电感耦合等离子体串联质谱法测定电解二氧化锰废渣浸出液中的重金属元素

Determination of Heavy Metal Elements in Leaching Solution of Electrolytic Manganese Dioxide Waste Residue by Inductively Coupled Plasma-Tandem Mass Spectrometry

电解二氧化锰废渣中的重金属元素在雨水淋滤下,通过地表径流对下游水生态系统及农业生态系统造成不同程度的环境污染和安全隐患,因此,准确测定电解二氧化锰废渣浸出液中的重金属元素含量具有重要的现实意义。电解二氧化锰废渣浸出液中的重金属元素含量通常很低,采用原子吸收光谱法、电感耦合等离子体发射光谱法测定,检出限通常难以满足测定要求。采用电感耦合等离子体质谱法(ICP-MS)测定,消除复杂质谱干扰面临挑战。本文采用电感耦合等离子体串联质谱(ICP-MS/MS)测定电解二氧化锰废渣浸出液中的重金属元素含量。电解二氧化锰废渣中6种重金属元素Cr、Ni、As、Cd、Hg、Pb经硫酸和硝酸混合酸浸出后直接采用ICP-MS/MS进行测定,利用串联质谱的O 2反应模式消除分析过程中Cr、Ni、As、Cd受到的质谱干扰,通过考察不同分析模式下52 Cr、60 Ni、75 As、111 Cd的背景等效浓度(BEC),评价质谱干扰对分析结果的影响。结果表明:在MS/MS模式下选择O 2为反应气,采用质量转移法和原位质量法可以消除52 Cr、60 Ni、75 As、111 Cd的所有质谱干扰。Cr、Ni、As、Cd、Hg、Pb检出限分别为3.06、9.31、3.50、2.72、2.03、1.89ng/L,加标回收率在95.6%~106.2%之间,相对标准偏差(RSD)≤3.9%。所建立的方法已应用于电解二氧化锰废渣浸出液中重金属元素的测定。

BACKGROUND:The heavy metals in electrolytic manganese dioxide waste residue can cause different degrees of environmental pollution and hidden dangers to downstream aquatic ecosystems and agricultural ecosystems through surface runoff under rainwater leaching.Therefore,it is of great practical significance to determine the content of heavy metal elements in leaching solution of electrolytic manganese dioxide waste residue.Usually,the detection limits of atomic absorption spectrometry and inductively coupled plasma-optical emission spectrometry are insufficient to meet the measurement requirements,since the content of heavy metal elements in the leaching solution of electrolytic manganese dioxide waste residue is typically very low.The challenge is to eliminate complex spectral interference.OBJECTIVES:To find an efficient method for the determination of six heavy metal elements in leaching solution of electrolytic manganese dioxide waste residue.METHODS:The objective was determined by inductively coupled plasma-tandem mass spectrometry(ICP-MS/MS).The six heavy metal elements Cr,Ni,As,Cd,Hg and Pb in the electrolytic manganese dioxide waste residue were directly measured by ICP-MS/MS after H 2 SO 4-HNO 3 mixed acid leaching.The O 2 reaction mode was adopted to eliminate the spectral interference of Cr,Ni,As and Cd during analysis.The background equivalent concentrations(BECs)of 52 Cr,60 Ni,75 As and 111 Cd in the different analytical mode were investigated to evaluate the influence of spectral interference on the analysis results.RESULTS:In the MS/MS mode,O 2 was selected as the reaction gas,and the spectral interference of 52 Cr,60 Ni,75 As and 111 Cd was eliminated by using mass shift method and on-mass method.The limits of detection for Cr,Ni,As,Cd,Hg and Pb were 3.06,9.31,3.50,2.72,2.03,1.89ng/L,respectively.The spiked recoveries were between 95.6%and 106.2%.The relative standard deviation was no higher than 3.9%.CONCLUSIONS:The method has been successfully applied to the determination of heavy metal elements in leaching solution of electrolytic manganese dioxide waste residue.