Quantitative X-ray Fluorescence Analysis of Biomass: Objective Evaluation of a Typical Commercial Multi-Element Method on a WD-XRF Spectrometer

Andersen, Lars K.; Morgan, Trevor; Boulamanti, Aikaterini K.; Álvarez, Patricia; Vassilev, Stanislav V.; Baxter, David

doi:10.1021/ef4015394

Cited by 30 publications

(98 citation statements)

References 21 publications

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“…In our previous study, we observed -with some exceptions -that below 25 ppm (or below LOD) not all elements are consistently detected in all repeated XRF measurements. 9 The results of the current study are consistent with this observation. Note that some of the 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 27…”

supporting

confidence: 90%

“…The instrument and method are described briefly below and have been described in detail in our previous study. 9 Blank runs of pellets produced of 10 grams Hoechst Wax C showed the following concentrations: Cl: 81 ppm, Ru: 34 ppm, Cu: 9 ppm, Fe, Zn: 6 ppm and Ni: 5 ppm.…”

Section: Xrf Analysismentioning

confidence: 97%

“…9 For Na, the emitted Na Kα radiation only originates from a thin top-layer of the pellet, and the density and smoothness of this layer thus influences the detected intensity (and hence the measured Na concentration) significantly. Further, the Na results will easily reflect any inhomogeneity in the pellet -and especially if the top-layer has areas (grains) with a different Na concentration than the bulk pellet.…”

Section: Xrf Analysis and Repeatabilitymentioning

confidence: 99%

“…9,19 The value of µ is unknown, and both the reference value and the experimental XRF result are estimates of µ. In reality, we are comparing these two estimates, with the reference value (m ref ) being the best estimate (µ ≈ m ref ), and the XRF value (X N ) potentially having a bias, Z ≡ X -µ ≈ X N -m ref .…”

mentioning

confidence: 99%

“…This is consistent with our previous study. 9 Molybdenum (Mo) is only present significantly in Corn Stover ( 4 ppm reference value) and detected with 25 ppm by the XRF. This gross error is characteristic for Mo analysis by this particular XRF method and was associated with interferences or baseline problems in our previous study.…”

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confidence: 99%

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Quantitative X-ray Fluorescence Analysis of Biomass (Switchgrass, Corn Stover, Eucalyptus, Beech, and Pine Wood) with a Typical Commercial Multi-Element Method on a WD-XRF Spectrometer

et al. 2015

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Quick and reliable inorganic elemental chemical analysis of biomass (incl. solid biofuels) is of importance in the increasing utilization and trade of biomass. In particular, it is important for the exploitation of contaminated / dirty biomass / biomass waste, and potentially also as a tool in ascertaining the type/origin of biomass. X-ray fluorescence (XRF) spectrometry performed directly on the raw biomass with limited prior sample preparation is an attractive method for performing such inorganic elemental analysis. In the present study we therefore carefully investigate the performance of a commercial multi-element standardless XRF method by analyzing 5 common biomass types (switchgrass, corn stover, eucalyptus, beech, and pine wood). Sample preparation involves milling the raw biomass using cutter and rotor mills (avoiding ball-milling) and cold-pressing the powdered samples into pellets using binder (vax).XRF users often rely on this type of commercial pre-calibrated or 'standardless' methods delivered with their XRF spectrometer. However, these methods are often sold without any guarantee on performance. We recently demonstrated the quite good performance of a typical commercial pre-calibrated / standardless method when analyzing biomass in the ideal form of certified reference material. In the present article, we report now on analysis of common raw biomass using the same method purchased with a 4 kW wavelength dispersive (WD) XRF spectrometer. The accuracy (trueness and precision) is determined by comparing the XRF data with the elemental composition obtained by standard elemental analysis (ICP-OES and ionchromatography). The certified elements consistently detected by the XRF are: Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Sr, Mo. For elements above 25 ppm, the XRF data show a relative systematic error (bias, trueness) typically better than ±15% independent of the concentration. The elements present with > 1000 ppm (Mg, Si, Cl, K, Ca) consistently show a positive bias of 3 -18% relative. The relative precision (measured as the relative standard error) is better than ±5% (typically ±1%) for concentrations > 25 ppm (obtained with 10 -30 measurements). Quantifying elements below 25 ppm (Co, Ni, Cu, Zn, Sr, Mo) is possible in some cases, but it requires a more detailed study for each specific element. E.g. Cu can be determined down to a few ppm with an appropriate correction for the method bias. Occasionally, larger relative biases of up to 45% to 90% can occur for certain elements (Cl, Si) in certain samples, so care should be taken to carefully test the applied method for the particular samples and elements of interest. Quantification of silicon (Si) by XRF works well for concentrations > 100 ppm. The XRF method can further be used to estimate the ash yield from biomass combustion with a relative bias better than ±10%.It is shown that the errors on the elemental composition are dominated by systematic errors (biases) and therefore measuring the two sides of a single pellet combined with corre...

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supporting

confidence: 90%

Section: Xrf Analysismentioning

confidence: 97%

Section: Xrf Analysis and Repeatabilitymentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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