Ultrasound-assisted Emulsification Microextraction Method Research Articles

Development of an Ultrasound-Assisted Emulsification Microextraction Method for the Determination of Volatile Compounds in Wines

A fast and simple method based on ultrasound-assisted emulsification microextraction (USAEME) was developed for the analysis of volatile compounds in wines. A full factorial 24 screening design was built to investigate the main factors affecting the extraction of volatile components, namely the volume of extraction solvent, sonication time, salt content, and pH. Then, the factors with significant effects were optimized using an I-optimal design. The optimal value for all the variables studied was reached under the following experimental conditions: volume of extraction solvent 200 μL and salt content 5% m/v. The suitability of the optimized method was evaluated, resulting in very good linearity with coefficients of determination (R2) higher than 0.995 in all cases, while repeatability was lower than 8.4% except for d-limonene and p-cymene. Recoveries higher than 82% were observed for the groups of ethyl esters, acetate esters, alcohols, and terpenoid alcohols (linalool, α-terpineol). The recovery of acids ranged from 70.5% to 88.9%, whereas the three monoterpenes studied (d-limonene, γ-terpinene, p-cymene) were not extracted satisfactorily. The proposed method was effectively applied for the analysis of volatile compounds in laboratory-scale fermentations with selected strains of Saccharomyces cerevisiae.

A natural hydrophobic deep eutectic solvent-based microextraction method integrated with a spectrofluorimetric technique for the determination of daclatasvir as a direct-acting hepatitis C antiviral drug in plasma samples

An ultrasound-assisted emulsification microextraction method based on a natural hydrophobic deep eutectic solvent (USAEME-HDES) was developed for extraction and preconcentration of daclatasvir, a hepatitis C virus inhibitor, from plasma samples prior to spectrofluorimetric measurement. To make the deep eutectic solvent (DES) compatible with the fluorescence device, fatty acids were used as components of DES that can simultaneously act as hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA). Various parameters, such as the solvent effect on the fluorescence spectrum and the composition and ratio of DES, were investigated and optimized. Other parameters, including pH, DES volume, sonication time, and NaCl concentration, were investigated and optimized using the central composite design combined with the desirability function. Under optimal conditions, compared to other methods, this method had a wide linear range (5–600 ng/mL) with a good coefficient of determination (0.9985) and a low limit of detection (1.42 ng/mL). Drug analysis results in the plasma samples showed that the method has good accuracy. Finally, the Green Analytical Procedure Index (GAPI) tool was used to evaluate the greenness of the method, which demonstrates our method's superior eco-friendship in comparison to other reported methods.

Ultrasound-Assisted Emulsified Microextraction Based on Deep Eutectic Solvent for Trace Residue Analysis of Metribuzin in Urine Samples

Deep eutectic solvent was used as extraction solvent to develop and optimize a new sample preparation method for the determination of metribuzin in urine samples. In order to determine the optimal values of the effective factors in the deep eutectic solvent-based ultrasound assisted emulsification microextraction method, six effective parameters were selected. The design of experiments was performed using the onevariable- at-a-time method. Totally, 96 experimental runs were performed, and the samples were analyzed using high-performance liquid chromatography with a UV detector. Under the optimum conditions, the calibration curve for metribuzin was linear in the concentration range of 5 to 500 μg L-1 for urine samples. The accuracy and reproducibility of the introduced method were determined using the relative recovery (RR %) and relative standard deviation (RSD %) tests on the fortified urine samples. RR % and RSD % were found to be 96.3 – 101.7 % and 3.2 – 7.6 %, respectively. The limit of quantification and the limit of detection were obtained 5 and 0.8 μg L-1, respectively.

Analysis of Malathion pesticide residues in rice samples using ultrasound-assisted emulsification-microextraction coupled to UV photoionization source ion mobility spectrometry

The present paper describes the validation of ultrasound-assisted emulsification-microextraction method followed by ion mobility spectrometry (IMS) for determination malathion pesticides. Ultrasound radiation was applied for accelerating the emulsification of microliter organic solvent in aqueous solutions and enhancing the microextraction efficiency. This preconcentration step combined with IMS detection provided a precise and accurate method for determination of trace amounts of malathion pesticides. The effect of parameters influencing the extraction efficiency such as sonication time, type of extraction solvent, extraction solvent volume, and salt concentration were investigated and discussed. Under the optimum conditions, enrichment factors was 270 with corresponding LOD of 4 μg/L. Linearity with a coefficient of estimation (r2) were >0.99 in the concentration level range of 6–750 μg/L for extraction of Malathion in water samples. The applicability of the proposed method was evaluated by determination of the residues of the investigated pesticide in rice paddy water gathered from four stations during 60 days after spraying (June 2014), and in storage rice samples in Mazandaran province, Iran.

