No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Microwave-assisted extraction based on emulsion breaking with natural deep eutectic solvent for vegetable oil sample preparation prior to elemental determination by ICP OES
Abstract and Figures
This study presents a novel and efficient method for the extraction of Al, Ca, Cr, Cu, K, Mg, Mn, and Zn in vegetable oil samples using a Natural Deep Eutectic Solvent (NADES) as an extractor combined with microwave radiation (MW) in an emulsion system. The NADES prepared with choline chloride:oxalic acid:water (1:1:4 molar ratio) provided a high extraction rate using 5.0 mL of the sample, 1.7 mL of NADES, and 1.3 mL of Triton X-100. The optimum conditions were obtained with 36 s of vortexing, 5 min of extraction, and 10 s for emulsion-breaking in MW. Under these conditions, recoveries ranged from 91% to 110% and relative standard deviations <9.0% were obtained. The limit of quantification (mg kg-1) was: 0.018 (Al), 0.032 (Ca), 0.007 (Cr), 0.006 (Cu), 0.013 (K), 0.027 (Mg), 0.002 (Mn), and 0.019 (Zn). The proposed method showed comparable results to reference methods and advantages, such as speed, low cost, and simplicity. The combination of NADES and MW represents a sustainable and innovative approach to the elemental determination composition of vegetable oils and contributes to advances in sample preparation methods.
Figures - uploaded by Floriatan Santos Costa
Author content
All figure content in this area was uploaded by Floriatan Santos Costa
Content may be subject to copyright.
... Deep eutectic solvents have been proven to be reliable tools at different stages in the analytical process. Both hydrophilic and hydrophobic DESs have been applied in extraction procedures of metal ions from liquids [7][8][9][10][11][12][13][14][15] and solid samples [16][17][18][19][20][21][22][23][24][25][26][27][28], sample digestion [29][30][31][32], modification of solid sorbents [33][34][35][36], elution in solid-phase extraction (SPE) [37], and speciation analysis [38,39]. In some cases, their high compatibility with the plasma techniques can even improve the analytical performance [19]. ...
... In such cases, DESs have played a crucial role in the sample preparation, ensuring reliable extraction of metal ions and their further V. Andruch et al. Advances in Sample Preparation 13 (2025) 100158 determination by ICP-OES [13][14][15] or MIP-OES [7]. Regarding the chemical composition, hydrophilic DESs based on choline chloride (ChCl) as a hydrogen bond acceptor (HBA) have been preferentially used for this purpose. ...
... DES-based extraction procedures are generally considered to be a greener alternative to previously developed extraction methods. However, only a few studies assessed their environmental friendliness using green metrics (just over 15 % of the articles included in this review) [7,14,19,[27][28][29]38,43,47,50,54,57,76]. Green assessment tools, such as AGREE [73,92], AGREEprep [93], the Analytical Eco-Scale [94], the RGB additive color model (RGB) [95], the Blue applicability grade index (BAGI) [96], the Green Analytical Procedure Index (GAPI) [97], the Complementary Green Analytical Procedure Index (ComplexGAPI) [73], and the Chloroform-oriented Toxicity Estimation Scale (ChlorTox) [98], were most often used. ...
... This is due to the low concentration of trace metal ions present and interfering substances (Saraji & Yousefi, 2009;Soylak & Altin, 2014;Stoica et al., 2006). Nickel ions can be found in many different samples using different analytical techniques, such as inductively coupled plasma optical emission spectrometry (ICP-OES) (Costa et al., 2023;Martinez-Rubio et al., 2020), UV-VIS spectrophotometry (Youssef, 2023), flame atomic absorption spectrometry (FAAS) (Ahmed, Ozalp et al., 2023;Soylak, 2002), and graphite furnace atomic absorption spectrometry (GFAAS) (Ahmed, Mohammed et al., 2023). Among these, flame atomic absorption spectrometry (FAAS) is commonly used due to its cost-effectiveness, user-friendly nature, and ability to select specific metals, particularly in water and food products. ...
... In research concerning the separation and enrichment of trace substances, the actual composition of the sample is of significant importance (Ahmed, Mohammed et al., 2023;Ahmed, Ozalp et al., 2023;Costa et al., 2023). The results provide the highest acceptable levels of the examined cations and anions, resulting in a relative error of less than ± 2 % (Supplementary Table S2). ...
... 17 Currently, microwave-assisted digestion is the most extensively used sample preparation technique. 18 Despite its popularity and efficiency, the equipment used for microwave digestion is expensive to acquire and maintain. 17 As an alternative for preparing various types of samples for ICP-OES analysis, the Conductively Heated Digestion System (CHDS) using closed vessels is an efficient technique, offering lower equipment acquisition and maintenance costs. ...
This study presents a novel and efficient sample preparation method based on conductively heated digestion in closed vessels (CHDS), employing collagen capsules as a transfer medium. The method was specifically...
This review discusses developments in elemental mass spectrometry, atomic absorption, emission and fluorescence, XRF and LIBS, as applied to the analysis of specimens of clinical interest, foods and beverages. Sample preparation procedures and quality assurance are also included.
In this study, extraction methods using natural deep eutectic solvents (NADES) were proposed for the determination of arsenic (As), cadmium (Cd), and lead (Pb) in plant and food matrices. NADES are green and sustainable solvents with advantageous chemical properties for such applications. The NADES were prepared with different components, characterized, and applied in ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) methods. Experimental variables including temperature, extraction time, and sample-solvent ratio, were investigated using experimental designs to establish the optimal extraction conditions before analysis by ICP-MS. For the MAE method, the optimal conditions were extraction temperature of 100 °C, extraction time of 40 min, and SSR of 40:1 m v−1, resulting in recoveries of up to 84 %. For the UAE method, the optimal conditions were 40 °C, 40 min, and SSR of 30:1 m v−1, with recoveries ranging from 96 % to 109 %, all with relative standard deviations less than 11 %. The proposed methods provided low detection limits (mg kg−1), with values of <0.0160 for As, <0.0030 for Cd, and < 0.0090 for Pb for UAE and MAE. The methods were considered green, achieving scores of 0.54 (MAE) and 0.45 (UAE) on the analytical greenness metric for sample preparation. The use of NADES as efficient extractants, combined with multivariate optimization, resulted in optimal experimental conditions, good analytical performance, and enhanced sustainability. The proposed method is a promising approach for applications in food safety and public health studies.
Sample preparation plays a role in chemical analysis and is essential for addressing analytical applications. However, this step has become increasingly complex due to the demand for analyses of highly intricate samples and the growing interest in more efficient and sustainable methods. Therefore, in this thesis, innovative strategies were developed using deep eutectic solvents (DES) in alternative sample preparation methods, focusing on inorganic analyte extraction and elemental determination through atomic spectrometry techniques. Initially, a review of methods employing DES was conducted, evaluating their sustainability through green sample preparation metrics, combined with exploratory data analysis using a self-organizing map. Additionally, extraction methods were developed for various matrices, utilizing microwave radiation for the extraction of Cd, Cu, Fe, Mn, and Zn in medicinal herb samples, and a method based on emulsion-breaking for the determination of Al, Ca, Cr, Cu, K, Mg, Mn, and Zn in vegetable oils. Extraction methods using various solvents were also proposed for Pb extraction in printed circuit boards (electronic waste). All methods were developed based on the study of DES composition based on choline chloride and carboxylic acids, evaluation and optimization of experimental conditions using multivariate tools, evaluation of analytical performance parameters, and greenness assessment. The results indicate that the developed methods achieved significant performance in extracting inorganic analytes in different types of organic and inorganic matrix samples, with high extraction rates, precision, and accuracy compatible with adopted reference methods and according to performance criteria. Thus, this thesis contributes significant improvement in sample preparation and provides alternative methods for elemental determination, with advantages related to simplicity, efficiency, and sustainability.
