Browsing by Author "Chocholousova Havlikova Lucie"
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- ItemA comparison study of nanofiber, microfiber, and new composite nano/microfiber polymers used as sorbents for on-line solid phase extraction in chromatography system(Elsevier Ltd., 2018) Hakova Martina; Chocholousova Havlikova Lucie; Chvojka Jiří; Erben Jakub; Solich Petr; Švec FrantišekThree different approaches has been used to obtain nano/micro fibers and their diversity and extraction properties were examined. The effect of their structure on stability in an ultra-high-performance liquid chromatography (UHPLC) system during on-line SPE procedure was monitored. Five types of various nano/micro fiber polymers were used as sorbents: polyamide 6 nanofibers, polyvinylidene difluoride nanofibers, polyethylene microfibers, and two new polycaprolactone microfiber/nanofiber and polycaprolactone microfibers/polyvinylidene difluoride nanofibers composite polymers. The fiber polymers were filled in a cartridge directly connected to the UHPLC system and tested. For each polymer, the optimal conditions of the on-line extraction were found and potential applicability on real samples was tested. The determination of ochratoxin A (OTA) in beer matrix was chosen as a case study. Relevant factors such as the mechanical and chemical stability of the nano/microfibers, filling the cartridges, fiber reusability and the possibility and the repeatability of all processes were involved in the proposed study. A new nano/micro composite sorbent consisting of polycaprolactone microfibers/polyvinylidene difluoride nanofibers was chosen as the most suitable sorbent for the on-line extraction of OTA from a beer matrix. The tested validation parameters had the value of intra-day precision lower than 1.48%, linearity in the range from 0.5 to 100 μg L−1 with r2 ≥ 0.9999 for standard and matrix calibration curve, and recovery in the range 99.1–103.9% at five concentration levels. Long-term precision evaluated for 31 analyses over the period of three months did not exceed 2.9% RSD. It confirmed the column reusability and perfect stability of nano/micro composite sorbent in the presence of organic solvents and after repeated injection of a complex beer matrix.
- ItemNanofiber polymers as novel sorbents for on-line solid phase extraction in chromatographic system: A comparison with monolithic reversed phase C18 sorbent(Elsevier Ltd, 2018) Hakova Martina; Chocholousova Havlikova Lucie; Chvojka Jiří; Švec František; Solich Petr; šatinský Dalibor
- ItemAn on-line coupling of nanofibrous extraction with column-switching high performance liquid chromatography: A case study on the determination of bisphenol A in environmental water samples(2018) Hakova Martina; Chocholousova Havlikova Lucie; Chvojka Jiří; Solich Petr; šatinský DaliborPolyamide 6 nanofiber polymers were used as modern sorbents for on-line solid phase extraction (SPE) coupled with liquid chromatography. The on-line SPE system was tested for the determination of bisphenol A in river water samples. Polyamide nanofibers were prepared using needleless electrospinning, inserted into a mini-column cartridge (5 × 4.6 mm) and coupled with HPLC. The effect of column packing and the amount of polyamide 6 on extraction efficiency was tested and the packing process was optimized. The proposed method was performed using a 50-µL sample injection followed by an on-line nanofibrous extraction procedure. The influence of the washing mobile phase on the retention of bisphenol A during the extraction procedure was evaluated. Ascentis® Express C18 (10 cm × 4.6 mm) core-shell column was used as an analytical column. Fluorescence detection wavelengths (λex = 225 nm and λem = 320 nm) were used for identification and quantification of Bisphenol A in river waters. The linearity was tested in the range from 2 to 500 µg L−1 (using nine calibration points). The limits of detection and quantification were 0.6 and 2 µg L−1, respectively. The developed method was successfully used for the determination of bisphenol A in various samples of river waters in the Czech Republic (The Ohře, Labe, Nisa, Úpa, and Opava Rivers).
- ItemPoly-&epsi-caprolactone Nanofibrous Polymers: A Simple Alternative to Restricted Access Media for Extraction of Small Molecules from Biological Matrixes(ACS Publications, 2020) Raabová Hedvika; Hakova Martina; Chocholousova Havlikova Lucie; Erben Jakub; Chvojka Jiří; Solich Petr; Švec František; Šatínský Dalibor
- ItemPolycaprolactone Composite Micro/Nanofibrous Material as an Alternative to Restricted Access Media for Direct Extraction and Separation of Non-Steroidal Anti-Inflammatory Drugs from Human Serum Using Column-Switching Chromatography(MDPI, 2021) Raabová Hedvika; Chocholousova Havlikova Lucie; Erben Jakub; Chvojka Jiří; Švec František; Šatínský Dalibor
- ItemTesting of nylon 6 nanofibers with different surface densities as sorbents for solid phase extraction and their selectivity comparison with commercial sorbent(2018) Háková Martina; Raabová Hedvika; Chocholousova Havlikova Lucie; Chocholouš Petr; Chvojka Jiří; Šatinský DaliborNylon 6 nanofibers were tested for their ability to serve as a sorbent for solid phase extraction (SPE). The regular nanostructure providing a great sorption area and amidic functionality should lead to the assumption that nylon 6 nanofibers could be used as a novel sorbent with great potential for sample pre-treatment. However, due to the substantial differences between classical particle sorbents used for solid phase extraction and nanofibers, it is necessary to evaluate this novel approach. This article describes three types of laboratory fabricated nylon 6 nanofibers with different surface density (5.04 g m−2, 3.90 g m−2 and 0.75 g m−2) and corresponding surface areas for solid phase extraction of several groups of compounds with different structural and physicochemical properties (parabens, steroids, flavonoids and pesticides). The nanofibers were created by needleless electrospinning. Extraction columns were manually packed in classic 1- or 3-mL plastic syringe cartridges with 26–30 mg of nanofibers and the column bed was sealed with polypropylene frits. The SPE procedure followed a typical five-step protocol and the collected eluates were analyzed by HPLC with UV detection. Extraction recovery was used as a parameter to evaluate the behavior of the analytes within the SPE process. Under this set condition, the recovery of the SPE process ranged from 23.1% to 125.8%. SPE showed good repeatability (0.58–11.87% RSD) and inter-day reproducibility (3.86–9.79% RSD). The achieved results were compared with SPE using a classic particle sorbent column. Good mechanical and chemical stability of nanofibers was proved. Scanning electron microscope was used for the evaluation of morphological changes in nanostructure. Nylon 6 nanofibers proved being a cost-effective sorbent for repeated use in SPE. Nylon 6 nanofibers have great potential in miniaturized SPE enabling users to overcome troubles with high back-pressure.