Multi-element simplex optimization for inductively-coupled plasma/atomic emission spectrometry with a plasma torch fitted with a wide-bore injector tube : Part 2. Establishment of Optimum Conditions for Minimum Interference

The effect of sodium interference on the analytical performance of inductively-coupled plasma/atomic emission spectrometry is evaluated. A suitable response function based on the square of the percentage interference was used for multi-element simplex optimization to locate a minimum interference zone in the argon plasma. The plasma was optimized for minimum easily ionizable element interference for Tl, Mn, Mg and Sr. Interferences could be removed completely at the cost of losing sensitivity by up to a factor of 4. The optimization correctly identified an interference-free zone in the plasma. Stability of the injector gas flow rate was found to be vital for accurate location and long-term stability of this zone. Pressure fluctuations during nebulization were shown to be the major cause of high-frequency fluctuations of this zone.