# Recent Advances in Applications of Ionic Liquids in Miniaturized Microextraction Techniques
## 2 Ionic Liquids in Miniaturized Microextraction Techniques
### Stir Bar Sportive Extraction (SBSE)  
Stir bar sorptive extraction (SBSE) was initially introduced in 1999 by [PERSON] and co-workers [31]. It uses a stir bar for the extraction consisting of a magnet covered with glass, which in turn is coated by a layer (typically 0.5-1 mm) of sorptive material, usually polydimethylsiloxane (PDMS). The bar is subsequently inserted into a vial, which contains the aqueous sample and it is stirred until equilibrium of analytes concentration between sorbent and sample matrix is reached. After the extraction, the bar is removed and transferred to a clean vial, where the target compounds are analyzed by liquid or gas chromatography by liquid or thermal desorption [32].  
[PERSON] and co-workers introduced a novel approach for the extraction and determination of nonsteroidal anti-inflammatory drugs (NSAIDs) by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) [33]. The researchers synthesized an ionic liquid, 1-allyimidazolium tetrafluoroborate ([AIM][BF\({}_{4}\)I]) chemically bonded sol-gel coating for stir bar sorptive extraction using \(\gamma\)-(methacryloxymethyl)trimethoxysilane (KH-570) as a bridging agent, which showed excellent mechanical strength and chemical/thermal stability compared to the conventional PDMS-based or C18 coating materials. After the optimization of the critical parameters of the technique, such as stirring rate, extraction time, desorption solvent, pH, salt effect, the developed method showed satisfactory reproducibility with RSDs lower than 7.6% and high sensitivity (LODs: 0.23-0.31 ug L\({}^{-1}\)) for the determination of three NSAIDs. The proposed method is applicable in environmental, food and biological samples  
In the framework of the improvement and development of microextraction techniques, the combination of two or more techniques could induce significant enhancements to the extraction procedure reducing the extraction time, the cost, or the sensitivity. Two microextraction techniques that can be easily conflated is the stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) introducing the stir bar dispersive liquid microextraction (SBDME). In this approach, [PERSON] et al. used a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar as the extraction phase [34]. At low stirring rates it acts similar to SBSE while the MIL remains in the stir bar surface. At higher stirring speed the MIL disperses into the solution acting similar to DLLME. When the extraction is over, the stirring stops and the MIL retrieves onto the stir bar surface due to its magnetic properties. The desorption of the MIL-coated stir bar contained the preconcentrated analytes performed thermally in a gas chromatography-mass spectrometry (TD-GC-MS) system. The above approach was applied for the extraction of lipophilic organic UV filters from aqueous environmental water samples.  
In a recent work by [PERSON] et al. another successful combination of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) has been achieved and the stir bar dispersive liquid microextraction (SBDLME) was created for the determination of ten polycyclic aromatic hydrocarbons (PAHs) in natural water samples [35]. A neodymium stir bar magnetically coated with a magnetic ionic liquid (MIL), the [P\({}_{6,6,6,14}\)+][Ni(II)(hfacac)\({}_{3}\)-], was used as extraction device. After the stirring, the MIL is magnetically retrieved onto the stir bar and then subjected to thermal desorption-gas chromatography-mass spectrometry system (TD-GC-MS). In contrast to other methods for the determination of PAHs, this one requires less time and manipulation for the sample preparation, solvent evaporation is not a mandatory step and the sensitivity level is more than satisfactory allowing the determination of PAHs in aqueous sample at the low ng L\({}^{-1}\) levels.