火花放电原子发射光谱法精密度影响因素探讨

火花放电原子发射光谱法(SD-AES)是相对分析方法,其精密度非常重要。火花放电原子发射光谱仪稳定性、样品均匀性以及操作条件均影响SD-AES精密度。实验分析讨论了光谱仪运行和分析线对相对强度的变化,探讨了不同氩气压力和光谱样品分析面表面粗糙度(Ra)对SD-AES精密度的影响。结果表明,光谱样品分析面粗糙度越小,SD-AES精密度越高;例行分析选用分析面粗糙度0.2～2.5 μm,氩气工作压力选用额定压力或略低的压力,能获得较高的精密度;磨削加工能获得更小粗糙度的分析面;精心维护是保持光谱仪出厂性能的关键。并指出用表面粗糙度评定样品分析面质量的必要性。

Investigation on affecting factors of precision in spark discharge atomic emission spectrometry

Spark discharge atomic emission spectrometry (SD-AES) is a relative analysis method, and therefore its precision is very important. The stability of the spectrometer, homogeneity of the samples and operating conditions will directly influence on the precision of determination by SD-AES. The spectrometer operation and the changes of relative intensity of analytical line were discussed in experiments. The effects of argon operating pressures and surface roughness (Ra) of the samples on the precision of SD-AES were investigated. The results showed that the smaller Ra of the sample was, the higher the precision of SD-AES was. In order to obtain good precision and trueness, the Ra of the samples was in the range of 0.2-2.5 μm, and the operating pressures of argon was at the rated or smallish pressures for routine analysis. The grinding could obtain analytical surface with smaller roughness. Careful maintenance of the spectrometer was the key to maintain its original properties. The necessity of assessing surface quality of the samples with surface roughness was further pointed out.