Evaluation of the multi-element capabilities of electrothermal vaporization quadrupole-based ICP mass spectrometry

Abstract

Electrothermal vaporization (ETV) ICP mass spectrometry is a method that combines the ability of the graphite furnace to handle complex samples with the detection power of ICP-MS. It is somewhat surprising, however, that most works reporting on the application of this method have only described the “simultaneous” (from the same tube firing) determination of 1–3 elements. Different authors have attributed this fact to the limited capability of the quadrupole filter (the most commonly used mass spectrometer in ICP-MS instrumentation) to deal with the transient signals that electrothermal vaporization produces. Nevertheless, recent works suggest that the real multi-element capabilities of ETV quadrupole-based ICP-MS might have been largely underestimated. A systematic study of the number of mass-to-charge ratios that can be “simultaneously” monitored in ETV quadrupole-based ICP-MS without degrading the precision, the sensitivity and the limits of detection has been carried out. Three elements with different furnace behaviours (Cd, Co and Ti) were chosen for the study. The effect of the dwell time and the way of processing the analytical data were also evaluated. The results indicate that, when using ETV-ICP-MS with a quadrupole-based instrument, no detrimental effects on the precision, detection limits and sensitivity occur as long as a critical value of three or four points to define the signal profile is achieved. This requirement corresponds to the possibility of monitoring more than 20 elements for a standard peak width of 1.5–2 s. Several options for further improvements are also discussed, including the possibility of separating (with respect to time) the vaporization of elements with different furnace behaviours.