Dispersive Liquid-liquid Microextraction Method Research Articles

Air-assisted dispersive liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent for the preconcentration of benzophenone-type UV filters from aqueous samples.

Deep eutectic solvents are considered as new and green solvents that can be widely used in analytical chemistry such as microextraction. In the present work, a new dl-menthol-based hydrophobic deep eutectic solvent was synthesized and used as extraction solvents in an air-assisted dispersive liquid-liquid microextraction method for preconcentration and extraction of benzophenone-type UV filters from aqueous samples followed by high-performance liquid chromatography with diode array detection. In an experiment, the deep eutectic solvent formed by dl-menthol and decanoic acid was added to an aqueous solution containing the UV filters, and then the mixture was sucked up and injected five times by using a glass syringe, and a cloudy state was achieved. After extraction, the solution was centrifuged and the upper phase was subjected to high-performance liquid chromatography for analysis. Various parameters such as the type and volume of the deep eutectic solvent, number of pulling, and pushing cycles, solution pH and salt concentration were investigated and optimized. Under the optimum conditions, the developed method exhibited low limits of detection and limits of quantitation, good linearity, and precision. Finally, the proposed method was successfully applied to determine the benzophenone-type filters in environmental water samples with relative recoveries of 88.8-105.9%.

Optimization of dispersive liquid-liquid microextraction (DLLME) method for determination of 2, 4-D and MCPA in water by HPLC with using Box-Behnken design

Optimization of dispersive liquid-liquid microextraction (DLLME) method for determination of 2, 4-D and MCPA in water by HPLC with using Box-Behnken design

Development and validation of a dispersive liquid-liquid microextraction method for the determination of phthalate esters in perfumes using gas chromatography-mass spectrometry.

A simple, rapid, sensitive and eco-friendly method has been developed for the simultaneous determination, preconcentration and extraction of phthalate esters (dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate and bis(2-ethylhexyl) phthalate) in perfumes using dispersive liquid–liquid microextraction (DLLME) coupled to gas chromatography-mass spectrometry (GC-MS). Various factors affecting the DLLME efficiency, including the type and volume of the extracting and dispersing solvents, salt addition and vortex extraction time were optimized. Under optimum conditions, the proposed method provided low detection limits (0.003–0.070 ng mL−1), high extraction recovery (85.6–95.8%), wide linearity range (1.0–1000 ng mL−1) with good regression coefficients (>0.9984) and good precision (RSD% < 4.2%). The optimized method was successfully utilized for the analysis of different branded perfume samples and satisfactory results were obtained.

Ultra-Trace Determination of Silver in Water, Soil and Radiology Film Samples Using Dispersive Liquid-Liquid Microextraction and Microvolume UV–Vis Spectrophotometry

In this research, a Dispersive Liquid-Liquid MicroExtraction (DLLME) method coupled to UV-vis spectrophotometry was developed for the indirect determination of silver ion. The method is based on the catalytic effect of the silver ion on the oxidation of congo red by potassium peroxodisulphate and extraction with DLLME procedure using chloroform (extraction solvent) containing cetyltrimethyl ammonium bromide which provides counter ion and also acts as a disperser. After extraction, the phase separation is performed with a centrifugation, and the silver ion is determined in the enriched phase by UV-Vis spectrophotometry. Several factors affecting the microextraction efficiency, such as pH of the solution, extraction time, type and volume of extraction solvent were investigated. Under optimum conditions, a linear calibration graph in the range of 0.5-105.0 ng/mL of silver ion in the initial solution with r2 = 0.9987 (n=10) was obtained. Detection limit of the method was 0.2 ng/mL and the Relative Standard Deviation (RSD) for 3 and 70 ng/mL of silver ion was 3.5 and 1.7 (n=10), respectively. The enrichment factor was 54. The method was successfully applied to the determination of trace amounts of Ag(I) in radiology film and environmental matrices.

Dispersive liquid-liquid microextraction based on the solidification of deep eutectic solvent for the determination of benzoylureas in environmental water samples.

We present a novel dispersive liquid-liquid microextraction method based on the solidification of deep eutectic solvent coupled with high-performance liquid chromatography with a variable-wavelength detection for the detection of five benzoylureas in real water samples. In this work, a green solvent consisting of 1-octyl-3-methylimidazolium chloride and 1-dodecanol was used as an extraction solvent, yielding the advantages of material stability, low density, and a suitable freezing point near room temperature. Parameters that significantly affect extraction efficiency were optimized by the one-factor-at-a-time approach. Under optimal conditions, the recoveries of five target compounds were obtained ranging from 87.39 to 98.05% with correlation coefficients ranging from 0.9994 to 0.9997 for pure water. The limits of detection were in the range of 0.09-0.16 μg/L. The enrichment factors were in the range of 171-188. Linearities were achieved in the range of 0.5-500 μg/L. The proposed method was successfully applied to determine benzoylureas in environmental water samples with a satisfactory recovery of approximately 81.38-97.67%.

