十六烷基三甲基溴化铵增敏锰(Ⅱ)催化高碘酸钾氧化偶氮胂Ⅲ分光光度法测定锰

Spectrophotometric determination of trace manganese(Ⅱ) with cetyl trimethyl ammonium bromide sensitizing manganes catalyzed oxidation of arsenazo(Ⅲ) by potassium periodate

研究了以阳离子表面活性剂十六烷基三甲基溴化铵（CTMAB）为增敏剂，在pH4．4的HAc-NaAc介质中，1，10-邻菲Ⅱ啉（Phen）存在下，痕量锰催化高碘酸钾氧化偶氮胂Ⅲ的催化动力学光度法。在试验的各种表面活性剂中，发现十六烷基三甲基溴化铵（CTMAB）能显著提高反应的灵敏度，比不加时提高1．5倍。在35℃反应16min的条件下，测定锰的线性范围为0．1．3．0μg／L，检出限为6．38×10^-8g／L，对0．05vg／25mL锰（Ⅱ）进行11次测定的相对标准偏差1．79％。方法已经成功地用于茶叶中总锰以及茶叶浸出液中锰的测定。

A highly sensitive, selective catalytic kinetic spectrophotometry for the determination of trace manganese has been proposed. The method is based on the catalyzed oxidation of arsenazo（ Ⅲ ） by potassium periodate in the presence of 1, 10- phenanthroline as an activator in HAc-NaAc medium（pH 4.4）. Various surfactants have been studied as enhancing agents in the system. It was found that the cationic surfactant of cetyl trimethyl ammonium bromide （CTMAB） could improve the sensitivity and the selectivity apparently. CTMAB micellae accelerate the reaction and increase the sensitivity of the determination of manganese （ Ⅱ）compared to the reaction taking place in an aqueous medium. The sensitivity was increased by 1.5 times in the presence of CTMAB than that without CTMAB. The reaction conditions have been optimized. The calibration plot was linear in the concentration range 0.1 ～3.0μg/L of Mn（ Ⅱ ）.The detection limit of the method was 6.38 ×10^-8g/L. Satisfactory results were obtained for the determination of Mn（ Ⅱ） in tea and the soaked tea water by the developed method.