Air-assisted Liquid-liquid Microextraction Research Articles

An eco-friendly sample preparation procedure based on air-assisted liquid-liquid microextraction for the rapid determination of phthalate metabolites in urine samples by liquid chromatography-tandem mass spectrometry

Urinary phthalate metabolite (mPAEs) analysis is a reliable tool for assessing human exposure to phthalates. With growing interest in urinary biomonitoring of these metabolites, there is a need for fast and sensitive analytical methods. Therefore, a simple, rapid procedure for simultaneous determination of fifteen phthalate metabolites in human urine samples by liquid chromatography-tandem mass spectrometry was developed. The novelty of the present procedure is based on the use of diethyl carbonate as a green biobased extraction solvent and air-assisted liquid-liquid microextraction (AALLME) as a sample preparation step. A Plackett-Burman design was used for screening the factors that influence the AALLME extraction efficiency of mPAEs. The effective factors were then optimized by response surface methodology using a central composite rotatable design. Under the optimized conditions, good linearity can be achieved in a concentration range of 1.0–20.0 ng mL-1 with correlation coefficients higher than 0.99. The repeatability and reproducibility precision were in the range of 2–12% and 1–10% respectively. Recoveries ranging from 90% to 110%. This, and the low limits of detection, ranging from 0.01 to 0.05 ng mL-1, make the proposed procedure sensitive and suitable for human biomonitoring of phthalate exposures. For proof-of-principle, the new method was used to measure the urinary concentrations of mPAEs in 20 urine samples from Brazilian women. The high frequency of detections and in part high concentrations of mPAEs indicate to widespread exposure to several phthalates among Brazilian women.

Micro-extraction, pre-concentration, and microfluidic-based separation of organophosphate insecticides followed by the miniaturized electrochemical detection system

Introduction: A new analytical method based on the coupling of microextraction and microfluidics was developed and investigated for the pre-concentration, separation, and electrochemical detection of fenitrothion (FT) and parathion (PA) at the sub-ppm concentrations. Method: In the first step, the microchip capillary electrophoresis technique was used to serve as a separation and detection system. Analytes were injected into the 40 mm long microchannel with 10 mm sidearms. Then, they were separated by applying a direct electrical field (+1800V) between buffer and detection reservoirs. 2-(n-morpholino)ethanesulfonic acid (MES) buffer (20 mM, pH 5) was used as the running buffer. The electrochemical detection was performed using three Pt microelectrodes with the width of working, counter, and reference electrodes (50, 250, and 250 µm, respectively) in the out channel approach. Results: The system was devised to have the optimum detection potential equal to -1.2 V vs. Pseudo Ref. electrode. The dimensions of the SU-8 channel have 20 µm depth and 50 µm width. In the second step, an air-assisted liquid-liquid microextraction technique was used for the extraction and preconcentration of analytes from human blood plasma. Then, 1, 2 di-bromoethan was used as extractant solvent, the analytes were preconcentrated, and the sedimented solvent (50 µL) was evaporated in a 60 ˚C water bath followed by substitution of running buffer containing 10% ethanol. The optimum extraction cycles were found 8 with adding 1% NaCl to the aqueous phase. Analyzing time of the mentioned analytes was less than 100s, and the precision range was 3.3 – 8.2 with the linear range of 0.8 – 100 ppm and 1.2 - 100 ppm for FT and PA, respectively. The extraction recoveries were about 91% and 87% for FT and PA, respectively. The detection limits for FT and PA were 240 and 360 ppb, respectively. Finally, the reliability of the method was investigated by GC-FID. Conclusion: The proposed method and device were validated and can be used as in situ and portable detection system for detecting fenitrothion and parathion insecticides.

Air-assisted liquid-liquid microextraction and enantioselective gas chromatography-tandem mass spectrometry quantification of methyl jasmonate stereoisomers in tea (Camellia sinensis L.)

