Direct Measurement of Br and I in Brines by Collision Response-Inductively Coupled Plasma-Mass Spectrometry

Many routine methods to determine Br and I in environmental water by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) have been reported. However, there is little information about the determination of Br and I in brine with a high salt content. In view of the high salinity and high potassium content in the salt lake brine of Chaidamu Basin, a new method for the determination of Br and I in brine by ICP-MS is proposed in this paper. The mass spectrum interference was reduced by using collision response interface mode and using H₂ as the collision gas, such as of ³⁹K⁴⁰Ar⁺ to ⁷⁹Br⁺. The interferences of the matrix elements and instrument drift were corrected by using Rh as internal standard. The memory effect was eliminated by extending the time of fast pump flushing. The proposed method was applied to directly determine levels of Br and I in salt lake brine samples, which were diluted to 200 times. Detection limit and RSD (n=12) were 0.036 μg/mL and 2.77% for Br, 0.027 μg/mL and 2.19% for I. Values of recovery obtained were in the range of 91.6%-106.1% for Br and 94.4%-107.7% for I. The established method is also suitable for measuring Br and I for high potassium rock salt samples.