Elemental analysis of the volcanic samples by ICP-MS
Materials and methods: The method applied is described in detail in García de Madinabeitia et al. (2008).
A summary of the procedures is presented below:
Reagents:
HF: Merck Pro-Analysi.
HNO3: Merck Pro-Analysi, further distilled in the laboratory by surface distillation using a quartz distiller Acidest.
Ultrapure water: deionized water using a Millipore Elix system, further polished to a resistivity ≥ 18 MOhm.cm with a Barnstead EasyPure system.
LiBO2: anhydrous, grade pure from Corporation Scientifique Claisse.
In and Bi solutions as internal standard, multielemental solutions for the initial tuning and for the calibration of the mass spectrometer were prepared from 1000 ppm monolemental Merck Suprapur solutions for ICP, stabilized in HNO3 2 to 6 %. Internal standard solution was added by means of an automatic online addition kit in order to prevent random errors.
Weighing: In electronic balance GRAM SV 205-A, precision 0.1 mg.
Calcination (loss on ignition):In muffle furnace during 2 hours at 1050 °C to eliminate H2O and compounds of C.
Fusion-dissolution:The alkaline fusion of the samples is carried out using an automatic Claisse Fluxy 30 system over butane gas in Pt-Au (95-5) crucibles with lithium metaborate (LiBO2) as fluxer and LiBr as non-wetting agent. The melt is automatically poured onto a polystyrene beaker containing 100 ml of HNO3 and ca. 0.05 ml of HF placed in a magnetic agitator. The solution is gravimetrically diluted to a factor adequate for the analysis.
Elemental analysis:The elemental concentration was determined using a Thermo XSeries 2 inductively coupled plasma mass spectrometer (ICP-MS) equipped with collision cell (CCT), interphase specific for elevated total dissolved solids (Xt cones) and shielded torch. A concentric nebulizer and quartz expansion chamber were employed. Two operating modes were used, Standard and CCT (with collision cell) for the analysis of the different elements depending on the needs of sensibility and the possible isobaric interferences in each case. Cones and other parts of the spectrometer were conditioned with a solution of LiBO2 which was used also for inter-sample washing. Drift was controlled through the addition of an internal standard and was corrected using specific standards intercalated during the analytical run. The recoveries for the reference materials treated as the samples is between 90 and 110 % for most elements. In any case, this % depends on the concentration of the different elements in a given sample.
Reference
García de Madinabeitia S, Sánchez Lorda ME, Gil Ibarguchi JI (2008) Simultaneous determination of major to ultratrace elements in geological samples by fusion-dissolution and inductively coupled plasma mass spectrometry techniques. Analytica Chimica Acta, 625, 2, 117-130