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%.