双波长双指示剂褪色光度法测定大米中的痕量镉

在盐酸介质中,痕量镉离子对双氧水氧化茜素红S和硫堇具有较强烈的催化作用,因此建立了一种测定痕量镉离子的双波长双指示剂褪色光度法.实验结果表明,溶液的最大吸收波长分别出现在420 nm和610 nm.6次空白实验的标准偏差S=6.31×10-4,相对标准偏差为0.01％,检出限为4.878×10-2μg/mL.该方法用于大米样品中痕量镉的测定,结果令人满意.

Determination of Trace Cadmium in Rice by Double Wavelength Double Width Indicator with Fading Reaction Spectrophotometry

The trace Cd2+ could strongly catalyze the fading oxidation reaction of alizarin red S and thionine by hydrogen peroxide in the medium of hydrochloric acid.A new catalytic fading spectrophotometric method by the double wavelength double width indicator had been established for the determination of trace Cd2 +.The results showed that the maximum absorption wavelength of the solution were 420 nm and 610 nm,respectively.The standard deviation and the relative standard deviation of six blank experiments were 6.31 × 10-4 and 0.01％,the determination limit of the method was 4.878 × 10-2 μg/mL.The method had been applied to the determination of Cd2+ in rice with satisfactory results.