In this work, a novel deep eutectic solvent (DES) composed of thymol and 1-(o Tolyl)thiourea 9/1 (mol) is presented for the first time. This DES has not been described in the literature. This DES was first used as a stationary phase in an extraction column integrated into a flow injection analysis system for the simultaneous determination of mercury and copper in edible oils. The automated approach involves passing an aqueous sample solution obtained after microwave mineralization through a microcolumn of DES retained on polytetrafluoroethylene. This leading to the extraction and concentration of the analytes. The metals are then eluted with an aqueous thiourea solution for subsequent analysis by inductively coupled plasma-optical emission spectrometry. The limits of detection (LODs) for mercury and copper were 3 μg L⁻1 and 2.5 μg L⁻1, respectively. The approach demonstrated high accuracy. Relative standard deviations (RSD) for repeatability and inter-day reproducibility ranged from 3% to 11%. Extraction recovery of both metals exceeded 95%, indicating the high efficiency of the DES-based extraction process. Environmental assessment using the AGREEprep method yielded a favorable environmental index of 0.54, highlighting the robustness of the approach. This novel use of DES as a stationary phase in flow injection analysis system provides a robust, efficient and environmentally friendly approach to the determination of trace metals in edible oils. This method can also be applied to the analysis of other samples.
Currently, the processes of obtaining and producing food as well as consumption habits give rise to new challenges for food safety. The presence of heavy metals in edible vegetable oils has harmful effects for humans. In this study, the scientific literature which reports the presence of heavy metals in different types of vegetable oils was analysed. More than 25 heavy metals are evaluated in 35 different oils from 24 countries. The widely studied metals are Cd, Pb, Cu, and Fe in olive oil, sunflower oil, rapeseed oil, and corn oils, mainly in Brazil, Turkey, China, Iran, and India. Likewise, the presence of Antimony (Sb) as a product of migration from PET containers to edible vegetable oils is a topic of great interest in recent years. Additionally, the different analytical techniques used for this purpose and the standards are analysed. This study highlights the main findings and challenges in this research field.
Sample preparation is a key step in the analytical procedure and a critical component for achieving analytical greenness. AGREEprep is the first metric intended for evaluating the environmental impact of sample preparation methods. The approach consists of ten steps of assessment that correspond to the ten principles of green sample preparation and uses a user-friendly open-source software to calculate and visualize the results. Despite the simplicity of the approach, some assessment steps can be difficult to evaluate in a straightforward manner, either because essential data are not readily available or, in some cases, are poorly defined.
This walkthrough tutorial on AGREEprep serves as an in depth yet simple guide for new users that elucidates all aspects of the greenness assessment. It will prove beneficial to analysts wishing to assess the greenness of their own developed procedures or those found in the literature, which can be challenging taken that critical data is often not reported. Particular attention is given to the calculations involved in estimating the amount of waste generated and energetic requirements. The impact of weight values of criteria on the overall final score are discussed and using two hypothetical scenarios is related to the analytical goals of operators. Finally, several assessment examples are given in the supplementary information to familiarize assessors with all assessment steps.
Nowadays, critical environmental pollution needs some novel, simple, effective, and cost-effective catalysts with high efficiency in the visible region of the light. Thus, the AgI/BiOI coupled nanocatalyst sample (CS) was prepared and briefly characterized. The pH pzc values of 6.2, 5.4, and 4.5 were estimated for AgI, BiOI, and AgI/BiOI samples. Based on the PXRD results, average crystallite sizes of 35.2, 34.7, and 34.1 nm were obtained for AgI, BiOI, and AgI/BiOI samples from the Scherrer formula and 38.3, 25.6, and 25.6 nm by the Williamson-Hall formula. SEM image confirmed a sheet-like BiOI morphology covered by AgI nanoparticles. The simultaneous interactions of the influencing variables on the boosted photo-catalytic activity of CS sample towards Eriochrome Black T (EBT) were evaluated by response surface methodology (RSM) (under 100-W tungsten lamp irradiation with 230 mW/m 2 .nm irradiance). The goodness of the model was confirmed by the significance of the model (F value of 65.68 > F 0.05, 14, 13 = 2.55) and a non-significant LOF (F value of 0.97 < F 0.05, 10, 3 = 8.79) at a 95% confidence interval obtained in ANOVA analysis of the results. The center point runs have the following conditions: catalyst dose: 0.68 g/L; pH: 7.5; C EBT : 7.25 mg/L; and irradiation time: 53.5 min, while the optimal run included the following conditions: catalyst dose: 1.0 g/L; pH: 4; C EBT : 10 mg/L; and irradiation time: 80 min. About 95% of EBT molecules were degraded in the optimal conditions.
Sample preparation remains a key step in the analytical process. Herein, the ten principles of GSP are proposed with the aim of establishing a road map toward the development of overall greener analytical methodologies. Paramount aspects for greening sample preparation and their interconnections are identified and discussed. These include the use of safe solvents/reagents and materials that are renewable, recycled and reusable, minimizing waste generation and energy demand, and enabling high sample throughput, miniaturization, procedure simplification/automation, and operator’s safety. Further, the importance of applying green metrics for assessing the greenness of sample preparation methods is highlighted, next to the contribution of GSP in achieving the broader goal of sustainability. Green sample preparation is sample preparation. It is not a new subdiscipline of sample preparation but a guiding principle that promotes sustainable development through the adoption of environmentally benign sample preparation procedures.
In the present work, a method was developed for the determination of Ca, Fe, Mg, and Zn in edible oil samples using ultrasound-assisted emulsification followed by extraction induced by emulsion breaking (EIEB) and detection by high-resolution continuous source flame atomic absorption spectrometry (HR-CS FAAS). Multivariate tools were used to optimize the variables involved in the extraction performance. Constrained mixture design allows obtaining the proportions of the liquids (5.5 mL of sample, 2.5 mL of 3.0 mol L−1 HNO3, and 2.0 mL of 1.0% Triton X-114) to the emulsion formation. Doehlert design optimized the variables acid concentration (1.0 mol L−1), sonication time (12 min), and emulsion breaking temperature (90 °C). The limits of quantification obtained were 14.4 and 25.0, 36.7, and 26.3 μg L−1 for Ca, Fe, Mg, and Zn, respectively. The accuracy was accessed by addition/recovery tests, obtaining values in the range of 87–113%.
