Petroleum products and essential oils are complex mixtures of hydrophobic and volatile chemicals and are categorized as substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs). In aquatic testing and research of such mixtures, it is challenging to establish initial concentrations without the addition of cosolvents, to maintain constant concentrations during the test, and to keep a constant mixture composition in dilution series and throughout test duration. Passive dosing was here designed to meet these challenges by maximizing the surface area (Adonor/Vmedium = 3.8 cm2/mL) and volume (Vdonor/Vmedium > 0.1 L/L) of the passive dosing donor in order to ensure rapid mass transfer and avoid donor depletion for all mixture constituents. Cracked gas oil, cedarwood Virginia oil, and lavender oil served as model mixtures. This study advances the field by (i) showing accelerated passive dosing kinetics for 68 cracked gas oil constituents with typical equilibration times of 5-10 min and for 21 cederwood Virginia oil constituents with typical equilibration times < 1 h, (ii) demonstrating how to control mixture concentration and composition in aquatic tests, and (iii) discussing the fundamental differences between solvent spiking, water-accommodated fractions, and passive dosing.

中文翻译：

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疏水复合混合物的加速被动加药-控制水生试验中的含量和组成。

石油产品和香精油是疏水性和挥发性化学物质的复杂混合物，被分类为成分未知或可变的物质，复杂的反应产物或生物材料（UVCB）。在此类混合物的水质测试和研究中，挑战是要在不添加助溶剂的情况下建立初始浓度，在测试过程中保持恒定的浓度以及在稀释系列和整个测试过程中保持恒定的混合物组成。被动定量给料器旨在通过最大程度地增加被动定量给体的表面积（Adonor / Vmedium = 3.8 cm2 / mL）和体积（Vdonor / Vmedium> 0.1 L / L）来应对这些挑战，以确保快速传质并避免所有混合物成分的供体耗竭。裂化瓦斯油，雪松木弗吉尼亚油，和薰衣草油作为模型混合物。这项研究通过（i）显示了68种典型平衡时间为5-10分钟的裂化瓦斯油成分和典型平衡时间<1 h以下的21种弗吉尼亚州雪松木成分的加速的被动加料动力学，（ii）展示了如何在水生试验中控制混合物的浓度和组成，以及（iii）讨论溶剂加标，水吸收馏分和被动加料之间的根本区别。