微波消解-电感耦合等离子体质谱法测定超细粒度岩石和土壤样品中的稀土元素  

Determination of Rare Earth Elements in Ultra-fine Rock and Soil Samples by ICP-MS Using Microwave Digestion

作　　者：王娜[1,2] 徐铁民 魏双 王家松 曾江萍 张楠[1] WANG Na;XU Tie-min;WEI Shuang;WANG Jia-song;ZENG Jiang-ping;ZHANG Nan(Tianjin Center of Geological Survey,China Geological Survey,Tianjin 300170,China;Key Laboratory of Muddy Coast Geo-Environment,China Geological Survey,Tianjin 300170,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局泥质海岸带地质环境重点实验室,天津300170

出　　处：《岩矿测试》2020年第1期68-76,共9页Rock and Mineral Analysis

基　　金：中国地质调查局地质调查项目“地质调查标准化与标准制修订”(DD20190472)和“地质调查标准制修订与升级推广”(DD20160094)

摘　　要：应用电感耦合等离子体质谱法(ICP-MS)分析岩石和土壤样品中稀土元素的含量,取样量可低至数毫克级,但200目样品粒度要求分析取样100mg才能保证代表性,导致ICP-MS灵敏度高、取样量小的优势难以得到充分发挥。本文研究了研磨方式、研磨时间、物料比对超细粒度土壤和岩石样品制备的影响,结果表明采用乙醇作为分散剂进行湿法球磨,200目粒度的土壤、岩石样品分别研磨10min和15min,土壤样品的物料比采用物料7g、研磨球500个、分散剂45mL,岩石样品的物料比选取物料5g、研磨球500个、分散剂45mL,细化程度最佳。在此条件下制备的超细粒度土壤标准物质GBW07404、GBW07447的粒径分布D95可低至7.51μm、7.05μm,超细粒度岩石标准物质GBW07104、GBW07121的D95可低至8.42μm、8.30μm。在硝酸-氢氟酸-过氧化氢酸溶体系中微波消解处理超细粒度岩石标准物质GBW07104,取样量减少至5mg,总用酸量减少至0.25mL,消解时间降低为25min,稀土元素的测定值与认定值基本一致,相对标准偏差在1.64%~5.21%之间。该方法用于分析其他超细粒度标准物质(GBW07404、GBW07447和GBW07121)中的稀土元素,相对误差为0.17%~6.60%,满足《地质矿产实验室测试质量管理规范》的一级标准。BACKGROUND: The sampling weight can be as low as milligram level when the contents of rare earth elements in rock and soil samples are determined by inductively coupled plasma-mass spectrometry(ICP-MS). However, the size of 200 mesh samples requires 100 mg to ensure representativeness, which makes it difficult for ICP-MS to make full use of its advantages of high sensitivity and small sampling volume.OBJECTIVES: To establish the method for the determination of rare earth elements in ultra-fine rock and soil samples by ICP-MS with microwave digestion.METHODS: A method was developed for the determination of rare earth elements in ultra-fine rock and soil samples by ICP-MS with microwave digestion. The ultra-fine rock and soil samples were prepared by the planetary superfine pulverizing machine with wet grinding. Some parameters influencing the preparation of ultra-fine rock and soil samples, including grinding method, grinding time and the proportion of grinding balls were optimized. Microwave digestion of ultrafine-grained rock and soil samples in a nitric acid-hydrofluoric acid-hydrogen peroxide solution system, the sampling amount was reduced to 5 mg, the total acid amount was reduced to 0.25 mL and the digestion time was reduced to 25 minutes.RESULTS: The results indicated that the samples were best refined when the wet-milling was adopted with ethanol as a dispersant and the milling time was 10 minutes and 15 minutes for 200 mesh soil and rock samples, respectively. The material ratios were 7 g materials, 500 grinding balls, 45 mL dispersants for the preparation of ultra-fine soil samples, whereas 5 g materials, 500 grinding balls, 45 mL dispersants for the preparation of ultra-fine rock samples. The particle size distribution D95 of soil standard substance GBW07404 and GBW07447 can be as low as 7.51μm and 7.05μm, and the D95 of rock standard substance GBW07104 and GBW07121 can be 8.42μm and 8.30μm under the optimized conditions. Microwave digestion of ultrafine-grained rock sample GBW07104 in a nitric aci

关 键 词：岩石 土壤 稀土元素 超细样品制备 湿法球磨 乙醇 微波消解 电感耦合等离子体质谱法 

分 类 号：O657.63[理学—分析化学] P585[理学—化学]