The determination of radium and/or uranium concentrations in natural waters is useful in a wide range of environmental studies. In this work, a low-background liquid scintillation system (Wallac, Quantulus 1220) was used to determine simultaneously 226Ra and uranium (total) activities in natural water samples. Sample preparation involved filtration and 1 : 10 concentration by evaporation. Then,...

A comparison between two analytical techniques commonly used for the determination of sulphur concentrations in natural water samples is reported. Significant differences in the sulphur values obtained using inductively coupled plasma atomic emission spectrometry and ion chromatography are described. The contribution of a sulphur fraction (presumed to be organic S) not detected by ion chromatog...

A natural material, cotton fiber, has been applied as a solid-phase extraction (SPE) adsorbent for sample preparation for the analysis of polycyclic aromatic hydrocarbons (PAH) in water samples using high-performance liquid chromatography. The cotton fiber was used directly without any chemical modifications, which avoided a complex synthesis process and consumption of a large volume of organic...

A rapid continuous-Ñow technique for the quantitative determination of hydrogen isotope ratios in organic materials and water, at natural abundance levels, is described. Samples are pyrolysed in a helium stream at 1080 ÄC over an inert form of carbon. Hydrogen is separated from the other pyrolysis gases by gas chromatography and enters the ion source of the isotope ratio mass spectrometer (IRMS...