Analytical MethodsSolid-phase extraction of flavonoids in honey samples using carbamate-embedded triacontyl-modified silica sorbent
Introduction
In honey samples, flavonoids represent the most important active constituents, which have anti-aging, anti-tumor, antioxidant, anti-inflammatory, antibacterial and antiviral effects (Alvarez-Suarez et al., 2013, Alvarez-Suarez et al., 2010, Alvarez-Suarez et al., 2010, Alvarez-Suarez et al., 2012, Prasain et al., 2004). Types and contents of flavonoids in honey are important indices, reflecting its inherent quality. A good method is essential for determination of types and concentrations of flavonoids in honey sample to evaluate the quality of targeted honey (Jasicka-Misiak et al., 2012, Sergiel et al., 2014). However, the concentrations of flavonoids in real honey samples are extremely low, and the interferences of matrix are complex, which hinders direct analysis of flavonoids in honey. So, it is very important and necessary to develop a reliable method for the analysis of flavonoid contents in real honey samples.
Due to the low solubility of flavonoids in aqueous medium, various organic solvents such as methanol, ethanol, acetone, and ethyl acetate have been commonly used as the extraction solvents. Many extraction methods are used, including heat reflux extraction (HRE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), and ultrasound-assisted extraction (UAE), etc (Chen et al., 2007, Stalikas, 2007, Xiao et al., 2008, Xu et al., 2013). However, these methods usually require large amounts of solvent and long extraction time (Nam, Zhao, Lee, Jeong, & Lee, 2015). Solid-phase extraction (SPE) plays an important role in sample pretreatment, which has some advantages, such as high enrichment factor, rapid separation, low consumption of reagents, and easy operation. Furthermore, the sorbent can be recycled (Behbahani et al., 2013, Chen et al., 2007, Guo et al., 2013, Liu et al., 2015, Liu et al., 2015, Tahmasebi and Yamini, 2012, Vidal et al., 2012). Therefore, SPE has been developed rapidly for the trace analysis of complex sample matrices (Liu et al., 2015, Nam et al., 2015, Pardo et al., 2014, Tian et al., 2013, Xiao et al., 2014). The type of sorbent material is the soul of SPE determining the selectivity, sensitivity, enrichment factor, and recovery of the method (Wang, Gao, Zang, Li, & Ma, 2012). So far, various SPE sorbents have been developed and widely used in many fields successfully solving lots of practical problems (Jak et al., 2004, Lemos et al., 2007, Rao et al., 2004). Among them, silica C18 is the most widely used sorbent, which has excellent performance in the extraction of hydrophobic compounds. Through our experiments, we disappointedly found commercial silica C18 sorbent cannot achieve efficient extraction of flavonoids. Consequently, to develop a new SPE sorbent is meaningful and necessary focusing on the efficient extraction of flavonoids from honey samples.
The disadvantage of silica C18 may be ascribed to its total reliance on hydrophobicity. The absence of polar groups in commercial silica C18 sorbents, however, hampers the hydrophobic interaction between sorbent and flavonoids with multiple polar groups. To that end, we put forward a novel absorbing material of carbamate-embedded triacontyl modified silica sorbent (Sil-CBM-C30). The ultra-long triacontyl (C30) renders sorbent higher lipophilicity compared to C18. The carbamate polar group is expected to not only improve the wettability of silica material, but also endow polarity-related interactions, such as hydrogen bonding and π–π interactions. Consequently, the purpose of this study is to verify the extraction behavior of the novel Sil-CBM-C30 sorbent. Myricetin, quercetin, luteolin, kaempferol and isorhamnetin are selected as the model analytes to evaluate its adsorption capacities. Meanwhile, the comparisons between Sil-CBM-C30 and commercial silica C18 are to be conducted to reveal their differences of extraction performances.