This study aims to develop of a method based on extraction induced by emulsion breaking (EIEB) to determine Mg, Ca, Zn, and Na in cocoa butter by flame atomic absorption and emission spectrometry. The method has been optimized using Box-Behnken design as a response surface methodology for the variables: nitric acid concentration, extraction time, and surfactant concentration. Optimal conditions were the following, for 1.00 g of sample: 1.0 mL of solution extractor containing 0.7% (w v−1) Triton X-114 surfactant in 1.8 mol L−1 nitric acid, and 7 min for extraction, being the emulsion breaking promoved by heating to 96 °C in a water bath followed of centrifugation. Under this conditions, quantitation limits were 0.33, 0.67, 0.05, and 0.33 mg kg−1 for Mg, Ca, Zn, and Na, respectively; precision, obtained by values of RSD%, was less than 9.6%; accuracy, evaluated by addition and recovery test on three different cocoa butter samples and comparison of extraction with a reference method established in the literature, was between 90 and 117%. The proposed method of EIEB has been applied to cocoa butter samples, and the found concentrations (mg kg−1) varied between 15.8 and 37.1 (Mg), 1.20 and 5.18 (Ca), 0.20 and 1.05 (Zn), and 0.60 and 1.93 (Na). Therefore, the EIEB method is simple, efficient, with low cost and reagent consumption, presents good precision and accuracy, and is an excellent alternative for the element determinations in cocoa butter.
The development of a method based on extraction induced by emulsion breaking (EIEB) aiming copper determination in gasohol using graphite furnace atomic absorption spectrometry (GF AAS) is reported. Emulsification of the gasohol samples was carried out using nitric acid solution, (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol surfactant (Triton X-114), and ultrasound energy. The variables related to the extraction efficiency were optimized by multivariate approaches (two-level factorial fractional design and Doehlert design). The best results were obtained when the emulsion was formed with 5.0 mL of the sample, 0.200 mL of 2.4 mol L-1 HNO3, 0.100 mL of 10% Triton X-114 and 10 min of sonication. A fast and efficient emulsion breaking was performed at 90 ºC. A volume of 6.65 mL of the copper-rich hydroalcoholic phase was extracted, separated from the organic phase and analyzed. Under these conditions, the following analytical characteristics were obtained: 0.61 and 2.0 µg L-1 for limits of detection and quantification, respectively; precision (percentage of relative standard deviation, 10 µg L-1) of 2.8%; and analytical sensitivity of 0.011 L µg -1. Accuracy was assessed by spike tests, and values in the range of 95-110% were achieved. The method was applied in the determination of copper in Brazilian gasoline samples (gasohol with 27% ethanol).
Natural deep eutectic solvents (NADESs) are defined as mixtures of certain molar ratios of natural compounds such as sugars, organic acids, amino acids, and organic bases that are abundant in organisms. The melting points of these mixtures are considerably lower than those of their individual ingredients and far below ambient temperature. The first publications on the NADES concept in 2011 created a great expectation regarding their potential as green solvents that could replace conventional organic solvents in a wide range of applications. This was largely because many of the drawbacks of conventional synthetic ionic liquids (ILs) and deep eutectic solvents (DESs), particularly their toxicity and environmental hazards, could be solved using NADESs. Throughout the last 7 years, the interest in NADESs has increased enormously as reflected by the exponential growth of the number of related publications. The research on NADESs has rapidly expanded particularly into the evaluation of the feasibility of their application in diverse fields such as the extraction of (targeted) bioactive compounds from natural sources, as media for enzymatic or chemical reactions, preservatives of labile compounds, or as vehicles of non–water-soluble compounds for pharmaceutical purposes. Along with the exploration of these potential applications, there have been a large number of other studies related to their physicochemical features, the search for new NADESs, the research into the interactions between NADES components or with solutes, the recovery of solutes from NADES solutions, and the ways of circumventing inherent problems of NADESs such as their high viscosity and the consequent difficulties in handling them. This article contains a review of the applications of NADESs as extraction solvents, reaction media, and preservative, providing also a perspective of their future.
In the present study, a simple, mono step deep
eutectic solvent (DES) extraction was developed for selective
extraction of copper from sediment samples. The optimization
of all experimental parameters, e.g. DES type,
sample/DES ratio, contact time and temperature were performed
with using BCR-280 R (lake sediment certified reference
material). The limit of detection (LOD) and the limit
of quantification (LOQ) were found as 1.2 and 3.97 µg L−1,
respectively. The RSD of the procedure was 7.5%. The proposed
extraction method was applied to river and lake sediments
sampled from Serpincik, Çeltek, Kızılırmak (Fadl
and Tecer region of the river), Sivas-Turkey.
In the present work, simple and sensitive extraction methods for selective determination of manganese have been successfully developed. The methods were based on solubilization of manganese in deep eutectic solvent medium. Three deep eutectic solvents with choline chloride (vitamin B4) and tartaric/oxalic/citric acids have been prepared. Extraction parameters were optimized with using standard reference material (1573a tomato leaves). The quantitative recovery values were obtained with 1.25 g/L sample to deep eutectic solvent (DES) volume, at 95 °C for 2 h. The limit of detection was found as 0.50, 0.34, and 1.23 μg/L for DES/tartaric, DES/oxalic, and DES/citric acid, respectively. At optimum conditions, the analytical signal was linear for the range of 10–3000 μg/L for all studied DESs with the correlation coefficient >0.99. The extraction methods were applied to different real samples such as basil herb, spinach, dill, and cucumber barks. The known amount of manganese was spiked to samples, and good recovery results were obtained.
Emulsified systems are characterized by an immiscible liquid dispersed in another liquid in the form of droplets. These systems can be classified according to the size of the dispersed droplets obtained in coarse emulsions (0.5 to 50 µm) or microemulsions (0.01 to 0.10 µm). These systems have several properties that make them interesting in several fields of technology, and the emulsion formed by oil droplets dispersed in an aqueous phase (O/A) is the most used in analytical determinations due to its low viscosity and organic load. This manuscript discusses the characteristics of emulsified systems, their obtention, stabilization, properties and use in the development of analytical methods for elemental analysis in matrices with high organic content such as oils, fatty foods and fuel matrices.
The present study investigated the potential of several indigenous fungal strains to produce industrially important exo-polygalacturonase (exo-PG) utilizing locally available agro-industrial wastes in solid-state fermentation (SSF). Amongst various substrates employed, wheat bran supported the highest biosynthesis of exo-PG. Different process variables such as, fermentation duration, moisture level, pH and temperature were optimized using one-variable-at-a-time (OVAT) statistical approach. Results revealed that an initial medium pH of 3.0 at 35 °C together with MnSO
In this work, an innovative ultrasound-assisted matrix solid-phase dispersion (UA-MSPD) method and microwave-assisted extraction (MAE) were applied with amino acids-based deep eutectic solvents (AADES) for the extraction of arsenic (As) from medicinal herbs. Multivariate optimization by Doehlert design (DD) was performed to determine the optimal experimental conditions. The effects of temperature (TP), time (TM), and sample-solvent ratio (SSR) were evaluated, and the optimized conditions were 50 °C, 60 min, and 10:1 mg mL-1 for UA-MSPD and 100 °C, 40 min, and 40:1 mg mL-1 for MAE, employing AADES 2 (β-alanine, citric acid, and water), where the hydroxyl and carboxyl groups of the citric acid structure favored formation of a chelate complex with the analyte. AADES 3 (β-alanine, xylitol, and water) was effective for MAE, while AADES 1 (β-alanine, malic acid, and water) proved to be inefficient for As extraction. The parameters of the analytical methods were evaluated using certified reference materials. The accuracy, based on percentage recovery, was in the range 77-101%, while the limits of detection and quantification were in the ranges 0.010-0.039 mg kg-1 and 0.011-0.130 mg kg-1, respectively. The analytical curves presented R2 > 0.99. The proposed methods were shown to be environmentally friendly, based on the Analytical Eco-Scale and RGB 12 procedures. Both optimized methods were applied for the determination of As in commercial medicinal herbs (0.059-0.101 mg kg-1), with the values obtained being within the maximum daily intake limit established by the World Health Organization (WHO). It should be noted that there are no previous reports in the literature concerning the application of a sample preparation method using AADES, employing their solid precursors, with no requirement for prior solvent synthesis, as proposed here in the case of the UA-MSPD method.
