Applications of liquid-phase microextraction procedures to complex samples assisted by response surface methodology for optimization

Development, optimization and comparison of solid-liquid and liquid-liquid microextraction for the determination of four flavonols in Schinus molle L. using high-performance liquid chromatography coupled with second-order data modeling

Flavonoids are particularly interesting because they have a broad spectrum of biological effects, including antioxidant and free radical scavenging activities. In this work, solid-liquid microextraction and dispersive liquid-liquid microextraction enhanced by ultrasound were developed and compared with the conventional method (Soxhlet extraction) to optimize the extraction of four flavonoids: rutin, quercitrin, quercetin, and myricetin in samples of Schinus molle (Aguaribay). During the development of the analytical method, different chemometric tools were used to optimize the microextraction procedure. In addition, an analytical method based on high-performance liquid chromatography with diode array detector (HPLC-DAD) and second order calibration using multivariate curve resolution-alternating least square (MCR-ALS) is presented to quantify the flavonoids with limits of quantification between 0.011 and 0.082 µg mL-1. Finally, solid-liquid microextraction using 4.00 mL water/ethanol (54.3:45.7%), 14 s vortex, and 45 min was selected as the most suitable method due to its high recovery rate and environmental friendliness (with a greenness score of 0.78). After the optimization step, the concentrations found in the plant samples were 1825.3, 632.6, 110.2, and 18.9 µg g-1 for rutin, quercitrin, quercetin, and myricetin, respectively. The present work is the first achievement of simultaneously determining these four analytes with exceptional sensitivity, demonstrating lower LOQs compared to previous reports.

Ponceau 4R elimination from fruit juice: An integrated optimization strategy utilizing artificial neural networks, least squares, and chitosan-nickel ferrite Nano Sorbent

The goal of present work is to examine the efficiency of aminated-chitosan/NiFe2O4 nanoparticles (AmCs/NiFe2O4 NPs) produced for removing Ponceau 4R (P4R) from fruit juice through an adsorption process. The resulting nanoparticles were characterized using various techniques. The modeling of results was done using least squares (LS) and Radial basis function-artificial neural network (RBF-ANN). The optimum removal of P4R (91.43 %) was obtained at the following optimum conditions: pH 4.47, adsorbent dosage 0.047 g/L, contact time approximately 57.78 min, and initial concentration P4R 26.89 mg/L. The highest adsorption capacity (qm) was found to be 208.33 mg g-1. The P4R adsorption mostly followed the Freundlich and pseudo-second-order isotherm kinetic models. Both LS-based models and RBF-ANN provided good predictions for independent variables. The dye elimination efficacy for juice samples were approximately 90.34 %. Therefore, based on the obtained results, it can be claimed that the prepared AmCs/NiFe2O4 NPs can be used to remove P4R.

Antimycobacterial and Antifungal Activities of Leaf Extracts From Trichilia emetica

The global problem of infectious and deadly diseases caused by microbes such as candida and mycobacteria presents major scientific and medical challenges. Antimicrobial drug resistance is a rapidly growing problem with potentially devastating consequences. Various pathogens can cause skin infections, such as bacteria, fungi, and parasites. Antimicrobial resistance has caused the urgency to seek alternative treatment options from available natural resources. Plant-derived medicinal compounds can provide novel alternative treatment avenues against pathogenic microbes. The objective of this study was to determine the antimycobacterial and antifungal activity of leaf extracts of Trichilia emetica against Mycobacteria smegmatis, Mycobacteria aurum, Candida tropicalis, and Candida albicans. The leaf extracts were prepared using hexane, ethyl acetate, acetone, dichloromethane (DCM), methanol, ethanol, water, DCM:methanol, and 70% ethanolic aqueous solution. The microbroth dilution was used to determine the minimum inhibitory concentration (MIC) of each extract against the four test organisms. The mode of action by which these extracts inhibit growth was also investigated. The effects of the extract on the cell wall of C. tropicalis were determined using the sorbitol assay. The effects of the extracts on the membrane integrity of the test organisms were determined using propidium iodide, which binds to nucleic acids, and the Bradford reagent, which reacts with proteins. The ethyl acetate and 70% ethanolic aqueous extracts were most potent against the organisms tested with MICs ranging from 125 to 1000 μg/mL. However, the two extracts did not inhibit the growth of C. tropicalis in the presence of sorbitol. The extracts caused the leakage of nucleic acids and proteins in C. tropicalis and M. smegmatis only and not in M. aurum. It is concluded that the leaf extracts of T. emetica have antimycobacterial or antifungal activities. The disruption of cell membranes resulting in protein and nucleic acid leakage could be the plant's possible mode of action.

