Solid-liquid Extraction Research Articles

Soybean Oil as a Green Solvent for the Recovery of Carotenoids from Banana Peel: Evaluation of the Storage and Processing on Final Product

This study aimed to recover carotenoids from banana peel by employing a solid-liquid extraction using soybean oil as a green solvent. The oil with the highest total carotenoid content was evaluated for storage stability (30 °C/90 days) and thermal processing (100 and 200 °C/1–2 h). The results for changing temperature (33–67 °C), solid-liquid ratio (1:6–1:74 w/w), and agitation (132–468 rpm) were combined to evaluate the recovery of carotenoids from banana peel in extractions performed for 1 h. The highest total carotenoid concentration obtained from banana peel with 13% residual moisture was 756 µg of β-carotene/mL of oil at 50 °C with a solid-liquid ratio of 1:6 and 300 rpm agitation, resulting in a 55% recovery, which is superior to the extraction using acetone as the solvent (50%). Nutritionally, the carotenoid-rich oil can substantially increase vitamin A intake since a 13-mL serving can correspond to 63–117% of the daily intake of vitamin A for different groups. Regarding storage, no differences were observed in the fatty acid profile of the carotenoid-rich oil and the control (pure soybean oil) after 90 days (p > 0.05). The fatty acid profile also remained the same after thermal processing, regardless of temperature and exposure time, except for linolenic acid. 84% retention of total carotenoids was observed after storage. For thermal processing at 100 and 200 °C, regardless of the processing time, a 91 and 31% retention were observed, respectively. Therefore, the use of banana peel as a raw material to obtain carotenoids using soybean oil as a green solvent can add value to production chains, and it is aligned with Sustainable Development Goals 2 and 12 of the UN 2030 Agenda, which aims to end hunger, achieve food security, promote sustainable agriculture and ensure sustainable consumption and production patterns, respectively.

Assessing Matrix Solid-Phase Dispersion Extraction Strategies for Determining Bisphenols and Phthalates in Gilthead Sea Bream Samples

Microplastics (MPs) and nanoplastics (NPs) are widely spread in the environment, generating significant concern due to their potential impact on environmental health. Marine species usually ingest plastic fragments, mistaking them for food. Many toxic compounds, such as plastic additives that are not chemically bound to the plastic matrix, can be released from MPs and NPs and reach humans via the food chain. This paper highlights the development and validation of a straightforward solid–liquid extraction clean-up procedure in combination with a matrix solid-phase dispersion method using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) detection, enabling facile, precise, and reliable identification and quantitation of a total of six bisphenols and phthalates in gilthead sea breams. Under the optimized conditions, the developed method showed good linearity (R2 > 0.993) for all target compounds. The recoveries obtained were between 70 and 92%. The relative standard deviations (RSDs) for reproducibility (inter-day) and repeatability (intra-day) were less than 9% and 10%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the target compounds ranged from 0.11 to 0.68 µg/kg and from 0.37 to 2.28 µg/kg, respectively. A new, efficient extraction methodology for the determination of BPA, BPS, BPF, DBP, DEP, and DHEP in gilthead seabream has been optimized and validated.

Molecular Docking Studies and In Vitro Activity of Paliurus spina-christi Mill Extracts as Pancreatic Lipase Inhibitors.

Obesity is a risk factor for the onset of chronic diseases. One of the most promising approaches to treating obesity consists of reducing dietary fat absorption using extracts from plants because they contain phenolic compounds, especially flavonoids. Paliurus spina-christi, belonging to the Rhamnaceae family, is one of the five species belonging to the Paliurus genus. Herein, the aerial parts of the plant were extracted with methanol through the pressurized cyclic solid-liquid extraction using the Naviglio extractor®. The extracts were analyzed with High Performance Thin Layer Chromatography and investigated for their in vitro biological potential. The phytochemical analysis revealed that rutin has been shown to be the most abundant flavonoid component. The best antiradical activity was observed for the fruit extract with an IC50 value of 53.41 ± 1.24 µg/mL. This extract also has a better inhibitory capacity on lipid peroxidation evaluated at a different time of incubation. Potent lipase inhibitor activity of the extract from fruits was also demonstrated with in vitro experiments. This property can be attributed to a direct interaction of main components of P. spina-christi extract with the human pancreatic enzyme as demonstrated by the results of molecular docking experiments conducted on the crystallographic structures of lipase.

