Matrix interference diagnostics for the automation of inductively coupled plasma mass spectrometry (ICP-MS)

Matrix interferences in inductively coupled plasma mass spectrometry (ICP-M S) were examined to extend the total interference level (TIL) concept from ICP-AES. The TIL model is based on measurements with different interferents to determine a set of interference coefficients. Interference is assumed t o be linear with interferent concentration, since that assumption allows de termination of the model parameters with the fewest experiments. The TIL mo del was designed to indicate when a simple external standards calibration m ethod is inadequate for a desired level of analytical accuracy and was also tested on a simple form of internal standards. The TIL concept was tested in both an initial calibration and a daily calibration mode on the interfer ents Na, K, Al, Ba and Cs and works well for situations where external stan dards are used, recommending an inaccurate method for only 3% of cases wher e 10% accuracy was desired. The TIL model also works well with the very dif ferent calibration technique of internal standards, recommending an inaccur ate method for 9% of cases where 10% accuracy was desired.