Isotope dilution determination for the trace level of 4(5)-methylimidazole in beverages using dispersive liquid-liquid microextraction coupled with ESI-HPLC–MS/MS

In this study, a rapid and reliable pretreatment method called dispersive liquid-liquid microextraction (DLLME) was developed for the determination of 4(5)-methylimidazole (4-MeI) in beverages. The clean-up samples were analyzed by a high performance liquid chromatography coupled with triple quadrupole mass spectrometer (HPLC–MS/MS) using a reversed-phase C18 column (250 mm × 4.6 mm, 5 μm). The matrix effects and the fault of DLLME operation were corrected by the isotope dilution technique. The developed method exhibited the limit of quantification (0.3 μg L−1) and excellent linearity (R2 = 0.999). In addition, the recovery values of 4-MeI in carbonated beverage were ranging from 102.60% to 113.22%, in soft drinks were ranging from 103.24% to 108.85%. The content 4-MeI was detected in thirteen beverage samples treated with DLLME and solid phase extraction method (SPE) (ranging from 6.4 to 165.5 μg L−1). The consistent result of 4-MeI content detected by DLLME and SPE method concluded that the established method on the basis of DLLME was rapid, robust and accurate for the trace 4-MeI determination in beverages.

Response surface methodology optimized dispersive liquid–liquid microextraction coupled with surface plasmon resonance of silver nanoparticles as colorimetric probe for determination of captopril

A response surface methodology (RSM) based on central composite design was developed to optimize a novel method for the determination of trace levels of captopril by combination of dispersive liquid–liquid microextraction (DLLME) and surface plasmon resonance of silver nanoparticles (AgNPs). In this study AgNPs as a colorimetric sensor were synthesized in situ and used in a versatile DLLME method using carbon tetrachloride as extraction solvent and ethanol as disperser. The presence of captopril affected the production of AgNPs in the organic phase, thereby resulting in an increase of plasmon absorbance intensity of nanoparticles. The effect of different variables such as CTAB, sodium hydroxide and ascorbic acid concentration and also volume of extraction and disperser solvent was investigated and optimized by RSM at two steps. The calibration curve was linear in the range of 0.77–22.50nmolL−1 of captopril, limit of detection was 0.51nmolL−1 and the relative standard deviation for 11.54 and 19.23nmolL−1 of captopril was 2.12 and 0.72%, respectively. The developed method was applied to the determination of the analyte in pharmaceutical, human serum and urine samples with good accuracy and excellent precision.

Determination of lead at trace levels in mussel and sea water samples using vortex assisted dispersive liquid-liquid microextraction-slotted quartz tube-flame atomic absorption spectrometry

In this study, dispersive liquid-liquid microextraction (DLLME) and slotted quartz tube (SQT) were coupled to flame atomic absorption spectrometry (FAAS) to increase the sensitivity of lead. Conditions such as the formation of the lead-dithizone complex, efficiency of the DLLME method and the output of the SQT were systematically optimized to improve the detection limit for the analyte. The conventional FAAS system was improved upon by about 3.0 times with SQT-FAAS, 32 times with DLLME-FAAS and 142 times with DLLME-SQT-FAAS. The method was applicable over a wide linear range (10–500 μg L−1). The limit of detection (LOD) determined by DLLME-SQT-FAAS for seawater and mussel were 2.7 μg L−1 and 270 μg kg−1, respectively. The percent recoveries obtained for mussel and seawater samples (spiked at 20 and 50 μg L−1) were 95–96% and 98–110%, respectively.

Effervescence assisted dispersive liquid-liquid microextraction based on cohesive floating organic drop for the determination of herbicides and fungicides in water and grape juice

A novel effervescence assisted dispersive liquid-liquid microextraction method based on cohesive floating organic drop has been developed for simultaneous determination of triazine herbicides and triazole fungicides in aqueous samples followed by ultra-high pressure liquid chromatography tandem a triple quadrupole mass spectrometer. In this method, 1-undecanol as extractant was well dispersed by effervescence. In order to obtain relatively high extraction efficiency, the effects of salt, volume of effervescence mixture, volume of extraction solvent and temperature were investigated. Under the optimum conditions, the proposed method showed good linearity within the range of 0.05–10μgL−1 with correlation coefficients of 0.9987–0.9999. The recoveries of analytes were in the range of 72.4–101.5% with relative standard deviations ranging from 2.6% to 11.7%. The limits of detection were varied from 2.7 to 9.7ngL−1. This method has been successfully used to simultaneously analyze triazine herbicides and triazole fungicides in surface waters and grape juice.

