环境水样中痕量镉的明胶增溶镉(Ⅱ)-碘化钾-孔雀绿体系分光光度测定法  

Determination of Trace Cadmium (Ⅱ) in Water by Spectrophotometry in Cadmium (Ⅱ)-Potassium Iodide-Malachite Green-Gelatine

作　　者：刘梅[1,2] 樊静[1] 

机构地区：[1]河南师范大学化学与环境科学学院河南省环境污染控制重点实验室,河南新乡453007 [2]河南焦作师范高等专科学校理化生系,河南焦作454000

出　　处：《环境与健康杂志》2008年第9期807-809,共3页Journal of Environment and Health

基　　金：河南省科技攻关计划重点项目(072102320007)

摘　　要：目的建立水中痕量镉的高灵敏分光光度测定方法。方法在磷酸介质中,镉(Ⅱ)-碘化钾-孔雀绿形成三元离子缔合物,加入明胶对该反应体系具有增溶、增敏作用。缔合物在680nm 处有最大吸收。笔者研究了试剂用量、温度、干扰物等因素对明胶增溶镉(Ⅱ)-碘化钾-孔雀绿体系分光光度法测定环境水样中痕量镉的影响。结果在优化的实验条件(在25 ml 容量瓶中依次加入40%的碘化钾-抗坏血酸溶液6.0 ml、5.0 mol/L 的磷酸溶液0.5 ml、0.5%的明胶溶液0.5 ml、1.0×10^(-3)mol/L 的孔雀绿溶液1.5 ml,加水稀释至刻度,摇匀后立即测量)下.镉的浓度在0.02～0.80 μg/ml 范围内服从比尔定律,线性回归方程为ΔA=0.011+0.957 c,表观摩尔吸光系数(ε)为1.08×10~5 L/(mol·cm),相关系数为0.998 5.该法检出限为0.02 μg/ml,RSD 为1.36%-3.58%,回收率为97.0%～101.5%,缔合物的组成的物质量的比为孔雀绿(MG)∶Cd∶I^-=2∶1∶4。结论该方法使用仪器简单,操作方便,无需萃取可直接在水相中测定,方法的线性范围宽,灵敏度高,用于水中镉含量的测定.结果满意。Objective To establish a high sensitive speetrophotometry for determination of trace cadmium in the water. Methods A complicated ion-association complex of Cd （ Ⅱ ）-potassium iodide-malachite green was formed in the phosphate acid, and the addition of gelatine could enhance the sensitivity of the reaction. The maximum absorption of the ion-association complex was at 680 nm, the effect of experimental conditions such as the reagents concentration,the temperature and the influence of foreign matters were considered. Results In the optimum condition （6.0 ml of 40% potassium iodide-aseorbie acid solution, 0.5 ml of 5.0 mol/L phosphate acid solution,0.5 ml of 0.5% gelatine solution, 1.5 ml of 1.0×10^-3 mol/L malachite green solution in a 25ml volumetric flask, diluted with water and mixed well and determined immediately）, the linear regression equation was △A =0,011 ＋ 0.957 c, r=0.998 5. Beer＇ s law was obeyed in the range of 0.02 ug/ml to 0.80 ug/ml for Cd（ Ⅱ ） and the limit detection was 0.02 ug/ ml. The composing ratio of the complex was MG：Cd：I^-=2：1：4, and its apparent molar absorptivity coefficient was 1.08×10^5 L/（mol · cm）. The recovery rates of Cd （ Ⅱ ） were 97.0%-101.5%, RSDs were 1.36%-3.58%. Conclusion This method is sensitive,simple, rapid and is applicable to the determination of the trace Cd（ Ⅱ ） in water.

关 键 词：镉 明胶 孔雀绿 碘化钾 分光光度法 

分 类 号：O657.3[理学—分析化学]