Raman spectroscopy combined with partial least squares (PLS) based on hybrid spectral preprocessing and backward interval PLS (biPLS) for quantitative analysis of four PAHs in oil sludge

Polycyclic aromatic hydrocarbons (PAHs) contained in a large amount of oily sludge produced in petroleum and petrochemical production has become one of the main environmental protection concerns in the industry. The accurate determination of PAHs is of great significance in the field of petroleum geochemistry and environmental protection. In this study, Raman spectroscopy combined with partial least squares (PLS) based on different hybrid spectral preprocessing methods and variable selection strategies was proposed for quantitative analysis of phenanthrene, fluoranthrene, fluorene and naphthalene (Phe, Flt, Flu and Nap) in oil sludge. At first, PAHs in oily sludge was extracted by solid–liquid extraction with methanol as extractant, and Raman spectra of 21 oily sludge samples were collected by portable Raman spectrometer. And then, the influence of first derivative (D1st), wavelet transform (WT) and their hybrid spectral preprocessing on the predictive performance of the PLS calibration model was discussed. Thirdly, biPLS (backward interval partial least squares) was used to optimize the input variables before and after the hybrid spectral preprocessing methods, and the influence of biPLS and the hybrid spectral preprocessing sequence on the predictive performance of the PLS calibration model was discussed. Finally, the predictive performance of the PLS calibration model was optimized according to the results of leave-one-out cross-validation (LOOCV) method. The results show that the biPLS-D1st-WT-PLS calibration model established by using biPLS first to select the characteristic variables, followed by hybrid spectral preprocessing of the characteristic variables, has better prediction performance for Flt (determination coefficient of prediction (R2P) = 0.9987, and the mean relative error of prediction (MREP) = 0.0606). For Phe, Flu and Nap, the WT-biPLS-PLS calibration model has a better predictive effect (R2P are 0.9995, 0.9996 and 0.9983, and MREP are 0.0426, 0.0719 and 0.0497, respectively). In general, portable Raman spectroscopy combined with PLS calibration model based on different hybrid spectral preprocessing and variable selection strategies has achieved good prediction results for quantitative analysis of four PAHs in oily sludge. It is a new strategy to firstly select the characteristic variables of the original spectra, and secondly to preprocess the characteristic variables by the hybrid spectral preprocessing, which will provide a new idea for the establishment of quantitative analysis methods for PAHs in oily sludge.

Capillary electrophoresis tandem mass spectrometry to determine multiclass cyanotoxins in reservoir water and spinach samples

Cyanotoxins constitute a group of toxic secondary metabolites, the presence of which in any water body poses a major health risk. Moreover, advanced organisms such as edible plants exposed to these toxins, are a possible pathway for human exposure. Green analytical chemistry is demanding environmentally friendly analytical techniques. In this sense, we propose the use of capillary electrophoresis coupled to tandem mass spectrometry (CE-MS/MS) to determine a mixture of eight cyanotoxins belonging to three different classes: cyclic peptides (microcystin-LR, microcystin-RR and nodularin), alkaloids (cylindrospermopsin and anatoxin-a) and three isomeric non-protein amino acids (β-methylamino-l-alanine, 2,4-diaminobutyric acid and N-(2-aminoethyl)glycine). Separation was achieved by using an acidic background electrolyte consisting of 2 M formic acid and 20% acetonitrile in water. Parameters affecting MS/MS detection and the sheath-liquid interface were also studied. Finally, a combination of pH-junction, field-amplified sample stacking (FASS) and acid barrage as online preconcentration strategies, was employed to improve sensitivity and efficiency. The online preconcentration applied, in combination with a dual cartridge solid-phase extraction (SPE) system, allows to obtain limits of detection in the very low range of µg·L−1 for these multiclass cyanotoxins in reservoir water samples (from 0.005 to 0.10 µg·L−1). Furthermore, for the first time cyanotoxins are analysed in spinach samples through CE-MS/MS using the same SPE procedure, following lyophilisation and solid-liquid extraction with 6 mL 80 % aqueous MeOH.

