5-Br-DMPAP分光光度法测定食品中微量铬

Spectrophotometric Determination of Trace Chromium in Food with 5-Br-DMPAP

研究了以5-Br-DMPAP分光光度法测定食品中微量Cr,对实验条件及共存离子的干扰进行了探讨。在C_2H_5OH存在下,Cr(Ⅲ)和5-Br-DMPAP在pH4.5～5.5范围内形成有色络合物,ε=6.75×10~4L.mol^(-1).cm^(-1),Cr在0～12μg/25ml范围符合比耳定律,变异系数和回收率分别在2.6%～8.7%和90.2%～95.3%之间。

A spectrophotometric method for the determination of trace Chromium in food by 5-Br-DMPAP has been investigated. The experimental conditions and interference from coexisting ions were studied. In the presence of ethanol in weak acidic solution Cr(Ⅲ) and 5-Br-DMPAP forms a coloured complex. The apparent molar absorptivity of 6.75×10~4L. mol^(-1). cm^(-1). Beer's law is obeyed when Cr concentration is in the range of 0～12μg per 25ml. The variation and recovery rate from this method are within 2.6%～8.7% and 90.20%～95.3% respectively.