火焰原子吸收光谱法测定土壤中铬时金属离子干扰的研究

Study of metal ions interference in determination of total chromium in soil by flame atomic absorption spectrometry

对火焰原子吸收光谱法测定土壤中铬时共存金属离子对测定结果的干扰进行研究。结果表明,在单纯基体的溶液中,钙、镁、铁、铝、钛、锰、钒、镍、钴对铬的测定有显著影响,但由于不同元素共存及浓度不同,干扰效应也不同,可通过加入氯化铵基体改进剂消除此干扰;在实际土壤样品和有证标准物质样品消解试样中添加干扰元素后,由于自身基体复杂,各元素干扰作用相互抵消,无论添加基体改进剂与否,有证标准物质均能够满足保证值要求,实际样品铬的测定无显著差异,基体改进剂的作用弱化。在实际分析工作中,土壤铬试样可以与其它金属元素(铜、锌、镍、铅、镉等)的试样一同制备,不需额外添加基体改进剂,简化了样品预处理的过程,提高了分析测试速度。

To investigate the interference of various metal ions existed simultaneously in the determination of chromium in soil,by flame atomic absorption spectrometry,a multi-factor and multi-level experiment was conducted.It was found that in the solution of simple matrix,calcium,magnesium,iron,aluminum,titanium,manganese,vanadium,nickel and cobalt had significant effects on the determination of chromium,which can be eliminated by adding ammonium chloride as a matrix modifier.Depending on the differences of elements and concentration,the effects were also different.However,in the digestion solution of the actual or standard soil samples,there was no significant difference in the determination of chromium due to the complex matrix which can offset each other whether the matrix modifier was added or not.Therefore,soil samples for analysis of chromium can be prepared together with other metal elements(copper,zinc,nickel,lead,cadmium,etc.)without adding matrix modifier in the practical determination.