Validation of Electrothermal Vaporization for the Analysis of Biomass Samples and Comparison with Other Methods of Analysis

Abstract: The analysis of the chemical composition of biomass plays an important role in all steps of the life cycle of biomass, especially in thermal conversion processes. Electrothermal vaporization (ETV) coupled with inductively coupled plasma optical emission spectrometry (ICP-OES) is a promising approach for biomass analysis as almost no sample preparation is required, samples can be analysed quickly, and the release of elements from the sample can potentially be quantified with temperature resolution. In this work, the concentration of seven important side and trace elements is determined in beechwood, torrefied wood, wheat straw, miscanthus, and spruce bark. For comparison and validation of the ETV setup, four additional methods of analysis are applied to determine the elemental concentration. Chemical fractionation analysis (CFA) is conducted to investigate the chemical association form. In addition, microwave pressure digestion is carried out with two different acid solutions (HNO₃ and HBF₄). X-ray fluorescence (XRF) analysis is performed to determine the ash composition of all samples. The spread between most of the results of the different measurement techniques is with less than 20 % well within the expected range for heterogeneous biomass samples. Large deviations, such as the sulphur concentration in the XRF analysis, can be explained by the method used. The ETV results are in very good agreement with the CFA and microwave pressure digestion results. As these methods are well established, ETV analysis has proven to be suitable for the analysis of side and trace elements in biomass. Graphical Abstract: [Figure not available: see fulltext.].