## 4 Applications of Microextraction Techniques to the Determination of Organic Micropolultants
### Pharmaceuticals  
The presence of pharmaceutical compounds in aquatic media is a challenge during environmental monitoring. These substances are pervasive in rivers, lakes and oceans due to their dispersion through wastewater [86]. Although many countries use advanced technologies, such as ozonation, reverse osmosis, and granular active carbon, to treat potable water, some compounds resist treatment [87]. Despite the existence of numerous pharmaceutical compounds, few studies utilised liquid chromatography with mass spectrometric detection (LC-MS) with microextraction techniques, as shown in Table 3.  
Two studies have used SPME to extract similar antibiotics compounds in liquid samples. [PERSON] _et al._[88] used Carbowax/divinylbenzene (CW/DVB) fibres to extract ten sulphonamide antibiotics from different wastewater samples, revealing a viable method for overcoming the matrix effects. [PERSON] _et al._[89] optimised a SPME method using Carbowax-template resin (CW/TPR) fibres to collect antibiotics (five of nine compounds were sulphonamides) in influent and effluent samples simultaneously. The LODs obtained in this study were better (\(\mathrm{ng\cdot L}^{-1}\)) than those obtained by [PERSON] _et al._[88]. A multi-residue analysis of the pharmaceutical compounds in wastewater through dual solid-phase microextraction (dSPME) was realised by [PERSON] _et al._[90]. Two CW/TPR fibres with different pH values were used to obtain excellent recoveries (89.2%-109.7%) for numerous compounds. [PERSON] _et al._[91] developed an analytical method by combining C\({}_{18}\)/SCX mixed thin-film microextraction (TFME) and desorption electrospray ionisation mass spectrometry (DESI-MS) to determine pharmaceuticals in aqueous samples. Combining both techniques improves the analysis time considerably compared to traditional liquid chromatography mass spectrometry (LC-MS). The results were compared, and good agreement was found through a concentration range spanning three orders of magnitude. Serious matrix effects were observed in treated wastewater, but the lower limits of detection were still in the low \(\mathrm{ng\cdot L}^{-1}\) range. IT-SPME was used by [PERSON] _et al._[92] to extract five fluoroquinolones (FQs) from environmental waters using a fully automated method with a Carboxen 1010 PLOT capillary column-like IT-SPME system coupled to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system. The extracted compounds were easily desorbed using the mobile phase. The LODs of the five FQs ranged from 7 to 29 \(\mathrm{ng\cdot L}^{-1}\). The IT-SPME method had between 60-94-fold higher sensitivity than the direct injection method. [PERSON] _et al._ developed an IT-SPME method using a Carboxen 1006 PLOT capillary column to simultaneously determine 15 non-steroidal anti-inflammatory drugs (NSAIDs) in environmental water [93]. The LODs of the NSAIDs ranged from 5 to 65 ng\(\cdot\)L\({}^{-1}\). This method could be used to analyse surface and wastewater samples without any pre-treatment or interference peaks. Although IT-SPME has achieved good recoveries (above 80%) and limits of detection (ng\(\cdot\)L\({}^{-1}\)) for the analysed compounds, it is rarely used with LC-MS detection. In recent years, stir bar solid extraction (SBSE) has been used to determine different pharmaceutical compounds. SBSE with different commercial external coatings, such as PDMS (polydimethylsiloxane), EG Silicone (ethylene glycol-silicone) and PA (acrylate), can be used [72]. Moreover, new SBSE coatings have been prepared. In this context, [PERSON] _et al._[94] synthesised and evaluated a monolithic and hydrophilic stir bar coating based on a methacrylic acid and divinylbenzene copolymer [poly(MAA-co-DVB)] for the SBSE of polar pharmaceuticals from complex environmental water samples. The extraction performance of the synthesised stir bar was compared to the extraction performance of a commercially available polydimethylsiloxane stir bar.