An Insight on Salting-out Assisted Liquid-Liquid Extraction for Phytoanalysis

Determination of bisphenols in beeswax based on sugaring out-assisted liquid-liquid extraction: Method development and application in survey, recycling and degradation studies

The methodology of sugaring out-assisted liquid-liquid extraction (SULLE) coupled with high-performance liquid chromatography-fluorescence detection was devised for quantifying bisphenol A (BPA) and bisphenol B (BPB) in beeswax. The effectiveness of SULLE was methodically explored and proved superior to the salting out-assisted liquid-liquid extraction approach for beeswax sample preparation. The analytical performance underwent comprehensive validation, revealing detection limits of 10 μg/kg for BPA and 20 μg/kg for BPB. The method developed was employed to analyse commercial beeswax (n = 15), beeswax foundation (n = 15) and wild-build comb wax (n = 26) samples. The analysis revealed BPA presence in four commercial beeswax samples and three beeswax foundation samples, with the highest detected residue content being 88 ± 7 μg/kg. For BPB, two beeswax foundation samples were positive, with concentrations below the limits of quantification and 85 ± 4 μg/kg, respectively. No bisphenols were detected in wild-build comb wax. Furthermore, the bisphenol removal efficacy of two recycling methods-boiling in water and methanol extraction-was assessed. The findings indicated that after four recycling cycles using water boiling, 9.6% of BPA and 29.2% of BPB remained in the beeswax. Whereas methanol extraction resulted in approximately 7% residual after one recycling process. A long-term study over 210 days revealed the slow degradation of bisphenols in comb beeswax. This degradation fitted well with a first-order model, indicating half-lives (DT50) of 139 days for BPA and 151 days for BPB, respectively. This research provides the first report on bisphenol contamination in beeswax. The low removal rate during the recycling process and the gradual degradation in beeswax underscore the significance of bisphenol contamination and migration in bee hives along with their potential risk to pollinators warranting concern. Furthermore, the developed SULLE method shows promise in preparing beeswax samples to analyse other analytes.

A Simple High-Throughput Field Sample Preparation Method Based on Matrix-Induced Sugaring-Out for the Simultaneous Determination of 5-Hydroxymethylfurfural and Phenolic Compounds in Honey

In the present work, a high-throughput field sample preparation method was reported for the simultaneous determination of 5-hydroxymethylfurfural and phenolic compounds in honey. Combining a simple and green homogenous liquid−liquid extraction, matrix-induced sugaring-out, with the use of a 96-deepwell plate and multichannel pipette, the proposed method showed its merits in instrument-free and high-throughput preparation. Due to the high-throughput property, the parameters of the method were rapidly and systematically studied using a constructed 4 × 2 × 4 × 3 array (sample amount × ratio of ACN:H2O × standing time × replicates) in a 96-deepwell plate. Analytical performance was fully validated, and the limits of detection and limits of quantification were in the range of 0.17−1.35 μg/g and 0.51−4.14 μg/g, respectively. Recoveries were between 83.98 and 117.11%, and all the precisions were <5%. Furthermore, the developed method was successfully applied in the outdoor preparation of commercial honey samples and the in-field preparation of raw honey samples in apiary. The current work presented a simple, rapid, and high-throughput method for the field sample preparation of honey and provides a valuable strategy for the design of field and on-site sample preparation.