Development of novel methods based on GC-HRMS and LC-HRMS for the determination of non-phthalate plasticizers in soil

Non-phthalate plasticizers (NPPs) are a suitable alternative to phthalates, which are harmful compounds for human, animal health, and the environment. In this study, 28 commercial non-phthalate plasticizers (NPPs) from different families, including adipates, citrates, phosphates, sebacates, trimellitates, benzoates and cyclohexanoates, were determined. Two novel methods for determining these alternative compounds in soil were developed using gas chromatography coupled to high-resolution mass spectrometry (GC-HRMS-Q-Orbitrap) and liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS-Q-Orbitrap). Solid-liquid extraction (SLE) with ethyl acetate or acetonitrile, along with water as extraction solvents, were employed. In most cases, the GC method exhibited recoveries ranging from 84.9 % to 110.8 % at 20, 40 and 200 μg/kg, while the LC method achieved recoveries between 73.1 % and 115.4 % at 10, 20, 40 and 200 μg/kg. Most of the relative standard deviation (RSD) values were below 20 % for both methods. The validated methods were then applied to analyse soil samples collected from four different areas in Almeria. The results indicated that the compounds detected most frequently at high concentrations were 1-hydroxycyclohexyl phenyl ketone (HCPK) using GC, in the range 29.1–67.4 μg/kg and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) using LC, in the range 39.9–51.5 μg/kg. Additionally, suspect and unknown analysis were carried out, and other plasticizers as phthalates, were also detected, in addition to other substances present in the analysed samples. All the soils exhibited the presence of a few plasticizers, either phthalic and/or non-phthalic.

Mathematical modeling by fractional calculus applied to separation processes

Process modeling is a way of representing real problems through equations and while the traditional models of mass and heat transfer processes consider the transient term as a first-order derivative, fractional order modeling is applied to verify that the order of the derivative of the transient term would not be represented by a non-integer number. In this context, the objective of this work was to apply fractional calculus to the kinetics study of adsorption and extraction processes and compare the results obtained with traditional models. The Caputo derivative was used to solve the proposed equations, and the analyzed processes were the adsorption of glycerol for biodiesel at different temperatures and the solid–liquid extraction of antioxidant compounds from corn for different proportions of solvent. For the adsorption, the fractional order model was compared with the pseudo-first, pseudo-second, and first-order models, and the fractional order model represented adsorption satisfactorily, with method efficiencies of 0.9603 and 0.9433 for the temperatures of 45 °C and 60 °C, respectively, while the performance of traditional models depends on the mechanisms that control the process. In addition, the α values obtained with the fractional order model were less than 1, indicating that glycerol adsorption does not follow an integer order derivative and implies that the adsorption exhibits a level of complexity that is not fully characterized by traditional models. The extraction of antioxidant compounds was analyzed and compared with the first-order and So and MacDonald’s models. It was verified that the derivative order values for the fractional order model were close to 1 and, therefore, the behavior is similar to the first order model and with indications that diffusion occurs as described by Fick’s law of diffusion. Thus, the results indicated that fractional order modeling can be used efficiently to describe chemical engineering processes such as adsorption and extraction.

Development of a green analytical methodology based on a deep eutectic solvent for the determination of pesticide residues in industrial hemp

In this study, in accordance with the green analytical chemistry principles, the use of eco-friendly solvents has been proposed for the first time for the analysis of pesticide residues in industrial hemp (Cannabis sativa L.). With this aim, betaine-based natural deep eutectic solvents with lactic acid and propylene glycol were explored as extraction solvents in the solid–liquid extraction of fifteen pesticides from hemp samples. The mixture composed of betaine:propylene glycol at molar ratio 1:4 (n/n) was selected due to its better analytical performance. The separation, identification and quantification of pesticides were carried out by gas chromatography coupled to tandem mass spectrometry. The extraction protocol was optimised through the step-by-step strategy, evaluating NADES composition, water addition to the solvent, solid–liquid ratio, and re-extraction solvent. The analytical methodology was validated in terms of calibration (linear regression with R2 ≥0.9966), trueness and precision (average relative recovery of 63–77% with relative standard deviation ≤20%) and sensitivity (limits of quantification of 0.663–3.625 µg/kg). These results successfully demonstrated the convenience of the developed approach for the determination of pesticides in industrial hemp, which has industrial applications such as the production of food and supplements, cosmetics, and textiles, which should not compromise the health of consumers. In addition, the comparison with previously reported research in this field showed that not only the present method is more sensitive, but also more sustainable and economical.

