Mixture Of Extraction Solvent Research Articles

Evaluation of Extraction Techniques for Recovery of Microalgal Lipids under Different Growth Conditions.

Microalgal lipids contain a wide array of liposoluble bioactive compounds, but lipid extraction remains a critical limitation for their commercial use. An accelerated solvent extraction (ASE) was used to extract lipids from Chlamydomonas reinhardtii, Arthrospira platensis (Spirulina), and Chlorella vulgaris grown under either standard or nitrogen depletion conditions. Under standard growth conditions, ASE using methanol:chloroform (2:1), methyl tert-butyl ether (MTBE):methanol:water, and ethanol at 100 °C resulted in the highest recovery of total lipids (352 ± 30, 410 ± 32, and 127 ± 15 mg/g biomass from C. reinhardtii, C. vulgaris, and A. platensis, respectively). Similarly, the highest total lipid and triacylglycerols (TAGs) recovery from biomass cultivated under nitrogen depletion conditions was found at 100 °C using methanol:chloroform, for C. reinhardtii (total, 550 ± 21; TAG, 205 ± 2 mg/g biomass) and for C. vulgaris (total, 612 ± 29 mg/g; TAG, 253 ± 7 mg/g biomass). ASE with MTBE:methanol:water at 100 °C yielded similar TAG recovery for C. reinhardtii (159 ± 6 mg/g) and C. vulgaris (200 ± 4 mg/g). Thus, MTBE:methanol:water is suggested as an alternative substitute to replace hazardous solvent mixtures for TAGs extraction with a much lower environmental impact. The extracted microalgal TAGs were rich in palmitic (C16:0), stearic (C18:0), oleic (C18:1,9), linoleic (C18:2n6), and α-linolenic (C18:3n3) acids. Under nitrogen depletion conditions, increased palmitic acid (C16:0) recovery up to 2-fold was recorded from the biomasses of C. reinhardtii and C. vulgaris. This study demonstrates a clear linkage between the extraction conditions applied and total lipid and TAG recovery.

D-optimal Design Optimization of Solvent Mixture for Flavonoid Extraction from Phalaenopsis Leaves with Antioxidant Activity.

This study aimed to optimize the extraction of flavonoids and antioxidants from Phalaenopsis leaves by using solvent mixtures. The total flavonoid content (TFC) and antioxidant activity were evaluated using the colorimetric method and ferric-reducing antioxidant power (FRAP), respectively. Maceration extracts from fresh leaves were used for the analysis. The study used the Design Expert 13.0 program to optimize the solvents (water, acetone, and methanol) and their combined ratio. The results showed that 100% acetone was the best solvent for both responses, with a desirability value of 0.884, TFC of 0.434 mg QE/g fresh weight (FW) and FRAP of 713.53 μmol TE/g FW. Screening of the most potent Phalaenopsis genotypes for obtaining the most active leaf extract showed that P. amboinensis and P. pantherina were the best genotypes for TFC (0.786-0.797 mg QE/g FW) and FRAP activity (862.25-891.48 μmol TE/g FW). This study demonstrates an easy and useful way to obtain flavonoids and antioxidants from Phalaenopsis materials that can be used in the flower-based industry to make new functional ingredients.

ЭКСТРАКЦИЯ ЦЕЗИЯ И СТРОНЦИЯ ИЗ АЗОТНОКИСЛЫХ РАСТВОРОВ КРАУН-ЭФИРАМИ В ТЯЖЕЛЫХ РАЗБАВИТЕЛЯХ

The extraction ability of crown-ethers has been studied with respect to cesium and strontium from nitric acid solutions in heavyweight polar organic solvents: chloroform; 1,2-dichloroethane; bis(2-chloroethyl)ether; nitrobenzene; 1,1,7-trihydrododecafluoroheptyl alcohol. Using bis(2-chloroethyl)ether as a new polar solvent in the extraction processes of dibenzo21-crown-7 and 4,4' (5')-ditretbutyldibenzo-18-crown-6, rather high distribution coefficients of cesium are achieved (DCs) from solutions with a nitric acid concentration of 1-5 mol / dm3. In the extraction of dicyclohexyl-18-crown-6 strontium, the highest DSr values were obtained, using chlorine-substituted hydrocarbons and bis(2-chloroethyl)ether with an extraction maximum of 1-3 mol / dm3 HNO3, depending on the diluent used. Extraction systems based on selective crown-ethers in a solvent mixture for the joint extraction of cesium and strontium from chemically complex nitric acid solutions are proposed.

