铅试金-激光剥蚀电感耦合等离子体质谱法测定地球化学样品中痕量铂钯  

Determination of trace platinum and palladium in geochemical sample by laser ablation-inductively coupled plasma mass spectrometry with lead fire assay

作　　者：赵一帆 肖芳[1,2,3] 毛香菊 樊蕾[1,2,3] 王甜甜 倪文山 ZHAO Yifan;XIAO Fang;MAO Xiangju;FAN Lei;WANG Tiantian;NI Wenshan(Zhengzhou Institute of Multipurpose Utilization of Mineral Resources,CAGS,Zhengzhou 450006,China;China National Engineering Research Center for Utilization of Industrial Minerals,Zhengzhou 450006,China;Key Laboratory of Polymetallic Ores′Evaluation and Utilization,MNR,Zhengzhou 450006,China)

机构地区：[1]中国地质科学院郑州矿产综合利用研究所,河南郑州450006 [2]国家非金属矿资源综合利用工程技术研究中心,河南郑州450006 [3]自然资源部多金属矿评价与综合利用重点实验室,河南郑州450006

出　　处：《冶金分析》2024年第7期34-41,共8页Metallurgical Analysis

基　　金：国家自然科学基金项目(22106148);中国地质调查项目(DD20243355)。

摘　　要：本文报道了铅试金富集和激光剥蚀电感耦合等离子体质谱(LA-ICP-MS)相结合测定地球化学样品中痕量Pt和Pd的新方法。采用自制并提纯的碱式碳酸铅分离Pt和Pd,并通过加Ag保护灰吹的方式将Pt和Pd富集在银合粒中,将银合粒经清洁、称重、退火并被压制成银片后,采用LA-ICP-MS多点剥蚀(10点)银片直接固体进样,以^(195)Pt、^(105)Pd和^(109)Ag为待测同位素,用经验系数法和内标法相结合的方式进行定量,实现了对地球化学样品中痕量Pt和Pd的测定。实验表明,采用自制并提纯的碱式碳酸铅为捕集剂,测得的Pt和Pd空白值均较使用氧化铅时降低了2个数量级,显著降低了铅试金流程中Pt和Pd的空白值;采用铂族元素标准物质制备标准系列银片绘制校准曲线,实现了标准系列与实际样品的基体匹配,克服了基体效应;采用激光剥蚀银片直接固体进样,避免了溶液中大量O、H和Cl等带来的多原子分子离子质谱干扰以及制成溶液的稀释效应;将银合粒在700℃灼烧退火后再压制成片,^(195)Pt、^(105)Pd的多次激光剥蚀进样测定信号更加稳定,可消除组织缺陷并提高合粒的均匀性。以^(195)Pt和^(105)Pd的质谱强度与^(109)Ag的质谱强度比值为纵坐标,银片中Pt和Pd的含量为横坐标绘制校准曲线,相关系数分别为0.9997和0.9996,方法检出限分别为0.066和0.028 ng/g(10 g样品)。将实验方法应用于不同类型的地球化学样品中痕量Pt和Pd的分析,Pt和Pd测得结果的相对标准偏差(RSD,n=5)分别为4.5%~13.9%和4.8%~10.7%,测得结果与铅试金-高分辨率连续光源石墨炉原子吸收光谱法吻合性较好。按实验方法测定地球化学标准物质中痕量Pt和Pd,测定值与认定值一致。In this paper,a novel method for the determination of trace platinum(Pt)and palladium(Pd)in geochemical samples by lead fire assay(Pb-FA)enrichment and laser ablation-inductively coupled plasma mass spectrometry(LA-ICP-MS)was reported.The self-made and purified basic lead carbonate was used for the separation of Pt and Pd.Pt and Pd were enriched into silver(Ag)composite granule by cupellation with Ag protection.The Ag granule was cleaned,weighted,annealed and compressed into thin slices,and then determined by LA-ICP-MS via direct solid sampling with multipoint ablation(10 points).^(195)Pt,^(105)Pd and ^(109)Ag were selected as the isotopes to be measured.The determination of trace Pt and Pd in geochemical samples was realized by quantification via empirical coefficient method and internal standard method.The experiments showed that when the self-made and purified basic lead carbonate was used as the collector,the measured blank values of Pt and Pd reduced by two orders of magnitudes compared to lead oxide.The blank values of Pt and Pd in lead fire assay were reduced significantly.The certified reference materials of platinum family elements were for the preparation of Ag slices to draw the calibration curves,which realized the matrix matching of certified reference materials and actual samples,thus overcoming the matrix effect.The direct solid sampling of laser ablation Ag slices avoided the polyatomic molecular and ion mass spectrum interference caused by much O,H and Cl in solution as well as the dilution effect caused by solution preparation.If the Ag granule was ignited at 700℃followed by annealing and sample preparation,the determination signals of ^(195)Pt and ^(105)Pd after laser ablation for several times were more stable,which could eliminate the structure defects and improve the uniformity of granule.The calibration curve was drawn using the mass spectrum intensity ratio of ^(195)Pt and ^(105)Pd against ^(109)Ag as the y-coordinate,and using the content of Pt and Pd in Ag slice as the x-coordinate.The

关 键 词：铅试金 加银保护灰吹 经验系数法 激光剥蚀电感耦合等离子体质谱(LA-ICP-MS) 铂 钯 

分 类 号：O657.31[理学—分析化学]