Space charge effects and internal standardization in a four ion lenses interface: What is changing in quadrupole inductively coupled plasma mass spectrometry?

Abstract

Space charge effects and internal standardization were evaluated in quadrupole inductively coupled plasma mass spectrometry (ICP-MS). Changes in analyte ion sensitivities as a function of analyte ion mass (11B+, 24Mg+, 45Sc+, 60Ni+, 71Ga+, 75As+, 111Cd+, 138Ba+ and 172Yb+) due to the presence of seven different matrix elements (23Na+, 63Cu+, 89Y+, 115In+, 159Tb+, 175Lu+ and 205Tl+) were measured by a current ICP-MS instrument arrangement. Elements with different masses (light, middle and high mass range) were evaluated as internal standard (IS): 7Li+, 88Sr+ and 209Bi+. Space charge effects generally becomes more severe for matrices containing elements with middle mass (115In+) and high masses (159Tb+, 175Lu+ and 205Tl+) but are not dependent on the masses of most analyte ions, differently from which was known about space charge effects when using first generation ICP-MS instruments. Thus, a single IS was effective for minimize the matrix induced changes (range from −20 to +20%) for analytes with different masses in In matrix (except to mass-to-charge ratio lower than 50); Tb matrix (except to 7Li+); Lu matrix (except to 175Yb+); and Tl matrix (except to 25Mg+).