The diffusive gradients in thin films (DGT) technique is an environmental chemistry technique for the detection of elements and compounds in aqueous environments, including natural waters,[1] sediments[2] and soils.[3] It is well suited to in situ detection of bioavailable toxic trace metal contaminants.[4][5][6] The technique involves using a specially-designed passive sampler that houses a binding gel, diffusive gel and membrane filter. The element or compound passes through the membrane filter and diffusive gel and is assimilated by the binding gel in a rate-controlled manner. Post-deployment analysis of the binding gel can be used to determine the time-weighted-average bulk solution concentration of the element or compound via a simple equation.
According to DGT theory, the concentration of an analyte, [C], tends toward 0 (μg/L, ng/L, etc.) as the analyte approaches the binding layer, passing through the diffusive boundary layer (DBL, ẟ) and the DGT device's diffusive gel (thickness of Δg). No reverse diffusion of the analyte back into the solution is assumed to occur.
^Chaudhary M, Quanz M, Williams J, Maltby E, Oakes K, Spooner I, Walker TR (September 2020). "Assessment of metal(loid) concentrations using Diffusive Gradient Thin (DGT) films in marine, freshwater and wetland aquatic ecosystems impacted by industrial effluents". Case Studies in Chemical and Environmental Engineering. 2: 100041. doi:10.1016/j.cscee.2020.100041.
^Zhang H, Davison W, Gadi R, Kobayashi T (August 1998). "In situ measurement of dissolved phosphorus in natural waters using DGT". Analytica Chimica Acta. 370 (1): 29–38. doi:10.1016/S0003-2670(98)00250-5.
^Wilkins CL (October 1983). "Hyphenated techniques for analysis of complex organic mixtures". Science. 222 (4621): 291–6. Bibcode:1983Sci...222..291W. doi:10.1126/science.6353577. PMID 6353577.
^"Diffusive Gradients in Thin-films (DGT): A Technique for Determining Bioavailable Metal Concentrations" (PDF). International Network for Acid Prevention. March 2002. Archived from the original (PDF) on 28 February 2015. Retrieved 23 April 2015.
^Strivens J, Hayman N, Johnston R, Rosen G (May 2019). "Effects of Dissolved Organic Carbon on Copper Toxicity to Embryos of Mytilus galloprovincialis as Measured by Diffusive Gradient in Thin Films". Environmental Toxicology and Chemistry. 38 (5): 1029–1034. doi:10.1002/etc.4404. PMID 30840314. S2CID 73466599.
^Strivens J, Hayman N, Rosen G, Myers-Pigg A (April 2020). "Toward Validation of Toxicological Interpretation of Diffusive Gradients in Thin Films in Marine Waters Impacted by Copper". Environmental Toxicology and Chemistry. 39 (4): 873–881. doi:10.1002/etc.4673. PMID 32004383.
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