Internal standards in inductively coupled plasma mass spectrometry using kinetic energy discrimination and dynamic reaction cells

Abstract

ICP-MS is a sensitive element analysis technique used for analyzing several different sample types. This can result in difficult matrixes which can affect both physical parameters and create overlaps of analyte elements. Some of the possible overlaps can be reduced by the use of reaction and/or collision cells, while the use of internal standards can help with reducing the physical interferences caused by a matrix. While both internal standardization and the use of cells have been studied separately, their effects on each other have not been investigated earlier. In this study ICP-MS was used to analyze ²⁴Mg, ²⁷Al, ⁴⁷Ti, ⁴⁹Ti, ⁵¹V, ⁵²Cr, ⁵³Cr, ⁵⁵Mn, ⁵⁷Fe, ⁵⁹Co, ⁶⁰Ni, ⁶¹Ni, ⁶²Ni, ⁶³Cu, ⁶⁵Cu, ⁶⁶Zn, ⁶⁷Zn, ⁷⁵As, ⁷⁸Se, ⁸²Se, ¹¹¹Cd, and ²⁰⁸Pb with ⁹Be, ⁸⁹Y, ⁶⁹Ga, ¹⁰³Rh, ¹¹⁵In, ¹⁹³Ir, and ²⁰⁵Tl as internal standards with high concentrations of either HNO₃, PBS-buffer, or Triton X-100 as the matrix, in reaction-, collision- and standard-cell modes. This was done to investigate which internal standards would compensate matrix effects in different cell modes. All internal standards, except Be, compensated fairly well (relative sensitivity RSD < 10%) even for severe matrix effects for most elements regardless of similarity in mass in the different cell modes. For Zn, As and Se no proper internal standard could be found, of the ones investigated.