Simultaneous determination of nineteen azo dyes in water samples by gas chromatography-mass spectrometry after Fe3O4@COF based dispersive solid phase extraction

This study was performed for the determination of nineteen azo dyes at trace levels in stream water sample by gas chromatography-mass spectrometry (GC-MS). The selected analytes were preconcentrated with the help of dispersive solid phase extraction (DSPE). Fe3O4 magnetic nanoparticle was modified with covalent organic framework (COF) and the synthesized Fe3O4@COF nanocomposite was used as adsorbent for the separation of the analytes from aqueous solution. The synthesized Fe3O4@COF was introduced to the literature for the first time in this study. Five different parameters (pH, volume of buffer solution, volume of desorption solvent, mixing period and amount of adsorbent) were univariately optimized to acquire high extraction outputs for each analyte. Under the optimum Fe3O4@COF-DSPE-GC-MS conditions, limit of detection (LOD), limit of quantitation (LOQ), linear range (LR), coefficient of determination (R2) and percent relative standard deviation (%RSD) were calculated using external calibration plots belonging to each analyte. LOD values were found between 2.8 and 70.7 μg/kg with corresponding LOQ values ranging between 9.5 and 235.7 μg/kg. In addition, %RSD values were lower than 12.8%. Matrix matching calibration method was used in spiking experiments. Percent recovery results obtained for spiked stream water samples were between 83.1 and 122.4%, with %RSD ≤ 17.5. The high percent recoveries confirmed the accuracy and applicability of the developed Fe3O4@COF-DSPE-GC-MS method for stream water samples.

Method development and optimization for dispersive liquid-liquid microextraction factors using the response surface methodology with desirability function for the ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry determination of organic contaminants in water samples: risk and greenness assessment

A simple, cost effective, and efficient dispersive liquid-liquid microextraction method was developed and optimized for the determination of organic contaminants in different environmental water matrices followed by UHPLC-QTOF-MS analysis. In the preliminary experiments, the univariate optimization approach was used to select tetrachloroethylene and acetonitrile as extraction and disperser solvents, respectively. The significant factors influencing DLLME were screened using full factorial design, and the optimal values for each variable were then derived through further optimization using central composite design with desirability function. The optimal conditions were achieved with 195 μL of tetrachloroethylene as the extraction solvent, 1439 μL of acetonitrile as the disperser solvent, and a sample pH of 5.8. Under these conditions, the method provided detection limits ranging from 0.11-0.48 μg L-1 and recoveries ranging from 23.32-145.43% across all samples. The enrichment factors obtained ranged from 11.66-72.72. The proposed method was then successfully applied in real water samples. Only benzophenone was detected in the concentration range of 0.79-0.88 μg L-1 across all the water samples. The calculated risk quotient resulting from benzophenone exposure in water samples showed a low potential risk to human health and the aquatic ecosystem. The method was also evaluated for its environmental friendliness using various metrics tools such as Analytical Eco-Scale (AES), Green Analytical Procedure Index (GAPI), Analytical GREEnness (AGREE), Analytical Greenness for Sample Preparation (AGREEprep), and Sample Preparation Metric of Sustainability (SPMS). Only AES qualified the method as green while it was considered acceptable and sustainable when assessed using SPMS.

Optimizing Encapsulation of Active Compounds of Carrot By-Product in TPP-Chitosomes

Liposomes coated with chitosan by ionic gelation with tripolyphosphate (TPP-chitosomes) are interesting particles for stabilizing active compounds. However, the encapsulation condition must be optimized. The aim of this study was to optimize the encapsulation of phenolics and carotenoids of carrot pomace in TPP-chitosomes by using a Central Composite Design 23 and response surface methodology. The independent variables were the phospholipid (0.8-4.2 mg/mL), chitosan (2.6-9.4 mg/mL), and carrot pomace (4-14 g/100 mL of ethanol) concentrations; the responses were the encapsulation efficiency in TPP-chitosomes (EE) of phenolics, a-carotene, and b-carotene and the particle size and zeta potential of the particles. The zeta potential ranged from +17 to +37 mV, indicating that the liposomes were coated with chitosan and that the particle sizes were in the nanometric to submicrometric scale. The optimized condition for encapsulating carotenoids was 2.5 mg/mL phospholipids, 6.0 mg/mL chitosan, and 12 g of carrot pomace/100 mL of ethanol. In this condition, the EE of phenolics and α- and β-carotene was 95%, 98%, and 99%, respectively. Therefore, TPP-chitosomes containing encapsulated phenolics and carotenoids, which can be obtained from agro-industrial by-products, have potential application as natural pigments in food or cosmetics. TPP-chitosomes can also be used to encapsulate other types of natural pigments.

Ionic-liquid/Carbowax 20 M functionalized capsule phase microextraction platform for the extraction of phosphodiesterase-5 inhibitors from human serum and urine prior to their determination by LC-MS

Capsule phase microextraction (CPME) is an efficient bioanalytical technique that streamlines the sample preparation by integrating the filtration and stirring mechanism directly into the device. A novel composite sorbent designed to be selective towards the target analytes consisting of mixed-mode sorbent chemistry synthesized by sol-gel technology is found promising and superior to the conventional C18 sorbents. Herein we describe the encapsulation of an ionic liquid (IL)/Carbowax 20M-functionalized sol-gel sorbent (sol-gel IL/Carbowax 20 M) in the lumen of porous polypropylene tubes for the capsule phase microextraction of three phosphodiesterase-5 inhibitors namely avanafil, sildenafil, and tadalafil in human serum and urine samples. The CPME device was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR). The experimental parameters of CPME procedure (e.g. sample pH and ionic strength, extraction time, stirring rate, elution solvent and volume) were carefully optimized to achieve the highest possible extraction efficiency for the analytes. Method validation was conducted in terms of precision, linearity, accuracy, matrix effect, lower limits of quantification, and limits of detection (LOD). The method linearity was investigated in the range of 50-1000 ng mL-1 for all analytes while the precision was less than 11.8 % in all cases. For all analytes, the LOD values were 17 ng mL-1. The IL/CW 20M-functionalized microextraction capsules could be reused at least 25 times both for urine and serum samples. The green character and the applicability of the proposed method were evaluated using the ComplexGAPI and BAGI indexes. The optimized CPME protocol exhibited reduced consumption of organic solvent and generation of waste, cost-effectiveness, and simplicity. Finally, the proposed method was successfully applied to the analysis of sildenafil in human urine after administration of drug-containing formulation.

Bioactive Substances and Biological Functions in Malus hupehensis: A Review

Malus hupehensis (MH), as a natural resource, contains various active ingredients such as polyphenols, polysaccharides, proteins, amino acids, volatile substances, and other components. Increasingly, studies have indicated that MH showed a variety of biological activities, including antioxidant, hypoglycemic, hypolipidemic, anti-cancer, anti-inflammatory activities, and other activities. Hence, MH has attracted wide interest because of its high medical and nutritional value. It is necessary to review the active components and biological activities of MH. This paper systematically reviewed the chemical substances, biological activities, and potential problems of MH to further promote the related research of MH and provide an important reference for its application and development in medicine and food.

The Determination Method of Total Polyphenol in Tea and Substitute Tea Based on [Ag(HIO6)2]5--Luminol Chemiluminescence System

BACKGROUND

Scientific, accurate, and rapid detection of the composition and content of tea polyphenols is an important basis for their rational use and giving full play to their physiological effect. The spectrophotometric assays for total polyphenols have poor selectivity. Therefore, there is a need to develop a simple and reliable method for the determination of the total polyphenolic level in tea products.