Different stereoisomers of phytohormones may have different roles in plants while the quantification for stereoisomers still remains a challenge. The chiral separation method for methyl jasmonate (MeJA) in tea (Camellia sinensis L.) was developed by air-assisted liquid-liquid microextraction (AALLME) with enantioselective gas chromatography-mass spectrometry (Es-GC-MS/MS). The Plackett-Burman factorial design was introduced to optimize the multiple parameters of AALLME. Sensitive Es-GC-MS/MS enabled the quantification of the MeJA stereoisomers, which were separated from each other with resolutions of 3.5, 2.7, and 2.5. The linearities were R2 > 0.9971, the limits of detection were 0.08–0.12 ng/mL, the limits of quantification (LOD) were 0.28–0.39 ng/mL, and the recovery range was 80.60–107.03%. The method was applied to analyze the MeJA stereoisomer profiles in tea plants after geometrid feeding and mechanical wounding. (+)-MeJA appeared to be the main bio-active monomer that responded to injury stress. (+)-MeJA similarly increased in tea shoots at only 30 s after geometrid attack or mechanical wounding. The proposed method is superior as air-assisted liquid-liquid microextraction could induce the loss of volatile MeJA in a much shorter time, compared to the conventional enrichment procedure. A novel assay protocol for relative quantification of MeJA stereoisomers in plants responding to different injuries was applied.

Investigation of the applicability of fatty acid-based deep eutectic solvent based air assisted liquid liquid microextraction for the rapid determination and extraction of butylparaben in cosmetic products

In this research paper, fatty acid-based deep eutectic solvents (FA-DESs) were prepared and investigated for the extraction of butylparaben (BP) from cosmetic products by air assisted liquid liquid microextraction (AA-DLLME). The amounts of BP were determined by UV/Vis spectrophotometry. By combining single factor optimization and Box-Behnken design based multivariate approach, key extraction parameters affecting the FA-DES AA-LLME procedure were systematically optimized. Under the optimized conditions, wide working range (5–800 μg L−1) was obtained with a good r2:0.9972 and high enrichment factor (205). For three replications run of 10 μg L−1 (low), 300 μg L−1 (medium) and 600 μg L−1 (high) of BP, the percent extraction recovery and relative standard deviation were in the range of 92 ± 4%-98 ± 2% and 1.8–2.6%, respectively. The limit of detection and the limit of quantification were 1.5 μg L−1 and 5 μg L−1, respectively. The study of the matrix effect showed that the proposed method has high selectivity for measuring BP in the selected samples. Therefore, it has great potential in sample pre-treatment and quantification of trace BP in cosmetic products.

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.

Dispersive liquid–liquid microextraction with back extraction based on in situ deep eutectic solvent decomposition and air-assisted for determination of some antidepressant drugs in biological samples prior to HPLC-UV

ABSTRACT In this study, a dispersive liquid–liquid microextraction along with a back-extraction step (DLLME-BE) has been developed for the determination of thre antidepressant drugs (citalopram, sertraline, and venlafaxine) in biological samples prior to HPLC-UV. Briefly, the method involved two main steps: first, a deep eutectic solvent (DES) composed of tetrabutylammonium bromide (TBABr as a dispersive agent) and 1-dodecanol (as the extraction solvent) was decomposed in an aqueous phase and led to in situ dispersion of the organic phase and extraction of analytes. . Second, Air-assisted liquid–liquid microextraction (AALLME) was applied to back-extract analytes into 50 µL of an aqueous acceptor phase while many interferences were not able to extract into the acceptor solution. By performing this developed extraction method, a high sample clean-up was achieved. The maximum efficiency of analytes was obtained based on the optimisation of the main parameters. Validation of the method indicated that the limits of detection (LODs) and limits of quantifications (LOQs) were in the range of 0.7–3.9 µg L−1 and 2.1–9.8 µg L−1 respectively. The extraction recoveries and enrichment factors of analytes were obtained to be in the range of 87.1–99.1% and 89–102, respectively. Finally, the method was utilised for extraction of three antidepressant drugs in water, human urine and plasma samples.

