# Fabric Sol-gel Phase Sorptive Extraction Technique: A Review
## 4 Applications of Fabric Phase Sorptive Extraction
[24] developed a simple FPSE-HPLC-UV method for the isolation of three sulfonamides, SMTH, SIX, and SDMX, from untreated milk samples. The highly polar sol-gel PEG coated on a cellulose substrate was used for the extraction of the selected sulfonamides. The FPSE procedure was the same as the previous method [18]. After the extraction, the FPSE medium was first inserted into a clean vial with 250 \(\upmu\)L MeOH for 8 min and then into another vial with 250 \(\upmu\)L ACN for a further 5 min for the elution of the analytes. The resulting solution was filtered prior to HPLC injection to remove any particulate matter. The same medium could be reused up to 30 times without any significant loss in extraction performance. The precision of the method was estimated for within-day repeatability and between-day repeatability with RSDs ranging from 5.6% to 6.7% respectively. The flexibility of the FPSE medium facilitates the easy insertion of the fabric into the sample solution, resulting in the fast extraction of the analytes. In addition, neither prior pretreatment of the sample was carried out including protein precipitation, nor solvent evaporation was performed followed by sample reconstitution. Another application from the same group, using the sol-gel PEG FPSE medium on cellulose substrate and offering the same advantages regarding the reduction of sample preparation steps, was reported for the extraction of four penicillin antibiotic residues (PENG, CLO, DICLO, and OXA) from cows' milk [37]. Sol-gel PEG FPSE medium was adopted for method optimization and validation among sol-gel C\({}_{18}\) and sol-gel PEG-PPG-PEG all coated on cellulose substrates, as the first one provided better absolute recovery values ranging between 22% and 58%, than 5% provided by the two other sorbent FPSE media. FPSE has been also employed for the preconcentration of four endocrine disruptor alkylphenol molecules, namely, 4-TBP, 4-SBP, 4-TAP, and 4-CP in aqueous and soil samples followed by HPLC-UV detection [33]. The sol-gel PTHF on a cellulose substrate was selected for the extraction procedure. The sample was stirred at a speed of 1000 rpm for an extraction time of 25 min and then elution with methanol followed, for 6 min. The eluent was centrifuged for 5 min, filtered with a syringe filter and finally it was injected into the HPLC system. Relative recoveries were satisfactory and ranged from 91% to 97% in aqueous samples, while for soil and sludge samples they were lower between 89% and 91%, probably due to the complicated sample matrix. Another interesting application of FPSE using UPLC-MS(QqQ) is for migration analysis of several non-volatile additives in food packaging materials [34]. Three different sol-gel coated FPSE media with diverse polarities were investigated: sol-gel PDMS (non-polar), sol-gel PTHF (medium polar) and sol-gel PEG (highly polar) all coated on cellulose substrates as well as several extraction parameters were optimized. The proposed method was applied for 18 plastic additives: eight plasticizers (DEP, TBC, DBM, TBoAC, TXIB, DBP, 2 EHadip, 2 EHSeb), five antioxidants (IRGA38, TOPAC, IRGA1076, IRGA168 and IRGA1010), four UV absorbers (TINU326, CHIMA81, TINU327, CYA1084) and one antistatic agent (HAA C12). Three different food simulants with concentration of 300 ug\(\cdot\)L\({}^{-1}\) of the target analytes: A, ethanol 10%; B, acetic acid 3%, and D1, ethanol 50% were prepared to optimize the FPSE protocol. Better retention was achieved using sol-gel PTHF and sol-gel PEG coated FPSE media with analytes dissolved in ethanol 10% or acetic acid 3%. For these simulants, the retention efficiency was over 75%. On the other hand, they were slightly retained using ethanol 50% as simulant. The extraction of these compounds with the low polar sol-gel PDMS was, as expected, lower than the other FPSE media, especially for DEP. Generally, compounds with low logP values proved to have higher enrichment factors, especially with sol-gel PTHF and sol-gel PEG FPSE media.