Influence of Maceration Solvent on Chemical Composition of Gemmotherapy Macerates—A Case Study on Olea europaea Young Shoots

Gemmotherapy, a natural therapy based on bud macerates, has recently gained importance in the field of food supplements. However, two coexisting extraction methods employ a glycerin-based solvent, either in a binary or ternary solvent mixture. The absence of an official method for bud preparation leads to non-standardized bud macerates. Given this context, this study aimed to (i) assess the influence of solvent composition on the chemical profile of olive young shoot macerates obtained using glycerin-based solvents or using different solvent extractions and (ii) to compare the two coexisting traditional bud extraction methods described by Dr Pol Henry and by the European Pharmacopoeia. A comprehensive phytochemical analysis of all macerates was conducted using HPLC-DAD-ELSD-MS2, identifying 50 metabolites divided into 7 classes through dereplication. The extracts obtained with the solvent described by the European Pharmacopoeia (ethanol/glycerin) and by Dr Pol Henry (water/ethanol/glycerin) appeared to be the most diversified in terms of metabolite distribution and possessed higher rates of secondary metabolites. These observations reinforce the interest in a glycerin-based solvent mixture for bud extraction in gemmotherapy. In addition, the difference in composition between the two traditional solvents was highlighted. Indeed, iridoids were predominant in both macerates, representing about 50% of the chemical composition, but differences were observed from one macerate to another regarding the proportions of the other chemical classes. This emphasizes the necessity for standardized gemmotherapy macerates.

Effects of Extraction Process Factors on the Composition and Antioxidant Activity of Blackthorn (Prunus spinosa L.) Fruit Extracts.

This study aimed at establishing the optimal conditions for the classic extraction of phenolic compounds from Prunus spinosa L. fruits. The effects of different parameters, i.e., ethanol concentration in the extraction solvent (mixture of ethanol and water), operation temperature, and extraction time, on process responses were evaluated. Total phenolic content (TPC), total anthocyanin content (TAC), antioxidant capacity (AC), and contents of protocatechuic acid (PA), caffeic acid (CA), vanillic acid (VA), rutin hydrate (RH), and quercetin (Q) of fruit extracts were selected as process responses. A synergistic effect of obtaining high values of TPC, TAC, AC, PA, and VA was achieved for the extraction in 50% ethanol at 60 °C for 30 min. At a higher level of process temperature, the extraction of protocatechuic acid and vanillic acid was enhanced, but the flavonoids, i.e., rutin hydrate and quercetin, were degraded. A lower temperature should be used to obtain a higher amount of flavonoids. TPC, TAC, AC, and phenolic acid contents (PA, CA, and VA) in the extract samples obtained at an ethanol concentration of 50-100%, a temperature of 30-60 °C, and an extraction time of 30 min were strongly directly correlated.

An accurate and precise liquid chromatography–tandem mass spectrometry method for the determination of six phosphatidylethanol homologues in whole blood with phospholipid interferences minimized

