激光诱导击穿光谱结合标准加入法定量分析未知样品中铅含量

摘要

利用激光诱导击穿光谱结合标准加入法定量分析了铅蓄电池厂含铅污泥中重金属铅元素含量，标准加入法有效避免了外标法与内标法制作标准曲线时基质不同对L IBS检测结果的影响，且样品处理过程简单。实验采用中心波长为1064 nm的Nd∶YAG脉冲激光器作为激发光源，以高分辨率、宽光谱段的中阶梯光栅光谱仪和增强型电荷耦合器件为谱线分离与探测器件，选取铅的PbⅠ：405.78 nm特征谱线作为分析线，以FeⅠ：404.58 nm特征谱线作为内标线进行结果计算。预实验确定较佳的实验条件后（激光脉冲能量：128.5 mJ ，延时：2.5μs ，门宽：3μs），对铅蓄电池厂的未知铅泥样品中铅元素进行定量分析，结果表明加入铅在0～25000 mg・kg －1范围内谱线不会产生自吸收，PbⅠ：405.78 nm信号强度与铅加入量呈很好的线性关系，由此确定合适的铅加入量为0～25000 mg・kg －1。在此基础上配制四个样品，基质均为铅蓄电池厂含铅污泥，加入铅浓度分别为5000，10000，15000，20000 mg・kg －1，每个样品设置三个平行样，验证实验重复性及可靠性，并与IC P-M S检测结果对比，结果直线外推误差为－14.8％。12个样品单次计算结果误差介于为－24.6％～17.6％之间，含铅量平均值为43069 mg・kg －1，相对误差为－2.44％。%The standard addition method with laser induced breakdown spectroscopy was used to analyze an unknown sample taken from a lead battery factory .the matrix influence on the results was effectively avoided when the external or internal stand-ard method was used ,and the pretreatment of samples was simple and quick .The Nd∶YAG pulse laser with wavelength 1 064 nm was used as the excitation source .The echelle spectroscopy with high resolution and wide spectral range was used as the spectral separation device ,and the intensified charge coupled device (ICCD ) as the spectral detection device in the experiment . The characteristic line at 405.78 nm was chosen as the analysis line to measure Pb concentration .FeⅠ :404.58 line was chosen as the internal standard .Pre-experiment was carried out to confirm the appropriate condition .Under the laser energy of 128.5 mJ ,the delay time of 2.5 μs ,and the gate width of 3 μs ,it was determined that with the addition of Pb to the sample in the range of 0 and 25 000 mg・kg -1 ,there wasn’t self-absorption .There was a good linear relationship between the intensity of the spectral line of 405.78 nm and the addition of Pb .The appropriate concentration of Pb added into the sample for analysis was de-termined by this series of samples .On this basis ,four samples were prepared with three parallel samples for each sample in or-der to verify the repeatability and reliability of the method ,i .e .5 000 ,10 000 ,15 000 ,20 000 mg・kg -1 Pb was added into the original sample .The results were compared with the result of ICP-MS .The twelve samples’ relative errors were between-24.6% and 17.6% .The average result was 43 069 mg・kg -1 with the relative error -2.44% .