OBJECTIVE

The aim of this research was to develop a flow injection chemiluminescence (FI-CL) method based on the Ag(III)-luminol system for the total polyphenol content analysis of tea and substitute tea.

METHOD

Through Box-Behnken experimental design, we selected the optimum determination condition. The Ag(III) concentration was 5 × 10-5 mol/L, and the luminol concentration was 3 × 10-7 mol/L (including 0.15 mol/L NaOH). The peristaltic pump is 25 r/min, and the photomultiplier voltage is 600 v. Sample extracts were diluted 100 000 times for the FI-CL assay.

RESULTS

Under optimal conditions, CL intensities were proportional to total polyphenol content (in terms of gallic acid concentrations) in the range of 0.1∼100 μg/L. The LOD and LOQ were 0.03 μg/L and 0.1 μg/L. The recovery values were in the range of 86.3-111.0% with a RSD of 1.04∼2.62%. The polyphenolic content of 12 teas and 6 substitute teas was determined, and the results of the developed method and Folin-Ciocalteu method were highly correlated (r = 0.9493 for tea and r = 0.8533 for substitute tea).

CONCLUSIONS

The proposed method is better than the Folin-Ciocalteu method in terms of selectivity, sensitivity, and accuracy. It is suitable for the determination of polyphenol content not only in tea, but also in substitute tea.

HIGHLIGHTS

We developed a new flow-injection analysis method for polyphenolic content determination based on the Ag(III)-luminol chemiluminescence system. It is simple, rapid, sensitive, and accurate. It is suitable for the determination of polyphenols content not only in tea, but also in substitute tea.

Vortex-assisted supramolecular solvent dispersive liquid–liquid microextraction of ketoprofen and naproxen from environmental water before chromatographic analysis: response surface methodology optimisation

A microextraction procedure that is rapid and simple to extract and preconcentrate ketoprofen and naproxen is proposed. An environmentally friendly supramolecular solvent was applied as an extraction solvent and proved to be efficient in the extraction of ketoprofen and naproxen from environmental water. The design of experiment approach was used to screen, optimize significant parameters, and determine optimum experimental conditions. Under optimized experimental conditions, the vortex-assisted supramolecular solvent dispersive liquid–liquid microextraction provided a good linearity (0.57–700 µg L−1), low limits of detection (0.17–0.24 µg L−1) and extraction reproducibility below 9%. The high percentage relative recoveries (93.6–101.4%) indicated that the method is not affected by matrix. The practical applicability of the method was assessed by analysing ketoprofen and naproxen in river water and effluent wastewater samples. Both analytes were found in effluent wastewater.

Enhanced production of cordycepic acid from Cordyceps cicadae isolated from a wild environment

Cordyceps acid is an active component of Cordyceps cicadae and has a variety of medicinal uses, including anti-tumor effects, the prevention of cerebral hemorrhaging and myocardial infarction, and the inhibition of a wide range of bacteria. The objectives of this study were to identify C. cicadae fungi and optimize the culture conditions to obtain a high yield of cordycepic acid. First, a wild C. cicadae was identified by morphological observation and rDNA sequence analysis. Secondly, the optimal fermentation conditions were determined using a single-factor method, a Plackett-Burman design, and a Box-Behnken response surface. Finally, using the yield of fruit bodies and the content of cordyceps acid as indices, combined with a single-factor experiment and a response surface design, the best combination of conditions for cultivation was determined. The results showed that the best combination was as follows: sucrose 2%, tryptone 2%, KH2PO4 0.4%, MgSO4·7H2O 0.4%, an initial pH of the fermentation liquid of 7.0, 5% inoculum, fermentation for 4.5 d, a ratio of medium to liquid of 1:1.7, illumination intensity 150 Lux, illumination time 15 h per day, and 70% humidity. The content of cordycepic acid in the fruiting bodies developed in cultivation was 2.07-fold higher than that in the wild C. cicadae. This study provides a theoretical basis for the large-scale cultivation of C. cicadae with a high concentration of cordycepic acid.

