The first step in the isolation and purification of bioactive compounds from plant material is extraction. Extraction of secondary metabolites such as phenolic acids and flavonoids is difficult due ...to their insoluble nature. While conventional extraction methods such as Soxhlet, heat reflux, and maceration are successful procedures in the extraction of bioactive compounds and the equipment involved in these methods are distinct from each other. An appropriate extraction technique that balances product quality, process efficiency, production costs, and environmentally acceptable methods should be used for the extraction of bioactive compounds from plant tissues. The application of innovative extraction methods in the food industries has been extensively investigated, due to increased consumer expectations for greener options that do not include hazardous chemicals, as well as industry concerns about sustainable, nontoxic extraction techniques. Innovative technologies, such as high hydrostatic pressure (HHP), ultrasound (US), pulsed electric field (PEF), supercritical fluid (SF), and others, are increasingly replacing the conventional methods. The use of novel and combined novel technologies increases extractability, resulting in yields with higher extraction rates. It also yields lower impurities in the final extract and preserves thermo-sensitive compounds, uses different inorganic solvents, and consumes low energy. The purpose of the present review is to evaluate the efficiency of the different conventional, novel, and combined novel technologies involved in the extraction of bioactive compounds from plant materials.
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•The various conventional techniques for extraction of bioactive compounds are reviewed.•The paper also reviewed the various novel technologies for extraction of bioactive compounds.•The focus of the paper is combined novel technologies for extraction of bioactive compounds.•Efficiency of the extraction process can be increased by combining two technologies.
•A novel photoresponsive molecularly imprinted polymer (MIP) for selective recognition of guanine in aqueous media is developed.•The MIP displays good selectivity toward guanine over other competing ...compounds.•The MIP can efficiently extract guanine from complicated beer and then photocontrolled release it in aqueous media for quantitative analysis.
A novel photoresponsive molecularly imprinted polymer (MIP) was developed for the selective extraction of guanine from complex samples. The photoresponsive MIP was fabricated using guanine as the template, water-soluble 5-(4-(methacryloyloxy)phenyl)diazenylisophthalic acid as the functional monomer, and water-soluble triethanolamine trimethacrylate as the cross-linker. The MIP displayed good selectivity toward guanine with a dissociation constant of (2.70±0.16)×10−5molL−1 in aqueous media. The density of the guanine-specific receptor sites in the MIP material was (4.49±0.22)μmolg−1. Quantitatively release and uptake of guanine by the MIP occured with irradiation at 365 and 440nm, respectively. The MIP could efficiently extract guanine from beer and then release it into aqueous media under photocontrol. This method could be used for selective separation and subsequent determination of a specific analytes from complex samples.
Operative vaginal delivery Yeomans, Edward R
Obstetrics and gynecology (New York. 1953),
03/2010, Volume:
115, Issue:
3
Journal Article
Peer reviewed
Operative vaginal delivery remains a valid option when problems arise in the second stage of labor. The most common indications are fetal compromise and failure to deliver spontaneously with maximum ...maternal effort. There is a clear trend to choose vacuum extraction over forceps to assist delivery, but the evidence supporting that trend is unconvincing. Recent literature confirms some advantages for forceps (eg, a lower failure rate) and some disadvantages for vacuum extraction (eg, increased neonatal injury), depending on the clinical circumstances. To preserve the option of forceps delivery, residency training programs must incorporate detailed instruction in forceps techniques and related skills into their curricula. Simulation training can enhance residents' understanding of mechanical principles and should logically precede clinical work.
This work presents a strategy based on the in‐line coupling of SPE and CE for the chiral determination of cathinones (R,S‐mephedrone, R,S‐4‐methylephedrine, and R,S‐ methylenedioxypyrovalerone) in ...urine samples, using a sample pretreatment based on liquid‐liquid extraction. The chiral separation of the compounds is achieved by adding a mixture of 8 mM 2‐hydroxypropil β‐CD and 5 mM β‐CD to the BGE, which consists of 70 mM of monosodium phosphate aqueous solution at pH 2.5. Oasis HLB was the selected sorbent for the in‐line SPE device, and to reduce analysis time and LODs, several parameters affecting the in‐line SPE system were evaluated, such as pressure and time of sample injection and dimensions of the SPE device. The highest preconcentration factors were achieved by using 3 bar of injection pressure for 20 min with an in‐line SPE device of 2 mm length and 150 µm of i.d. The developed method was applied to determine the presence of the compounds in spiked urine samples. The LODs obtained were between 3 and 8 ng/mL, and these levels were below the usual concentrations at which these drugs are present in urine from cathinone abusers. Thus, the optimized method has the potential to be applied for toxicological and forensic purposes.