Development of an ultrasound-assisted emulsification microextraction method for the determination of chlorpyrifos and organochlorine pesticide residues in honey samples using gas chromatography with mass spectrometry.

A simple, rapid, and efficient ultrasound-assisted emulsification microextraction method followed by gas chromatography mass spectrometry in selected ion monitoring mode was developed for the determination of organochlorine pesticides in honey samples. The type and volume of organic extraction solvent, pH, effect of added salt content, and centrifuging time and speed were investigated. Under the optimum extraction conditions, 30 μL of 1, 2-dibromoethane (extraction solvent) was immersed into an ultrasonic bath for 1 min at 40°C. The limits of detection and quantification for all target pesticides were 0.003-0.06 and 0.01-0.2 ng/g, respectively. The extraction recovery was 91-100% and the enrichment factors were 168-192. The relative standard deviation for the method was <6% for intraday (n = 6) and <8% for interday precision (n = 4). The proposed method was successfully applied for the analysis of organochlorine pesticides in honey samples.

Ultrasound-assisted emulsification microextraction and preconcentration of trace amounts of silver ions as a cyclam complex

Silver has been recognized as a toxic element for biological systems. A low level of exposure to silver compounds is widespread owing to the use of soluble silver compounds to disinfect water for drinking and reaction purposes. The present paper describes an ultrasound-assisted emulsification microextraction method for the preconcentration and determination of silver ions in drinking water. Determination was carried out using 1,4,8,11-tetraazacyclotetradecane as a complexing reagent and chloroform as extracting solvent, followed by flame atomic absorption determination of silver ions. The main factors affecting microextraction efficiency, such as extraction solvent type and volume, concentration of chelating reagent, concentration of picrate ions, and pH, were optimized. Under optimal conditions, a limit of detection and enrichment factor of 6.79 ng mL−1 and 9.8 were obtained for silver ions, respectively. The analytical curve was linear in the range of 0.055–1.5 μg mL−1, with a correlation coefficient (R 2) of 0.997. The use of ultrasound as a powerful energy for the microextraction and determination of silver was proposed. The main advantages of the method are as follows: minimum use of toxic organic solvent and wide linear dynamic range.

Ionic Liquid-Based Ultrasound-Assisted Emulsification Microextraction of Cadmium in Biological Samples: Optimization by a Multivariate Approach

An ionic liquid-based ultrasound-assisted emulsification microextraction method was developed for the preconcentration and determination of cadmium followed by flame atomic absorption spectrometry. Cadmium was complexed with 4-(2-pyridylazo) resorcinol, and then extracted into fine drops of 1-butyl-3-methylimidazolium hexafluorophosphate that served as the ionic liquid. The pH, ligand concentration, volume of ionic liquid, sonication time, and temperature were optimized by a multivariate technique. The results showed that concomitant ions did not affect the determination of cadmium. The detection limit and enhancement factor under the optimal conditions were 0.21 micrograms per liter and 92, respectively. The relative standard deviation of 10 micrograms per liter of cadmium was less than 5.0 percent. The validity of the method was investigated by the analysis of a spinach leaves standard reference material. The method was suitable for the preconcentration of cadmium in food and biological samples.

An Investigation on Heavy Metals Bio-Sorption by Azolla filiculoides in the International Anzali Wetland

The ultrasound assisted emulsification microextraction (USAEME) method followed by inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used for preconcentration and determination of bismuth (Bi), indium (In) and lead (Pb) in the plant Azolla filiculoides Lam. Calix (4) pyrrole was used as a chelating agent and tetrachloroethylene was selected as extraction solvent. The main parameters of the USAEME method were optimized by using response surface methodology (RSM). The optimal conditions were as follows: 130 µL for volume of extraction solvent, 4 min for sonication time, 6.75 (w/v %) for salt concentration, 890 mg/L for concentration of chelating agent and 7.5 for pH. The calibration graphs were linear in the range of 1-1500 µg/L for Bi and In, and 1-1000 µg/L for Pb with the determination coefficients (R 2 ) of 0.9983, 0.9974 and 0.9997, respectively. The limits of detection (LODs) for Bi, In and Pb were 0.57, 0.76 and 0.84 µg/L, respectively. Under the optimal conditions, the method was successfully applied to the determination of Bi, In and Pb in Azolla filiculoides Lam. tissues in Anzali wetland and satisfactory relative recoveries (94-97%) were achieved.

