DETERMINATION OF TRACE ELEMENTS BY ATOMIC ABSORPTION SPECTROMETRY AFTER PRECONCENTRATION ON A FINELY DIVIDED ION-EXCHANGE RESIN

石墨炉原子吸收光谱法是测定水中痕量元素最常用的方法之一。然而，它对镉和铅的敏感性不足以直接测定饮用水中的这些元素。到目前为止，已有许多技术用于水样中微量元素的富集。^1富集技术的最重要条件之一是与后续测定技术的简单连接。本研究的目的是建立一种用细离子交换树脂和吡咯烷二硫代氨基甲酸铵（APDC）联合测定自来水中镉和铅的简单预富集方法。由于离子交换树脂颗粒同时具有亲水性和疏水性，因此在体溶液中可以作为亲水性有机固体，并且可以提取具有疏水性的物质。在pH为6的条件下，在树脂上同时提取镉和铅的apdc配合物。将含有镉-铅- apdc配合物的树脂颗粒通过过滤分离，并分散在1.0 ml含100马克钯（II）的0.1 mol 1<@D1-1@>D1盐酸中。所得到的悬浮液通过自动取样器直接引入石墨炉。根据空白值标准偏差的3倍计算，150 ml样品中镉和铅的检出限分别为0.17和5.7 ng 1<@D1-1@>D1。本方法应用于1997年9月9日至18日供应本实验室的自来水中镉和铅的测定。金属离子浓度为6.52(]SY.+- [)0.75 ng 1<@D1-1@>D1, 136(]SY.+-。[)12 ng 1<@D1-1@>D1为引线，<@D12@>D1

Graphite-furnace atomic absorption spectrometry is one of the most widely used techniques for the determination of trace elements in water. However, its sensitivity for cadmium and lead is not sufficient for a direct determination of these elements in drinking water. So far, many techniques have been used for the enrichment of trace elements in water samples. ^1 One of the most important conditions of the enrichment techniques is simple connection to the subsequent determination techniques.The aim of this work was to develop a simple preconcentration method for the determination of cadmium and lead in tap water with the combined use of a finely divided ion-exchange resin and ammonium pyrrolidinedithiocarbamate (APDC). Since the ion-exchange resin particles have both hydrophilic and hydrophobic properties, they can act as a hydrophilic organic solid in the bulk solution, and can extract species with hydrophobic pyoperties. Cadmium-and lead-APDC complexes were extracted simultaneously on the resin at pH 6. The resin particles holding the cadmium- and lead-APDC complexes were separated by filtration and dispersed in 1.0 ml of 0.1 mol 1<@D1-1@>D1 hydrochloric acid containing 100 mug of palladium (II). The resulting suspension was introduced directly into the graphite furnace by an automatic sampler. The detection limits of cadmium and lead in a 150-ml sample aliquot were 0.17 and 5.7 ng 1<@D1-1@>D1、respectively, based on three times the standard deviation of blank values. The proposed method was applied to the determination of cadmium and lead in the tap water supplied to our laboratory during the period from 9th to 18th September, 1997. The concentration of the metal ions for 10 days were 6.52(]SY.+-。[)0.75 ng 1<@D1-1@>D1 for cadmium and 136(]SY.+-。[)12 ng 1<@D1-1@>D1 for lead, respectively.<@D12@>D1