A novel modification in μ-SPE was introduced by packing sorbent and stir-bar inside the porous polypropylene membrane.SB-μ-SPE enhances effective surface area of the sorbent exposed to target ...compounds in the sample solution.SB-μ-SPE was successfully applied for trace level determination of PCBs in human serum samples.
In present work, a new configuration of micro-solid phase extraction was introduced and termed as stir-bar supported micro-solid-phase extraction (SB-μ-SPE). A tiny stir-bar was packed inside the porous polypropylene membrane along with sorbent material and the edges of membrane sheet were heat sealed to secure the contents. The packing of stir-bar inside the μ-SPE device does not allow the device to stick with the wall or any corner of the sample vial during extraction, which is, however, a frequent observation in routine μ-SPE. Moreover, it enhances effective surface area of the sorbent exposed to sample solution through continuous agitation (motion and rotation). It also completely immerses the SB-μ-SPE device in the sample solution even for non-polar sorbents. Polychlorinated biphenyls (PCBs) were selected as model compounds and the method performance was evaluated in human serum samples. After extraction, samples were analyzed by gas chromatography mass spectrometry (GC⿿MS). The factors that affect extraction efficiency of SB-μ-SPE were optimized. Under optimum conditions, a good linearity (0.1⿿100ngmL⿿1) with coefficients of determinations ranging from 0.9868 to 0.9992 was obtained. Limits of detections were ranged between 0.003 and 0.047ngmL⿿1. Acceptable values for inter-day (3.2⿿9.1%) and intra-day (3.1⿿7.2%) relative standard deviations were obtained. The optimized method was successfully applied to determine the concentration of PCB congeners in human serum samples.
•This study assesses the feasibility ofchromiumuptake onto the residue of alginate extraction.•Superior maximum biosorption capacity for Cr total in comparison to Cr(III).•The biosorption of Cr(VI) ...is followed by the reduction of hexavalent to trivalent chromium.•Extraction residue is a suitable, economic and easily available biosorbent for chromium uptake.
The Brazilian brown seaweed Sargassum filipendula was treated for alginate extraction and the residue was used for removing Cr(VI) and Cr(III) from aqueous solutions. The seaweed was characterized in terms of alginate and residue yields. Alginate and residue contents were 17% and 39%, respectively. Kinetic experiments were carried out and different models were applied in order to elucidate the rate-controlling mechanism: pseudo-first order, pseudo-second order and intra-particle diffusion. The biosorption of Cr(VI) in residue is followed by the reduction of hexavalent to trivalent chromium. The application of Langmuir model to equilibrium data showed a superior maximum biosorption capacity (qmax) for total chromium (0.819mmolg−1) in comparison to trivalent chromium (0.635mmolg−1). The biosorption capacities obtained were close to the values found for the removal of chromium by different species of brown seaweeds.
