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

Abstract

The diffusive gradients in thin films (DGT) passive sampling technique has been increasingly used to provide time-weighted average concentrations of the biorelevant fraction of organic contaminants in waters, with high spatial and temporal resolutions at low cost. This study was tested for the effects of biofouling and compound degradation/loss during sample handling/storage on the DGT measurement of a range of emerging organic pollutants. Biofouling was tested using biofilms collected from the influent and effluent of a typical urban wastewater treatment plant. Most (85%) target compounds showed no detectable effect on the DGT measurement when 8- and 15-day biofouled membrane filters were used. Four storage methods were designed to test for within-sampler degradation/loss for up to 2 months. Intact samplers can be simply stored in polyethylene bags at ambient temperature (18–26 °C) with most compounds stable (mass loss <20%) for at least 1 week. Keeping intact samplers at 4 °C or binding gels in solvent gave good recoveries, with most chemicals being stable for up to 2 months, although the best results were obtained when binding gels were kept in solvent at 4 °C. Recommendations are made for sample handling and storage of DGT samplers used for determination of trace organics in monitoring and surveillance campaigns.

In Situ Catchment Scale Sampling of Emerging Contaminants Using Diffusive Gradients in Thin Films (DGT) and Traditional Grab Sampling: A Case Study of the River Thames, UK

“…50 The analytes were also shown to have little degradation/loss in the sampling, transport and storage conditions of this study. 50 Therefore, the passive sampling system here is shown to have good QC. DGT sampling provides in situ TWA concentrations for the deployment period, e.g.…”

“…They are important ECs in river systems with well-developed DGT methods 23 and can be monitored using one DGT configuration (see sampler details later). 24,26,27,[48][49][50] Thirteen target chemicals were selected across EC types, as follows: S3 and their structures in Figure S3. Isotope-labelled chemicals were used as surrogate internal standards (SIS): SMX-d4, CAF-13C3, MEP-13C6, PRP-13C6, BUP-13C6, PHBA-d4 and E3-d2.…”

“…They were stored in a refrigerator (4 °C) before sonication extraction at Lancaster laboratory within one week, following a method detailed elsewhere. 50 217 In total, 25 grab samples and 66 DGT samplers were collected (summarized in Table S4).…”

Effects of biofouling on the uptake of perfluorinated alkyl acids by organic-diffusive gradients in thin films passive samplers

“…1–3 These advantages include the ability to obtain time-weighted average concentrations over a defined deployment period, simplified and cleaner sample extractions, 4 and stable and compact long-term freezer preservation of retrieved samplers. 5–7…”

“…Challis et al 18 found that biofilms did not appear to affect the uptake of a suite of pharmaceuticals and pesticides by comparing wastewater-deployed samplers with grab sampling concentrations. Recently, Wang et al 7 showed that biofouled hydrophilic polypropylene filter membranes deployed in wastewater for two weeks would not affect the application of DGT for some organic pollutants. However, analyte diffusivity may be greatly reduced by biofilms.…”