Elevated Temperature Air-Assisted Liquid-Liquid Microextraction of Pseudoephedrine from Human Urine Samples Coupled with High-Performance Liquid Chromatography-Ultraviolet Detection

Background: Pseudoephedrine is a broadly used drug for the clinical treatment of bronchitis, respiratory allergies, and cancer pains. However, the use of pseudoephedrine is restricted by several medicinal commissions like International Olympic Committee (IOC). In this study, a reliable, inexpensive, green, and sensitive microextraction method has been developed for extraction and preconcentration pseudoephedrine in urine samples. Methods: It is based on an air-assisted liquid-liquid microextraction (AALLME) technique in which choline chloride: p-chlorophenol deep eutectic solvent (DES) was used as the extraction. The extracted analyte was determined by a high-performance liquid chromatography (HPLC)-ultraviolet detector. The effective factors on the efficiency of the method such as kind of extraction solvent, pH of sample solution, extraction time, and ionic strength were investigated. Results: Under the optimized conditions, the extraction recovery (ER) and enrichment factors(EFs) were 89% and 222, respectively. The method detection limit, relative standard deviation(RSD), and linear range were 0.21 ng mL-1, 4.9%, and 0.69-1000 ng mL-1, respectively. Conclusion: The validated method was successfully performed on different urines samples obtained from the persons who were under treatment with pseudoephedrine.

Air-assisted liquid-liquid microextraction of total 3-monochloropropane-1,2-diol from refined edible oils based on a natural deep eutectic solvent and its determination by gas chromatography-mass spectrometry

In this paper, a fast, sensitive, and selective sample preparation procedure was presented for the determination of 3-monochloropropane-1,2-diol (3-MCPD) in refined edible oils using gas chromatography-mass spectrometry. In this method, firstly, the sample lipids and analyte fatty esters are saponified by sodium hydroxide under sonication. After that the analyte was derivatized using phenylboronic acid (as the derivatization agent) and the obtained derivative was extracted during an air-assisted liquid-liquid microextraction procedure (AALLME). Six different deep eutectic solvents (DESs) were prepared as the extraction solvents and the most effective extraction for 3-MCPD was obtained in the presence of a natural DES (NDES) consisting of choline chloride (ChCl)-acetic acid (AcOH). Important variables such as sodium hydroxide concentration and volume, sonication time, temperature, extraction solvent type and volume, and phenylboronic acid concentration and volume have been optimized. Using the optimum conditions, broad linear range (0.88-1000 ng g–1), suitable coefficient of determination (0.995), and low limits of detection (0.26 ng g–1) and quantification (0.88 ng g−1) were obtained. Relative standard deviations for intra– (n=8) and inter-day (n=6) precisions at a concentration of 5 ng g−1 were 2.6 and 3.2%, respectively. The developed method has been successfully applied to 3-MCPD determination in refined edible oil samples including sunflower, corn, and canola oils.

Air-Assisted Alkanol-Based Nanostructured Supramolecular Liquid-Liquid Microextraction for Extraction and Spectrophotometric Determination of Morin in Fruit and Beverage Samples.

A new air-assisted liquid–liquid microextraction method based on alkanol nanostructured supramolecular solvents coupled to spectrometric analysis was developed for extraction, preconcentration, and spectrophotometric determination of morin. Al(III)-morin complex was performed at pH 4.5. Four different alkanol-based SUPRAS (supramolecular solvents) were prepared for the separation and preconcentration of Al-morin complex from aqueous solution by using vortex and centrifugation. Effect of analytical variables and tolerance limit of matrix ions were investigated. Under the optimum conditions, detection limit, quantification limit, relative standard deviation, preconcentration factor, and enhancement factor were found as 3.5 µg L−1, 10 µg L−1, 3.1%, 120, and 95, respectively. The accuracy of the method was performed with standard addition. The obtained results demonstrated the applicability of the method for the separation, preconcentration, and determination of morin in fruit and beverage samples. The method also complies with green chemistry principles as it uses green solvents, reduces reagent volumes, and produces low amounts of waste.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12161-021-02111-3.

