Suppression of analyte signal in inductively-coupled plasma/mass spectrometry and the use of an internal standard

The signal suppression of 9Be, 27Al, 64Zn, 85Rb, 115In and 208Pb in the presence of increasing amounts of sodium chloride is studied. The suppression does not depend significantly on the analyte element considered. The use of 115In as internal standard thus allows correction for the matrix effect. It is shown that the suppressive effect decreases in the order CsCl>NaCl>NH 4Cl. The use of the internal standard also significantly improves the precision. The signal suppression is probably due largely to an increasing number of extracted ions resulting in a more pronounced space-charge effect.