Segmented sediment probe for diffusive gradient in thin films technique

A new modification of a constrained sediment probe was tested for application in the diffusive gradient in thin films technique (DGT). The sediment probes packed with agarose based resin and diffusive gels were exposed under laboratory conditions to well-mixed test solutions of cadmium and nickel as model elements. The reproducibility of metal uptake in segments (strips) of resin gel with anchored 8-hydroxyquinoline functional groups (Spheron-Oxin (R) ion exchanger) was studied. The relative yield of uptake of metals in resin gel strips, determined as the ratio of the time-averaged DGT-measured metal concentration and the concentration of a metal in the test solution, showed that the effective sampling area was larger than the geometric area of the resin gel strip. This relative yield is in very good agreement with the theoretical value obtained by the Finite Element Method (FEM) in calculation of diffusion processes. The performance of the modified constrained probe is demonstrated by an example of uranium, iron and manganese depth profiling in a spiked sediment core. Utilization of the new segmented sediment probe in the DGT technique is very simple. Its application does not require special devices and labor-intensive procedures. It can provide sediment depth profiles of metals with the resolution down to the millimetre level.