Comparison of different microextraction based sample preparation methods for Pt (IV) and Pd (II) ions in environmental water samples followed by flame atomic absorption spectrometry

ABSTRACT In present study, efficiency of three rapid, simple, and reliable sample preparation methods namely dispersive liquid–liquid microextraction (DLLME), air-assisted liquid–liquid microextraction (AALLME), and CO2-assisted liquid–liquid microextraction (CO2-ALLME) have been compared for the extraction and preconcentration of Pt(IV) and Pd(II) ions in environmental water samples prior to flame atomic absorption spectrometry. In this regard, the effect of various experimental parameters on efficiency of the methods like nature and amount of the disperser and extraction solvents, ionic strength, temperature, pH, etc., are investigated to reach high enrichment factors. Due to organic solvent consumption at µL level, all of the studied methods are inexpensive and convenient. The linear ranges of the calibration curves were 10.0–200, 6.0–175, and 6.0–175 μg L−1 for Pd(II), and 20–200, 4.0–200, and 7.0–200 μg L−1 for Pt (IV) ions in DLLME, AALLME, and CO2-ALLME methods, respectively. Extraction recoveries of 81.4, 92.1, and 88.9% for Pd (II) and 85.3, 98.4, and 93.4% for Pt(IV) ions were obtained in DLLME, AALLME, and CO2-ALLME, respectively. Finally, the developed methods were successfully used for the analysis of Pt(IV) and Pd(II) in various water samples.

Combining a liquid-liquid extraction with successive air assisted liquid-liquid microextraction for the analysis of phytosterols present in animal based butter and oil samples

In this study, an elevated temperature liquid–liquid extraction combined method with successive air-assisted liquid–liquid microextraction has been proposed for the extraction of four phytosterols in cow milk butter and animal oil samples prior to gas chromatography–flame ionization detector. The method is started by combining a few grams of the melted butter or oil samples with ethanol. The mixture is vortexed and placed into a water-bath adjusted at 50 ⁰C. After a few minutes, the mixture is allowed to cool at room temperature. In this step, the butter or oil is become stiff and ethanol is collected on top of the sample. The separated ethanol phase is collected and mixed with deionized water to obtain a homogenous solution. After that, a few microliters of ethyl methyl ammonium chloride: pivalic acid deep eutectic solvent is added into the solution and the mixture was pulled into a glass test tube and pushed back to the tube for five times. After centrifugation, whole of the collected phase at the bottom of tube was withdrawn and transferred into a microtube and contacted with sodium hydroxide solution. The mixture is withdrawn and released to the tube 2 times to remove the extracted fatty acids. The validation data verified that high enrichment factors (385-450) and extraction recoveries (77–90%), low limits of quantification (2.6–5.2 ng g–1) and detection (0.73–1.5 ng g–1), and satisfactory relative standard deviations (≤ 9.3%) can be obtained with this method. At last, the developed method was successfully used for the analysis of phytosterols in various butter and oil samples marketed in Tabriz, Iran.

Combination of a smart phone based low-cost portable colorimeter with air-assisted liquid-liquid microextraction for speciation and determination of chromium (III) and (VI)

In this study, a simple, cheap and rapid technique has been developed for speciation analysis of chromium in different water samples using air-assisted liquid-liquid microextraction and digital image decomposition into the primary colors Red (R), Green (G) and Blue (B). In the proposed method, Cr(VI) was mixed with 1,5 diphenyle carbazid (DPC) in an HCl medium and then formed an ion pair with sodium dodecyl sulfate (SDS). The obtained ion pair was extracted into 350 µL of chloroform and then digital image of extraction phase was obtained by a smartphone and converted to the RGB-values using a free application. Considering the color of extraction phase, the value of G channel was taken as analytical signal. Total chromium is subjected to a similar extraction procedure after oxidation. Then Cr(III) has been calculated by subtracting.Cr(VI) from the total chromium. The effects of different parameters influencing the extraction efficiency were investigated in detail. Under the optimal conditions, the limit of detection (LOD) and quantitation (LOQ) were 0.9 and 3 µg L−1, respectively. Also the relative standard deviation for five replicate determinations of 100 μg L−1 Cr(VI) was 3.2%. The developed method was validated by recovery experiment and independent analysis by Graphite Furnace Atomic Absorption Spectrometry technique and successfully applied to speciation of Cr(III) and Cr(VI) in environmental water samples.

