阻抑动力学光度法测定痕量铬(Ⅵ)

INHIBITORY KINETIC PHOTOMETRIC DETERMINATION OF TRACE AMOUNTS OF CHROMIUM(Ⅵ)

基于存在增溶剂乳化剂OP ,将非均相体系转变为均相体系 ,铬 (Ⅵ )阻抑过氧化氢氧化PAN的反应 ,拟订了测定痕量铬的阻抑动力学光度法。在乳化剂OP存在下 ,铬 (Ⅵ )的线性范围为 0 .0 15～ 0 .0 8mg·L- 1,检出限为 5 .2 4× 10 - 9g·ml- 1,可用于水样中铬 (Ⅵ )

It was found that the decoloration reaction of PAN with hydrogen peroxide was inhibited by hexavalent chromium in an acetate buffer medium of pH 4.5. Nonionic surfactant OP was added as solubilizing agent to render the solution in a homogeneous state. The extent of the inhibitory effect was proportional to the concentration of chromium(Ⅵ) ion, and linearity was kept in the range of 0.015～0.08mg of Cr(Ⅵ) per liter of solution. Based on these phenomenon an inhibitory kinetic photometric method for the determination of trace amounts of chromium(Ⅵ) was established. The photometric measurements were made at 520nm, which happened to be the absorption maxima of PAN in the buffer medium. The detection limit was found to be 5.24×10 -9g·ml -1. The proposed method has been applied to water analysis.