Alcohol consumption is associated with a wide risk of different diseases, injury and death, and has significant social and economic consequences worldwide. Phosphatidylethanol (PEth) is a group of promising direct alcohol biomarkers, with a significantly longer half-life in blood than ethanol, which can be measured to predict different drinking patterns, such as heavy- and social drinking. This study aimed to develop and validate an accurate and precise LC-MS/MS method for the determination of six PEth homologues in whole blood with minimal interference from unwanted phospholipids. Different organic solvent mixtures for liquid-liquid extraction were investigated to obtain satisfactory recovery of PEth homologues and removal of the lyso-phospholipids and other early eluting phospholipids. The mixture of heptane/2-propanol (80:20, v:v) gave lower phospholipid background and better signal/noise values for the PEth peaks. An LC-MS/MS TQ-S system from Waters was used for the instrumental analysis. The main part of unwanted phospholipids were separated from the PEth homologues on an Acquity BEH C18 column (50 × 2.1 mm ID, 1.7 µm particles) using a buffer-free mobile phase of 0.025 % ammonia in Type 1 water, pH 10.7, as solvent A and methanol as solvent B. Validation and quantification of 22 authentic blood samples showed that the developed LC-MS/MS method is sensitive, precise and accurate for the determination of the six PEth homologues in whole blood. Lower limit of quantification was 10 nM for all compounds. No matrix effects were observed, possibly due to the successful strategies incorporated to avoid the influence of unwanted phospholipids.

Ultrasound-Assisted Extraction of Total Phenolic Compounds and Antioxidant Activity Evaluation from Oregano (Origanum vulgare ssp. hirtum) Using Response Surface Methodology and Identification of Specific Phenolic Compounds with HPLC-PDA and Q-TOF-MS/MS.

Oregano is native to the Mediterranean region and it has been reported to contain several phenolic compounds particularly flavonoids that have been related with multiple bioactivities towards certain diseases. Oregano is cultivated in the island of Lemnos where the climate promotes its growth and thus it could be further used in promoting local economy. The aim of the present study was to establish a methodology for the extraction of total phenolic content along with the antioxidant capacity of oregano by using response surface methodology. A Box-Behnken design was applied to optimize the extraction conditions with regard to the extraction time, temperature, and solvent mixture with the use of ultrasound-assisted extraction. For the optimized extracts, identification of the most abundant flavonoids (luteolin, kaempferol, and apigenin) was performed with an analytical HPLC-PDA and UPLC-Q-TOF MS methodology. The predicted optimal conditions of the statistical model were identified, and the predicted values confirmed. The linear factors evaluated, temperature, time, and ethanol concentration, all showed significant effect (p < 0.05), and the regression coefficient (R2) presented a good correlation between predicted and experimental data. Actual values under optimum conditions were 362.1 ± 1.8 and 108.6 ± 0.9 mg/g dry oregano with regard to total phenolic content and antioxidant activity based on 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, respectively. Additionally, further antioxidant activities by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) (115.2 ± 1.2 mg/g dry oregano), Ferric Reducing Antioxidant Power (FRAP) (13.7 ± 0.8 mg/g dry oregano), and Cupric Reducing Antioxidant Capacity (CUPRAC) (1.2 ± 0.2 mg/g dry oregano) assays were performed for the optimized extract. The extract acquired under the optimum conditions contain an adequate quantity of phenolic compounds that could be used in the production of functional foods by food enrichment procedure.

Ultrasound-Assisted Extraction of Specific Phenolic Compounds from Petroselinum crispum Leaves Using Response Surface Methodology and HPLC-PDA and Q-TOF-MS/MS Identification

Petroselinum crispum is native to the Mediterranean region and has been reported to contain several phenolic compounds in addition to the highest quantity of apigenin among several natural raw materials. The aim of the present study was to establish an extraction method for the most abundant phenolic compounds of Petroselinum crispum leaves by using response surface methodology. A Box–Behnken design was applied to optimize the extraction conditions with regards to the extraction time, temperature, solvent mixture, and sample to solvent ratio with the use of ultrasound-assisted extraction. An analytical HPLC-PDA methodology was developed to accurately quantify the phenolic compounds in the extracts. Identification of the most abundant phenolic compounds (luteolin, caffeic acid, and apigenin) was also performed with an UPLC-Q-TOF MS methodology. The predicted optimal conditions of the statistical model were identified, and the predicted values confirmed. Actual values of 23.92 ± 1.86 with 100 mL/g, 40% ethanol, 70 °C and 40 min, 19.10 ± 0.75 with 20 mL/g, 0% ethanol, 70 °C and 40 min, and 25.29 ± 1.82 μg/g dry parsley with and 100 mL/g, 0% ethanol, 25 °C and 40 min of luteolin, caffeic acid, and apigenin respectively, were estimated. Total phenolic content and antioxidant activities by DPPH, ABTS, FRAP, and CUPRAC assays were performed for the extracts. The extracts acquired under the optimum conditions contain an adequate quantity of phenolic compounds that could be used in the production of functional foods by food enrichment prcedure.