Extraction Induced by Emulsion and Microemulsion Breaking for Metal Determination by Spectrometric Methods - A Review

This review focuses on extraction induced by the destabilization of emulsified systems combined with spectrometric techniques for metal analysis in oily samples. This approach is based on the formation and breaking of an emulsion (extraction induced by emulsion breaking - EIEB) or microemulsion (extraction induced by microemulsion breaking - EIMB) to transfer the analytes from the oil sample to the aqueous phase, which is separated in the process. Its simplicity, speed, and low cost have contributed to its growing popularity among researchers. However, the potential of EIEB and EIMB is far from being fully exploited. Therefore, this paper aims to provide relevant information to expand the applicability of these methods. The principle of the methods is discussed, and a brief description of emulsified systems is presented. The parameters affecting the extraction efficiency and calibration strategy are also critically discussed. Furthermore, the analytical applications of the methods are reviewed. Trends and opportunities in this field are also considered.

An enhanced dispersive liquid–liquid microextraction method based on solidification of floating organic drops for the determination of pyrethroid pesticides in tea infusions

A novel enhanced dispersive liquid–liquid microextraction method based on solidified floating organic solvents containing [P4,4,4,12][PF6] and a hydrophobic solvent mixture for the determination of four pyrethroid insecticides in tea infusions.

Design of experiments (DoE) to develop and to optimize nanoparticles as drug delivery systems

Nanotechnology has been widely applied to develop drug delivery systems to improve therapeutic performance. The effectiveness of these systems is intrinsically related to their physicochemical properties, so their biological responses are highly susceptible to factors such as the type and quantity of each material that is employed in their synthesis and to the method that is used to produce them. In this context, quality-oriented manufacturing of nanoparticles has been an important strategy to understand and to optimize the factors involved in their production. For this purpose, Design of Experiment (DoE) tools have been applied to obtain enough knowledge about the process and hence achieve high-quality products. This review aims to set up the bases to implement DoE as a strategy to improve the manufacture of nanocarriers and to discuss the main factors involved in the production of the most common nanocarriers employed in the pharmaceutical field.

Preparation of environmental samples for chemical speciation of metal/metalloids: A review of extraction techniques

Chemical speciation is a relevant topic in environmental chemistry since the (eco)toxicity, bio (geo)chemical cycles, and mobility of a given element depend on its chemical forms (oxidation state, organic ligands, etc.). Maintaining the chemical stability of the species and avoiding equilibrium disruptions during the sample treatment is one of the biggest challenges in chemical speciation, especially in environmental matrices where the level of concomitants/interferents is normally high. To achieve this task, strategies based on chemical properties of the species can be carried out and pre-concentration techniques are often needed due to the low concentration ranges of many species (μg L^-1 - ng L^-1). Due to the significance of the topic and the lack of reviews dealing with sample preparation of metal (loid)s (usually, sample preparation reviews focus on the total metal content), this work is presented. This review gives an up-to-date overview of the most common sample preparation techniques for environmental samples (water, soil, and sediments), with a focus on speciation of metal/metalloids and determination by spectrometric techniques. Description of the methods is given, and the most recent applications (last 10 years) are presented.

One-minute and green synthesis of magnetic iron oxide nanoparticles assisted by design of experiments and high energy ultrasound: Application to biosensing and immunoprecipitation

The present study is focused on the ultrafast and green synthesis, via the co-precipitation method, of magnetic nanoparticles (MNPs) based on iron oxides using design of experiments (DOE) and high energy sonochemical approach, considering two main factors: amplitude (energy) of the ultrasound probe and sonication time. The combination of these techniques allowed the development of a novel one-minute green synthesis, which drastically reduced the amount of consumed energy, solvents, reagents, time and produced residues. This green sonochemical synthesis permitted to obtain mean particle sizes of 11 ± 2 nm under the optimized conditions of amplitude = 40% (2826 J) and time = 1 min. Their composition, structure, size, morphology and magnetic properties were assessed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM & TEM), and vibrating sample magnetometry (VSM). The characterization results indicate the proper formation of MNPs, and the correct functionalization of MNPs with different coating agents. The functionalized MNPs were used as: i) biosensor, which could detect mercury in water in the range of 0.030-0.060 ppm, and ii) support onto which polyclonal antibodies were anchored and successfully bound to an osteosarcoma cell line expressing the target protein (TRIB2-GFP), as part of an immunoprecipitation assay.