Mass transfer research on solid-liquid separation of extracted coal tar residue based on diffusion model

A large amount of coal tar residue (CTR) produced in the process of coal coking and tar processing is recognized as hazardous industrial waste with a high carbon content and strong carcinogenic polycyclic aromatic hydrocarbons. Through solvent extraction, CTR can be separated into economically valuable tar and fixed carbon, and waste recycling can be realized. In this paper, a mathematical model of CTR solid-liquid extraction is established based on a diffusion model and experiments, and the mass transfer law, mass transfer equation, and influence of different conditions of solid-liquid separation of CTR from toluene extraction are studied. First, the empirical formula is used to derive the change in the mass transfer coefficient kf outside the particles during extraction, and the kf gradually decreases as the extraction progresses. The particle swarm optimization is used to obtain the best effective diffusion coefficient Deff, inside the particles, which is 9.65 × 10−14 m2/s. The effective diffusion coefficient, Deff, was determined and corrected based on experimental data. A second-order function was fitted to describe the variation of Deff with temperature. MATLAB software was used to solve the model the concentration change law and extraction law during extraction were obtained. According to the model simulation, the influence of different conditions such as agent residue ratio, stirring speed, particle radius, and temperature on the extraction process is calculated.

Comparative extraction and antioxidant potential of bioactive compounds from Fucus vesiculosus: Kinetic modeling and UPLC-Q-TOF-MS phenolic profiling

This study explores efficient bioactive compounds extraction from Fucus vesiculosus (FV) seaweed using Ultrasound-assisted extraction (UAE) and Solid Liquid Extraction (SLE). Varied ultrasound intensities (UI) (58.8, 103.1 and 164.5 kW m−2 for U1, U2 and U3, respectively) were employed, and Peleg's model simulated extraction kinetics, revealing UAE's remarkable 10-min equilibrium contrasted with SLE's 3 h, showcasing UAE's time efficiency. UAE, particularly at U3, yielded significantly higher Total Phenolic Content (TPC) and Uronic Acid Content (UAC) compared to SLE, reaching maximum concentrations of 2.26 ± 0.01 g PGE 100 g−1 DFV and 7.87 ± 0.11 g GAE 100 g−1, respectively. Increased UI enhanced DPPH and ABTS antioxidant activities, while low UI resulted in higher FRAP values. After 20 min of extraction, U3 demonstrated superior DPPH scavenging activity (5.75 ± 0.23 μM TE g−1 DFV), surpassing that of SLE after 20 h of extraction (4.76 ± 0.11 μM TE g−1 DFV). Additionally, U3 displayed elevated ABTS values (8.92 ± 0.33 μM TE g−1 DFV) compared to 6.46 ± 0.41 μM TE g−1 DFV for SLE, with no significant difference observed in FRAP values. These results highlight U3's enhanced antioxidant potential in comparison to SLE. The chromatographic analysis identified six main compounds through UPLC-Q-TOF-MS and HPLC. Higher concentrations of phloroglucinol, gallic acid, catechin, protocatechuic acid, and chlorogenic acid were observed in U3. However, SLE exhibited a higher ferulic acid content. Future research aims to explore phloroglucinol derivatives and FC, contributing to FV' potential applications.

Experimental study on alkali reduction of film-coated porous ecological concrete by microbial calcium carbonate precipitation technology

Some plants do not grow due to the high pH levels of ecological concrete pore solutions. In this paper, we design and build an integrated device featuring a combined microbial film and a transverse/U-shaped grouting film. We have applied to the China Intellectual Property Office for an invention patent on this device. The device overcomes the blockage of the grouting port caused by microbial and vertical grouting. The vertical grouting tube leaves holes inside a specimen, reducing the compressive strength, while the integrated device optimizes and decreases variation in the recycling of microbial bacteria. The reduction in the pore alkalinity of porous ecological concrete resulting from the microbial grouting film of this device is larger than that resulting from a microbial sprayed film. The pH values of porous ecological concrete with microbial grouting films and microbial sprayed films are obtained by the pure slurry soaking method and solid–liquid extraction method, respectively. The pH value is lower for the film obtained by the pure slurry soaking method than for that obtained by the solid–liquid extraction method. Conversely, the pH value of porous ecological concrete with a microbial grouting film is reduced to approximately 8 at an age of 56 days. The compressive strengths of the porous ecological concrete specimens with the two films are almost the same. The results of this study provide the necessary theoretical basis for developing alkali reduction technology for porous ecological concrete with environmental and economic benefits.

