The determination of niobium, molybdenum, tungsten, iron and titanium in tantalum metal is described. After dissolution of the metal a d extraction of the tantalum by a chromatographic method using tributyl phosphate, the trace elements are determined on thin-film samples by x-ray fluorescence spectrometry. The thin-film samples are prepared either by spotting the sample solutions directly on to filter-paper or by coprecipitation with indium. The limits of detection on the thin film are 0.05-0.7 pg, depending on the element being measured.

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An account is given of the formulation and preparation of synthetic standards suitable for the routine analysis of minerals, ores and ore concentrates by instrumental neutron activation. Fifteen standards were prepared, each containing from one to seven elements. The standards contain forty‐four elements that produce isotopes with half‐lives longer than 12 hours. An evaluation of the accuracy and precision of the method of preparation is given.

This paper describes the determination of the individual platinum-group elements by X-ray fluorescence after nickel-sulphide fire-assay collection. The platinum-group sulphide residue obtained after the dissolution of the nickel is dissolved in acid, and reduced to the metal by use of sodium borohydride. The finely divided metals are then filtered onto a millipore filter, and measured by X-ray fluorescence spectroscopy. The procedure makes use of gold as an internal standard. Factors affecting the accuracy and precision are investigated.