Section snippets
Reagents and materials
The parameters of porous silica particles were 15 μm (average diameter), 16 nm (pore size), 150 m2 g−1 (specific surface area) and they were synthesized using polymerization-induced colloid aggregation method in our laboratory. The volume of SPE cartridges was 3 mL and pore size of polyethylene sieve plate was 5 μm, which were all purchased from Shenzhen Biocomma Biotech Corp. (Shenzhen, China). The model of Welchrom®C18 SPE cartridge was 200 mg sorbent in 3 mL cartridge and they were purchased from
Characterization of the sorbent
As confirmed by elemental analyses of Sil-CBM-C30, the contents of carbon, nitrogen and hydrogen are 5.95%, 0.38% and 1.24%, respectively. The contents of carbon and nitrogen are attributed to the bonding of carbamate and C30 to silica. According to the contents of carbon and nitrogen to calculate the C30 bonding content, respectively, the calculated data are not the same. The value calculated from nitrogen is higher than that from carbon, which is attributed to that the reaction between
Conclusions
In this paper, a novel Sil-CBM-C30 material was developed and successfully applied as efficient sorbents. To evaluate the extraction performance of the resultant sorbents, five flavonoids were selected as the test analytes. From the results of comparative experiments, the extraction performance of Sil-CBM-C30 apparently surpassed that of commercial C18 sorbents. Sil-CBM-C30 material sorbents showed excellent capability for the extraction of flavonoids, which was attributed to the hydrophobic,
Acknowledgements
We acknowledge that financial supports from the National Natural Science Foundation of China (21475142), the Funds for Distinguished Young Scientists of Gansu (1506RJDA281) and the top priority program of “One-Three-Five” Strategic Planning of Lanzhou Institute of Chemical Physics, CAS.
References (27)
- et al.
Phenolics from monofloral honeys protect human erythrocyte membranes against oxidative damage
Food and Chemical Toxicology
(2012) - et al.
Synthesis and characterisation of nano structure lead (II) ion-imprinted polymer as a new sorbent for selective extraction and preconcentration of ultra trace amounts of lead ions from vegetables, rice, and fish samples
Food Chemistry
(2013) - et al.
Simultaneous determi nation of 15 flavonoids in Epimedium using pressurized liquid extraction and high-performance liquid chromatography
Journal of Chromatography A
(2007) - et al.
Simultaneous determination of five estrogens and four androgens in water samples by online solid-phase extraction coupled with high-performance liquid chromatography–tandem mass spectrometry
Journal of Chromatography A
(2013) - et al.
Phenolic compounds and abscisic acid as potential markers for the floral origin of two Polish unifloral honeys
Food Chemistry
(2012) - et al.
Application of polyurethane foam as a sorbent for trace metal pre-concentration
Spectrochimica Acta Part B: Atomic Spectroscopy
(2007) - et al.
Double carboxyl silicane modified graphene oxide coated silica composite as sorbent for solid-phase extraction of quarternary alkaloids
Analytical Methods
(2015) - et al.
Quercetin-imprinted chromatographic sorbents revisited: Optimization of synthesis and rebinding protocols for application to natural resources
Journal of Chromatography A
(2014) - et al.
Mass spectrometric methods for the determination of flavonoids in biological samples
Free Radical Biology Medicine
(2004) - et al.
Characterisation of honeys according to their content of phenolic compounds using high performance liquid chromatography/tandem mass spectrometry
Food Chemistry
(2014)
Facile synthesis of new nano sorbent for magnetic solid-phase extraction by self-assembling of bis-(2,4,4-trimethyl pentyl)-dithiophosphinic acid on Fe3O4@Ag core@shell nanoparticles: Characterization and application
Analytica Chimica Acta
Ionic liquid-function alized silica for selective solid-phase extraction of organic acids, amines and aldehydes
Journal of Chromatography A
Graphene-based solid-phase extraction combined with flame atomic absorption spectrometry for a sensitive determination of trace amounts of lead in environmental water and vegetable samples
Analytica Chimica Acta
Cited by (46)
An updated review of extraction and liquid chromatography techniques for analysis of phenolic compounds in honey
2022, Journal of Food Composition and AnalysisSeparation of soy isoflavones from soy sauce residue by MIL-100(Fe)
2022, Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences