The development of a method for the determination of trace elements in fuel alcohol by electrothen-nal vaporization-inductively coupled plasma mass spectrometry using external calibration

A method for the determination of Ag, As, Cd, Cu, Co, Fe, Mn, Ni, Pb, Sri and Tl in fuel alcohol by electrothermal vaporization inductively coupled plasma mass spectrometry is proposed. The determinations were carried out by external calibration against ethanolic solutions, without a chemical modifier, employing the following pyrolysis and vaporization temperatures: 400 degrees C and 2300 degrees C for the more volatile analytes and 1000 degrees C and 2500 degrees C for the less volatile analytes. The determination of As, Cd, Pb, Sri and Tl was additionally carried out using Pd as modifier at 800 degrees C pyrolysis and 2400 degrees C vaporization temperatures. The temperatures were optimized through pyrolysis and vaporization curves. Seven common fuel ethanol, one fuel ethanol with additive and one anhydrous fuel ethanol sample have been analyzed. The measured concentrations were at the mu g L-1 level or lower. Since there is no certified reference material for fuel ethanol, the accuracy of the method was checked by the recovery test, with recoveries from 75% to 124%. The limits of detection (LODs), in mu g L-1, and the relative standard deviations for 5 replicates were, for the elements in the conditions without modifier: Ag: 0.015 and 9.1%, Co: 0.002 and 10%, Cu: 0.22 and 6.6%, Fe: 0.72 and 4.3%, Mn: 0.025 and 12%, Ni: 0.026 and 9.3%, and for the elements with Pd: As: 0.02 and 2.9%, Cd: 0.07 and 25%, Pb: 0.02 and 3.1%, Sri: 0.010 and 6.0%, Tl: 0.0008 and 2.5%. Electrothermal vaporization avoids the loading of the plasma with organics, allowing the analysis of fuel ethanol by ICP-MS with good accuracy and reasonable precision. (c) 2004 Elsevier B.V. All rights reserved.