Strengthening the Attainment of Major Competencies of Program Outcomes through Open-ended Experiment using Statistical Designs

Abstract—Unit operations are very essential part of the chemical engineering and allied disciplines; and hence, basic knowledge about the principles and equipment used for various unit operations is mandatory for process engineer. Unit operations course introduces the foundation of process engineering concepts at the second year of undergraduate program of Bachelor of Engineering in Biotechnology. This course mainly focuses on the most essential unit operations utilized in Chemical and allied process industries such as mass transfer, heat transfer, momentum transfer and mechanical operations. The conventional teaching approach practiced so far in Unit Operations Laboratory course was not so effective in the attainment of certain specific core competencies of Program Outcomes (POs). To tackle this challenge, we introduced a system of classifying laboratory experiments into four distinct categories: Demonstration, Exercise, Structural Inquiry, and Open-ended experiments. These categorized experiments were thoughtfully crafted to target various significant technical and professional outcomes such as Investigations of Complex Engineering Problems, Communication, Life-long learning, Follow of Standard Operating Procedure (SOP) and Good Laboratory Practices (GLP). The evaluation criteria for each type of experiment were aligned with program outcomes, competencies, and performance indicators. This alignment proved highly beneficial in achieving a more precise assessment of program outcomes. This study focuses on implementing an interactive and collaborative learning approach in the Unit Operations laboratory course. of Experiments. More precisely, the study employs Central Composite Design (CCD) and Response Surface Methodology (RSM) concepts to examine how various factors influence the Leaching (Solid-Liquid Extraction) process. The leaching process is most important unit operations used in the extraction of substances from solids. The study helped in addressing several important competencies pertaining to the Program Outcomes- PO-4: Demonstrating the capacity to design, execute experiments, and analyze data; PO-10: Exhibiting effective communication skills; PO-12: Embracing lifelong learning; PSO-13: Adhering to Standard Operating Procedures (SOP) and Good Laboratory Practices (GLP). The assessment of student performance employed a rubric-based approach, and the attainment of program outcomes was documented. It was observed that, open-ended experimental approach, led to the improvements in the attainment of PO’s in terms of competencies and performance indicators. To enhance the teaching-learning process, formal and anonymous feedback was gathered from students to identify areas of improvement and deficiencies. Keywords—Central Composite Design; Collaborative learning; Design of experiments; Open-ended experiment; Program outcome; Response Surface Methodology;

Separation and Purification Residual Salt from Glycerine Pitch from Waste of Refined Glycerine Production

The glycerol refining process produces 5%wt/ton waste in the form of glycerine pitch (GP) and has the potential to pollute the environment if not properly handled and expensive handling costs. In this study, GP was characterized by its chemical composition and spectroscopic analysis using FTIR and UV-Vis. The sodium chloride content of 15-30% contained in GP was separated and purified by solid-liquid extraction. Solvent selection (methanol, ethanol and acetone), solvent ratio (1:3, 1:5 and 1:10) and extraction time (10, 15 and 30 min) were evaluated using one factor at the time (OFAT) method. The methanol was found to be the optimum solvent and the best ratio at 1:5 produced sodium chloride purity around 81%. However, the effect of extraction time was declared not significant with a pvalue above 0.05. The TOC result of residual salt was 44 ppm and residual methanol content was not detected after heating. The integrated process of separation and purification of residual salt from GP is easy to apply and zerowaste potential in organic waste after extraction can be achieve by combustion in boiler with a calorific value obtained of 3000-3200 cal/g.

Ammonium halide selective ion pair recognition and extraction with a chalcogen bonding heteroditopic receptor.

The first example of a heteroditopic receptor capable of cooperative recognition and extraction of ammonium salt (NH4X) ion-pairs is described. Consisting of a bidentate 3,5-bis-tellurotriazole chalcogen bond donor binding cleft, the appendage of benzo-15-crown-5 (B15C5) substituents to the tellurium centres facilitates binding of the ammonium cation via a co-facial bis-B15C5 sandwich complex, which serves to switch on chalcogen bonding-mediated anion binding potency. Extensive quantitative ion-pair recognition 1H NMR titration studies in CD3CN/CDCl3 (1 : 1, v/v) solvent media reveal impressive ion-pair binding affinities towards a variety of ammonium halide, nitrate and thiocyanate salts, with the heteroditopic receptor displaying notable ammonium halide salt selectivity. The prodigious solution phase NH4X recognition also translates to efficient solid-liquid and liquid-liquid extraction capabilities.