Ultrasound-enhanced air-assisted liquid-liquid microextraction for the UPLC determination of organophosphorus pesticides in river water

Organophosphorus pesticide (OPP) residues in environment are harmful to ecosystem and human health. In this study, an ultrasound-enhanced air-assisted liquid–liquid microextraction (UE-AA-LLME) method was developed for ultra-high performance liquid chromatography (UPLC) determination of OPPs in water samples. The UE-AA-LLME was performed in a 1.5-mL centrifuge tube under ultrasound condition by sucking in and pushing out the mixture of aqueous solution and extraction solvent using a 2-mL syringe. After centrifugation, the sediment layer was collected and analyzed by UPLC. The parameters affecting the extraction efficiency including the type and volume of extraction solvent, pH, and extraction cycles were optimized. Under the optimized conditions, the limit of detection (LOD) of target OPPs ranged from 0.04 to 0.15 μg/L, and good linearities were acquired with correlation coefficients higher than 0.9927. The recoveries of target OPPs were evaluated to be 75.4–112.6 %, with relative standard deviations (RSDs) lower than 14.9 %. The proposed UE-AA-LLME method was successfully employed for the UPLC determination of OPPs in an urban river of Hangzhou, China. The results revealed that six OPPs were detected in the river waters at the levels of 0.06–0.54 μg/L, and the levels of OPP residues in autumn were higher than those in winter. The risk assessment suggested that there was no human health risk of OPP residues in the river water for adult and child by ingestion pathway.

Development of an in–syringe gas–assisted density tunable solidification of floating organic droplet–based dispersive liquid phase microextraction method coupled with HPLC–MS/MS for monitoring amikacin in biological fluids

A new sample preparation method named in–syringe gas–assisted density tunable dispersive liquid phase microextraction based on solidification of floating organic droplet has been introduced. This method was coupled with high–performance liquid chromatography–tandem mass spectrometry and used for the extraction and quantification of amikacin in plasma and exhaled breath condensate (EBC) samples of the patients receiving amikacin. In the proposed approach, an inert gas is bubbled into a syringe barrel containing aqueous solution of the analyte and a mixture of low density extraction solvent and volatile density modifier. Consequently, the density modifier is evaporated and the analyte is migrated into the released extractant droplets. Basic parameters affecting efficiency of the developed method were optimized. Under optimum conditions, the method limits of detection were 0.06 and 0.29 ng/mL in EBC and plasma, respectively. The extraction recoveries were 90% and 87% in EBC and plasma, respectively. Also, the obtained relative standard deviations were below 9.5% and 9.8% for EBC and plasma, respectively. Considering these results, the developed method provides a quick and efficient way to determine amikacin in patients’ biological fluids and can be used widely in drug monitoring and clinical studies.

Influence of Extraction Solvent on Nontargeted Metabolomics Analysis of Enrichment Reactor Cultures Performing Enhanced Biological Phosphorus Removal (EBPR).

