title: Direct analysis of Al2O3 powders by total reflection X-ray fluorescence spectrometry.
abstract: A direct analysis procedure for the determination of trace impurities of Ca, V, Cr, Mn, Fe, Ni, Cu, Zn and Ga in Al2O3 ceramic powders by total reflection X-ray fluorescence spectrometry (TXRF) is described. The powders were analysed in the form of slurries containing 1-10 mg mL(-1) of powder. The use of the procedure in the case of powders with differing grain size and for different slurry concentrations was investigated. Three different quantification possibilities were compared, namely the use of Al as a matrix component, the use of Fe as a trace element contained in the sample or of Co added in concentrations of 200 microg g(-1) as internal standard. The homogeneity of elemental distributions in sample layers deposited on the TXRF quartz carriers by evaporating 5 microL of the 10 mg mL(-1) slurries was studied by scanning the 4- to 5-mm-diameter spots of two samples by synchrotron radiation TXRF at Hasylab. For powders with differing graininess but mainly finer than about a few 10 microm, no systematic influence of the grain size on the accuracy of the determinations of Ca, V, Fe, Ni, Cu and Zn could be observed. The measurement precision, however, seemed to be limited by inhomogeneous distributions of the trace elements in the samples as testified by the synchrotron radiation TXRF scans. Detection limits of the developed TXRF procedure for Ca, V, Cr, Mn, Fe, Ni, Cu, Zn and Ga were found to be in the 0.3-7 microg g(-1) range and were shown to increase slightly with the grain size of the samples. Quantification using Al (matrix) as internal standard led to systematically higher values out of the accuracy required, whereas the other two approaches in all cases led to reliable results.
authors: Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany.
authors: Birgit U
authors: BU
authors: Peschel
authors: Ursula E A
authors: UE
authors: Fittschen
authors: Giancarlo
authors: G
authors: Pepponi
authors: Christoph
authors: C
authors: Jokubonis
authors: Christina
authors: C
authors: Streli
authors: Peter
authors: P
authors: Wobrauschek
authors: Gerald
authors: G
authors: Falkenberg
authors: José A C
authors: JA
authors: Broekaert
mesh_terms: D000537:Aluminum Oxide / Q000032:analysis* / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D005708:Gallium / Q000032:analysis; D010316:Particle Size; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D014131:Trace Elements / Q000032:analysis*
chemical_list: D014131:Trace Elements; D005708:Gallium; D000537:Aluminum Oxide; D002118:Calcium