分光光度法测定中药茶中微量铜的研究

目的]研究中药茶中微量铜的测定方法。方法]采用标准曲线法,以空白试剂作对照,用1cm比色皿在波长675nm处依次测定标准溶液及样品的吸光度,计算样品含量。结果]Cu（Ⅱ）的加入使体系的最大吸收波长红移111nm,λmax从564nm变为了675nm,溶液颜色由紫红色变为纯蓝色。675nm被选为测定波长。pH值2.2～3.7溶液的吸光度最大且无显著变化,缓冲溶液用量被选为1.0ml。在1.6×10-5～2.4×10-5mol/L浓度范围内吸光度达最大且基本不变。温度的影响不大。辛基酚聚氧乙烯醚（OP）浓度在0.2%～0.5%溶液吸光度保持稳定,且灵敏度提高8%;TritionX-100浓度为0.05%～0.40%时溶液吸光度基本不变,灵敏度提高约14%;乙醇对反应体系无影响。平行测定的吸光度平均值为0.396。线性方程为A=0.3182C-0.0313,相关系数为0.9992,表观摩尔吸光系数为1.77×104（L.mol）/cm,桑德尔灵敏度为0.00359μg/cm2。结论]该方法适用于中药茶中微量铜的测定。

Study on the Determination on Trace Cu in Chinese Herbal Tea by Spectrophotometry with Microwave Digestion

Objective]The purpose was to study the determination method of trace Cu in Chinese herbal tea.Method]With blank agent as CK,the standard curve method and 1 cm cell were used to determine the absorbance of standard solution and sample solution at the wavelength of 675 nm and the sample content was calculated out.Result]The addition of Cu(Ⅱ)made red shift of 111 nm in maximum absorption wavelength of the system and the value of λmax was changed from 564 nm to be 675 nm,and the color of solution was changed from prunosus to be pure blue.675 nm was selected as determination wavelength.The absorbance of solution with pH value of 2.2-3.7 was maximum and had no significant change and the dosage of buffer solution was selected as 1.0 ml.In the concn.range of 1.6×10-5～2.4×10-5 mol/L,the absorbance reached its maximum and was consistent basically.The influence of temperature was little.The absorbance of solution with OP concn.in 0.2%-0.5% was kept stable and its sensitivity was enhanced by 8%;the absorbance of solution with TritionX-100 concn.in 0.05%-0.40% was consistent basically and its sensitivity was enhanced by 14%;the ethanol had no influence on reaction system.The mean absorbance of parallel determinations was 0.396.Its linear equation,correlation coefficient,apparent mole absorbancy index and Sandell's sensitivity were A=0.3 182C-0.0 313,0.999 2,1.77×104(L·mol)/cm and 0.003 59 μg/cm2.Conclusion]The method was suitable for determination on trace Cu in Chinese herbal tea.