Air-assisted liquid-liquid microextraction based on the solidification of floating deep eutectic solvents for the simultaneous determination of bisphenols and polycyclic aromatic hydrocarbons in tea infusions via HPLC

Deep eutectic solvents (DESs) are a new class of green “designer solvent”; its physicochemical properties can be easily tuned by adjusting DES′ constituents, chemical ratio and water content. In this study, three hydrophobic DESs with low viscosity, low density, and melting points close to room temperature were designed and synthesized. Based on these DESs, an air-assisted liquid–liquid microextraction technique was developed based on the solidification of floating DESs for the simultaneous determination of bisphenols and polycyclic aromatic hydrocarbons (PAHs) via HPLC. The microextraction parameters were optimized via the Plackett-Burman design and response surface methodologies. The method shows satisfactory linearity (R2 ≥ 0.9928), a low limit of detection (0.16–0.75 μg L−1) and satisfactory precision (≤2.3%), and was successfully applied for the simultaneous determination of bisphenols and PAHs from tea infusions with satisfactory recoveries (82.0–116.6%). This method is simple, rapid, economical, environmentally compatible, dispersive solvent-frees and centrifugation-free, and has promising applications in food safety.

Determination of Morin and Quercetin in Fruit Juice Samples using Air-Assisted Liquid-Liquid Microextraction Based on Solidification of Floating Organic Droplet and HPLC-UV

In this study, a rapid and efficient method has been used for the extraction and determination of morin and quercetin in fruit juice samples based on air-assisted liquid-liquid microextraction based on solidification of floating organic droplet and HPLC-UV. The effects of 7 important parameters on the extraction recovery were examined and were optimized by Plackett-Burman design and Central Composite design. According to the Plackett-Burman design results, ionic strength of the sample solutions, the aspiration/dispersion cycles, and the rate and time of centrifuge did not show significant effects on the extraction of morin and quercetin. The optimized conditions of extraction were as follows; the volume of the extraction solvent of 83.6 µL, pH of 4.34 for the sample, and 1-undecanol as extraction solvent. Under these conditions, the linear calibration curve was in the ranges of 1-1000 ng/mL and 0.5-1000 ng/mL for morin and quercetin, respectively, with the determination coefficient values above 0.99. The limit of detection of morin and quercetin was 0.3 and 0.2 ng/mL, respectively. The extraction recoveries for 10 ng/mL of morin and quercetin were 98.9% and 96.5%, respectively; while, relative standard deviations (n = 3) were lower than 3.2%.

Air-assisted liquid-liquid micro-extraction based on the solidification of a floating organic droplet for the determination of three strobilurin fungicides in water samples

ABSTRACT A simple, fast, air-assisted liquid-liquid micro-extraction technique using the solidification of a floating organic droplet method was developed for the extraction of three strobilurin fungicides in water samples before analysis by high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD). In this method, a low-density solvent (1-dodecanol) was used as the extraction solvent. Fine extraction solvent droplets were rapidly formed and dispersed into the water samples through air-pumping by syringe rather than an organic disperser solvent. The extractant droplets with its freezing point near room temperature could be gathered from the top of the water sample after solidification in anice bath. Under optimal extraction conditions (200 μL of 1-dodecanol, four extraction cycles, 150 mg of NaCl), good linearities were obtained with correlation coefficients exceeding 0.996 and the limits of detection varied between 0.73 and 8.49 ng mL−1. The practical applicability of the proposed method was verified by the determination of three strobilurin fungicide contents in tap water, river water, well water and seawater. Extraction recoveries were between 75.3% and 98.3% with relative standard deviations ranging from 1.2% to 8.5%.The results prove that the method has promising applications for low-cost, accurate and rapid determination of strobilurin fungicides in water samples.