Simple, rapid, low cost, selective, and sensitive analytical method was developed using fatty acid-based ternary deep eutectic solvents (TDESs) for extraction and determination of tetracycline in honey, milk and water samples by vortex assisted (VA) microextraction and Uv-vis spectrophotometer. Four different TDES were prepared through by combination of nonanoic acid, dodecanoic acid, decanoic, hexanoic acid, octanoic acid. Analytical parameters such as pH, TDES types and its molar ratio, dispersive solvent types and its volume, salt effect were optimized. VA-TDES method was good recovery of tetracycline in the samples from 94 to 99%. The LOD and LOQ values were found 1.0 and 3.3 µg L⁻¹, respectively. The linear range of calibration graph was 3.3 and 450 µg L⁻¹. Intra-day and inter-day precision was found 2.8-4.1% and 3.6-5.2 %. Enhancement factor was found 109. The factorial design was drawn to evaluate the significant level of factors and effects of variables on the recovery of tetracycline. Standard addition method was used for the validation and accuracy of the method. Present VA-TDES method was successfully applied to real samples.
A fast, simple and environmentally friendly method for the digestion of solid samples of Gentiana rigescens Franch. ex Hemsl. (G. rigescens) based on deep eutectic solvent (DES) was established, and inductively coupled plasma-optical emission spectrometry (ICP-OES) was used to quantify Ni, Zn, Co, Cr and Cu in DES digestion solution. Under optimized conditions, limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.4 to 2.5 and 1.2-8.2 μg g-1, respectively. The intra-day and inter-day precision were carried out by relative standard deviation (RSD) ranged from 0.8% to 4.9% and 0.6%-1.4%, and the spiked recoveries ranged from 90.6% to 111.9%, respectively. The results of quantitative analysis by the developed method were in good agreement with those of microwave digestion. At the same time, the contents of the metal ions in the G. rigescens decoction liquid and freeze-dried powder solution of the decoction liquid of G. rigescens (crude extract) were determined by ICP-OES. The results showed that the contents of Ni, Zn, Co and Cu in the decoction liquid and crude extract were significantly lower than the contents in DES digestion liquid, and Cr was not detected. Then, the oxidative damage model of LO2 cells induced by H2O2 was established. The protective effect of crude extract of G. rigescens on damaged liver cells and the effect of metal ions with the same contents of decoction liquid on liver protection of G. rigescens were investigated for the first time. The results show that H2O2 could induce the decrease of LO2 cell viability and damage the cell morphology. GPS and crude extract could inhibit H2O2-induced liver injury by adjusting the antioxidant enzyme system. Metal ions corresponding to the content of the decoction liquid may weaken the hepatoprotective effect of GPS or crude extract by regulating the antioxidant enzyme system.
The principles of green analytical chemistry have led to the development of analytical procedures that are increasingly sustainable. Different metrics have been created for the evaluation of greenness, although determination of the green nature of new analytical methods remains challenging, including for extraction methods that involve the use of natural deep eutectic solvents (NADES). In this study, the following five chemical metrics for the evaluation of greenness were considered: National Environmental Methods Index (NEMI), Green Analytical Procedure Index (GAPI), Analytical Eco-Scale, Analytical GREEnness (AGREE), and White Analytical Chemistry (WAC). These methods were applied in evaluation of the environmental and sustainability characteristics of three different methods for the preparation of plant material samples: microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and microwave-assisted acid digestion (MW-AD). These methods employed different NADES as extraction solvents, as well as dilute nitric acid as an oxidizing agent, for the determination of As, Cd, Pb, and V by inductively coupled plasma mass spectrometry (ICP-MS). The NEMI metric found no differences between the MAE-NADES and UAE-NADES methods. The GAPI metric found differences between the MAE-NADES and UAE-NADES methods and identify the disadvantageous aspects of each step of the methods. The Analytical Eco-Scale and AGREE identified the MAE-NADES method as the greenest, while WAC-12 RGB indicated the UAE-NADES method as the greenest procedure. A detailed discussion is provided of the application of each metric, together with their differences and advantages.
Trace elements play an important role in humans as some are essential for the proper functioning of the body while others may have negative impact in health. Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of nine elements (Cd, Cr, Cu, Fe, Mn, Ni, Ti, V e Zn) in olive oil, soy oil and margarine. Samples were treated with nitric acid solution (10 % v/v) and heated at 50 °C for 30 min. This mixture was placed in an ultrasonic bath for 20 min, in order to obtain quantitative extraction of trace-elements into the acid solution, which was directly aspirated into the ICP-MS to be quantified, using analytical curves constructed with aqueous standards. This simple sample preparation procedure along with an efficient sample introduction strategy (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber) facilitated the overall analytical process. Internal standardization with Rh was used to correct matrix effects and signal fluctuations. Limits of detection in the ng g⁻¹ range were achieved for all elements and were appropriate for the intended application. The method was tested by the analysis of samples before and after fortification with metalo-organic standards and recoveries between 88 and 117% were achieved. The method was found to lead to reliable results using a fast and simple procedure.
The aim of present study was to determine the arsenic in water, honey and rice samples using a new and green vortex-assisted liquid phase microextraction (VA-LPME), which is based on deep eutectic solvent (DES) by hydride generation-atomic absorption spectrometry. Ethylenediamine-N,N'-disuccinic acid (EDDS) was used as chelating reagent for As(III) ions. Four different DES was prepared by using different combination and molar ratios of hydrogen bond donor (HBD) as benzyltriphenylphosphonium chloride, tetra-n-butylammonium bromide, choline chloride and hydrogen bond acceptor (HBA) groups as ethylene glycol, glycerol and diethanolamine. Different parameters such as pH, chelating agent amount, DES types, molar ratio and its volume, emulsifier agents and its volume, vortex time and sample volume were optimized. The accuracy of the method was confirmed with certified reference materials. The DES-VA-LPME method was validated by using linearity r² 0.9985, working range 20–600 ng L⁻¹, limit of detection 6.5 ng L⁻¹, limit of quantitation 20 ng L⁻¹ and enhancement factor 70. Intra and inter day relative standard deviation was found in the range of 3.6 and 4.1% and 4.2 and 4.9%, respectively. The developed procedure was successfully utilized for determination of arsenic in water, honey and rice samples. The factorial design was used to investigate the individual and combined effects of variables as well significant and insignificant effects.
