Development and Calibration of an Organic-Diffusive Gradients in Thin Films Aquatic Passive Sampler for a Diverse Suite of Polar Organic Contaminants

Abstract

A unique configuration of the diffusive gradients in thin films sampler for polar organics (o-DGT) without a poly(ether sulfone) membrane was developed, calibrated, and field-evaluated. Diffusion coefficients (D) through agarose diffusive gels ranged from (1.02 to 4.74) × 10 cm/s for 34 pharmaceuticals and pesticides at 5, 13, and 23 °C. Analyte-specific diffusion-temperature plots produced linear (r > 0.85) empirical relationships whereby D could be estimated at any environmentally relevant temperature (i.e., matched to in situ water conditions). Linear uptake for all analytes was observed in a static renewal calibration experiment over 25 days except for three macrolide antibiotics, which reached saturation at 300 ng (≈15 d). Experimental sampling rates ranged from 8.8 to 16.1 mL/d and were successfully estimated with measured and modeled D within 19% and 30% average relative error, respectively. Under slow flowing (2.4 cm/s) and static conditions, the in situ diffusive boundary layer (DBL) thickness ranged from 0.023 to 0.075 cm, resulting in a maximum contribution to mass transfer of <45%. Estimated water concentrations by o-DGT at a wastewater treatment plant agreed well with grab samples and appeared to be less influenced by the boundary layer compared to that of polar organic chemical integrative samplers (POCIS) deployed simultaneously. The o-DGT sampler is a promising monitoring tool that is largely insensitive to the DBL under typical flow conditions, facilitating the application of measured/modeled diffusion-based sampling rates. This significantly reduces the need for sampler calibration, making o-DGT more widely applicable, reliable, and cost-effective compared to current polar passive samplers.

Pharmaceuticals and pesticides archived on polar passive sampling devices can be stable for up to 6 years

“…All chemicals were of 95% purity or higher. Further details of o-DGT preparation and extraction are available [16]. Further details are published elsewhere [16].…”

“…Limits of detection for all analytes ranged from 0.18 to 1100 ng/L [16]. Criteria for positive identification of all samples relied upon quantifier and qualifier tandem mass spectrometry transitions and retention time matching with analytical standards.…”

“…Site and deployment/retrieval details can be found elsewhere [16]. In total, 3 duplicate pairs of o-DGT were deployed at the final effluent site of a wastewater treatment facility in northern Manitoba.…”

“…Whereas both POCIS and the o-DGT used in the present study [16] employ the same Oasis HLB sorbent (Waters), the nature of how the sorbent is configured within these 2 samplers differs markedly. Whereas both POCIS and the o-DGT used in the present study [16] employ the same Oasis HLB sorbent (Waters), the nature of how the sorbent is configured within these 2 samplers differs markedly.…”

“…Whereas both POCIS and the o-DGT used in the present study [16] employ the same Oasis HLB sorbent (Waters), the nature of how the sorbent is configured within these 2 samplers differs markedly. The high water content (> 95% [16]) of hydrogels results in concerns about analyte stability because of potential hydrolysis and physical damage from the freeze/thaw process. The high water content (> 95% [16]) of hydrogels results in concerns about analyte stability because of potential hydrolysis and physical damage from the freeze/thaw process.…”