Rapid determination of indapamide in human urine using novel low-density solvent based ultrasound assisted emulsification microextraction coupled with high performance liquid chromatography-variable wavelength detection

Indapamide belongs to the class of thiazide-type diuretic drugs and is widely used in the treatment of hypertension and nephrolithiasis. In this work, a simple, rapid and efficient low density solvent (LDS) based ultrasound assisted emulsification microextraction (USAEME) method combined with high performance liquid chromatography-variable wavelength detection (HPLC-VWD) was investigated for the determination of a popular drug of abuse, indapamide, in human urine samples. The target compound was extracted from acidified sample solution with a few microliter amount of LDS by a USAEME method. The influence of several important experimental variables such as selection of the extraction solvent and its volume, ultrasonication time, pH and ionic strength were thoroughly examined and optimized. Under optimal conditions, the calibration was linear in concentration range from 1–100 ng mL−1 with a correlation coefficient of 0.9977 for the target analyte. The limit of detection based on signal to noise ratio of 3 was 0.3 ng mL−1 and the relative standard deviations varied from 1.2–6.6%. The proposed method provides a rapid, sensitive, low cost, easy to handle, and convenient procedure to determine indapamide in human urine samples.

Optimisation of ultrasound-assisted emulsification microextraction method with solidification of floating organic drop for the analysis of cork taint responsible compounds in wine

This paper presents the optimisation of a method based on ultrasound assisted-emulsification method (USAEME) combined with solidification of floating organic drop (SFOD) for the sensitive determination of cork taint responsible compounds in wine. Haloanisoles (2,4,6-trichloranisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA) and pentachloranisole (PCA)) and their halophenolic precursors were determined by gas chromatography with electron capture detection (GC-ECD). The derivatisation of the halophenols was performed simultaneously with the extraction. To perform the optimisation, the main parameters affecting both extraction and derivatisation were exhaustively studied in different steps. Once the extraction solvent and the pH and time conditions had been determined, experimental design was applied for the simultaneous study of the volumes of acetic anhydride and extraction solvent, temperature and ionic strength conditions. Then, the analytical characteristics of the optimised method were evaluated achieving satisfactory linearity (with correlation coefficients over 0.984), repeatability (below 10.7%) and inter-day precision (below 10.6%) for all target analytes. Moreover, detection limits found were similar or even lower than the olfactory threshold of the studied compounds. Finally, the applicability of the proposed method was tested by analysing real wine samples. To the best of our knowledge, this is the first time that USAEME–SFOD method has been used to determine cork taint responsible compounds in wine.

Ultrasound Assisted Emulsification Microextraction Based on dimetyl (E)‐2‐[(Z)‐1‐acetyl)‐2‐hydroxy‐1‐propenyl]‐2‐butenedioate for Determination of Total Amount of Iron in Water and Tea Samples

AbstractAn ultrasound assisted emulsification microextraction (USAEME) is successfully used for extraction and determination of trace amount of iron in water and tea samples, followed by flame atomic absorption spectroscopy (FAAS). In this approach, a new synthetic ligand dimetyl (E)‐2‐[(Z)‐1‐acetyl)‐2‐hydroxy‐1‐propenyl]‐2‐butenedioate (DAHPB) is used as chelating agent and chloroform is selected as an extraction solvent. The factors influencing the complex formation and extraction by USAEME method are optimized. These factors are extraction solvent type as well as extraction volume, time, temperature, pH, and the amount of chelating agent. Under optimum conditions, an enrichment factor of 202.9 is obtained from only 7.1 mL of aqueous phase. The calibration graph using the preconcentration system for iron is linear between 40.0 and 800.0 μg L−1 with a detection limit of 7.4 μg L−1. The relative standard deviation (R.S.D) for ten replicate measurements of 500.0 μg L−1 of iron is 2.5%.

