Determination of chlorine, bromine and iodine in plant samples by inductively coupled plasma-mass spectrometry after leaching with tetramethyl ammonium hydroxide under a mild temperature condition

A simple determination method for halogens (Cl, Br, and I) in plant samples using inductively coupled plasma-mass spectrometry (ICP-MS) was developed. In order to extract these halogens into aqueous solution, a leaching step with tetramethyl ammonium hydroxide (TMAH) under mild conditions was carried out, i.e. a 0.1-g dried sample was left overnight (ca. 12 h) in contact with 1 mL of 25% TMAH in a small PFA vial at 60 °C. Then the sample was transferred to a 50-mL centrifuge tube and diluted to 50 mL with deionised water. After centrifugation, halogens in the supernatant were determined by ICP-MS. When standard reference materials were measured by the method, the data were within the 95% confidence range of the certified values. The results also agreed well with the values obtained by neutron activation analysis with correlation factor r > 0.99.