Ž . Spectrochimica Acta Part B 54 1999 18491860 Correction for non-spectroscopic matrix effects in inductively coupled plasma-mass spectrometry by common analyte internal standardization Assad S. Al-Ammar, Rajesh K. Gupta, Ramon M. Barnes  Department of Chemistry, Lederle Graduate Research Towers, Uni  ersity of Massachusetts, Box 34510, Amherst, MA 01003-4510, USA Received 30 June 1999; accepted 7 September 1999 Abstract Ž . The Common Analyte Internal Standardization CAIS chemometric technique is extended to correct for Ž . non-spectroscopic matrix effects in inductively coupled plasma-mass spectrometry ICP-MS . The approach is based on using an internal reference element to correct for the matrix effect. Unlike the conventional internal reference method, the CAIS technique allows for the analyte to behave differently from the internal reference under the influence of the matrix. With the CAIS technique a single internal reference element is sufficient to correct for all the analytes. Experimental tests with 13 analytes in four different matrices using different ICP-MS instruments demonstrate that the CAIS is efficient and general for matrix effect correction. Not only is the corrected concentration more accurate, but the precision is significantly better. The capability of CAIS to correct for the effect of a mixture of two matrices was also established experimentally, and 20  30% matrix suppression was eliminated. Furthermore, the developed technique was used as a simple diagnostic quality assurance procedure to evaluate the performance of the mass spectrometer.  1999 Elsevier Science B.V. All rights reserved. Keywords: Matrix effect correction; Inductively coupled plasma-mass spectrometry; Common analyte internal Ž . standardization CAIS 1. Introduction Ž . Moderate amounts 0.01 0.5% of matrix ions can change analyte signal significantly when using  Corresponding author. inductively coupled plasma-mass spectrometry Ž .   ICP-MS 1  4 . This non-spectroscopic matrix effect has important ramifications in practical analysis. For example, standard and sample solu- tions need be closely matrix matched to ensure that the sensitivity of the analyte is consistent throughout the analysis. However, sometimes 0584-854799$ - see front matter  1999 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 5 8 4 - 8 5 4 7 99 00129-9