Zwitterion detection with a fluorescent squaramide cryptand: a study on size-dependent salt recognition and sensing

Size-dependent recognition was achieved by mechanochemical-assisted solid–liquid extraction of amino acids using a squaramide-based cryptand.

Experimental Intensification and Modeling of Solid–Liquid Extraction of Polyphenols From Rice Husk Waste Using Organic Solvents

In the present study, the experimental intensification and modeling of the extraction process of antioxidants from rice husks using different organic solvents (ethanol, methanol, and acetone, and their mixtures with water) were analyzed and discussed. The best experimental extraction conditions to recover polyphenols from rice husks were identified, and the extraction kinetic data were modeled using the mechanistic and pseudo–second‐order models. The experimental results showed that the solvent‐based extraction of polyphenols from rice husks was endothermic where the ethanol and methanol offered the best separation performance. The polyphenol extraction process using ethanol and acetone was mainly influenced by the percentage of water contained in the solvent mixture used as separation medium, whereas the extraction temperature significantly affected the polyphenol extraction with methanol. The rice husk‐based extracts obtained with methanol and ethanol showed the highest total content of polyphenols (66.72 and 60.68 of gallic acid equivalent/g of biomass) and antioxidant capacity (71.93% and 72.02% 2,2‐diphenyl‐1‐picrylhydrazyl [DPPH] inhibition). The mechanistic model offered the best performance to describe the experimental polyphenol extraction, and its results were used to discuss and analyze the mass transfer parameters associated with the intraparticle diffusion of this extraction process. These results contribute to the valorization of rice husk residues as a potential feedstock to be incorporated in the biorefinery context for obtaining value‐added products.

VALIDAÇÃO DE MÉTODO ANALÍTICO PARA QUANTIFICAÇÃO DOS ESTRÓGENOS NATURAIS (E1, E2 E E3) E SINTÉTICO (EE2) EM ÁGUA SUPERFICIAL E MATERIAL PARTICULADO EM SUSPENSÃO DE UM ESTUÁRIO SUBTROPICAL DO ATLÂNTICO SUL, BRASIL

VALIDATION OF ANALYTICAL METHOD FOR QUANTIFICATION OF NATURAL ESTROGENS (E1, E2, AND E3) AND SYNTHETIC (EE2) IN SURFACE WATERS AND SUSPENDED PARTICULATE MATERIAL OF A SOUTH ATLANTIC SUBTROPICAL ESTUARY, BRAZIL. Marine pollution has become relevant for coastal conservation units and ecosystems of great ecological importance. This study validated analytical methods to investigate the occurrence of the emerging contaminants 17β-estradiol (E2), estrone (E1), estriol (E3), and 17α-ethinylestradiol (EE2) in surface waters and suspended particulate matter (SPM) from Guaratuba Bay, South Atlantic, Brazil. The analysis was performed by liquid chromatography coupled to a fluorescence detector (LC-FLD) after pre-concentration of surface water samples by solid phase extraction (SPE) or solid-liquid extraction for SPM samples. The recovery percentages were between 48 and 87%, and the coefficient of variation (CV) between 3 and 24% for SPM and from 64 to 107% (CV of 4 to 42%) for surface water. The method thus proved to be accurate and precise at the concentrations studied (ng g-1 and µg L-1). The concentration ranged from 10 to 177 ng L-1 in surface waters and from 392 to 4108 ng g-1 in SPM. E2, EE2, and E3 were found in SPM under different climatic conditions and population occupation. EE2 was determined in all sampling campaigns, especially in summer, when the number of tourists increases considerably. The presence of EE2 in the SPM of Guaratuba Bay warns for possible implications for the health of coastal environments.

