Extending the capabilities of electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICPMS): Coupling the graphite furnace to a sector field instrument

Abstract

This paper reports on the capabilities of the combination of an electrothermal vaporization (ETV) unit and a state-of-art single-collector sector field inductively coupled plasma mass spectrometer (SF-ICPMS). The basic analytical characteristics of this set-up were evaluated and compared to those of the more traditional combination of ETV and quadrupole-based (Q) ICPMS instrumentation. ETV-SF-ICPMS seems capable of providing a superior performance in terms of sensitivity (15-to 20-fold improvement in low resolution mode) and, also in terms of selectivity, as in medium resolution mode significantly lower LODs were achieved, especially for some low-mass elements, for which the most abundant nuclide suffers from spectral overlap as a result of the occurrence of carbon-containing polyatomic ions (e.g., 52 Cr, 28 Si) at low mass resolution. No deterioration was established in terms of stability, linear dynamic range or tolerance to matrix effects in comparison with ETV-Q-ICPMS. Also the possibilities for multi-element monitoring were studied and shown to be similar (monitoring of up to approximately 20 nuclides during the same tube firing is feasible), owing to the enhanced scanning speed and reduced magnet settling time that current SF-ICPMS displays when compared to older SF instrumentation. It is demonstrated that this instrumentation still preserves the most relevant advantages of the ETV technique, such as i) the potential for temporal separation of overlapping isobaric signals (e.g., 102 Ru and 102 Pd; 192 Os and 192 Pt; 130 Te and 130 Ba) under optimum vaporization conditions, and ii) the ability to analyze solid samples directly, as shown by the determination of Cr and Si in biological reference materials. By operating the instrument at higher mass resolution (4000), interference-free conditions could be realized for several isotopes of the target elements and, thus, isotope dilution could be deployed for their quantification, enabling the matrix effects observed to be overcome.

Inductively Coupled Plasma Mass Spectrometry

“…With dependence on the type of mass spectrometer (Q, with or without C/RC or DRC, TOF, SF), different advantages are obtained . Although optimization of the ETV temperature program with or without the addition of chemical modifier can drastically reduce the risk of spectroscopic interference, as the solvent is usually evacuated during the drying step, which substantially reduces oxide and hydroxide ions formation, and at least a portion of the matrix is eliminated during the ashing step, the formation of carbon-based polyatomic ions can complicate the determination of elements, such as Cr and Si, which require a high vaporization temperature at which covaporization of graphite is important . The use of ICP-SFMS in medium mass resolution is sufficient to eliminate these spectroscopic interferences on several isotopes of the analytes, in turn allowing ID, which compensates for the matrix effects observed during direct solid analysis .…”

Atomic Spectroscopy: A Review

“…Vanhaecke and co-workers reported on the capabilities of the combination of an electrothermal vaporization (ETV) unit and an ICP-SFMS . The basic analytical characteristics of this setup were evaluated and compared to those of the more traditional combination of ETV-ICP-QMS.…”