微乳液介质分光光度法测定锰

Sectrophotometric Determination of Trace Manganese in Microemulsion Medium

研究了在pH9.0的氨性介质中,Mn(Ⅱ)-5-Br-PADAP-微乳液红色络合物形成的适宜条件和络合物的稳定性等.锰含量在0.1～0.5μg/mL范围内符合比尔定律,其A=1.659 4C+0.033 5(C的单位μg/mL),相关系数r=0.999 3,其表观摩尔系数1.068×10~5 L·mol^(-1)·cm^(-1).测定6次相对偏差小于3.0%,加标回收率在102.0%～106.8%.用该法测定茶叶中的锰,结果令人满意.

The formation condition and stability of 2- （5-bromo-2-pyridylazo） -5-diethylaminophe- nol （5-Br-PADAP） with Mn（II） in the presence of microemulsion are investigated by spectropho- tometry. Results show that a stable red complex is found in the medium of pH9.0. Beer＇s Law is obeyed for Mn（Ⅱ） in the range of 0.1～0.5μg/mL. The molar absorptivity at 565nm is 1.068×10^5 L·mol^-1·cm^-1. The relative standard deviation is less than 3.0%（6 determinations）.The recovery of standard addition is 102%-106.8%.The method has been applied to the determination of Mn（Ⅱ） in tea with satisfactory results.