Effectiveness of ammonia in reducing carbon-based polyatomic ion interferences in electrothermal vaporization collision cell inductively coupled plasma mass spectrometry

The effectiveness of NH3 gas used in a Dynamic Reaction Cell (DRC) in reducing or eliminating carbon-based polyatomic ions in electrothermal vaporization (ETV) inductively coupled plasma mass spectrometry is reported. Ammonia gas was found effective in reducing interfering polyatomic ions on both Cr and Mg isotope ions. The use of NH3 as a reaction gas for the reduction of polyatomic ion interferences on Si was not fully successful. However, the LODs for 28Si+ and 29Si+ were greatly improved over conventional ICP-MS. Ammonia was found to be unsuitable as a reaction gas for the determination of 30Si+. Results of signal to background studies indicate that the experimental conditions required to optimize the DRC were close for solution nebulization and ETV for Cr only. For Mg and Si, different optimization conditions were required.