Validation of Diffusive Gradient in Thin-films (DGT) Technique for Mercury and Methylmercury Measurements in Natural Environments

Oral Presentation

Prepared by A. Schierz1, D. Reible1, J. Grundy2, P. Bireta2
1 - Texas Tech Univeristy, Department of Civil & Environmental Engineering, Box 41023, Boston Ave 911, Lubbock, TX, 79409, United States
2 - The Univeristy of Texas at Austin, Civil, Architectural and Environmental Engineering Department-EWRE, Environmental & Water Resources Engineering , 301 E. Dean Keeton St. Stop C1700, Austin, TX, 78712, United States

Contact Information:; 919-381-8663


The Diffusive Gradient in Thin-films (DGT) technique has been shown to be useful for measurement of dissolved metals in water and sediments. However, the application for measuring mercury and methylmercury has mostly been limited to academic studies with the use of “in-house” produced DGTs. Limited information about handling and storage conditions, availability and quality of reagents and routine performance evaluation are only some aspects hindering commercial application and regulatory acceptance.

This study investigated several knowledge gaps with respect to the DGT technique for measurement of mercury and methylmercury. Challenges addressed include laboratory validation experiments for example acceptable recovery of the analyte from the matrix, measuring and quantifying of detection limits, assessing bias through method blanks and laboratory control spikes, reproducibility of results between laboratories, and other potential matrix effects. We explored the performance and evaluated the effect of different DGT binding layer compositions. 3-mercapto-propyl functionalized silica beads (3-MSH) were used as the adsorbent in the binding layer. Batch studies were performed evaluating the effect of resin thicknesses, binding capacities, chemical composition of diffusive and binding layers and quality of the adsorbent by testing commercially available 3-MSH resins from 4 different suppliers and optimizing elution conditions to validate reliable measurement of mercury and methylmercury using DGTs. Different experimental approaches for performance testing will be discussed as the guideline for accreditation including the application of associated quality assurance and quality control measures.