In this work deep eutectic solvents based on choline chloride and different hydrogen bond donors were systematically investigated for separation of singly- and multiply-charged metals (Ag, Al, B, Ba, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sn, Ti, V and Zn) from oil matrices. The effect of deep eutectic solvents precursors was shown to play a critical role in the extraction of different metals. Carboxylic acids, polyols, sugars, urea, and its derivatives were studied as hydrogen bond donors of deep eutectic solvents for metals separation. It was found that deep eutectic solvents based on carboxylic acids and sugars provided the highest extraction efficiency in the extraction of both singly- and multiply-charged metals from oil matrices. Moreover, the effect of water as precursor of deep eutectic solvent on metals’ separation was investigated. Among studied solvents, the deep eutectic solvent containing choline chloride, lactic acid and water provided the highest extraction recovery (up to 99 %). The extraction solvent was applied to elemental analysis of oil samples (vegetable oil and motor oil) by ICP-OES method. Under optimal conditions, the limits of detection were in the range 0.02 to 17 mg kg⁻¹. The developed procedure is not required a microwave digestion of oil samples for elemental analysis.
A novel automatic flow-batch platform coupled with atomic spectrometry for on-line acidic extraction induced by emulsion breaking with heating (FB-EIEBH) for metal determination in edible oils (corn, sunflower and olive oil), was developed for the first time. The proposed system was demonstrated for copper determination in conjunction with flame atomic absorption spectrometry. The extraction of metal is accomplished after the oil emulsification with an aqueous solution consisted of Triton X-114 and nitric acid, in an on-line programmed manner. All the main parameters affecting the extraction procedure, such as oil dilution, type and concentration of surfactant and nitric acid as well as temperature and time for the emulsion breaking and phase separation, have been investigated and optimized. A mixture of oil/xylene at 10:2 proportion was found to be appropriate to use in the flow manifold. Optimum conditions were verified employing 8.0 mL of oil sample, 990 μL of extractant solution containing 10.0% m/v Triton X-114 and 10.0% v/v HNO3. Emulsion breaking and phases separation were completed at temperature 90 °C, and time 300 s. The detection and quantification limit for copper determination was found to be 5.8 μg L⁻¹ and 19.3 μg L⁻¹, employing aqueous standards, which are proved to produce similar performance characteristics with oil-based standards. Recovery tests were executed by appropriate additions of oil-based standard solution of copper and the recoveries ranged between 94.2 and 102.4%.
In this study, a microwave-assisted extraction (MAE) method based on the natural deep eutectic solvent (NADES) was developed for the Cd, Cu, Fe, Mn, and Zn determination in medicinal herb samples. The experimental conditions were optimized and the method parameters were evaluated using certified reference material. The NADES composed of choline chloride-oxalic acid prepared in a microwave system showed better extraction rates and low-energy consumption. Optimal conditions in the MAE were obtained using 35 seconds of extraction time, 90% of microwave power, and a 50 mg/mL sample-solvent ratio. Recoveries in the range of 87 to 109% and relative standard deviation <8.45% were obtained. The limits of quantification (mg kg⁻¹) were: 0.0233 (Cd), 0.0229 (Cu), 1.10 (Fe), 0.06 (Mn), and 0.67 (Zn). The medicinal herbs were analyzed and daily intake values were estimated for Cu (<0.20%), Fe (<18.1%), Mn (<13.8%), and Zn (<0.64%); concentrations above threshold values for Cd were found. The optimization of experimental conditions combined and the use of an eco-friendly solvent provided excellent analytical parameters in the proposed method.
This work proposes for the first time, a metric tool that gives prominence to sample preparation. The developed metric (termed AGREEprep) was based on 10 categories of impact that were recalculated to 0-1 scale sub-scores, and then used to calculate the final assessment score. The criteria of assessment evaluated, among others, the choice and use of solvents, materials and reagents, waste generation, energy consumption, sample size, and throughput. Assessment was also based on the possibility to differentiate between criteria importance by assigning them weights. The assessment procedure was performed using an open access, intuitive software that produced an easy-to-read pictogram with information on the total performance and structure of threats. A compiled version of the open access software can be obtained from mostwiedzy.pl/AGREEprep. The applicability of AGREEprep was successfully demonstrated using six different methods as case studies.
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.
In this study, sodium hydroxide-induced homogenous liquid-liquid extraction was combined with effervescent assisted-dispersive liquid-liquid microextraction and used for the extraction of phytosterols (lupeol, β-sitosterol, stigmasterol, campesterol, and brassicasterol) from cream samples. Two types of deep eutectic solvents (water-miscible and water-immiscible solvents) were prepared and used in the extraction procedure. In this approach, firstly, the sample was dissolved in a mixture of n-hexane and tetrabutylammonium bromide: ethylene glycol deep eutectic solvent (as extraction/disperser solvent) and a homogenous solution was obtained. After that, a few microliters of sodium hydroxide solution (as fatty acid saponification and phase separation agent) was quickly injected into the mixture. By doing so, a three-phase system was formed. Then, the supernatant phase (tetrabutylammonium bromide: ethylene glycol deep eutectic solvent) was removed and mixed with tetrabutylammonium bromide: dichloroacetic acid: octanoic acid deep eutectic solvent. The obtained solution was applied in the microextraction step. To obtain effective, reliable, robust, accurate, and precise analytical results, the effective parameters for the presented method were investigated and optimized in detail. Detection limits, extraction recoveries, and enrichment factors were in the ranges of 0.06–0.26 µg kg–1, 86-93%, and 215–232, respectively. Intra- and inter-day repeatabilities were investigated at a concentration of 1.5 µg kg–1 (each analyte) and they were in the ranges of 5.3-7.5 and 7.2-8.8%, respectively. Finally, the presented method was easily used in analysis of the phytosterols in cow milk cream samples.
The synthesis of new environmentally friendly and biocompatible material is an exciting research field to remove various pollutants from water/wastewater samples. The main objective of this paper is the successful synthesis of an Eco-friendly and novel modified silica aerogel (NMSA) by adding a small amount of Quince seed mucilage (QSM, 0.05 wt%) to water glass precursor and an ambient pressure drying method. The prepared NMSA was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and N2 adsorption/desorption isotherms. Results showed that adding a small amount of QSM to the precursor causes the formation of relatively uniform nanoparticles with an approximate size of 20 nm. The synthesized NMSA was then used for Pb(II) removal from an aqueous solution. Pb(II) adsorption in NMSA was about 30% more than raw Silica aerogel (SA). After performing some preliminary experiments and confirming the excellent efficiency of the NMSA in Pb(II) removal, RSM (response surface methodology) study via a central composite design (CCD) optimization approach was made to study the effects of the interaction of the influencing variables on the adsorption efficiency. The maximum Pb(II)-removal efficiency of 75% was achieved for the optimized run with conditions of pH: 4, contact time: 62 min, NMSA dosage: 1.4 g/L, and initial Pb(II) concentration: 50 mg/L. The Pb(II) removal by the modified NMSA adsorbent well obeyed the Langmuir isotherm and a pseudo-second-order rate kinetics model.