Ultrasound-assisted, hybrid ionic liquid, dispersive liquid-liquid microextraction for the determination of insecticides in fruit juices based on partition coefficients.

An ultrasound-assisted, hybrid ionic liquid, dispersive liquid-liquid microextraction method coupled to high-performance liquid chromatography with a variable-wavelength detector was developed to detect ten insecticides, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, lufenuron, diafenthiuron, transfluthrin, fenpropathrin, γ-cyhalothrin and deltamethrin, in fruit juices. In this method, an appropriate extraction solvent was chosen based on the partition coefficient of the target compounds. A mixture of 1-octyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was used as the extractant. The extraction efficiency was screened using Plackett-Burman design and optimized using central composite design. Under the optimal conditions, good linearity was obtained for all the analytes in the pure water model and the fruit juice samples. In pure water, the recoveries of the ten insecticides ranged from 85.7 to 108.9%, with relative standard deviations for one day ranging from 1.24 to 2.64%. The limits of detection were in the range of 0.19-0.69μg/L, and the enrichment factors were in the range of 123-160. The logarithm of the n-octanol/water partition coefficient in this experiment is a useful reference to select a suitable extraction solvent, and the proposed technique was applied for the analysis of ten insecticides in fruit juice with satisfactory results.

Ultrasonic assisted dispersive liquid-liquid microextraction method based on deep eutectic solvent for speciation, preconcentration and determination of selenium species (IV) and (VI) in water and food samples

A novel ultrasound-assisted liquid phase microextraction (UALPME) based on environmental friendly extractants, deep eutectic solvent (DES) was first time presented for speciation of selenium. In present study, five DES solvents of different composition was prepared and used as efficient extractive medium for hydrophobic chelate of Se(IV) with 3,3′-Diaminobenzidine (DAB). The total inorganic Se species were determined after pre-reduction of Se(VI) to Se(IV), prior to applying developed method. The concentration of Se(VI) was calculated by the difference of Se(IV) values and total selenium contents. The concentration of Se in DES rich phase was measured with electrothermal atomic absorption spectrometer (ETAAS). The effects of different parameters on extraction efficiency of study analyte, including pH, ligand concentration, type and volume of DES, sonication time, volumes tetrahydrofuran and aqueous samples were examined. At the optimum conditions, limit of detection and quantification, preconcentration factor, and relative standard deviation (RSD %) were determined as 4.61ngL−1, 15.4ngL−1, 50% and 4.1%, respectively. The accuracy of the presented method was confirmed by analysis of certified reference material and standard addition method for different water and ice tea samples. The developed method was effectively applied to real water and food samples.

Determining heterocyclic aromatic amines in aqueous samples: A novel dispersive liquid-liquid micro-extraction method based on solidification of floating organic drop and ultrasound assisted back extraction followed by UPLC-MS/MS

A novel dispersive liquid-liquid microextraction based on solidification of floating organic droplet combined with ultrasound assisted back extraction for the determination of four heterocyclic aromatic amines in natural water samples prior ultra high-performance liquid chromatography-tandem mass spectrometry was developed. The analytes were extracted from the water samples by a dispersive liquid-liquid microextraction procedure based on solidification of floating organic drop, which was performed by a mixture composed by a less dense than water extraction solvent, 1-undecanol, and a dispersive solvent, methanol. After that, a novel ultrasound assisted back extraction step was performed in order to make the clean-up/enrichment procedure compatible with the detection requirements. Under optimum conditions, linearity ranged from 2.2 to 50ngmL−1, with enrichment factors from 130 to 136-folds. Thus limits of detection between 0.7 and 2.9ngmL−1 were obtained. Precision of the method was evaluated in terms of repeatability, relative standard deviations varied from 4.3% to 6.7%. Relative recoveries ranged from 92% to 106% for all analytes. The satisfactory performance demonstrated that the proposed methodology has a strong potential for application in the multi-residue analysis of heterocyclic aromatic amines present in complex environmental matrices.

Simultaneous determination of pyrethroids and pyrethrins by dispersive liquid-liquid microextraction and liquid chromatography triple quadrupole mass spectrometry in environmental samples.