Application of a modified lighter than water organic solvent-based air-assisted liquid–liquid microextraction method for the efficient extraction of aflatoxin M1 in unpasteurized milk samples

ABSTRACT An efficient analytical method has been developed for the extraction and quantification of aflatoxin M1 in milk samples using a modified air-assisted liquid-liquid microextraction method combined with high-performance liquid chromatography-fluorescence detector. Firstly, defatted milk is transferred into a glass test tube and its proteins are participated with zinc acetate solution. After vortexing and centrifugation of the mixture, the obtained supernatant is removed and transferred into a conical bottom glass test tube. Then, the adsorbed analyte onto the precipitated proteins is eluted with acetonitrile and after centrifugation, the eluant is mixed with the supernatant obtained from the previous step. A few microlitres of toluene (as an extraction solvent) is added into the solution and the mixture is sucked into a glass syringe and pushed out in the tube for four times. The obtained cloudy solution is centrifuged to collect the extraction solvent. Then, the lower aqueous phase is withdrawn by a glass syringe to transfer the extraction solvent to the conical section of the tube. The method was validated and under optimal conditions, it was found that the method has low limits of detection (0.9 ng L−1) and quantification (3 ng L–1), good linearity (r2 = 0.9976), and satisfactory repeatability (relative standard deviation ≤9% for intra- (n = 8) and inter-day (n = 6) precisions). The extraction recovery and enrichment factor of AFM1 were 87% and 87, respectively. Finally, the proposed method was applied on different milk samples and concentration of aflatoxin M1 was determined in the studied samples.

Comparison of Directly Suspended Drop Microextraction with Dispersive Liquid-liquid Microextraction Method for Extraction of Doxepin in Water and Biological Samples Prior to UV-Vis Spectrophotometer

The present research describes the use of directly suspended drop microextraction and air-assisted dispersive liquid-liquid microextraction method coupled with UV-Vis spectrophotometer for the analysis of doxepin in water and biological samples. Several important parameters which influence the extraction efficiencies of these two microextraction methods, such as the kind of extracting solvent, volume of the aqueous sample solution (donor phase), the volume of the organic extraction solvent (acceptor phase), pH of the donor phase, salt effect, extraction time, stirring rate and number of the air injection were investigated. Under the optimal conditions, the enrichment factors were above 30. The linearity of the methods has been investigated between the ranges of 0.005-1.5 and 0.003-1 µg/mL. The precisions of two methods which are based on the average relative standard deviations are lower than 6, for three different concentrations of the analyte. Finally, the proposed methods were applied for the determination of doxepin in real samples including environmental water, urine and human plasma samples under the optimal conditions and the reasonable relative recoveries were obtained.

Hydrophobic borneol-based natural deep eutectic solvents as a green extraction media for air-assisted liquid-liquid micro-extraction of warfarin in biological samples

In the present study, a new generation of water-immiscible natural deep eutectic solvents (DESs) was synthesized using borneol as a hydrogen-bonding acceptor and decanoic acid, oleic acid, and thymol as a hydrogen-bonding donor in different molar ratios. These green hydrophobic solvents which are chemically stable in aqueous solutions were used as extraction solvents for isolation and pre-concentration of warfarin in biological samples. In this method, fine droplets of DESs were dispersed into the sample solution by using the air-assisted liquid-liquid micro-extraction method to accelerate the cloudy emulsion system formation and increase the mass transfer of the analyte to the DES-rich phase. The borneol based deep eutectic solvent is a worthy generation of the extraction solvents in the ALLME method due to low-cost and less toxicity. A Plackett-Burman design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design (BBD). Optimized extraction conditions were pH of sample solution of 3.9, number of aspiration/dispersion cycles of 15, the volume of DES of 60 μL, and rate and time of centrifuge of 6000 rpm and 10 min, respectively. Under the optimized conditions, the developed NADES-ALLME method exhibited a wide linear range of 5–500 µg L − 1 for plasma and urine samples with satisfactory recoveries above 88.80%. Limit of detections (LODs) and Limit of quantifications (LOQs) of warfarin were in the ranges of 0.5–2.7 and 1.65–8.91, respectively. The enrichment factors were obtained in the range of 148–164 and precisions were lower than 5.87%. Finally, the proposed method was successfully employed for the analysis of warfarin in human urine and plasma samples.

