Rapid elemental analysis of sediment samples by isotope source XRF

Abstract

Energy dispersive isotope-source X-ray fluorescence (XRF) analysers are little used in academic environmental research, in spite of being ideally suited to a number of tasks. In this paper an XRF method is tested by measuring a wide range of environmental materials of known elemental composition. Precision, accuracy and detection limits are presented.

Using isotope-source X-ray fluorescence analysis, the total concentrations of Si, Ti, Ca, K, Fe, Mn, Cl, S, Nb, Ni, Pb, Rb, Sr, Zn and Zr can be determined in soils and sediments at a rate of >70 samples per day. The combination of speed and accuracy makes the technique ideal for three classes of application within environmental research. First, in sediments and soils that are highly heterogeneous, reliable characterisation is more dependent upon the number of samples measured than on measurement precision or accuracy. Under these circumstances the method is sufficiently accurate to be used alone. This is also the case where there is high and wide ranging contamination of sediment or soil by Pb and Zn. Second, major elements (Si, Ti, Fe, Ca, K and S) can be measured with sufficient accuracy in sediments and soils to aid the interpretation of other sediment chemical analyses. Third, the technique is ideal for the rapid screening of sediment or soil, allowing effective targeting of samples for more time consuming or expensive analyses. The XRF method presented here offers rapid, non-destructive total elemental analysis of sediments and soils that is sufficiently accurate to be useful in environmental research.