An automated accelerated salting-out assisted solvent extraction (A-ASASE) was developed. This approach made full use of the advantages of both the accelerated solvent extraction (ASE) technique and ...salting-out assisted liquid-liquid extraction (SALLE), without any modifications at the level of the ASE machine. The A-ASASE combined an automated extraction at high temperature/pressure and an enrichment step using eco-friendly solvents (e.g., water and ethanol) in a fully integrated and simple way that required only low volumes of solvents. The A-ASASE was successfully applied to extract three stilbenoids, namely E-resveratrol, E-ε-viniferin and E-vitisin B, present in grapevine (Vitis vinifera L.) by-products as a proof-of-concept compound. First, factors affecting the yield of stelbenoids by SALLE were investigated by means of a design of experiment model (DOE). The SALLE was then incorporated into ASE. Various ASE operational parameters such as temperature and number of cycles were also investigated. The highest yield was obtained using a mixture of ethanol-water, 70:30 (v/v) at 60 °C, using three extraction cycles and with 5 min of contact each. The highest yields of stilbenoids were 5.87 ± 0.28 g kg−1 dry weight, 3.27 ± 0.72 g kg−1 dry weight and 1.81 ± 0.2 g kg−1 dry weight for resveratrol, E-ϵ-viniferin and vitisin B, respectively. The A-ASASE was then successfully applied to extract the same stilbenoids from the roots of Vitis vinifera L. These results highlight the applicability of A-ASASE methodology to the extraction and enrichment of the extract in compounds of medium-high polarity in an easy and fully automated way.
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•Salting-out liquid-liquid extraction (SALLE).•The influence of different factors on the yield of stilbenoids by SALLE was discussed.•Automated Accelerated Salting-out Assisted Solvent Extraction (A-ASASE).•Extraction of stilbenoids from branches of Vitis vinifera L.•Comparison with QuEChERS and accelerated solvent extraction (ASE).
Natural pigments improve aesthetic value as well as antioxidant potential of a food product. This study was designed to determine the effects of green extraction techniques on carotenoids, ...polyphenols and antioxidant activities of pulp and peel of two varieties of pumpkin (
). Innovative green extractions (IGE; Ultrasound and Microwave-Assisted Extractions) synergised with corn oil (used as green solvent) were compared with conventional extraction (CE; hexane/isopropyl alcohol; 60:40,
/
). Results showed total carotenoids to be almost double on employing IGE (PM2-UAE-peel = 38.03 ± 4.21; PM4-UAE-peel = 33.78 ± 1.76 µg/g) when compared to conventional extraction (PM2-CE-peel = 19.21 ± 4.39; PM4-CE-peel = 16.21 ± 2.52 µg/g). Polyphenolic contents ranged between 510.69 ± 5.50 and 588.68 ± 7.26 mg GAE/100 g of extract in IGE, compared with conventional extracts (269.50 ± 2.17 to 318.46 ± 6.60 mg GAE/100 g) and percent inhibition of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) ranging between 88.32 ± 1.51 and 93.53 ± 0.30% in IGE when compared with conventional extraction (50.61 ± 1.44 to 57.79 ± 2.09%). Further, oxidative stability of carotenoids extracts from IGE (protection factor = 1.59 ± 0.01 to 1.81 ± 0.05) were found to be significantly higher (
< 0.05) than conventional extracts. Based on results, this study supports the use of innovative green extraction techniques to obtain bioactive pigments like carotenoids. It is anticipated that results generated will find potential applications in food, pharmaceutical and cosmetic industries.
Deep eutectic solvents were used in both dispersive liquid–liquid microextraction and solid‐phase extraction for the purification of chloromycetin and thiamphenicol from milk. In the dispersive ...liquid–liquid microextraction procedure, deep eutectic solvents mixed with chloroform at different ratios (0:1–5:1, v/v) were used as the extraction agent to optimize the procedure, and the ratio of 2:1 v/v was found to be the best extraction agent with 87.23 and 83.17% recoveries of chloromycetin and thiamphenicol, respectively. Furthermore, deep eutectic solvents were also used to modify molecular imprinted polymers in solid‐phase extraction procedure, and the polymers were used to purify chloromycetin and thiamphenicol from milk. Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy were used to characterize the polymers. The solid‐phase extraction recoveries with deep eutectic solvents with molecularly imprinted polymers (chloromycetin and thiamphenicol, two templates), molecularly imprinted polymers (without deep eutectic solvents), and nonimprinted polymers (without a template) for chloromycetin were 91.23, 82.64, and 57.3%, respectively, and recoveries for thiamphenicol were 87.02, 79.03, and 52.27%, respectively. The recoveries of chloromycetin and thiamphenicol from milk in the solid‐phase extraction procedure were higher than using deep eutectic solvents mixed with chloroform as the extraction agent in the dispersive liquid–liquid microextraction procedure.
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