Novel nanofibrous sorbents for the extraction and determination of resveratrol in wine
Graphical abstract
Introduction
Polyphenolic compounds present in grapes have significant health benefits [1] since they possess antioxidant activity, which plays a role in preventing and repairing damage caused by oxidative stress. Resveratrol and its effects on human body were widely reported [[2], [3], [4]]. It has anti-inflammatory and antioxidant [3] as well as anticancer effects [5]. It helps to cure neurodegenerative processes, ischema reperfusion, and metabolic diseases [6,7]. These health-related properties led to development of a broad spectrum of analytical methods enabling determination of resveratrol in various products such as wine, berries, and grapes [8,9]. For example, some of these methods used direct injection of wine in absence of extraction procedure [[10], [11], [12]]. However, this simple approach decreased the sensitivity and selectivity of resveratrol determination in wine matrix. Most of the alternative analytical methods included sample pretreatment for matrix removal, and increase in selectivity and sensitivity. Among them, conventional procedures such as solid phase extraction (SPE) [13,14] and liquid-liquid extraction (LLE) [14,15] were favored. These time-consuming methods required multiple steps and often consumed large volume of organic solvents. Modern approaches such as solid phase microextraction (SPME) were also used [9]. For example, the miniaturized solvent-free SPME method can be used as an alternative to conventional sample pretreatment methods [16]. Yet, SPME is time-consuming and demands high operator skills. Vinas et al. published a paper in 2008 describing the determination of resveratrol in wines, musts, and juices that included SPME followed by HPLC [17]. They compared two techniques, SPME and stir bar extraction. The complete procedure including extraction and desorption required more than 40 min. Aresta et al. tested different types of SPME fibers. Their extraction procedure was 45 min long [9].
Recent trends in sample pretreatment focus on saving solvents, time, and operator skills. The on-line extraction methods meet these requirements. Several alternative extraction sorbents coupled on-line to SPE-HPLC currently exist including molecularly imprinted polymers, different types of polymers, monolithic columns, and nanofibrous materials. Only one paper describing the determination of resveratrol using the on-line SPE HPLC method was published. Its authors used the molecularly imprinted polymers for the extraction of resveratrol from the Polygonum Cuspidatum, a plant used in the traditional Chinese medicine [18]. To our best knowledge, no method describing the on-line extraction of resveratrol from red wine has been published. Table 1 summarizes the reported methods for the determination of resveratrol in wine using HPLC and classical off-line extraction.
In this report, we present a new on-line SPE-UHPLC method using different types of nanofibrous materials as sorbents for the determination of resveratrol in wine. The fibrous materials applied were polyamide 6 (PA6) and polyacrylonitrile (PAN) nanofibers, composite polycaprolactone nanofibers placed on polycaprolactone microfibrous scaffold (nPCL/μPCL), and poly(vinylidene difluoride) nanofibers on polycaprolactone microfibrous scaffold (nPVDF/μPCL). We also introduced a novel sorbent, dopamine-coated nPCL/μPCL (PCL-D). Results obtained with these fibrous sorbents were compared with a commercial C18 monolithic sorbent. Method using the fibers was most effective for sample clean-up and recovery. Finally, our method using nPVDF/μPCL composite material for on-line SPE was validated and applied to real-life samples - wines.
Section snippets
Chemicals and materials
All used chemicals are summarized in the supplementary materials (Section S1 - Chemicals, materials).
Instrumentation and software
The meltblown system (Laboratory equipment J&M Laboratories, USA) equipped with small needleless electrospinning was used for the preparation of the composite fibers. Detailed description of the process was published elsewhere [19]. A scheme of device is presented in supplementary material (Fig. S1). Production of nanofibers using electrospinning is green-marked while production of microfibers
Stability of the fibrous polymers in solvents
Long-term stress stability of all our micro/nanofibrous materials was explored before their use. The long-term stability was tested for 24 h at a temperature of 25 °C while the stress stability was tested for 15 min in an ultrasonic bath at a temperature of 35 °C. Detailed description of the procedures was published elsewhere [19,21]. PCL based sorbents were not stable in organic solvents at higher temperature. Therefore, the column oven temperature for the analysis was set to 20 °C.
Conclusion
Five types of nanofibrous or microfibrous polymers were tested and compared as sorbents for the on-line SPE-UHPLC extraction of resveratrol from red wines. Two different versions of the PCL were among the tested materials and their extraction properties were evaluated. Compared to nPVDF/μPCL and nPCL/μPCL polymers, dopamine coated fibers featured an enhancement in retention of polar impurities present in the red wines. nPVDF/μPCL exhibited a similar clean-up potential as nPCL/μPCL. However,
Acknowledgements
Financial support of the GACR project no. 17-08738S and EFSA-CDN project (No. CZ.02.1.01/0.0/0.0/16_019/0000841) co-funded by ERDF is gratefully acknowledged. M. H. acknowledges the financial support of specific research of Charles University no. SVV 260 412. The result was obtained through the financial support of the Ministry of Education, Youth and Sports of the Czech Republic and the European Union (European Structural and Investment Funds - Operational Program Research, Development and
References (22)
- et al.
Centrifugal partition chromatography followed by HPLC for the isolation of cis-epsilon-viniferin, a resveratrol dimer newly extracted from a red Algerian wine
Food Chem.
(2009) - et al.
Analysis of phenolic constituents of biological interest in red wines by high-performance liquid chromatography
J. Chromatogr. A
(2001) - et al.
Trans-resveratrol in wines from the Canary Islands (Spain). Analysis by high performance liquid chromatography
Food Chem.
(2002) - et al.
Optimisation of sample preparation for the determination of trans-resveratrol and other polyphenolic compounds in wines by high performance liquid chromatography
Anal. Chim. Acta
(2001) - et al.
Separation of phenolic compounds by high-performance liquid chromatography with absorbance and fluorimetric detection
J. Chromatogr. A
(2001) - et al.
Review of geometries and coating materials in solid phase microextraction: opportunities, limitations, and future perspectives
Anal. Chim. Acta
(2017) - et al.
A comparison of solid-phase microextraction and stir bar sorptive extraction coupled to liquid chromatography for the rapid analysis of resveratrol isomers in wines, musts and fruit juices
Anal. Chim. Acta
(2008) - et al.
A comparison study of nanofiber, microfiber, and new composite nano/microfiber polymers used as sorbents for on-line solid phase extraction in chromatography system
Anal. Chim. Acta
(2018) - et al.
Electrospun nanofiber polymers as extraction phases in analytical chemistry – the advances of the last decade
Trends Anal. Chem.
(2019) - et al.
Nanofiber polymers as novel sorbents for on-line solid phase extraction in chromatographic system: a comparison with monolithic reversed phase C18 sorbent
Anal. Chim. Acta
(2018)