Deep eutectic solvents based on choline chloride, carboxylic acids, urea, and polyols were investigated for separation of 14 metals from plant samples. It was found that carboxylic acid as precursor of DES played key-role for effective metals separation. It was established that the solvent synthesized from choline chloride and malic acid provided highest extraction recovery (from 73 to 88%). Mixing and heating the solvent and sample for 30 min at a temperature of 70 °C provided effective separation of metals from plant sample. The developed procedure is not required a microwave digestion of samples. After separation the solvent phase containing analytes was dissolved in aqueous phase and analyzed. The developed procedure was applied to elemental analysis of plant tobacco and lettuce samples by inductively coupled plasma optical emission spectroscopy. Limits of detection calculated as three times the signal-to-noise ratio were in the range from 0.2 to 17 mg kg⁻¹.
Advanced methodologies were applied for the detection of some elements at trace levels in edible oils. Trace elements play a role in oil stability, quality of edible oils and fats. In the present study, problems were addressed related to simple, cheap, less time consuming and suitable pretreatment advanced methods for suitable sample introduction and calibrations as well as the strategies and techniques are discussed. The present review is aimed to discuss the significance of simplifying sample treatments are offered for trace elements in oils. The period covered by this review is last twenty years. However, the various applications of advanced methodologies including extraction and microextraction. The scope of spectrometric techniques used for the analysis of trace elements in edible oils was discussed by new instrumental development trends.
This paper describes the simultaneous determination of Ba, Co, Fe, and Ni in nuts by high-resolution continuum source atomic absorption spectrometry after extraction induced by solid-oil-water emulsion breaking. Extraction yields ranged from 94.9 for Ba to 109.8% for Fe. Simultaneous measurements were carried out at secondary lines of Ba, Co, Fe, and Ni. The limits of detection and quantification were, respectively, 3.819 and 1.146 mg L⁻¹ for Ba, 2.274 and 7.421 µg L⁻¹ for Co, 0.095 and 0.285 mg L⁻¹ for Fe, and 2.138 and 6.614 µg L⁻¹ for Ni. The precision ranged from 3.1 to 4.2%, 1.5 to 8.0%, 1.6 to 6.6%, and 0.4 to 6.1% for Ba, Co, Fe and Ni, respectively. The method accuracy was assessed by recovery tests and comparison of the results obtained by the proposed extraction method with those obtained after acid digestion. Recoveries ranged from 93.5 for Ni to 104.5% for Co.
Extraction induced by emulsion breaking was combined with graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of tin in edible oil samples. Emulsion preparation was carried out by vortex agitation with Triton X-114 in diluted nitric acid. The emulsion breaking was reached by heating. Calibration curves were obtained by GF AAS and ICP-MS from 10 to 100 µg L⁻¹ and from 0.1 to 10 µg L⁻¹, respectively. The limits of detection were 1.1 and 0.009 µg L⁻¹, respectively, and the limits of quantification were 3.6 and 0.03 µg L⁻¹, respectively. Accuracy was assessed by spike and recovery tests and also by comparison with microwave-assisted acid digestion. The results obtained by both sample preparation methods were consistent for oil samples of olive, corn, and fish. In addition, the potential of the proposed analytical method was investigated for other 17 chemical elements.
A natural deep eutectic solvent (NADES) synthesised from malic acid, xylitol, and water was used as a solvent in ultrasound-assisted extraction (UAE) for the determination of As and Cd in fish and shellfish samples by inductively coupled plasma mass spectrometry. The formation of the solvent was confirmed by infrared spectroscopy analysis, which showed the presence of hydrogen bonds between the components. Evaluation was made of elemental determinations performed using standard and kinetic energy discrimination (KED) modes. Higher sensitivity was observed using KED mode, which could be attributed to charge transfer between carbon and the analytes when the NADES introduced into the plasma. The detection limits were 12.7 and 0.100 µg kg⁻¹ for As and Cd, respectively, and the accuracy of the extraction procedure was assessed by comparing methods. The Cd concentrations in the fish and shellfish samples were below the limits of quantification, while the As concentrations varied between 1.88 and 12.0 µg g⁻¹, exceeding the maximum values recommended by regulatory agencies.
As synthesized AgBr nanoparticles (NPs) and g-C3N4 nanosheets were synthesized and coupled to obtain the AgBr-g-C3N4 catalyst, It showed a boosted activity in the photodegradation of methyl orange (MO) in aqueous solution (1.6 and 1.3 times greater than just the AgBr and g-C3N4 NPs in the initial degradation experiments without any optimization, respectively). The composite was characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), cyclic voltammetry (CV), etc. The modified carbon paste electrode by the composite showed a significant increase in peak current, confirming a significant increase in charge transfer between the semiconductors of the coupled system. The bandgap energies of the samples were estimated by both DRS and CV methods. The composite with an AgBr:g-C3N4 mole ratio of 2:1 showed the best photocatalytic activity. The initial pH of the MO solution was changed from 6.5 to 5.5 during the photodegradation process. Experimental design by RSM was used for the study of the interaction effects between the influencing variables. The conditions of the optimized run were: pH: 3.5, Catalyst dosage: 0.9 g/L, Time: 83 min, CMO: 3.2 ppm, while those of the central point were: pH: 6.1, Catalyst dosage: 0.99 g/L, Time: 82.50 min, CMO: 2.9 ppm. Various degradation intermediates such as benzene, phenol, catechol, hydroquinone, aniline, dimethylamine, benzoquinone, p-amino phenol, ethendiol, ethylene glycol, oxalic acid, maleic acid, 1-propenoic acid, sulfate, etc. were detected by GC-Mass. Further attacking of hydroxyl and superoxide radicals can easily mineralize these intermediates to water, carbon dioxide, and other inorganic species.
The presence of heavy metals in oily matrices (edible oils or crude-oil and its derivatives) cannot be controlled or prevented as they occur naturally during oil genesis. However, the presence of these metal ions in oils has negative effects, because some metal ions can act as catalyst poisons, refinery corroders and environmental pollutants during refinery processes. Additionally, some metal ions have negative health impacts when consumed by living organisms. Therefore, evaluation of metal extraction methods prior to spectrometric determination is critical for monitoring of metal concentration levels and oil quality assurance purposes. It has to be noted that there are numerous reviews that have been published, which evaluates the use of direct (analysis without sample preparation) and indirect (dry and wet digestion) spectrometric determination of metals in oily matrices. Therefore, the current review focuses on evaluation of extraction methods followed by spectrometric determination of metals published from 2005 to 2020 (16 years). The acquired data shows that extraction induced by emulsion breaking (EIEB) has been the most preferred metal extraction method using Triton X-114 as a surfactant and atomic absorption spectrometer (AAS) as a detection technique.
Deep eutectic solvents are compounds formed by a donor and an acceptor of hydrogen bond; and are in liquid state at ambient temperature. They are non-volatile, with high thermal stability and readily dissolve many organic and inorganic compounds. They are recognized as green and cheap alternatives to ionic liquids. They have recently appeared in analytical practice but have already found wide application in various fields of analytical chemistry; mainly as effective extractants. However, their use as extractants does not limit the scope of their capabilities. This review is primarily devoted to the description of new possibilities of applications of deep eutectic solvents in analytical chemistry; including such areas as chromatographic separation, electrochemical analysis, sample preparation, synthesis and modification of new sorption materials. In addition, the stability of deep eutectic solvents, terminology, classification, further trends and some errors and inaccuracies associated with their applications are discussed.