Metabolome profiling is becoming more commonly used in the study of complex microbial communities and microbiomes; however, to date, little information is available concerning appropriate extraction procedures. We studied the influence of different extraction solvent mixtures on untargeted metabolomics analysis of two continuous culture enrichment communities performing enhanced biological phosphate removal (EBPR), with each enrichment targeting distinct populations of polyphosphate-accumulating organisms (PAOs). We employed one non-polar solvent and up to four polar solvents for extracting metabolites from biomass. In one of the reactor microbial communities, we surveyed both intracellular and extracellular metabolites using the same set of solvents. All samples were analysed using ultra-performance liquid chromatography mass spectrometry (UPLC-MS). UPLC-MS data obtained from polar and non-polar solvents were analysed separately and evaluated using extent of repeatability, overall extraction capacity and the extent of differential abundance between physiological states. Despite both reactors demonstrating the same bioprocess phenotype, the most appropriate extraction method was biomass specific, with methanol: water (50:50 v/v) and methanol: chloroform: water (40:40:20 v/v/v) being chosen as the most appropriate for each of the two different bioreactors, respectively. Our approach provides new data on the influence of solvent choice on the untargeted surveys of the metabolome of PAO enriched EBPR communities and suggests that metabolome extraction methods need to be carefully tailored to the specific complex microbial community under study.

Levels of Alternaria Toxins in Selected Food Commodities Including Green Coffee.

Alternaria toxins are emerging mycotoxins, candidates for regulation by European Authorities. Therefore, highly sensitive, confirmatory, and reliable analytical methodologies are required for their monitoring in food. In that context, an isotope dilution LC-MS/MS method was developed for the analysis of five Alternaria toxins (Altenuene, Alternariol, Alternariol monomethylether, Tentoxin, and Tenuazonic Acid) in a broad range of commodities including cereals and cereal-based products, tomato-based products, tree nuts, vegetable oils, dried fruits, cocoa, green coffee, spices, herbs, and tea. Validation data collected in two different laboratories demonstrated the robustness of the method. Underestimation of Tenuazonic Acid level in dry samples such as cereals was reported when inappropriate extraction solvent mixtures were used as currently done in several published methodologies. An investigation survey performed on 216 food items evidenced large variations of Alternaria toxins levels, in line with data reported in the last EFSA safety assessment. The analysis of 78 green coffee samples collected from 21 producing countries demonstrated that coffee is a negligible source of exposure to Alternaria toxins. Its wide scope of application, adequate sample throughput, and high sensitivity make this method fit for purpose for the regular monitoring of Alternaria toxins in foods.

A sensitive determination method for trace bisphenol A in bottled water and wastewater samples: Binary solvent liquid phase microextraction-quadrupole isotope dilution-gas chromatography-mass spectrometry

A sensitive, accurate and precise methodology was established for the preconcentration and determination of bisphenol A in bottled water and wastewater samples at trace levels. A binary solvent liquid phase microextraction (BSLPME) method was optimized to extract bisphenol A before determination by gas chromatography-mass spectrometry (GC-MS). The type of binary solvent/disperser solvent, vortex period and mode of adding extraction and disperser solvent mixture to aqueous solution were determined by univariate optimization. Three significant parameters including volume of binary solvent, volume of dispersive solvent and ratio of binary solvent were optimized using Box-Behnken Design. Low limit of detection (0.30 ng/g) and limit of quantitation (0.99 ng/g) values were recorded for the BSLPME-GC-MS method. Hence, 173 times enhancement in the detection limit of the GC-MS system was achieved by the developed microextraction method. Quadrupole isotope dilution (ID4) strategy was used to augment the extraction method to achieve high accuracy and precision. When the developed BSLPME method was combined with the ID4 strategy, bottled water and wastewater samples spiked at approximately 200 ng/g recorded excellent recovery results of 100.3 ± 0.4% and 100.0 ± 0.5%, respectively. Therefore, accurate and precise determination of bisphenol A at trace levels was achieved by a low cost, rapid and green analytical method.

