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常规喷雾火焰原子吸收光谱法测定一个元素,一般消耗0.5～2ml试液。本文采用只需注射100μl试液的小体积“注射法”,若每个元素平行测定三次,只需300μl试液即可测定一个元素。故可于2ml试液中测定6个元素,特别适用于试液来源有限的物质的多元素分析。我们使用微量注射器和聚四氟乙烯试液皿,以人工进样方式研究了测定Cu、Mn、Pb、Zn、Cd和Cr 的条件。采用直接蒸发浓缩湖水的预处理富集微量金属元素,简化了测定天然水中微量金属元素的化学前处理。将湖水蒸发浓缩50倍,本法可以测定10~(-2)ppm数量级的微量元素。配备x—Y函数记录仪或其它快速峰高读出装置的原子吸收分光光度计,都适用于小体积注射法。使用国产401型原子吸收分光光度计,在对火焰原子化系统未作重大改进的情况下,我们发现:小体积注射法的灵敏度比常规法约低1/3～1/2。连续注射时,吸光度读数的相对标准偏差一般在2%左右。保持了火焰原子吸收法干扰小,测量精度高的优点。
Conventional spray flame atomic absorption spectrometry for the determination of an element, the general consumption of 0.5 ~ 2ml test solution. This article uses a small volume “injection” method that injects only 100 μl of the test solution. If each element is measured three times in parallel, only 300 μl of the test solution is needed to determine one element. It can be measured in 2ml test solution 6 elements, especially for multi-element analysis of the source of limited test solution. We investigated the conditions for Cu, Mn, Pb, Zn, Cd and Cr by manual injection using a micropipette and teflon test cell. The pretreatment of direct evaporation of concentrated lake water enriches trace metal elements and simplifies the chemical pretreatment for the determination of trace metal elements in natural water. The lake is concentrated by 50 times evaporation, the law can measure the 10 -2 ppm levels of trace elements. Atomic absorption spectrophotometers equipped with x-Y function loggers or other rapid peak height readers are suitable for small volume injections. Using the domestic 401 atomic absorption spectrophotometer, we found that the sensitivity of the small volume injection method is about 1/3 to 1/2 lower than that of the conventional method. Continuous injection, the relative standard deviation of absorbance readings generally about 2%. Maintain the flame atomic absorption interference, high measurement accuracy.