Читать книгу Analytical Methods for Environmental Contaminants of Emerging Concern - Группа авторов - Страница 34

The determination of pharmaceuticals in soils/sediments is problematic due to the complexity of these matrices, the low concentration of targets and the lack of reference methods. These difficulties have been highlighted by numerous authors such as Białk-Bielińska [33], Brinkman [34], Pavlovic [35], Kemper [36], Buchberger [37], Tadeo [38], Babic and Mutavdzic [39] or Havens [40], who have presented reviews on the methods of determining of pharmaceuticals in soils available over the last decade. The developed methods are multi-steps with sample pre-treatment, solid-solvent extraction (assisted or not by ultrasounds or microwaves) and extract clean-up. A step-by-step summary of exemplary extraction techniques of pharmaceuticals from solid samples is presented in Table 2.2. Clean-up of extract by the solid-phase extraction (SPE) technique using HLB (hydrophilic-lipophilic adsorbent) columns is a common practice (Table 2.2). The most commonly used solvents are a mixture of acetonitrile and citric acid [41, 42], acetonitrile and EDTA-McIlvaine buffer [43, 44], and methanol with water [45–47]. In a nutshell, the extraction of pharmaceuticals from the soil can be carried out in various ways, depending on the chosen technique of quantification (GC or LC coupled with MS) and the properties of the analytes. For example, Aznar et al. [48] presented a method that allows the determination of pharmaceuticals belonging to three different therapeutic groups, in which they used ultrasound-assisted extraction (UAE). Kumirska et al. [49] used microwave-assisted extraction (MAE) to extract 13 NSAIDs and oestrogens from solid matrices such as sediment, sludge and soils. It may be concluded that both Aznar et al. and Kumirska et al. presented a rather standard approach to analysing pharmaceuticals in soil. The other methods used for this purpose are usually modifications or extensions of those mentioned above. A novel approach was characterized by the research conducted by Mijangos et al. [50], in which 11 endocrine-disrupting compounds were extracted from the soil using focused ultrasonic solid-liquid extraction (FUSLE), and the purification of the extract was performed using dispersive solid-phase extraction (dSPE). The use of FUSLE along with the simplified clean-up technique requires the use of only small samples, ranging from 0.01 to 1 g. The required amount of solvent ranges from 5 to 15 mL, and the extraction time can be several minutes or even seconds. So, it is an attractive method not only from the point of view of efficiency, but also of greenness and economy.