A dual radiotracer speciation technique with emphasis on probing of artefacts: a case study for technetium and spinach (Spinacia oleracea L.)

Speciation is required for obtaining information on chemical reactivity, to xicity and bioavailability of an element. In this work, a novel analytical speciation methodology, using a dual radiotracer technique is described. Th e approach is illustrated with the speciation of Tc-99, a pure beta(-)-emit ter, in spinach plants. The actual leaf concentration of two technetium spe cies, i.e. (TcO4-)-Tc-99 and (TcX)-Tc-99 (plant-formed Te species), is dete rmined as a function of incubation time with (TcO4-)-Tc-99 in the substrate . Addition of (TcO4-)-Tc-95m or (TcO4-)-Tc-99m, both containing a gamma-emi tting radioisotope of technetium, to the substrate allows easy radiotracing , while addition of (TCO4-)-T-99m or (TcX)-Tc-95m yield tracers during the analytical homogenisation procedure makes it possible to correct for proced ural losses and redox conversions. For TcO4- significant procedural losses were observed, while for TcX procedural recovery was nearly quantitative. S ignificant procedural conversions of TcO4- or TcX were not observed. Specia tion of other elements might benefit from this novel methodology. (C) 1999 Elsevier Science B.V. All rights reserved.