An appraisal of experimental designs: Application to enantioselective capillary electromigration techniques

Enantioresolution processes are vital tools for investigating the enantioselectivities of chiral compounds. An analyst resolves to optimize enantioresolution conditions once they are determined. Generally, optimization is conducted by a one-factor-at-a-time (OFAT) approach. Although this approach may determine an adequate condition for the method, it does not often allow the estimation of the real optimum condition. Experimental designs are conducive for the optimization of enantioresolution methods via capillary electromigration techniques (CETs). They can efficiently extract information from the behavior of a method and enable the estimation of the real optimum condition. Furthermore, the application of the analytical quality by design (AQbD) approach to the development of CET-based enantioselective methods is a trend. This article (i) offers an overview of the application of experimental designs to the development of enantioselective methods from 2015 to mid-2020, (ii) reveals the experimental designs that are presently employed in CET-based enantioresolutions, and (iii) offers a critical point of view on how the different experimental designs can aid the optimization of enantioresolution processes by considering the method parameters.

Hollow fiber liquid-phase microextraction combined with supercritical fluid chromatography coupled to mass spectrometry for multiclass emerging contaminant quantification in water samples

The hollow fiber liquid-phase microextraction allows highly selective concentration of organic compounds that are at trace levels. The determination of those analytes through the supercritical fluid chromatography usage is associated with many analytical benefits, which are significantly increased when it is coupled to a mass spectrometry detector, thus providing an extremely sensitive analytical technique with minimal consumption of organic solvents. On account of this, a hollow fiber liquid-phase microextraction technique in two-phase mode combined with supercritical fluid chromatography coupled to mass spectrometry was developed for quantifying 19 multiclass emerging contaminants in water samples in a total chromatographic time of 5.5 min. The analytical method used 40 μL of 1-octanol placed in the porous-walled polypropylene fiber as the acceptor phase, and 1 L of water sample was the donor phase. After extraction and quantification techniques were optimized in detail, a good determination coefficient (r² > 0.9905) in the range of 0.1 to 100 μg L^-1, for most of the analytes, and an enrichment factor in the range of 7 to 28,985 were obtained. The recovery percentage (%R) and intraday precision (%RSD) were in the range of 80.80-123.40%, and from 0.48 to 16.89%, respectively. Limit of detection and quantification ranged from 1.90 to 35.66 ng L^-1, and from 3.41 to 62.11 ng L^-1, respectively. Finally, the developed method was successfully used for the determination of the 19 multiclass emerging contaminants in superficial and wastewater samples.

Multivariate optimization of a dispersive liquid-liquid microextraction method for the determination of six antiparasite drugs in kennel effluent waters by using second-order chromatographic data

Six veterinary active ingredients (imidacloprid, albendazole, fenbendazole, praziquantel, fipronil and permethrin) were extracted and quantified by liquid chromatography with diode array detection in water samples from a wetland system used for the treatment of waste from a dog breeding plant. Response surface methodology, based on least-squares and artificial neural networks modelling, was applied for the optimization of a dispersive liquid-liquid microextraction (DLLME) procedure. Firstly, two experimental designs were built for screening and optimization, respectively. Then, the desirability function was implemented for the simultaneous optimization of the six recoveries (chromatographic areas of the six compounds). The optimum conditions were: 600 μL of acetone (dispersive solvent), 670 μL of dichloromethane (extractant solvent) and 0.6 min of vortex mixing. The preconcentration factor was 37.5. Then, in order to identify and quantify the six drugs, second-order calibration with MCR-ALS modeling of HPLC-DAD data was implemented attaining successful results. The limits of quantification were 4 ng mL^-1 for imidaclopril, albendazole and fenbendazole; 8 ng mL^-1 for praziquantel and fipronil; and 26 ng mL^-1 for permethrin. The developed method allowed the quantitation of the target analytes, even in the presence of unexpected compounds from dirty water samples. The following maximum levels of veterinary drugs were found (in ng mL^-1): imidaclopril, 7; albendazole, 46; fenbendazole, 21; praziquantel, 29; fipronil, 29 and permethrin, 217.