# Fabric Sol-gel Phase Sorptive Extraction Technique: A Review
## 4 Applications of Fabric Phase Sorptive Extraction  
Since the presentation of FPSE in 2014 as a novel sample pretreatment technique prior to high performance liquid chromatography for the determination of selected estrogens, various applications for organic and inorganic analytes have been reported in the literature. All reported FPSE methods are presented briefly in Table 4, containing information about all FPSE procedures for sample preparation, the main parameters with the analytical performance characteristics, as well as the analytes and the types of samples. Most of the reported methods were applied for drugs and pharmaceuticals using HPLC or UPLC coupled with DAD, MS or MS/MS. Figure 3: SEM images of (**a**) uncoated cellulose at 100\(\times\) magnification; (**b**) PEG coated FPSE media at 100\(\times\) magnification; (**c**) uncoated cellulose at 500\(\times\) magnification; (**d**) PEG coated FPSE media at 500\(\times\) magnification. Reproduced from [18] with permission of Elsevier. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{Analytical Technique} & \multicolumn{2}{c}{**Sol-grid**} & \multirow{2}{*}{**Fabric**} &  
In the first FPSE application, [PERSON] et al. (2017) developed a FPSE-HPLC-FLD method for selected estrogen (BPA, E2 and EE2) determination in urine and environmental (ground, river and drinking) water samples by HPLC coupled with an FLD detection system. The estrogens which are medium polar compounds, were extracted using a medium polar FPSE medium prepared by sol-gel PTHF coated on a cellulose substrate. The FPSE procedure took place in a glass vial containing the target analytes along with the coated FPSE medium and followed by magnetic stirring for an efficient adsorption. A volume of 500 \(\mu\)L of methanol was used to elute the analytes from the fabric. After 5 min centrifugation and filtration of the eluent, it was injected into the HPLC system. The proposed method presented good analytical characteristics as shown in Table 4.  
[PERSON] et al. (2016) used the FPSE technique for the determination of selected benzodiazepines, APZ, BRZ, DZP, and LRZ in blood serum by HPLC-DAD. Benzodiazepines are commonly prescribed drugs with sedative, anti-depressive, tranquilizing, hypnotic, and anticonvulsant properties. Their determination in biological fluids is of great importance not only in clinical assays, but also in forensics and toxicological studies. Three different FPSE sorbents were examined; the sol-gel PEG and sol-gel PTHF coated on cellulose substrates and the sol-gel PDMDPS coated on a polyester substrate. The optimization experiments showed that sol-gel PEG was the most appropriate FPSE medium to extract benzodiazepines. After conditioning the FPSE medium, it was inserted into a glass vial containing the sample solution along with a Teflon-coated magnetic stirrer. The sample was stirred for about 20 min and then, elution followed by immersing the FPSE medium into another vial containing an elution solvent system of acetonitrile: methanol (50:50 \(v/v\)). The elution time was 10 min. The extracted benzodiazepines were analyzed directly in the HPLC instrument with photodiode array detector (DAD) operated at 240 nm. In this work, the FPSE sol-gel PEG medium was introduced directly into the matrix without prior deproteinization, resulting in the minimization of sample preparation steps as well as in the elimination of probable errors during the sample pretreatment procedure. However, it is not mentioned if the FPSE medium is replaced for each analytical cycle as it could become clogged from complex matrices like blood, milk, etc. [PERSON] et al. (2016) developed a simple, fast and sensitive method for the quantification of natural and synthetic steroid hormones, androgens and progestogens by coupling sol-gel PTHF coated FPSE medium with UHPLC-MS/MS.