Determination of nitrophenols using ultrahigh pressure liquid chromatography and a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method based on solidification of a floating organic droplet

Nitrophenols are toxic compounds in the wastewater. In the proposed method, a new technique using a manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) method based on solidification of a floating organic droplet combined with ultrahigh pressure liquid chromatography (UHPLC) has been developed for the extraction and determination of nitrophenols in aqueous samples. In this method, the low toxicity extraction solvent 1-undecanol was used to extract the nitrophenols. After centrifugation, ice bath was used to solidify the floating extraction solvent, using microtubes to collect the floated extraction solvent and diluting with 30μL of dimethyl sulfoxide, then injecting into the UHPLC for further analysis. The relative standard deviations (RSD) were 6–12%, enrichment factors (EFs) were 62–500, the relative recoveries (RR) of this method were 80–110% for spiked lake water samples. The detection limits of this method were 0.5–3.0μgL−1 for spiked lake water and 0.6–3.2μgL−1 for spiked agriculture water. The further performance of the proposed method was gauged by analyzing field samples.

Development of an ultrasound-assisted emulsification–microextraction method for the determination of the main compounds causing cork taint in wines

In this work, an ultrasound-assisted emulsification–microextraction method has been optimised for the determination in wine of haloanisoles (2,4,6-trichloranisole (TCA), 2,3,4,6-tetrachloroanisole (TeCA), 2,4,6-tribromoanisole (TBA) and pentachloranisole (PCA)) responsible for the so-called cork taint. Their halophenolic precursors (2,4,6-trichlorophenol (TCP), 2,3,4,6-tetrachlorophenol (TeCP), 2,4,6-tribromophenol (TBP) and pentachlorophenol (PCP)) have also been simultaneously determined. For this purpose, parameters affecting the USAEME–derivatisation procedure were exhaustively investigated. Firstly, extraction solvent, basic conditions and extraction time were selected to, subsequently, employ experimental design methodology for the simultaneous optimisation of the volumes of acetic anhydride and extraction solvent, temperature and ionic strength conditions. Once optimised, the evaluation of the analytical performance of the method confirmed its suitability for the determination of the studied compounds in wines. The proposed method showed satisfactory linearity (correlation coefficients over 0.981), repeatability (below 10.9%) and inter-day precision (below 11.0%). Detection limits obtained were similar or even lower than previously reported. In addition, the proposed method was successfully applied to the analysis of real samples. To our knowledge, this is the first time that USAME method has been optimised for the simultaneous determination of haloanisoles and halophenols in wine.

Extraction and determination of biphenyl and biphenyl oxide in water samples by using ultrasound-assisted emulsification microextraction-gas chromatography-flame ionization detection

In this article, a fast, simple and efficient method for determination of biphenyl and biphenyl oxide in water samples was developed using an ultrasound-assisted emulsification microextraction (USAEME) method based on applying low density organic solvents. 14 μL of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample without salt addition that was located inside an ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Under the optimum conditions, enrichment factors (EFs) of 883 and 1066 for biphenyl and biphenyl oxide, respectively, were obtained. The method performance was studied in terms of linear dynamic range (LDRs from 0.5 μg L−1 to 200 μg L−1 for both analytes), linearity (r2 ≥ 0.995) and precision (repeatability ≤ 8%). Also, we obtained limits of detection (LODs) of 0.1 μg L−1 for biphenyl and biphenyl oxide. The applicability of the USAEME method was evaluated by the extraction and determination of biphenyl and biphenyl oxide from different water samples.

Determination of endocrine-disrupting phenols in water samples by a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method

Manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) combined with ultraperformance liquid chromatography (UPLC) with UV detection has been developed for the determination of five endocrine-disrupting phenols (EDPs) in seawater samples and detergent samples: 4-tert-butylphenol (4-t-BP), 4-cumylphenol (4-CP), 4-tert-octylphenol (4-t-OP), 2,4-di-tert-butylphenol (2,4-di-t-BP) and 4-nonylphenol (4-NP). Optimum conditions were found to be: 25 μL 1-bromohexadecane as extraction solvent, 5 mL of aqueous sample and 1 g of NaCl to control the ionic strength; manual shaking for 10 s; ultrasonication for 1 min; centrifugation for 3 min at 5000 rpm (speed). For MS-USAEME, manual shaking for 10 s is essential for effective extraction when the ultrasonic extraction time is as brief as 1 min. The small volume of aqueous sample enhances the effect of manual shaking significantly. For seawater samples, the limit of detection (LOD) was 0.5-2.8 ng mL(-1), the limit of quantification (LOQ) was 1.8-9.3 ng mL(-1) with the relative standard deviation (RSD) in the range 4.2-10.3%. For detergent samples, the LOD was 0.4-2.4 ng mL(-1), LOQ was 1.6-8.2 ng mL(-1) and RSD 4.7-10.0%. The relative recovery was 96-109% for seawater samples and 81-106% for the detergent samples.

