Reliability of the ICP-AES for trace elements studies of biological materials.

In order to investigate the reliability of the Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) for trace element analysis of biological materials, we have carried out extensive investigations on human plasma, using an Applied Research Laboratory's ICP-AES. When we aspirated the untreated plasma into the spectrometer, we obtained unreliable and nonreproducible results. However, when we pretreated the plasma by wet digestion (to destroy all the organic material), we achieved reproducible and consistent results. It is, therefore, suggested that biological samples should be pretreated, preferably by wet digestion, before being aspirated into the ICP-AES for analysis.

Determination of the rare-earth elements in geological materials by thin-film X-ray fluorescence and inductively-coupled plasma atomic-emission spectrometry.

Thin-film XRF and ICP-AES analytical procedures for the determination of the rare-earth elements (REE) in rocks, involving preconcentration by ion-exchange and co-precipitation with Fe(OH)(3) for thin-film preparation, and matrix modification, are described. The REE in five international reference rocks have been determined, with correction for spectral line overlap whenever necessary. The results obtained by using X-ray fluorescence spectrometry compare well with those of inductively-coupled plasma atomic-emission spectrometry, and with other values reported in the literature.

Dissolution of geological material with orthophosphoric acid for major-element determination by flame atomic-absorption spectroscopy and inductively-coupled plasma atomic-emission spectroscopy.

An analytical procedure has been developed for the determination of major elements in geological material by both flame atomic-absorption spectrometry and inductively-coupled plasma atomic-emission spectrometry. Condensed phosphoric acid was used for the decomposition of 70 natural minerals containing sulphide, oxide, silicate or carbonate constituents. The results were compared with those obtained when a perchloric acid and orthophosphoric acid mixture was used for the decomposition, to ensure dissolution of even the most acid-resistant minerals. The procedure can be applied to rocks, ores, soils, slags and refractory material as a means of rapid and complete dissolution for the analysis of even the most insoluble material.

Dissolution of smooth platinum electrodes in biological fluids.

Quantitative measurements of the dissolution of smooth platinum electrodes resulting from stimulation of physiological saline with sinusoidal, square biphasic, square monophasic and direct currents have been made by spectrophotometric analysis of the stimulated solution. Results presented give an indication of the stimulus parameter region in which platinum dissolution is minimal and therefore potentially suitable as an implant electrode material.