⅱ） at concentrations between 0.01 and 0.21μg per 50mL of solution with a relative standard deviation of 2.3%. The detection limit of the method is 2.0×10^-7g/L. It has been used to determine trace cobalt （Ⅱ） in water with satisfactory results.