Simultaneous determination of aluminum, copper, iron and zinc in Oscillatoria, Juncus littoralis tissues and wetland water samples by ultrasound-assisted emulsification-microextraction combined with ICP-OES

Ultrasound-assisted emulsification microextraction (USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) for simultaneous extraction, preconcentration and determination of trace levels of aluminum, copper, iron and zinc in Oscillatoria, Juncus littoralis tissues and wetland water samples is presented. Sodium diethyldithiocarbamate trihydrate (Na-DDTC·3H2O) was used as a chelating agent and tetrachloroethylene was selected as an extraction solvent. The effective parameters of the USAEME method including volume of extraction solvent, ultrasonic time, salt concentration, temperature, concentration of ligand and pH were investigated by a fractional factorial design. The results showed that temperature had no considerable effect on the efficiency. A Box-Behnken design (BBD) was applied to optimize the effective parameters. The optimal conditions were obtained as 48 μL for volume of extraction solvent, 6 min for ultrasonic time, 16.6 (w/v %) for salt concentration, 1440 mg L−1 for concentration of the ligand and 7 for pH. The linear dynamic range (LDR) was 1–1000 μg L−1 with determination coefficient of 0.994–0.998. The limits of detection (LODs) and relative standard deviations (RSDs) were 0.64–0.91 μg L−1 and 2.6–5.3%, respectively. The method was successfully applied to the determination of Al, Cu, Fe and Zn in real environmental samples and satisfactory relative recoveries (92–99%) were obtained.

Extraction of organophosphorus pesticides in water and juice using ultrasound‐assisted emulsification–mixroextraction

In this study, a microextraction method termed as ultrasound-assisted emulsification-microextraction (USAEME) has been developed for the extraction of organophosphorus pesticides (OPPs) in water and orange juice samples. In the USAEME method, aliquots of 50 microL chlorobenzene used as extraction solvent was added to 10 mL water sample in a conical glass centrifugal tube. Factors influencing the USAEME extraction efficiency such as sonication time, extraction solvent, extraction volume and salt addition were evaluated. Under the optimum conditions, enrichment factors ranged from 241 to 311, LOD varied from 5.3 to 10.0 ng/L and linearity with a coefficient of estimation (r(2)) varied from 0.9991 to 0.9998 in the concentration level range of 0.05-2.5 microg/L for the extraction of OPPs in water samples. Finally, the proposed USAEME method was used for the extraction of OPPs from water and orange juice. The recoveries were in the range of 80.0-110.0%, and the repeatability of the method expressed as RSD (n=3) varied between 1.6 and 13%. The USAEME method has the advantage of being easy to operate, low consumption of organic solvent and high extraction efficiency.

Ultrasound-assisted emulsification microextraction method based on applying low density organic solvents followed by gas chromatography analysis for the determination of polycyclic aromatic hydrocarbons in water samples

In this study, a fast, simple and efficient ultrasound-assisted emulsification microextraction (USAEME) method was successfully developed based on applying low density organic solvents. Fourteen microliters of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene (about 4 μL) was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Some polycyclic aromatic hydrocarbons (PAHs) were selected as model compounds for developing the method and evaluating its performance and to compare the efficiency of the proposed method with previously reported techniques. Several factors influencing the emulsification, extraction and collection efficiency such as the nature and volume of organic solvent, emulsification–extraction temperature, ionic strength and equilibrium and centrifugation times were investigated and optimized. Under the optimum conditions, preconcentration factors (PFs) in a range of 1776–2714 were obtained. The performance of the proposed method was studied in terms of linear dynamic range (LDRs from 0.05 to 100 μg L −1), linearity ( R 2 ≥ 0.994), precision (repeatability: RSD% ≤ 7.9, reproducibility: RSD% ≤ 14.6) and extraction percents (59.2–90.5%). Limits of detection (LODs) in the range of 0.02–0.05 μg L −1 were obtained for different PAHs. The applicability of the proposed method was evaluated by the extraction and determination of PAHs from several natural water samples.