Determination of 26 Inorganic Elements in Dairy Products by Inductively Coupled Plasma-Tandem Mass Spectrometry

An inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) method was established for the analysis of 26 inorganic elements in dairy products. Under MS/MS conditions, the 26 elements were detected in the no gas, collision gas (He) or reaction gas (H₂, O₂, NH₃/He) mode and the optimal mode was selected for each of the elements. The results showed that calibration curve with good linearity was obtained for each element in the appropriate detection mode with a correlation coefficient greater than 0.9990. The detection limits of the 26 inorganic elements ranged from 0.00003361 to 0.04371 mg/kg. The spiked recoveries were between 95.50% and 104.21%, with a relative standard deviation (RSD) ≤ 3.94% (n = 11). The contents of Na, Mg, K, Ca, P, Fe and Zn were higher and the contents of the heavy metal elements Cr, As, Cd and Pb were lower in six kinds of dairy products, all of which were lower than the national standard limits. The method was characterized by simple pretreatment, high sensitivity, low limit of detection and high accuracy and could be used for the detection of inorganic elements in dairy products.