Exploring Various Techniques for the Chemical and Biological Synthesis of Polymeric Nanoparticles

Nanoparticles (NPs) have remarkable properties for delivering therapeutic drugs to the body’s targeted cells. NPs have shown to be significantly more efficient as drug delivery carriers than micron-sized particles, which are quickly eliminated by the immune system. Biopolymer-based polymeric nanoparticles (PNPs) are colloidal systems composed of either natural or synthetic polymers and can be synthesized by the direct polymerization of monomers (e.g., emulsion polymerization, surfactant-free emulsion polymerization, mini-emulsion polymerization, micro-emulsion polymerization, and microbial polymerization) or by the dispersion of preformed polymers (e.g., nanoprecipitation, emulsification solvent evaporation, emulsification solvent diffusion, and salting-out). The desired characteristics of NPs and their target applications are determining factors in the choice of method used for their production. This review article aims to shed light on the different methods employed for the production of PNPs and to discuss the effect of experimental parameters on the physicochemical properties of PNPs. Thus, this review highlights specific properties of PNPs that can be tailored to be employed as drug carriers, especially in hospitals for point-of-care diagnostics for targeted therapies.

Rapid and simultaneous determination of trigonelline, caffeine, and chlorogenic acid in green coffee bean extract

A simple, inexpensive, and rapid method for simultaneous determination of trigonelline, caffeine, and chlorogenic acid from green coffee bean extract was proposed based on salting-out assisted liquid-liquid extraction, using QuEChERS salt and acetonitrile followed by UV-Vis analysis. The proposed method represents acceptable linearity for trigonelline (0.9978), caffeine (0.9995), and chlorogenic acid (0.9996) with excellent correlation (0.93 and 0.83) for trigonelline and caffeine, respectively, when compared to RP-HPLC-DAD. The proposed method could be used in coffee industries for quality control and geographical origin traceability studies of green coffee samples.

LC-ESI/LTQOrbitrap/MS Metabolomic Analysis of Fennel Waste (Foeniculum vulgare Mill.) as a Byproduct Rich in Bioactive Compounds

Food industries produce a high amount of waste every year. These wastes represent a source of bioactive compounds to be used to produce cosmetic and nutraceutical products. In this study, the possibility to retrain food waste as a potential source of bioactive metabolites is evaluated. In particular, metabolite profiles of different parts (bulb, leaves, stems and little stems) of fennel waste were investigated by liquid chromatography coupled with mass spectrometry (LC-ESI/LTQ Orbitrap MS). To discriminate the different plant parts, a Multivariate Data Analysis approach was developed. Metabolomic analysis allowed the identification of different metabolites mainly belonging to hydroxycinnamic acid derivatives, flavonoid glycosides, flavonoid aglycons, phenolic acids, iridoid derivatives and lignans. The identification of compounds was based on retention times, accurate mass measurements, MS/MS data, exploration on specific metabolites database and comparison with data reported in the literature for F. vulgare. Moreover, the presence of different oxylipins was relieved; these metabolites for the first time were identified in fennel. Most of the metabolites identified in F. vulgare possess anti-inflammatory, antioxidant and/or immunomodulatory properties. Considering that polyphenols are described to possess antioxidant activity, spectrophotometric tests were performed to evaluate the antioxidant activity of each part of the fennel.

High-throughput subzero-temperature assisted homogenous liquid-liquid extraction for the fast sample preparation of multiple phenolic compounds in propolis

In the present study, a high-throughput homogenous liquid-liquid extraction method was developed for fast sample preparation of multiple phenolic compounds in propolis. This method was proposed based on cooling samples array in subzero temperature to induce phase separation of ACN-H₂O extractant. Due to the high-throughput ability, optimization of extraction parameters was rapidly achieved by using a 5 × 4 × 3 samples array. In addition, multiple arrays were investigated for evaluating the analytical performance of the high-throughput method, which indicated that limits of detection and quantification were ranged from 0.04 to 0.35 µg/mL and 0.12 to 1.05 µg/mL, respectively. Recoveries and precisions in inter-day high-throughput studies were in the range of 90.55-105.50% and 2.58-4.30%, respectively. Comparing with the conventional liquid extraction method, this ecofriendly high-throughput method presented remarkable advantages in reducing sample and chemical consumption, as well as saving labor and time cost. The proposed method might provide a valuable strategy for the design of high-throughput extraction procedures.