A sample pretreatment based on an extraction process by emulsion breaking for multi-element determination in edible oils was developed. The determination of eight trace elements (Al, Ba, Cu, Cr, P, Ni, Ti, and Zn) was carried out by microwave-induced plasma optical emission spectrometry (MIP OES) after the extraction procedure. A D-optimal mixture experimental design was used to obtain the best experimental conditions for the extraction induced by emulsion breaking (EIEB). The proportion of HNO3 solution Triton X-100 solution and sample was evaluated in a multivariate manner. The best recovery efficiency was obtained with 1.0 mL of 30% (v/v) HNO3, 1.0 mL of 30% (w/v) Triton-X 100 and 3.0 mL of the sample. The precisions, established as the relative standard deviation (RSD, %), were better than 2.5% for all analytes. The developed method was applied to the analysis of commercial vegetable oils with low limits of detection and good precision.
In this work, a simple, easy, and fast ultrasound-assisted extraction procedure for the determination of Cu, Fe, Mn, and Zn in plant samples was developed. Sample preparation conditions were optimized in a multivariate manner using mixture design and Box-Behnken. The extraction condition adequate to obtain the maximum response was 90% power, 10 minutes, 40 °C temperature, using extraction solution composed of HNO3 and HCl in the concentration of 0.5 and 1.1 mol L⁻¹, respectively, for a volume 10 mL and 250 mg of sample. Accuracy was verified from the analysis of certified reference material (Apple leaves, NIST 1515) yielding recoveries between 89 and 98% for procedure. Precision was evaluated in a repeatability study (n = 10), yielding RSDs less than 6.7%, and the limits of quantification (mg kg⁻¹) were 0.95, 2.42, 1.31, 1.18 for Cu, Fe, Mn, and Zn, respectively. The concentrations determined in the stem and leaf of the mangrove species varied according to the collection point and the tissue, being consistent with other studies. The proposed procedure was efficient and reliable for the elemental determination in plant samples, with the advantage of low cost and reagent consumption besides short analysis time as a valid alternative to conventional sample preparation procedure.
In this work is presented the development of a method for As and Se determination in crude palm oil samples by hydride generation atomic fluorescence spectrometry and Hg by cold vapor atomic fluorescence spectrometry after ultrasound-assisted emulsification and extraction induced by emulsion breaking (EIEB). The optimization of the method was carried out by multivariate designs. The developed method has presented limits of quantification (LOQ) of 0.72, 0.12, and 1.5 μg L-1 for As, Hg, and Se, respectively. The precisions of the proposed method expressed as repeatability were 0.92, 2.2, and 3.7% RSD for 2 µg L-1 (n = 10) of As, Hg and Se, respectively. The developed methodology was applied in palm oil samples collected in the Bahia State. Concentrations (μg L-1) found in the samples were between <LOQ - 1.3 for As and 3.0-15 for Se. For Hg, all analyzed samples were below the limit of quantification.
In this paper we present a novel combined electrochemical-spectroscopic approach suitable to monitor trace levels of heavy metals directly in edible oils. The method is based on the electrochemical preconcentration/extraction of the analyte from the tested real matrix by cathodic deposition onto a Pt working electrode, then transfer and anodic re-oxidation of the metallic deposit to a "clean" aqueous solution, suitable for the subsequent spectroscopic analysis. The procedure has been here focused to the determination of lead in extra virgin olive oil (EVOO), performed by applying ICP-QMS or GFAAS techniques. To this aim, the EVOO samples were mixed with proper amounts of the room temperature ionic liquid (RTIL) [P14,6,6,6]+[NTf2]-, in order to obtain a non-aqueous supporting electrolyte suitable for the electrodeposition process. The feasibility and performance of the analytical strategy were at first tested in standard solutions of Pb(II) in RTIL, produced by anodic dissolution of lead in the RTIL, as well as in olive oil samples mixed with 0.5 M RTIL and spiked with known amounts of Pb(II). The optimisation of the electrochemical parameters was achieved by applying a D-Optimal Design, properly set up to optimise the efficiency of the deposition and re-oxidation steps, quantitative recovery and measurement time. Finally, the analytical procedure was applied to the determination of Pb content in some Italian EVOOs, without any need of performing mineralization pretreatments. Data obtained with the proposed procedure satisfactorily agree with those achieved by ICP-QMS analysis after microwave digestion, being differences between the two approaches within 10%, with the advantage of reducing to half the pretreatment time, operating at room temperature and avoiding the use of aggressive solvents.
The development of microwave (MW) assisted processes involving the use of deep eutectic solvents (DESs) is a fast-expanding research topic. However, there is a lack of information about the heating behavior of DESs under MW irradiation. In this work, a family of DESs composed by choline chloride and two types of hydrogen bond donors (carboxylic acids or polyols) was prepared and its MW heating response and thermal heating behavior were investigated as well as compared to that of the single components. The MW absorption properties were explored using different MW applied power at fixed MW irradiation times. The thermal behavior and the analysis of the evolved gases during the DESs thermal decomposition were assessed by TG-FTIR analysis. A strong interaction of DESs with MWs was found in all cases. Polyol-based DESs showed the highest MW response, ChCl-glycerol being the best MW absorbing system. The thermal heating behavior revealed that a decomposition process of entire DES occurred rather than a sum of evaporation steps of their single components. This decomposition can be ascribed to a synergy effect of heating and H-bond acidity strength in DESs network. Different thermal decomposition pathways for all DESs were thus proposed. All studied DESs showed thermal decomposition behavior and MW absorption properties more similar to ionic liquids (ILs) than molecular solvents. These unique properties make DESs suitable green solvents for the development of MW assisted chemical processes.
This work reports a study on the evaluation of extraction induced by emulsion breaking (EIEB) for Ni and V extraction from crude oil. Graphite furnace atomic absorption spectrometry (GF AAS) was employed for the determination of the analytes in the extracts. The extraction procedure was based on the preparation of oil-in-water emulsions, by mixing the crude oil with the aqueous extractant solution containing HNO3 and Triton X-114 as surfactant, which were subsequently broken by heating. After emulsion breaking, two phases were formed: a top phase containing the original crude oil sample and a bottom phase, which was the aqueous extract containing the extracted Ni and V. The aqueous phase was collected, appropriately diluted and analyzed by GF AAS for the determination of Ni and V in the extracts and subsequent calculation of extraction efficiency. The extraction procedure was firstly studied using water-in-ol emulsion, best extraction conditions were achieved with 2.5 g of sample (about 3 mL) emulsified in 1 mL of extraction solution containing 6.5 mol L-1 of nitric acid and 20% (m/v) of Triton X-114. However, the extraction efficiency was only about 10% for Ni and V. The influence of the sample/extractant volume ratio showed that sample volume lower than 3 mL resulted in higher extraction efficiency for both analytes, highlighting the use of oil-in-water emulsion to increase Ni and V extraction efficiency. Maximum extraction of Ni and V was obtained when the crude oil (approximately 0.3 g) was diluted with 2.5 mL of mineral oil free of metals. The diluted sample was emulsified by vigorous manual agitation with 3 mL of an extractant solution containing 20% (m/v) Triton X-114 and 6.5 mol L-1 HNO3. The emulsion breaking was induced by heating at 90 °C for 40 min, followed by centrifugation at 5000 rpm for 15 min. The EIEB procedure was applied to five crude oil samples and the extraction efficiency was accessed from the total concentration of Ni and V in the samples determined by direct analysis by GF AAS and ICP-MS. The optimized EIEB procedure provided extraction of 82–103% of the Ni contained in the tested samples and 50–74% of the V.