A simple and environmentally friendly dispersive liquid-liquid microextraction (DLLME) method coupled with electrospray ionization liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) was developed for the simultaneous determination of 17 synthetic and natural pyrethroids. A comparison of solid-phase extraction (SPE) versus DLLME for water samples and only "dilute and shoot" versus the additional extract cleanup by DLLME for sediment samples is reported. Chloroform was the extracting solvent in the DLLME technique for both water and sediment samples. Ultrasonic energy was applied to fully extract the analytes into fine droplets, providing high recoveries in short times. Method detection limits (MDLs) ranged from 0.12 to 0.62ngL-1 and recoveries from 70 to 119% with RSD values 2-15% (n=5) for water samples. In sediment samples, MDLs ranged from 0.50 to 2.50ngg-1 and recoveries from 71 to 112% with RSDs 2-16% (n=5). The proposed method showed a good linearity within the range of 10-500ngmL-1, with coefficients of determination (R 2) higher than 0.99. Matrix effects were observed for most compounds in water and sediment (ME%<-10%). The proposed methodology was applied for the analysis of water and sediment samples from Albufera wetland and Turia River. Acrinathrin (48ngg-1) and etofenprox (16ngg-1) were detected in sediment samples. Graphical abstract Pyrethrins and pyrethroid determination in water and sediments by DLLME and LC-MS/MS.

Determination of antimony and tin in beverages using inductively coupled plasma-optical emission spectrometry after ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction

The aim of this study was to develop a simple and fast ultrasound-assisted ionic liquid dispersive liquid-liquid phase microextraction (UA-IL-DLLME) method for preconcetration of trace antimony and tin in beverage samples. The novelty of this study was based on the application of ligandless UA-IL-DLLME using low-density ionic liquid and organic solvents for preconcentration of Sb and Sn. The concentration of Sb and Sn were quantified using ICP-OES. Under the optimum conditions, the calibration graph was found to be LOQ-250µgL−1 (r2=0.9987) for Sb and LOQ-350µgL−1 for Sn. The LOD and LOQ of Sb and Sn ranged from 1.2to 2.5ngL−1 and 4.0 to 8.3ngL−1, respectively, with high preconcentration factors. The precisions (%RSD) of the proposed method ranged from 2.1% to 2.5% and 3.9% to 4.7% for Sb and Sn, respectively. The proposed method was successfully applied for determination of Sb and Sn in beverages.

Simultaneous determination of selected hormones, endocrine disruptor compounds, and pesticides in water medium at trace levels by GC-MS after dispersive liquid-liquid microextraction.

The need to enhance food safety has led to major advancements in pesticide productions, and though many benefits have been gained, environmental contamination has also risen from these chemicals that tend to persist in the environment. Some pesticides, together with other chemicals commonly called endocrine disruptor compounds, block the receptor sites of hormones or mimic displaced hormones, leading to imbalanced hormonal levels that result in health disorders and diseases. These chemicals occur at trace levels and are not directly detected by conventional analytical methods. A dispersive liquid-liquid microextraction method was therefore developed for preconcentration of 12 analytes including hormones, endocrine disruptor compounds, and pesticides, to be analyzed by gas chromatography mass spectrometry. This was achieved by optimizing parameters such as extractor solvent type and amount, dispersive solvent type and amount, pH, and salt effect that affect extraction output. The limits of detection and quantification of the developed method were between 0.09 and 3.36 and 0.31 and 11.19ngmL-1, respectively. The calibration plots of the analytes also showed good linearity and low percent relative standard deviations. Recovery studies were performed for tap water and wastewater samples, and the percent recoveries recorded were between 84 and 109%.

Determination of Total Arsenic in Water and Food Samples by Pressure-induced Ionic Liquid-based Dispersive Liquid-Liquid Microextraction Method Prior to Analysis by Hydride Generation Atomic Absorption Spectrometry

Determination of Total Arsenic in Water and Food Samples by Pressure-induced Ionic Liquid-based Dispersive Liquid-Liquid Microextraction Method Prior to Analysis by Hydride Generation Atomic Absorption Spectrometry

Determination of cadmium at ultratrace levels by dispersive liquid-liquid microextraction and batch type hydride generation atomic absorption spectrometry

This study describes the development of a dispersive liquid-liquid microextraction method for the extraction of cadmium and its determination by hydride generation atomic absorption spectrometry. The extraction method served as a clean-up of analyte from its matrix and also concentrated it to get lower detection limits. The hydride generation system was optimized to obtain high cadmium hydride generation efficiency and its transport to the quartz tube atomizer for atomization. Under the optimum experimental conditions, the limits of detection and quantification were 4.2ngL−1 and 14.1ngL−1, respectively. Sensitivity was enhanced about 10,000 folds if compared with conventional FAAS system. The calibration showed good linearity over a wide range and the low relative standard deviations indicated high precision for the extraction process and instrumental readings. The accuracy of the method was validated by the agreement of experimented results to the value of a wastewater certified reference material (EU-L-2). Appreciable recovery results were obtained for wastewater spiked at different concentrations.

