Flavonoids are group of polyphenolic compounds that exhibits biological effects such as anti-oxidative, anti-inflammatory, anti-allergenic, antithrombotic, hepatoprotective and antiviral activities. They have divided into subclasses of flavones, isoflavones, flavonols, flavanals, flavanones, anthocyanidins and chalcones (Wang et al. 2006; Erlund et al. 2008; D’Andrea 2015). Quercetin (flavonol) is one of the most abundant flavonoids present in various foods including vegetables and fruits like black and green tea, cocoa powder, apple, onion, tomato, broccoli and other leafy green vegetables(Neustadt 2006). Quercetin shows high affinity for bind to transition metal ions and free radical scavengers which reduces oxidative stress and related damages. Therefore, quercetin has an exceptional place in antioxidant therapy(Nabavi et al. 2015). Quercetin is a protective agent against various diseases such as cancer, pulmonary, cardiovascular and osteoporosis(Edwards et al. 2007; Boots et al. 2008). Therefore, due to the unique properties of quercetin, it is important to develop efficient, selective and simple methods for the determination of quercetin.
Many different analytical methods have been used to detect and determination of quercetin such as high-performance liquid chromatography (HPLC)(Kumar et al. 2016; Hamedi and Hadjmohammadi 2017), gas chromatography–mass spectrometry (GC–MS)(de Souza Dias et al. 2013), capillary electrophoresis (CE)(Zhang et al. 2014), electrochemical sensor(Yao et al. 2018) and spectrophotometry (Pejic et al. 2004). Among these methods, spectrophotometry provides the relatively inexpensive and easy-to-use tool, which is available in most laboratories. However, determination of quercetin at low concentrations in complex matrices makes sample preparation a critical step in any analytical method. Therefore, the main goals of sample preparation are efficient
sample cleanup and analyte preconcentration while maintaining low cost, short analysis time and high degree of environmental utility. Several sample preparation methods such as solid-phase extraction (SPE)(Watson and Oliveira 1999), Solid-phase microextraction (SPME)(Rahimi et al. 2019), liquid–liquid extraction (LLE)(de Souza Dias et al. 2013) and dispersive liquid-liquid microextraction (DLLME)(Campillo et al. 2015) had been reported for pre-concentration and extraction of the quercetin from food samples prior to its determination by different techniques. But new methods are needed to improve the selectivity and simplicity of the method.
Recently, microextraction in packed syringe (MEPS) have attracted increasing attention for
sample preparation due to its simplicity, sensitive, rapid and little solvent consumption. Microextraction in packed syringe (MEPS) appears as a new format for solid-phase extraction (SPE) that introduced by Abdel-Rehim in 2004(Abdel-Rehim 2004). In MEPS, a small amount of sorbent is packed inside the barrel of a syringe as a plug or between the barrel and the needle as a cartridge. The sample is drawn through the syringe (which pumps the sample up and down). When the sample has passed through the sorbent, the analytes adsorbed to the sorbent. For remove the other interfering materials, the solid phase is washed with water. Then, the analytes are eluted with an organic solvent. Usually, sorbent plays a very important role in selectivity and sensitivity of the MEPS method.
Molecularly imprinted polymers (MIPs) are attractive synthetic receptors that can specifically capture the target molecule(Hassanzadeh et al. 2016). For preparation of MIPs, the target compound (template) with functional monomer and cross-linker agent are polymerized. After polymerization, the template is removed from the polymeric structure leaving microcavities that are complementary to the template molecule in shape, size and functional groups. Regarding these features, MIPs are able to rebind the template molecule and it has high affinity and selectivity.
In recent years, due to advantages of MEPS over conventional sample preparation and high selectivity and low cost of MIPs, the combination of MEPS and MIPs has been welcomed as a simple, rapid, selective, sensitive, user-friendly and eco-friendly method for sample cleanup and analyte preconcentration in biological(Asgari et al. 2017), environmental(Prieto et al. 2011) and food samples(Fumes et al. 2016).
In this study, we developed a novel approach based on MIP- MEPS for efficient sample cleanup and analyte preconcentration prior to analysis with UV/Vis. The prepared MIP was coated on the surface of glass powder by sol–gel process which provides an inexpensive alternative, simple and direct for the extraction and determination of quercetin. The important factors that affected
the efficiency of MIP- MEPS were investigated and optimized. Finally, the method was used for the determination of quercetin in real samples.