Derivatization and deep eutectic solvent-based air–assisted liquid–liquid microextraction of salbutamol in exhaled breath condensate samples followed by gas chromatography-mass spectrometry

A microwave-induced air–assisted liquid–liquid microextraction method has been proposed for the pretreatment/quantization of salbutamol in exhaled breath condensate (EBC) samples prior to gas chromatography-mass spectrometry. In this procedure, 1-fluoro-2,4-dinitrobenzene and N,N-diethylethanolammonium chloride: dichloroacetic acid: octanoic acid deep eutectic solvent were exploited as derivatization reagent and extraction solvent, respectively. A mixture of the sample solution and pyridine was transferred into a test tube. Then, a mixture of extraction solvent and derivatization agent was placed at the bottom of the tube. After performing the predetermined extraction cycles in the microextraction method, the mixture was exposed to microwave irradiations to enhance derivatization and extraction efficiencies. The obtained turbid solution was centrifuged and a portion of the sedimented phase was used for quantification of salbutamol. The validated method showed low limits of detection (0.074 and 0.370 μg/L in deionized water and EBC, respectively), quantification (0.246 in deionized water and 1.23 μg/L in EBC), and lower limit of quantification (0.123 and 0.615 μg/L in deionized water and EBC, respectively). The method had appropriate repeatability, accuracy, and stability (expressed as relative standard deviation less than 9%). The developed method was used in quantification of salbutamol in the real samples collected from donors receiving salbutamol spray.

Comparison of the Effect of Acids in Solvent Mixtures for Extraction of Phenolic Compounds FromAronia melanocarpa

Thirty-two different solvent mixtures containing methanol and acid (acetic, formic, and hydrochloric); methanol, water, and acid; and pure methanol were tested for their efficiency for extraction of phenolic compounds from aronia ( Aronia melanocarpa) belonging to the groups of anthocyanins, flavonols, and hydroxycinnamic acid derivatives. Thirteen compounds were detected and quantified in the extracts using HPLC/DAD/ESI-MSn. The yield of each compound and group was evaluated with regard to the extraction solvent composition. Extraction mixtures containing HCl were superior to the ones containing acetic or formic acid for the extraction yield of total phenolic compounds, which was especially pronounced for anthocyanins. The solvent mixture containing methanol/water/HCl (90:8:2, v/v/v) gave best results for the qualitative and quantitative assay of anthocyanins. However, this solvent mixture caused O-methylation of 3- and 5-caffeoylquinic acids transforming them to 3- and 5-feruloylquinic acids, respectively, during extraction. This peculiar finding must be taken into account during sample preparation for the analysis of polyphenols in any sample. It was observed that this O-methylation is specific for dihydroxycinnamic acid compounds containing neighboring hydroxyl groups. These results suggest the need for a detailed study of the behavior of various polyphenolic compounds during extraction with solvent mixtures containing methanol/HCl since it is very often used for the analysis of anthocyanins.

Design of Solvent Mixtures for Selective Extraction by Quantifying Thermodynamic and Sustainability Aspects

The selection of suitable solvents for selective extraction is a challenging task due to expensive experimental studies and heavy reliance on heuristics which introduce errors and biased judgements. The development of computer-aided molecular design (CAMD) has facilitated the search for novel solvents by providing an efficient and systematic computational approach. In this work, a novel CAMD framework for the selection of most suitable solvents or solvent mixtures by quantifying thermodynamics and sustainability aspects has been developed. The overall solvent design methodology can be described via a multi-level approach. The first level involves the prescreening of molecular blocks by introducing a solubility model to identify the promising functional groups. The second level includes the implementation of a rigorous model to determine potential solvents based on phase equilibrium information such as selectivity and capacity. Finally, the third level incorporates safety and health parameters in the formulation of a multi-objective optimization problem. Here, a modified fuzzy algorithm is developed to address the trade-off between thermodynamic and safety and health properties. In cases where the selectivity and capacity show antagonistic behaviour, solvent mixture design is introduced to improve the extraction performance. The developed CAMD framework is illustrated through a case study on the extraction of 1,2-dichloroethane from cyclohexane.

