Investigating Potential Limitations of Current Diffusive Gradients in Thin Films (DGT) Samplers for Measuring Organic Chemicals

Abstract

The diffusive gradients in thin films (DGT) passive sampler has emerged as a 21 powerful tool for measuring in situ concentrations of organic contaminants in waters with 22 appropriate spatial and temporal resolution at low cost. This study addresses the property range of compounds which can be routinely sampled with the present design of DGT device.24 Sorption experiments and DGT deployment with 9 model chemicals [organophosphate esters 25 with a wide range of log K OW (0.8-9.5), molecular weight (182-435 Da)] and different 26 functional groups showed compounds with high hydrophobicity and aromatic rings are prone 27 to retention on membrane filters, which slows the supply of chemical to the binding resin of 28 the sampler. The current DGT sampler (PTFE membrane filter, agarose gel diffusion layer 29 and HLB binding layer) is potentially reliable for measuring hydrophilic [log K OW (0.8-2.6)]30 and non-aromatic-ring chemicals. For compounds of higher values of K OW or with aromatic 31 rings, knowledge of the lag phase is necessary to optimize sampling times to avoid biasing 32 subsequent laboratory analyses. A standard procedure is used to measure lag times (from 33 minutes to days), by exposing a series of DGT samplers in waters until linear mass 34 accumulation in samplers is achieved. We discuss how monitoring of a wide array of organic 35 contaminants across classes should be possible in future, with a range of validated new DGT 36 devices, optimized for the choice of membrane filter, diffusive material and binding resin.

Monitoring Organic Pollutants in Waters Using the Diffusive Gradients in the Thin Films Technique: Investigations on the Effects of Biofouling and Degradation

“…Studies have shown that the agarose diffusive gels in the DGT sampler can be completely destroyed because of aquatic organisms when a protective membrane filter is not used. , The diffusive gels can sometimes escape from the holder if a membrane filter was not used in the sampler. The lag time in uptake of higher K ow compounds caused by the filter membrane can be calculated and corrected for, as reported recently . We therefore advise using the filter membrane, as originally conceived for DGT.…”

“…The lag time in uptake of higher K ow compounds caused by the filter membrane can be calculated and corrected for, as reported recently. 37 We therefore advise using the filter membrane, as originally conceived for DGT.…”

Development and Applications of Novel DGT Passive Samplers for Measuring 12 Per- and Polyfluoroalkyl Substances in Natural Waters and Wastewaters

“…Recently, DGT samplers containing different binding layers based on Amberlite macroporous adsorbent resin (XAD18), − hydrophilic lipophilic balanced resin (HLB), , active carbon, and mixed-mode cation exchange resin (MCX) have been successfully used to measure organic pollutants, such as antibiotics, pesticides, psychiatric pharmaceuticals, bisphenols, phosphorus flame retardants, , illegal drugs, and household and personal care products (HPCPs) . Although Guan et al have developed a DGT method based on XAD18 as the binding layer to measure PFOA and PFOS in water, Wong et al used weak anion exchanger resin (WAX) as the binding layer to measure six common PFASs (perfluorobutanesulfonic acid (PFBS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluorooctanesulfonic acid (PFOS)).…”

Biomimetic Accumulation of Methamphetamine and Its Metabolite Amphetamine by Diffusive Gradients in Thin Films to Estimate Their Bioavailability in Zebrafish

“…To date, DGT has been applied to detect pharmaceuticals, 25,27 antibiotics, 27 estrogen, 28 anionic pesticides, 29 illicit drugs, 21,30 and organophosphate esters. 31 Guo et al confirmed that DGTs can be used for in situ monitoring of several illicit drugs, including METH, in waste waters and rivers. 21 In addition to their application in environmental monitoring, DGTs can be used to simulate the bioaccumulation of contaminants in the environment, as an alternative method for rapid evaluation of metal bioavailability in soils or sediments.…”

“…DGTs have been successfully applied to measure trace components in situ in aquatic environments, especially to monitor trace contaminants with high water solubility. − Since Chen et al applied DGT to detect the sulfonamide antibiotic in water in 2012, DGT has been gradually developed for the detection of various organic substances in aquatic environment. To date, DGT has been applied to detect pharmaceuticals, , antibiotics, estrogen, anionic pesticides, illicit drugs, , and organophosphate esters . Guo et al confirmed that DGTs can be used for in situ monitoring of several illicit drugs, including METH, in waste waters and rivers .…”