DETECTION OF TRACE RADIOISOTOPES IN SOIL, SEDIMENT AND VEGETATION BY GLOW-DISCHARGE MASS-SPECTROMETRY

The possibility for the determination of some radioisotopes of cesium, strontium, plutonium, uranium and thorium by glow discharge mass spec trometry (GDMS) in soils, sediments and vegetations is investigated. T he preparation of samples is described as a combination of the use of a conductive host matrix and a secondary cathode in order to decrease the dilution effect of the blending material for the trace level deter mination and to gain a stable discharge. Effects of interferences aris ing from the nature of the conductive host matrix and of the secondary cathode on the sensitivity of the method are discussed. The determina tion of Cs-137 and Sr-90 has been attempted and the results obtained w ere in agreement with those from other analytical techniques. Accuracy , internal and external precisions have been also evaluated. GDMS is s hown to be a helpful technique for the determination of radioisotopes in environmental samples. Radioisotopes can be determined according to the matrix of the sample (e.g. grass), also in presence of isobaric i nterferences. However, limitations still exist on the application of G DMS.