Air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent for the analysis of ultraviolet filters in water samples by high performance liquid chromatography with the aid of response surface methodology

For this work, a novel air-assisted liquid-liquid microextraction based on solidification of floating deep eutectic solvent (AA-LLME-SFDES), coupled with a high performance liquid chromatography (HPLC) method was developed for the detection of benzophenone and salicylate ultraviolet filters in water samples. Three types of fatty acid-based hydrophobic deep eutectic solvents (DESs) with low viscosity, low-density, and melting point close to room temperature were prepared and employed as extraction solvents. This air-assisted liquid-liquid microextraction was carried out in a glass centrifuge tube. Subsequently, the glass tube was introduced into ice-water bath and held for 3 min, during which the upper DES phase was solidified. The water phase was easily extracted using a syringe equipped with a long needle, and later, the glass tube was removed from ice-water bath. The solidified DES phase was immediately melted at room temperature and used for HPLC analysis. The response surface methodology was employed to optimize some influencing parameters such as the volume of the extraction solvent, the pH value of sample solution, the number of extraction cycles, and the addition of salt. A quadratic model, namely a central composite design, was used to replace the conventional single factor analysis. It was found that under optimal conditions, the limits of determination and quantification were 0.045–0.54 µg L−1 and 0.15–2.0 µg L−1, respectively. The relative standard deviations for inter-day (n = 5) and intra-day (n = 5) precision were ≤ 4.2%, whereas the enrichment factors for the ultraviolet filters were obtained from 41 to 50. Furthermore, this novel method was successfully employed for the detection of benzophenone and salicylate ultraviolet filters from real water samples. The recoveries ranged from 87.5% to 105.8%, whereas the RSDs were lower than 3.6%.

Preparation of ferrofluid from toner powder and deep eutectic solvent used in air-assisted liquid-liquid microextraction: Application in analysis of sixteen polycyclic aromatic hydrocarbons in urine and saliva samples of tobacco smokers

A new ferrofluid prepared from toner powder and deep eutectic solvent was used in air-assisted liquid-liquid microextraction procedure for extraction of sixteen polycyclic aromatic hydrocarbons from urine and saliva samples of tobacco smokers. In this work, initially, a water-immiscible deep eutectic solvent is synthesized by mixing choline chloride and stearic acid under mild conditions and used as a support solvent in the preparation of ferrofluid from toner powder. Then, a few microliters of the prepared ferrofluid is mixed with sample solution and dispersed in all parts of the solution by performing aspirating/dispersing cycles. To collect the ferrofluid, a magnet is deposited at the outside of the tube and the solution is discarded. The analytes in the collected phase are back-extracted into n-heptane and determined by gas chromatography–mass spectrometry. The validation parameters including limit of detection and quantification, stability, accuracy, linearity, selectivity, precision, enrichment factor, and extraction recovery were studied and the data showed that the method have low limits of detection (in the range of 6–21 ng L−1 in deionized water and 18–63 ng L−1 in saliva and urine samples, respectively) and quantification (in the range of 20–72 ng L−1 in deionized water and 60–216 ng L−1 in saliva and urine samples). Extraction recoveries and enrichment factors ranged from 61 to 84% and 305 to 420, respectively. Relative standard deviations of ≤9% for the extraction of 200 ng L−1of each analyte were obtained for intra– (n = 6) and inter–day (n = 6) precisions. Finally, urine and saliva samples of tobacco smokers were successfully analyzed using the proposed method.