SYSTEM FOR AUTOMATIC SELECTION OF OPERATING-CONDITIONS FOR INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROSCOPY

The design of a system for automatic parameter and methodology selecti on for inductively coupled plasma atomic emission spectroscopy (ICP-AE S) is presented, The ICP is an excellent excitation source that suffer s less from matrix effects than other sources but is not altogether pr oblem-free, To compensate, a variety of methodologies and approaches c an be used to minimize matrix-induced error present in an analysis, Fo r example, one can prepare matrix-matched standards, use standard addi tions or select instrumental parameters (rf power, pump rate and viewi ng height) specifically for the analytes of interest, Ideally, an Auto nomous Instrument, operating without human intervention, needs to have the ability to determine the analytical parameters and methodology to apply to a sample, A measure of expected analytical error for a sampl e to be used by an Autonomous Instrument, the total interference level (TIL), is introduced, The TIL applies the results from a semiquantita tive scan to a 'lookup' table to determine what the approximate expect ed error will be, It relies on a 'conservative' approach and assumes t he effect of interferences on a particular analyte are not only linear , but additive, This approach was applied to samples,pith high concent rations of interferents and works well, providing acceptable estimates in 90% of analyte-interferent combinations (at 10% error tolerance). The emphasis of the discussion is placed on how well this system deals with 'problematic' samples, i.e. those samples where matrix effects c ause considerable analytical error.