Dispersive liquid-liquid microextraction for a rapid determination of glyoxal in alcoholic beverages

Carbonyl compounds, like glyoxal, methylglyoxal, diacetyl or pentane-2,3-dione, among others, have been widely studied. Besides its endogenous origin, they are originated from foodstuffs and are related to sensorial characteristics in products such as wine and beer. Generally, for their determination, the analytes must be derivatised to adapt them for the detection system and this step takes long time. The main aim of this research was to develop a simultaneous derivatization and extraction method which takes place in only few minutes. 3,4-diaminopyridine, as derivatizing reagent, generate a fluorescent product. This reaction is selective for glyoxal. For this new dispersive liquid-liquid microextraction (DLLME) procedure combined with chromatographic determination of glyoxal, various parameters affecting the extraction were optimized and finally, a mixture of butan-1-ol as dispersant solvent and dichloromethane as extractant solvent were selected. Its chromatographic peak appears at 2.6min. Four Spanish wines and five Spanish beers have been analysed and the results showed that the levels of glyoxal are comprised between 2.8–9.5mgL−1. The proposed DLLME method drastically reduces the reaction time from 2 or 3–20min improving the methods found in the literature. The glyoxal concentration found in the wines and beers analysed do not suppose any health risk.

D -Limonene as a green bio-solvent for dispersive liquid–liquid microextraction of β-cyclodextrin followed by spectrophotometric determination

Abstract In this paper d -limonene and β-carotene are introduced as two natural products in a dispersive liquid–liquid microextraction (DLLME) method for spectrophotometric determination of β-cyclodextrin (β-CD). Dissolved β-carotene in d -limonene exhibits strong absorption exhibits strong absorption intensity after performing. The absorption intensity of the extracted phase is increased in the presence of β-CD due to its interaction (complex formation) with β-carotene. This increase in the absorbance of the extracted phase is related to the β-CD concentration and was utilized as an analytical signal for determination of β-CD. The effect of chemical variables such as pH of the sample solution, nature and volume of dispersive solvent, volume of extraction solvent and extraction time on the DLLME method was studied and optimum conditions were established. The calibration curve was linear in the range of 1 × 10−4–6 × 10−3 mol L−1 (r = 0.9956) with a limit of detection 4 × 10−5 mol L−1. The relative standard deviation for eight replicate determinations of 1 × 10−3 mol L−1 and 5 × 10−3 mol L−1 of β-CD was 1.82% and 0.88% respectively. The proposed method was successfully applied to the determination of β-CD in spiked water and pharmaceutical samples and good recoveries in the range of 94.2–108.0% were obtained.

Centrifugeless dispersive liquid-liquid microextraction based on salting-out phenomenon as an efficient method for determination of phenolic compounds in environmental samples.

A new centrifugeless dispersive liquid-liquid microextraction (DLLME) method was applied for the convenient extraction of some phenolic compounds from environmental samples. After dispersing the extracting solvent into the sample solution (10.0mL), the mixture was passed through a small column filled with 5g sodium chloride. As a result, phase separation was achieved via the salting-out phenomenon, and the extracting solvent was suspended on top of the sample solution. Using a low-toxic and solidifiable extracting solvent (1-dodecanol), after immersing the column into an ice bath, the extracting solvent was solidified, collected easily, and injected into an HPLC-UV instrument. The overall extraction time was 7min, consumption of the extracting solvent was efficiently reduced to 50μL, and the centrifugation step was simply eliminated, which made the automation of the procedure easier than the normal DLLME technique. A series of parameters influencing the extraction were investigated systematically. The optimal experimental conditions were found to be 50μL of 1-dodecanol as the extracting solvent, a flow rate of 2.0mLmin-1, and a pH value of 4.0 for the sample solution. Under these conditions, the method provided a good linearity in the range of 0.5-800ngmL-1, low limits of detection (0.1-0.3ngmL-1), good extraction repeatabilities (RSDs below 9.1%, n = 5), and enrichment factors of 100-160. Graphical Abstract Schematic diagram of the centrifugeless dispersive liquid-liquid microextraction.