Multi-element analysis of a thermographic material by means of solid sampling-electrothermal vaporization-inductively coupled plasma mass spectrometry

In spite of the advantages that the direct analysis of inorganic samples by means of solid sampling-electrothermal vaporization-inductively coupled plasma mass spectrometry (SS-ETV-ICPMS) may offer, especially in terms of sample throughput, most works until date have only dealt with less complicated organic matrices. This paper reports on the direct determination of seven elements (Al, Mg, Mn, Ni, Sb, Ti and Zr, with concentrations ranging between 0.6 and 150 μg/g) in a thermographic material. This is a challenging application and can be used to assess the real possibilities of SS-ETV-ICPMS for the analysis of inorganic samples. In order to cope with the complex composition of the matrix (Ag, Si and organic compounds), as well as with the different characteristics of the analytes, several approaches and chemical modifiers (HF, HCl, HNO3 and CH3Li) were studied. Finally, two different strategies were optimized. The simultaneous determination of Al, Mg, Mn, Ni, Ti and Zr is made possible by addition of 20 μl of 23M HF, which enables an efficient matrix removal at a pyrolysis temperature of 1200 °C. On the other hand, due to the higher volatility of Sb, an alternative approach, consisting of the removal of the organic matrix at 800 °C and the subsequent addition of 20 μl of 0.12 M HCl, was used for the determination of this element. In this way, antimony was efficiently vaporized at 1200 °C as a chloride, prior to the vaporization of Ag and Si. Quantitative results, obtained by using aqueous standards for calibration, were very satisfactory in terms of accuracy. The R.S.D. ranged between 8 and 12%. The results are hence promising, illustrating that the possibilities of ETV to deal with complex matrices are yet to be fully exploited.