Anthocyanin-rich extract from purple tea: Chemical stability, cellular antioxidant activity, and protection of human plasma

This study aimed to obtain an anthocyanin extract from the purple leaves of Camellia sinensis cv. Zijuan using a sustainable, non-toxic, and low-cost solid-liquid extraction, employing an aqueous citric acid solution (0.2 mol/L) as the extracting solvent, and to evaluate its chemical stability at different pH values, as well as its in vitro antioxidant properties in chemical and biological terms. The phenolic composition, in vitro antioxidant activity, and the stability of anthocyanins against pH, temperature, and light of the crude extract (CE) were evaluated, as well as the phenolic composition and bioactivity in the crude lyophilised extract (CLE). In the direct/reverse spectrophotometric titration, anthocyanins showed structural changes between pH 2 and 10, and reversibility of 80%. The antioxidant activity against the DPPH radical showed inhibition percentages of 73% (pH 4.5) to 39% (pH 10). Thermal stability was observed at 60 °C, and prolonged exposure of the extract to light caused photodegradation of the anthocyanins. Thirty-three phenolic compounds, including anthocyanins and catechins, were quantified in the CLE by UPLC-ESI-MS and HPLC, totalling 40.18 mg/g. CLE reduced cell viability (IC50 from 18.1 to 52.5 μg GAE/mL), exerted antiproliferative (GI50 from 0.0006 to 17.0 μg GAE/mL) and cytotoxic (LC50 from 33.2 to 89.9 μg GAE/mL) effects against A549 (human lung adenocarcinoma epithelial cells), HepG2 (hepatocellular carcinoma), HCT8 (ileocecal colorectal adenocarcinoma), and Eahy926 (somatic cell hybrid cells); and showed protection against oxidation of human plasma (635 ± 30 mg AAE/g). The results showed the diversity of compounds in the extracts and their potential for technological applications; however, temperature, pH, and light must be considered to avoid diminishing their bioactivity.

Discrimination of Diptera order insects based on their saturated cuticular hydrocarbon content using a new microextraction procedure and chromatographic analysis.

The nature and proportions of hydrocarbons in the cuticle of insects are characteristic of the species and age. Chemical analysis of cuticular hydrocarbons allows species discrimination, which is of great interest in the forensic field, where insects play a crucial role in estimating the minimum post-mortem interval. The objective of this work was the differentiation of Diptera order insects through their saturated cuticular hydrocarbon compositions (SCHCs). For this, specimens fixed in 70 : 30 ethanol : water, as recommended by the European Association for Forensic Entomology, were submitted to solid-liquid extraction followed by dispersive liquid-liquid microextraction, providing preconcentration factors up to 76 for the SCHCs. The final organic extract was analysed by gas chromatography coupled with flame ionization detection (GC-FID), and GC coupled with mass spectrometry was applied to confirm the identity of the SCHCs. The analysed samples contained linear alkanes with the number of carbon atoms in the C9-C15 and C18-C36 ranges with concentrations between 0.1 and 125 ng g-1. Chrysomya albiceps (in its larval stage) showed the highest number of analytes detected, with 21 compounds, while Lucilia sericata and Calliphora vicina the lowest, with only 3 alkanes. Non-supervised principal component analysis and supervised orthogonal partial least squares discriminant analysis were performed and an optimal model to differentiate specimens according to their species was obtained. In addition, statistically significant differences were observed in the concentrations of certain SCHCs within the same species depending on the stage of development or the growth pattern of the insect.

Highly selective solid-liquid extraction of microplastic mixtures as a pre-preparation tool for quantitative nuclear magnetic resonance spectroscopy studies.

Despite various developments in the application of quantitative nuclear magnetic resonance (qNMR) spectroscopy toward microplastics in recent years, this method still lacks suitable sample preparation and fractionation procedures. As this poses a crucial obstacle for its utilisation on environmental samples, which contain various mixtures of polymers along with other matrix substances, this research aims to address this missing link by presenting an easy-to-apply procedure based on common laboratory equipment. The process selectively separates microplastics from inorganic constituents while performing the necessary fractionation of different types of microplastics prior to qNMR analysis. It allows subsequent quantification of polystyrene (PS), polybutadiene rubber (BR), polymethylmethacrylate (PMMA), polyvinylchloride (PVC), polyethylene terephthalate (PET) and polyamide (PA) from a single sample, establishing recovery rates greater than 88% for all tested polymer types. Additionally, we extended our previous qNMR protocol to include two common polymer types: polymethylmethacrylate (PMMA) and polyacrylonitrile (PAN), achieving limits of detection down to 1.76 μg ml-1 and 12.53 μg ml-1 as well as limits of quantification down to 5.88 μg ml-1 and 41.78 μg ml-1, respectively. Thus, the qNMR method presented herein is now applicable to eight abundant polymer types, allowing the quantification of up to three different types simultaneously.