奶酪中多种微量元素的ICP-MS分析

建立了电感耦合等离子体质谱（ICP-MS）法直接测定奶酪中Cr、Mn、Co、Ni、Cu、Zn、As、Se、Mo、Cd、Hg、Pb等12种微量元素的分析方法。奶酪经正丙醇+二甲苯（70∶30,v/v）稀释后直接进入ICP-MS进行分析,该有机样品液可以长时间保持稳定以满足多元素的测定要求,在等离子体中引入少量氧气,以防止高浓度有机样品中的碳元素在质谱采样锥锥孔沉积导致分析元素的灵敏度降低。应用数学公式法校正了质谱分析过程中形成的多原子离子对待测元素产生的干扰,采用Sc、In、Bi为内标元素校正了质谱分析中的基体效应。12种微量元素的检出限在0.8⁴3.9ng/L之间,加标回收率在90.0%¹09.0%之间,相对标准偏差（RSD）为1.8%³.7%。 

Determination of trace elements in cheese by inductively coupled plasma mass spectrometry

This paper describes a simple method for the determination of Cr, Mn, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Hg and Pb in cheese by using inductively coupled plasma mass spectrometry ( ICP-MS) .The cheese was diluted with n- propanol /xylene ( 70 ∶ 30, v /v) then the above 12 trace elements in the solution were analyzed directly by ICP-MS. Organic sample was stabilized using n-propanol /xylene, which enabled long-time sample dispersion in the solution.The high carbon content of cheese, could lead to deposition of carbon on the sampling cone, eventually leading to clogging of the orifice and a reduction in sensitivity.A small amount of oxygen was added into the argon gas line to burn carbon.The polyatomic interference was eliminated by applying correction equations.The matrix effects and the instrument drift could be commendably calibrated with Sc, In and Bi as internal standard elements.Under the optimal conditions, the detection limits for 12 elements were in the range of 0.8⁴3.9ng /L, the recoveries of standard addition were in the range of 90.0% ¹09.0% and the RSD were 1.8% ³.7%.