# Fabric Sol-gel Phase Sorptive Extraction Technique: A Review
## 4 Applications of Fabric Phase Sorptive Extraction
Steroid hormones have been widely used in both human and veterinary medicine and their effective determination in water samples is of crucial importance for the assessment of the concentration levels and their related ecological risk. A UHPLC system coupled to a triple quadrupole detector was used for the quantification of selected androgens and progestogens, NORET, NOR, MGA, PRO, BOL, NAN, ADTD, DHEA, TES, and AND, in tap water and wastewater treated with different techniques as well as in urine samples. The FPSE procedure took place in glass vials with a Teflon coated magnetic stirrer. After submerging the FPSE medium into the sample solution (water or urine samples), it was stirred at 1000 rpm, with an extraction efficiency maximum achieved in 20 min and elution in 3 min. Methanol in a small quantity, approximately 0.75 mL, was used as the elution solvent. The recovery of the developed method ranged from 65.9% to 121.2%. Both repeatability values (intra-and inter-day) were in all type of samples lower than 20%. The FPSE technique was also applied for the determination of four non-steroidal anti-inflammatory drugs, namely: IBU, NAP, KET, and DIC, in environmental water samples in combination with GC-MS ([PERSON] et al., 2016). Up to now, this is the only method that associates FPSE with the GC-MS analytical technique. Three different sorbents, sol-gel PDMDPS on a polyester substrate, sol-gel PTHF and sol-gel PEG on cellulose substrates, were investigated. The sol-gel PEG coated FPSE medium was found to be the most efficient one for the NSAIDs analytes independently of the pH and the ionic strength. The FPSE extraction was performed in a glass screw-cap vial by immersing the FPSE medium into the sample solution with the help of a tweezers. The solution was magnetically stirred at 500 rpm for 2 h. Ethyl acetate was used to elute the analytes with an elution time of 15 min. For the elution of the compounds, the FPSE medium was introduced into a 1 mL sample of ethyl acetate for 15 min. Subsequently, the FPSE medium was removed from the vial and the extract was evaporated to dryness by nitrogen stream. The residue was reconstituted into a 100 \(\upmu\)L insert with 40 \(\upmu\)L of ethyl acetate and 10 \(\upmu\)L of MTBSTFA. The derivatization reaction took place in an oven at 60 \({}^{\circ}\)C for 60 min. After cooling to room temperature, the extract was ready for GC-MS analysis. The total runtime was 38.2 min. The instrument was a gas chromatograph equipped with a capillary column, combined with a quadrupole mass spectrometer. Recoveries were in the range of 82%-116% and RSDs between 3.5% and 18%. [PERSON] et al. [18] reported a facile sol-gel synthesis to incorporate short-chain PEG into the sol-gel matrix and anchor the growing sol-gel PEG network to a flexible hydrophilic cellulose substrate, resulting in a homogenous and ultra-thin, highly polar FPSE medium. The sol-gel PEG FPSE medium was applied for the first time to assess the concentration of amphenicol drugs in raw milk samples. The extraction of amphenicols residues, TAP, FF, and CAP from raw milk followed by HPLC-DAD was investigated. The sol-gel PEG FPSE medium together with an aliquot of milk sample (0.5 g) with 500 \(\upmu\)L DI water (or 0.5 g milk spiked with 500 \(\upmu\)L of amphenicols standard solution) was magnetically stirred for 30 min. Methanol was used as the elution solvent and elution was performed for 10 min. The extract was centrifuged for 15 min and filtered prior to HPLC. The FPSE medium could be reused by washing with 2 mL acetonitrile: methanol (50:50 \(v/v\)) for 5 min. The proposed method showed good linearity and sensitivity. The precision was evaluated within a day and between days and ranged from 1.0%-10.7% and 7.6%-14.0% for TAP, FF, and CAP respectively. In this study, no protein precipitation or solvent evaporation and sample reconstitution were necessary, thanks to the FPSE technique which reduces the sample preparation steps, ending up in a short extraction equilibrium time pretreatment technique. [PERSON] et al.