Abstract: In order to improve the sensitivity and stability of microwave digestion-inductively coupled plasma mass spectrometry (ICP-MS), an accurate method for the determination of selenium in tea was established. The sensitization effects of methanol, ethanol, isopropanol, n-butanol etc. as sensitizers were investigated, as well as the impact of adding 0-10% n-butanol to the internal standard on the accurate determination of total selenium content in tea were tested. By optimizing the pretreatment method and ICP-MS instrument parameters, a method for the accurate detection of total selenium content in tea using microwave digestion-ICP-MS with 3% n-butanol as the sensitizer was established. This method enhances the selenium signal intensity, thereby improving the accuracy and stability of the total selenium content detection in tea. To determine the optimum conditions for the determination of total selenium in tea, n-Butanol as sensitizer had lower detection limit and higher accuracy (0.001 71 mg·kg^-1), and 3% n-butanol had the best sensitizing effect. It was more accurate to determine the selenium content in tea reference materials. The linear correlation coefficient R² of selenium curve was greater than 0.999. The recovery of the added standard was from 86.0% to 104%, and the relative standard deviations (RSD) was between 1.10% and 4.44%. The paired t-test shows that the P value was greater than 0.05, and there was no significant difference between the two atomic fluorescence spectroscopy. This method is simple, showing high sensitivity, low detection limit, high precision and good reproducibility. This method is suitable for the accurate determination of selenium in tea.

Key words: microwave digestion, ICP-MS, n-butanol, tea, selenium