【摘要】 以直流电源为驱动,锥形铂棒为阳极,铂丝环绕的毛细管顶端溢出的液体为阴极,利用外加磁场增强元素的信号强度,构建了一种磁场辅助的溶液阴极辉光放电（MF-SCGD）原子发射光谱微分析系统.研究发现,在磁场作用下,等离子体中的带电离子受到磁约束,使得其运动路径发生变化,进而减缓了等离子体的膨胀,增加了等离子体的温度、密度以及碰撞频率,从而提高了Pb的激发效率和原子化效率;磁场的引入可以提高溶液的蒸发率,降低阳极铂棒的红热程度.在放电电压为650 V、溶液流速为2.4 mL·min^-1、 pH=1.0的HNO₃为电解质时,加入0.5 T的磁场可以使Pb的信号增强1.5倍,灵敏度提高1.4倍,放电功率低于25 W,检出限（LOD）降低到0.17 mg·L^-1.用MF-SCGD对环境标准样品（BW0610）和中药材中的Pb进行测试,发现测定值与标准值以及加标值基本一致,回收率为101%～105%,说明该方法对铅的测定准确可靠.MF-SCGD具有仪器紧凑、成本低、功率小、放电稳定性高等优点,是一种很有前景的微分析技术.更多还原

【Abstract】 A magnetic field-assisted solution cathode glow discharge（MF-SCGD） was constructed as a miniaturized excitation source for atomic emission spectrometry（AES）,in which a platinum spiralwrapped quartz capillary and a platinum needle tip were used as cathode and anode,respectively,and DC power supply was employed to drive glow discharge.It is found that the charged ions in the plasma are constrained by magnetic field,which changes their motion path,slows down the expansion of plasma,increases the temperature,density and collision frequency of plasma,and ultimately improves the excitation efficiency and atomization efficiency of Pb.Adding magnetic field can increase the evaporation efficiency of solution and reduce the red-hot degree of anode platinum rod.Under 650 V discharge voltage,2.4 mL·min^-1 solution flow rate,and pH=1.0 HNO₃ as electrolyte,adding 0.5 T magnetic field can enhance the Pb signal by 1.5 times and increase the sensitivity by 1.4 times.Discharge power is less than 25 W,and the detection limit（LOD） of Pb is reduced to 0.17 mg·L^-1.Pb in environmental standard sample（BW0610） and Chinese herbal medicine was determined by MF-SCGD.The results showed that the measured value is basically consistent with the standard value and added value,and the recovery rate is 101%～105%,indicating that the proposed method is accurate and reliable.MF-SCGD has the advantages of compact instrument,low cost,low power and high discharge stability,which is a promising miniaturized excitation source for atomic emission spectrometry.更多还原