An X-ray fluorescence method is described for the direct determination, without pretreatment, of up to 55 trace elements in coal and coal-derived materials. A single assay specimen is prepared by blending finely crushed sample with a binder and briquetting. Calibration is effected by a suite of synthetic calibration standards prepared from spectrographically pure materials blended into graphite. Variations in ash and sulphur content required matrix absorption corrections to analyte and background intensities, which were achieved by use of relationships with the measured Compton scattered radiation. Prior knowledge of or assumptions concerning the composition of the coal are not required. Accurate results are presented for three NBS coal standard reference materials. Certain elements (including T1, Hg, Te, In, Cd, Ag and most rare earths) are normally present in coal at levels below the detection capability of the described method and require quantification by alternative techniques. 0 Heyden

The Barnhart pulse pile-up and dead time correction method is used by a number of manufacturers of energydispersive x-ray analysers. This method may provide inadequate correction at moderately high count rates and/or in the presence of low-energy x-ray peaks. A correction scheme is proposed to overcome these difficulties and its effectiveness is illustrated by the analysis of several homogeneous mineral samples of well established composition.

The intensity performance of various common XRF crystals (LiF200, Ge, PET and LSM) has been investigated under fixed experimental conditions. Measured were the raw intensities of elements particularly suitable to a given crystal, and peak-to-background ratios at different elemental concentrations. Peak profiles for each crystal type were also recorded and analysed in terms of apparent crystallite size and mosaic spread. In general the LiF crystals showed least variability in performance, whereas the PET crystals demonstrated the most.

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Direct slurry analysis by FI ICP-AES has been tested on seven iron-containing and five zinc-containing minerals. Results indicate that the method can be applied for traces and majors in a range of different materials.