一种改进设计的液体阴极放电发射光谱金属元素检测研究

Determination of Metal by Liquid Electrode Discharge Atomic Emission Spectrometry with a New Design

针对已有的液体阴极辉光放电发射光谱装置,对放电的阴极加了一个锯齿型引流结构设计,锯齿顶端位于毛细管顶部下方2mm处,在液滴刚开始长大时便触到锯齿尖端,进而破坏液滴的表面张力,使液体顺着引流槽流下,从而大大改善了因阴极毛细管顶端液滴的周期性形成和坍塌造成的放电闪烁、电流改变,甚至放电熄灭,此种设计可持续放电至少3小时。利用新的结构还测定了铅、铬、镉、锌、钒、镍、铜、银、钴九种元素的线性方程,九种元素的线性度均在0.97以上,线性较好。仪器对银、铅、铜的灵敏度最好,三种元素的检测限分别为0.048,0.080和0.084mg.L-1,对镍、铬、钴、锌、镉的检测限在0.27～1.60mg.L-1之间,对钒的检测限最高为10.88mg.L-1。

A liquid electrode discharge atomic emission spectrometry has been developed with a new design.Plasma fluctuationfrom the variations in the gap between the W anode and liquid cathode was eliminated by providing a sawtooth-shaped drainagestructure.The sawtooth was placed at a distance of 2mm from the glass capillary top.When a solution is pumped through aglass capillary,the liquid drop forms and rises and on reaching the maximum size collapses while the next drop forms.This re-sults in a continuous change in the interelectrode distance which will cause the discharge current to change,plasma flickers and isextinguished.With the new design,the surface tension of the drop was destroyed before its growing up,and the solution wasflowing along the drainage groove.The discharge can last for 3hours at least with such arrangement.The analytical responsecurves for lead,chromium,cadmium,zinc,vanadium,nickel,copper,silver and cobalt demonstrated good linearity.The limitof detections of lead,chromium,cadmium,zinc,vanadium nickel,copper,silver and cobalt were determined to be 0.08,0.61,0.48,1.60,10.88,0.48,0.084,0.048and 0.27mg.L-1 respectively.