Comparison of the Partition Efficiencies of Multiple Phenolic Compounds Contained in Propolis in Different Modes of Acetonitrile⁻Water-Based Homogenous Liquid⁻Liquid Extraction

Homogeneous liquid–liquid extraction (HLLE) has attracted considerable interest in the sample preparation of multi-analyte analysis. In this study, HLLEs of multiple phenolic compounds in propolis, a polyphenol-enriched resinous substance collected by honeybees, were performed for improving the understanding of the differences in partition efficiencies in four acetonitrile–water-based HLLE methods, including salting-out assisted liquid–liquid extraction (SALLE), sugaring-out assisted liquid–liquid extraction (SULLE), hydrophobic-solvent assisted liquid–liquid extraction (HSLLE), and subzero-temperature assisted liquid–liquid extraction (STLLE). Phenolic compounds were separated in reversed-phase HPLC, and the partition efficiencies in different experimental conditions were evaluated. Results showed that less-polar phenolic compounds (kaempferol and caffeic acid phenethyl ester) were highly efficiently partitioned into the upper acetonitrile (ACN) phase in all four HLLE methods. For more-polar phenolic compounds (caffeic acid, p-coumaric acid, isoferulic acid, dimethoxycinnamic acid, and cinnamic acid), increasing the concentration of ACN in the ACN–H₂O mixture could dramatically improve the partition efficiency. Moreover, results indicated that NaCl-based SALLE, HSLLE, and STLLE with ACN concentrations of 50:50 (ACN:H₂O, v/v) could be used for the selective extraction of low-polarity phenolic compounds. MgSO₄-based SALLE in the 50:50 ACN–H₂O mixture (ACN:H₂O, v/v) and the NaCl-based SALLE, SULLE, and STLLE with ACN concentrations of 70:30 (ACN:H₂O, v/v) could be used as general extraction methods for multiple phenolic compounds.

Preparative HPLC for large scale isolation, and salting-out assisted liquid-liquid extraction based method for HPLC-DAD determination of khat (Catha edulis Forsk) alkaloids

Background

Khat (Catha edulis Forsk) is an evergreen shrub of the Celastraceae family. It is widely cultivated in Yemen and East Africa, where its fresh leaves are habitually chewed for their momentary pleasures and stimulation as amphetamine-like effects. The main psychostimulant constituents of khat are the phenylpropylamino alkaloids: cathinone, cathine and norephedrine.

Results

In this study, simple procedures based on preparative HPLC and salting-out assisted liquid–liquid extraction (SALLE) based methods were developed respectively for large scale isolation and the extraction of psychoactive phenylpropylamino alkaloids; cathinone, cathine and norephedrine, from khat (Catha edulis Forsk) chewing leaves, a stimulant and drug of abuse plant. The three khat alkaloids were directly isolated from the crude oxalate salt by preparative HPLC–DAD method with purity > 98%. In addition, a modified (SALLE) method has been developed and evaluated for the extraction efficiency of psychoactive phenylpropylamino alkaloids from khat (Catha edulis Forsk) chewing leaves. An in situ two steps extraction protocol was followed without dispersive SPE clean up. The method involves extraction of the samples with 1% HAc and QuEChERS salt (1.0 g of CH₃COONa and 6.0 g of MgSO₄) followed by subsequent in situ liquid–liquid partitioning by adding ethyl acetate and NaOH solution. The optimized method allowed recoveries of 80–86% for the three alkaloids from khat sample with relative standard deviation (RSD) values less than 15% and limits of detection (0.85–1.9 μg/mL).

Conclusion

The method was found to be simple, cost-effective and provides cleaner chromatogram with good selectivity and reproducibility. The SALLE based protocol provided as good results as the conventional extraction method (ultrasonic assisted extraction followed by solid phase extraction, UAE–SPE) and hence the method can be applicable in forensic and biomedical sectors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-017-0337-6) contains supplementary material, which is available to authorized users.