锰-铬天青S-邻菲罗啉-溴化十六烷基三甲铵四元络合物光度法测定茶叶中的锰

目的]探讨采用四元络合物分光光度法测定茶叶中的微量锰含量的效果与特点。方法]通过铬天青S（CAS）、1，10-邻菲罗啉（Phen）、溴化十六烷基三甲铵（CTMAB）与锰形成四元络合物，采用分光光度法测定茶叶中锰的含量。结果]Mn—CAS—phen-CTMAB四元络合物的最大吸收波长为618nm；锰含量在0～1．2μg/ml的范围内呈现良好的线性关系，相关系数为0．9984，摩尔吸光系数为ε618=7．4×10^4L／（mol·cm），方法的检出限为0．062μg/ml；回收率为98．1％～103．1％，测定结果的相对标准偏差为2．0％～2．6％。结论]该测定法加大了缓冲溶液的用量，保证了测定体系的pH值，确定最佳显色时间为35min，消除干扰离子影响的最佳掩蔽剂为5％KF2．0ml＋饱和硫脲1．0ml。该方法具有较高的选择性和灵敏度，是一种测定茶叶消化液中微量锰的准确可靠的方法。

Determination on Manganese in Tea by Spectrophotometry with Quaternary Complex Mn-CAS-Phen-CTMAB

Objective] The purpose was to discuss the effect and characteristics of determining the content of trace manganese in tea by spectrophotometry with quaternary complex. Method] The quaternary complex was made from CAS, Phen, CTMAB and manganese. The content of manganese in tea was determined by spectrophotometry. Result] The maximum adsorption wavelength of quaternary complex Mn-CAS-phen-CTMAB was 618 nm. The content of manganese showed good linear relationship in the range of 0-1.2 μg/ml, its correlation coefficient was detection limit of this method was 0.062 μg/ml, its recovery was 98.1%-103.1% and the relative standard deviation of its determination results was 2.0%-2.6%. Conclusion] This determination method increased the dosage of buffer solution, guaranteed pH of determination system. Its optimum coloration time was ascertained as 35 min and the optimum masking agent for eliminating the influences of interfering ions was 5%KF 2.0 ml + saturated thiourea 1.0 ml. This method had higher selectivity and sensitivity and it was an accurate and reliable method for determining trace manganese in the digestive juice of tea.