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

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 (<i>D</i>) through agarose diffusive gels ranged from (1.02 to 4.74) × 10^–6 cm²/s for 34 pharmaceuticals and pesticides at 5, 13, and 23 °C. Analyte-specific diffusion–temperature plots produced linear (<i>r</i>² > 0.85) empirical relationships whereby <i>D</i> could be estimated at any environmentally relevant temperature (i.e., matched to <i>in situ</i> 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 <i>D</i> within 19% and 30% average relative error, respectively. Under slow flowing (2.4 cm/s) and static conditions, the <i>in situ</i> diffusive boundary layer (DBL) thickness ranged from 0.023 to 0.075 cm, resulting in a maximum contribution to mass transfer of