Determination of the Non-metallic Elements in Herbal Tea by Inductively Coupled Plasma Tandem Mass Spectrometry

The feasibility of using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) to overcome spectral overlaps in the determination of non-metallic elements was investigated. The contents of Si, P, S, Cl, Br, and I in herbal tea were determined by using ICP-MS/MS after microwave digestion. In the MS/MS mode, O₂ and H₂ were consecutively used as reaction gases. Low background equivalent concentration (BEC) and limit of detection (LOD) of analytes were obtained when using O₂ mass shift, H₂ mass shift, and H₂ on-mass methods. The LODs for Si, P, S, Cl, Br, and I were 0.41, 0.048, 0.34, 0.76, 0.055, and 0.007 μg L^-1, respectively. Standard reference materials NIST SRM 1515 (apple leaves) and NIST SRM 1547 (peach leaves) were used to evaluate the accuracy of the analytical method. The developed method was used to analyze 20 herbal teas. The ranges of values for Si, P, S, Cl, Br, and I in herbal tea were 236-4100, 1830-4360, 1290-3850, 335-4620, 0.86-8.21, and 0.091-0.65 μg g^-1, respectively. The results showed that several non-metallic elements essential for the human body might be obtained by drinking herbal tea.