A rigorous evaluation of environmental contamination requires constant innovation in analytical approaches to gain early identification and accurate quantification of every substance able to compromise health and well-being, particularly when trace analysis of organic and inorganic contaminants, and their species, in complex environmental samples is required. The analytical process comprises several steps; above all, sample treatment, involving isolation of analytes, purification of extracts, and preconcentration often constitute the most time- and labor-consuming part. This review provides an overview of sample treatment procedures applied for the analysis of organic and inorganic compounds in environmental samples in recent years. The current state of the art is emphasized on those techniques and approaches that have already demonstrated their sufficient analytical performance.
The bio-relevant metals (and derived compounds) of the Periodic Table of the Elements ( PTE ) are in the focus. The bulk elements sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) from the s -block, which are essential for all kingdoms of life, and some of their bio-activities are discussed. The trace elements of the d -block of the PTE as far as they are essential for humans (Mn, Fe, Co, Cu, Zn, Mo) are emphasized, but V, Ni, Cd, and W, which are essential only for some forms of life, are also considered. Chromium is no longer classified as being essential. From the p -block metals only the metalloid (half-metal) selenium (Se) is essential for all forms of life. Two other metalloids, silicon and arsenic, are briefly mentioned, but they have not been proven as being essential for humans. All metals of the PTE and a plethora of their compounds are used in industry and many of them are highly toxic, like lead (Pb), which is discussed as a prime example. Several metals of the PTE , that is, their ions and complexes, are employed in medicine and we discuss the role of lithium, gallium, strontium, technetium, silver, gadolinium (the only f -block element), platinum, and gold.
A new liquid phase microextraction method based on deep eutectic solvent microextraction was developed for separation and preconcentration of lead, cobalt, nickel and manganese from edible oil samples like sunflower oil, baby oil, trout, waste frying oil and syrup-soaked pastry oil. A choline chloride deep eutectic solvent was used for microextraction. After extraction, analytical concentrations were determined by flame atomic absorption spectrometry. Effects of analytical parameters such as type and volume of deep eutectic solvent, sample volume, and temperature on extraction efficiency of lead, cobalt, nickel and manganese were optimized. The recoveries were generally >95%. The relative standard deviation (RSD, %, n = 7) of 50 μg/ L of analyte elements was in the range of 0.9–4.3%. Accuracy of presented microextraction method was checked by addition-recovery studies to oil samples. The presented deep eutectic solvent microextraction method was finally applied to edible oil samples and waste oils with different properties for the determination of analyte contents.
The concept of sustainable development has impacted in analytical chemistry changing the way of thinking processes and methods. It is important for analytical chemists to consider how sample preparation can integrate the basic concepts of Green Chemistry. In this sense, the replacement of traditional organic solvents is of utmost importance. Natural Deep Eutectic Solvents (NADES) have come to light as a green alternative. In the last few years, a growing number of contributions have applied these natural solvents proving their efficiency in terms of extraction ability, analyte stabilization capacity and detection compatibility. However, the arising question that has to be answered is: the use of NADES is enough to green an extraction process? This review presents an overview of knowledge regarding sustainability of NADES-based extraction procedures, focused on reported literature within the timeframe spanning from 2011 up to date. The contributions were analyzed from a green perspective in terms of energy, time, sample and solvent consumption. Moreover, we include a critical analysis to clarify whether the use of NADES as extraction media is enough for greening an analytical methodology; strategies to make them even greener are also presented. Finally, recent trends and future perspectives on how NADES-based extraction approaches in combination with computational methodologies can contribute are discussed.
An innovative and effective digestion method based on choline chloride (ChCl)–oxalic acid (Ox) deepeutectic solvent (DES) was proposed for the determination of Se and As in fish samples via electrothermal atomic absorption spectrometry (ETAAS). The impacts of different variables, including the composition and volume of ChCl–Ox, temperature, and acid addition, on analyte recovery were studied for optimization. In this procedure, an 80 mg sample was dissolved in a 1:2 molar ratio of ChCl–Ox at 105°C for 40 min, with the subsequent addition of 4.0 mL HNO₃ (1.0 M) and further heating at the same temperature for about 5 min. Next, centrifugation was applied, and the supernatant solution was filtered, diluted to a known volume, and measured by ETAAS. The accuracy of the developed method was tested using a Standard Reference Material (NIST SRM 1946 Lake Superior Fish Tissue). The proposed DES-based digestion method was successfully applied to the simultaneous extraction of Se and As from fish samples.
An efficient sample extraction method for determination of total Hg in fish samples was developed. The method is based on the complete dissolution of samples in a deep eutectic solvent (DES). Among the DESs considered, choline chloride-oxalic acid was the best, dissolving samples completely without additional microwave or pressure processing. After adding 7 mol L-1 HNO3 or higher, the sample was digested very quickly (~5 sec), and a residue-free and clear solution was obtained. Since there was no need for further steps such as centrifugation and filtration, the risk of the elemental contamination was greatly reduced. The Hg content of each sample was determined by cold vapor atomic absorption spectrometry. Under optimized conditions, the Hg extraction efficiencies of the spiked samples were in the range 94.5%–97.0%. The precisions based on relative standard deviations for five successive replications spiked at 1.0 and 5.0 µg g−1 were 2.0% and 5.5%, respectively. The limit of detection of the method was 0.03 µg g−1 (n = 8). Under optimized conditions, an excellent agreement between the obtained results and the certified values was observed. For comparison, different fish tissues (muscle and liver) were analyzed by both the proposed method and a conventional acid digestion method. Besides the high recoveries, our method was more rapid, energy saver, and environmentally friendly.
A simple, rapid, and reliable method is reported for the determination of Mg, Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb in biodiesel by inductively coupled plasma – mass spectrometry (ICP-MS). In order to overcome problems related to the organic matrix in the direct introduction of the samples, a new extraction approach was investigated. The method was based on emulsion breaking, in which metals were transferred from the biodiesel to an acidic aqueous phase after formation and breaking of a water-oil emulsion prepared by mixing biodiesel with aqueous Triton X-114 and HNO3. The pretreatment conditions were studied in detail. The dynamic reaction cell mode was employed for the determination of Mg, Ca, Cr, and Fe by ICP-MS to eliminate interferences. The limits of detection and quantification for Mg, Ca, Cr, Mn, Fe, Ni, Cu, Zn and Pb were from 0.007835 to 0.1896 µg/L and 0.02612 to 0.6320 µg/L, respectively. This method was validated by comparison with a well-established strategy of sample dilution and fortification.