建立了一套基于大气压液体阴极辉光放电原子发射光谱(electrolyte cathode atmospheric glow discharge atomic emission spectroscopy,ELCAD-AES)的水中金属离子检测装置,并在该装置上对水中金属离子铅(Pb)进行了检测,随着Pb浓度的增加,Pb元素的发射光谱强度显著增强,Pb浓度在10~80 mg·L-1范围内时,其发射信号强度与浓度呈现一定的线性关系.实验考察了放电电流、易电离元素对Pb发射光谱的影响,表明当电流增加到70 mA时,Pb元素的信号强度最强,溶液中的易电离元素对Pb元素信号强度产生微弱影响.同时探讨了酸化试剂对Pb发射光谱的影响,发现用HNO3酸化溶液时Pb发射光谱强度最强,而降低pH值可以有效的提高Pb发射光谱强度.研究了等离子体内不同区间的原子发射光谱强度,结果表明金属原子Pb的发射光谱集中在靠近阴极的区域,因此获得了Pb元素的最佳探测位置.计算得到采用便携式光谱仪作为探测系统的水体Pb元素痕量检出限为0.7 mg·L-1,相对标准偏差为1.7%,两种实际水样检测回收率分别为95%~106%,表明本方法有较好的准确性.研究结果为进一步开展水体痕量重金属元素液体阴极辉光放电光谱检测提供了方法.

A device based on electrolyte cathode atmospheric glow discharge atomic emission spectroscopy(ELCAD-AES) has been developed to determine the metal ion Pb in water.The emission intensity of Pb was significantly enhanced with the increase concentration of Pb,and the emission intensity has a linear relationship with concentration while the concentration of Pb in the range of 10~80 mg·L-1.The effects of discharge current and easily ionizable elements on the emission spectral of Pb were investigated,and the emission intensity reached greatest when the discharge current increased to 70 mA,and the easily ionizable elements generated weak effect on the emission spectral of Pb.The effect of acidification regent on emission spectral of Pb was discussed.It was found that it perform best when acidified with HNO3,and reducing the pH can improve the emission intensity of Pb effectively.The emission intensity of Pb at different region was detected near cathode region,thus obtained the best detection position.Under the optimized experimental parameters,the detection limit of Pb was 0.7 mg·L-1 and relative standard deviation was 1.7%.The recovery of samples was 95%~106%,result and shows that this method has better accuracy.These results provide an available method for further research of detection trace heavy mental elements in water using ELCAD-AES.