巯基棉富集-分光光度法测定地球化学样品中铂钯的野外快速分析方法研究

Field Rapid Determination of Platinum and Palladium in Geochemical Samples by Spectrophotometry with Sulfhydryl Cotton Enrichment

对于地球化学样品中铂钯的测定,传统和现代分析方法均是建立在试金或树脂及活性炭富集后用分光光度法或电感耦合等离子体质谱法测定,而在野外满足不了这些条件。本文基于样品的性质及分光光度法的适应性强等特点,开发了一种适合于野外简单条件下快速测定地质样品中铂和钯的分析方法。样品用盐酸-氯酸钾-氯化钠-氟化氢铵常温常压密闭分解,巯基棉分别富集铂和钯,灰化处理后采用三氯甲烷-石油醚(1∶3)为萃取剂,DDO为显色剂萃取比色测定铂、钯的含量。巯基棉对钯的吸附率可达98%;加入氯化亚锡-水合肼(还原剂)使铂的吸附率提高到99%。方法检出限为Pt 0.05μg/g,Pd 0.02μg/g,标准物质的测定值与推荐值基本一致,野外地质样品的测定值与实验室分析结果吻合。

For the determination of Pt and Pd in geochemical samples,traditional and modern analytical methods are based on assaying or activated carbon and resin preconcentration and determination by Spectrophotometry and Inductively Coupled Plasma-Mass Spectrometry. However,these requirements cannot be met in the field. Based on the character of samples and the applicability of Spectrophotometry, this study develops a method in rapid determination of Pt and Pd in geochemical samples in the field. Samples are decomposed in the sealed Teflon container by the mixing of hydrochloric acid,potassium chlorate,sodium chloride,and ammonium hydrogen fluoride under normal temperature and pressure. Platinum and palladium are preconcentrated by sulfhydryl cotton. Pt and Pd are determined using chloroform petroleum and ether（ 1 ： 3 ） as the extractant,and DDO as the chromogenic agent. The adsorption capacity of sulfhydryl cotton for Pt can reach 98%,and the adsorption capacity of stannous chloride-drazine hydrate（ reducing agent ）for Pd can reach 99%. The detection limits of the method are 0. 05 μg/g and 0. 02 μg/g for Pt and Pd,respectively. The analytical values of standard materials, GBW07291,GBW07293,and GBW07341 are consistent with the respectively recommended values. The direct determination values of geological samples in the field are consistent with the results of laboratory analyses.