Recent literature has demonstrated the utility of the organic-diffusive gradients in thin films (o-DGT) device as an effective passive sampler for polar organics in aquatic environments. Here, a new configuration comprising a polyacrylamide diffusive gel and Sepra™ ZT sorbent was developed and calibrated under multiple pH conditions. Linear uptake (r2 > 0.9) was observed at pH ≈ 5 for a suite of 31 pharmaceuticals and pesticides over 25 days, suitable for typical passive sampler deployments. At pH ≈ 8.5, linear uptake (r2 > 0.9) was observed for many of the same compounds. Comparisons of the uptake rates between the two pH experiments generally agreed (14% average relative error), with only 6 compounds exhibiting marked reduction with pH (e.g. sulfonamide antibiotics). These discrepancies may be explained by changes in analyte-sorbent interaction (H-bonding) due to speciation changes at varying pH. Samplers performed well in field evaluations conducted in an impacted river system, showing close agreement with the previously validated agarose/HLB o-DGT configuration deployed simultaneously. This work illustrates that polyacrylamide diffusive gels are a more robust and resistant outer-membrane material compared to agarose used in earlier o-DGT configurations. Sepra™ ZT binding gels served as an effective binding resin, offering a cost effective and commercially available sorbent.

中文翻译：

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pH 值对采样器吸收的影响，以改进薄膜无源采样器中有机扩散梯度的配置

最近的文献证明了薄膜 (o-DGT) 设备中的有机扩散梯度作为水生环境中极性有机物的有效被动采样器的实用性。在这里，开发了一种包含聚丙烯酰胺扩散凝胶和 Sepra™ ZT 吸附剂的新配置，并在多种 pH 条件下进行了校准。在 pH ≈ 5 时观察到一组 31 种药物和农药超过 25 天的线性吸收 (r2 > 0.9)，适用于典型的被动采样器部署。在 pH ≈ 8.5 时，对许多相同的化合物观察到线性吸收 (r2 > 0.9)。两个 pH 实验之间摄取率的比较普遍一致（平均相对误差为 14%），只有 6 种化合物随着 pH 值的升高而显着降低（例如磺胺类抗生素）。这些差异可以通过分析物-吸附剂相互作用（氢键）在不同 pH 值下的形态变化引起的变化来解释。采样器在受影响的河流系统中进行的现场评估中表现良好，显示与先前验证的同时部署的琼脂糖/HLB o-DGT 配置非常吻合。这项工作表明，与早期 o-DGT 配置中使用的琼脂糖相比，聚丙烯酰胺扩散凝胶是一种更坚固、更耐用的外膜材料。Sepra™ ZT 结合凝胶作为一种有效的结合树脂，提供具有成本效益的市售吸附剂。显示与先前验证的同时部署的琼脂糖/HLB o-DGT 配置非常一致。这项工作表明，与早期 o-DGT 配置中使用的琼脂糖相比，聚丙烯酰胺扩散凝胶是一种更坚固、更耐用的外膜材料。Sepra™ ZT 结合凝胶作为一种有效的结合树脂，提供具有成本效益的市售吸附剂。显示与先前验证的同时部署的琼脂糖/HLB o-DGT 配置非常一致。这项工作表明，与早期 o-DGT 配置中使用的琼脂糖相比，聚丙烯酰胺扩散凝胶是一种更坚固、更耐用的外膜材料。Sepra™ ZT 结合凝胶作为一种有效的结合树脂，提供具有成本效益的市售吸附剂。