Sample pre-treatment and analytical methodology for the simultaneous determination of pharmaceuticals and personal care products in sewage sludge

This work describes the design, optimization and validation of an analytical method for the simultaneous determination of 14 pharmaceuticals and personal care products (PPCPs) in sewage sludge. A thorough optimization of the sample pre-treatment was carried out. As a result, microwave-assisted extraction (MAE) was combined with an in-situ clean-up stage and a filtration step. A combination of MilliQ® water/MeOH 95:5 (v/v) adjusted to pH 9 turned out to be the optimal solvent mixture for extraction. The instrumental part of the method presents a significant novelty based on a fully automated sample preparation for the analysis of PPCPs. It consisted of a direct immersion solid phase microextraction followed by on-fiber derivatization, online coupled to gas chromatography - mass spectrometry (DI-SPME-On-fiber derivatization - GC-MS). An isotope dilution approach was used for quantifying, which conferred high reliability to the method. This methodology was validated for 10 compounds with good analytical performance, limit of detection below 20 ng g−1 and absolute recovery in the range of 30–70% for most of the compounds. It supposes an ecological analytical alternative for many routine analysis laboratories around the world. The developed method was applied to different real samples generated in both a pilot-scale thermal hydrolysis treatment plant and an anaerobic digester operated in mesophilic conditions. Salicylic acid and naproxen were found at concentrations above 1000 ng g−1.

Utilization of quaternary solvent mixtures for extraction of lipids from Scenedesmus obliquus microalgae

Solvent toxicity is of major concern in the extraction of lipid from algae biomass via the solvent extraction technique. This study was carried out to determine the optimal solvent mixture (chlorof...

Elevated temperature-assisted surfactant-enhanced emulsification microextraction based on solidification of a floating organic drop for the determination of UV filters in water samples by high-performance liquid chromatography coupled to a diode array detector

A rapid and reliable procedure named as elevated temperature-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop was developed for determination of UV filters in environmental water samples followed by high-performance liquid chromatography with diode array detection analysis. In the present work, a mixture of extraction solvent (1-undecanol) and emulsifier (Tween 80) was injected rapidly into the sample solution heated at an elevated temperature. The preheated sample dispersed the extraction solvent into sample solution immediately on injection of the mixture. Various parameters influencing the extraction efficiency including type and volume of extraction solvent, type and concentration of surfactant, temperature of aqueous solution, extraction time and solution pH were investigated and optimized. Under the optimum conditions, low limits of detection (0.8–1.4 ng mL−1) and limits of quantification (2.7–4.0 ng mL−1) were obtained. The precision of this method was investigated at 10 ng mL−1, and the relative standard deviations ranged between 1.2 and 5.1% for intra-day and inter-days determinations. The proposed method was successfully applied to determine the UV filters in genuine water samples with relative recoveries ranged from 88.8 to 98.2%.

In-syringe dispersive liquid-liquid microextraction using deep eutectic solvent as disperser: Determination of chromium (VI) in beverages

A novel approach for dispersive liquid-liquid microextraction based on the use of deep eutectic solvent as a disperser was presented for the first time. The procedure was automated based on an in-syringe flow system coupled with UV–Vis detection and demonstrated by the determination of chromium (VI) in beverages. This analytical task was used as a proof-of-concept example. The automated extraction procedure involved the aspiration of aqueous sample into a syringe pump with homogeneous mixture of extraction solvent (1-oсtanol) and deep eutectic solvent (tetrabutylammonium bromide – formic acid) containing color-forming reagent (1,5-diphenylcarbazide). This led to decomposition of deep eutectic solvent in aqueous phase resulting in dispersion of extraction solvent, oxidation of 1,5-diphenylcarbazide to 1,5- diphenylcarbazone in the presence of chromium (VI), and formation of colored chromium (III) complex with 1,5-diphenylcarbazone and its fast extraction. In this case composition of deep eutectic solvent played a key role for analyte extraction. Tetrabutylammonium bromide promoted mass transfer between aqueous phase and the extraction solvent droplets as a salting out agent, bromide ion acted as an ion-pare agent for analyte complex extraction, formic acid provided required pH value for analyte complex formation. Under the optimal conditions the limit of detection, calculated from a blank test based on 3s, was 0.2 μg L−1. The automated dispersive liquid-liquid microextraction using deep eutectic solvent as disperser can be considered as an available, efficient, rapid and environmentally friendly sample pretreatment approach.