Dispersive Liquid–Liquid Microextraction Followed by Magnetic Solid-Phase Extraction for Determination of Four Parabens in Beverage Samples by Ultra-performance Liquid Chromatography Tandem Mass Spectrometry

In this study, a two-step extraction technique was developed for extraction and preconcentration of parabens from beverage samples using ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) and magnetic solid-phase extraction (MSPE). In this IL-DLLME followed by MSPE method, ionic liquid (IL, 1-octyl-3-methylimidazolium hexafluorophosphate) formed hydrophobic microdroplets in beverage samples as an extractant of parabens; after the IL-DLLME process was completed, graphene modified Fe₃O₄ nanoparticles (Fe₃O₄@G) were placed to adsorb and isolate IL from the sample solution. After the supernatant was carefully moved, acetonitrile was added to elute the IL containing parabens from Fe₃O₄@G. The experimental variables affecting the extraction procedure have been systematically studied. Under optimal conditions, the detection limits were less than 1.53 ng/mL and the linear detection ranges were 2–500 ng/mL (R ² ≥ 0.998) for these analytes. The recoveries for spiked samples were 58.8–89.2% and satisfactory precision (RSD ≤ 4.8%) were obtained.     

Application and Optimization of Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography for the Determination of Oleuropein and Hydroxytyrosol in Olive Pomace

In the present study, a new method based on microwave-assisted extraction and dispersive liquid–liquid microextraction (MAE–DLLME) followed by high-performance liquid chromatography (HPLC) was proposed for the separation and determination of oleuropein (Ole) and hydroxytyrosol (HyT) from olive pomace samples. The effective factors in the MAE–DLLME process such as microwave power, extraction time, the type and volume of extraction, and dispersive solvents were studied and optimized with the aid of response surface methodology (RSM) based on a central composite design (CCD) to obtain the best condition for Ole and HyT extraction. At the optimized conditions, parameter values were 220 W microwave power, 12 min extraction time, 60 μL extracting solvent, and 500 μL dispersive solvent. The calibration graphs of the proposed method were linear in the range of 10–500,000 μg L^?1, with the coefficient of determination (R²) higher than 0.99 for Ole and HyT. Repeatability of the method, described as the relative standard deviation (RSD), was 4.12–5.63% (n?=?6). The limits of detection were 35 and 20 μg L^?1 for Ole and HyT, respectively. The recoveries of these compounds in the spiked olive pomace sample were from 93 to 98%. The proposed method, MAE–DLLME–HPLC–UV, was an accurate, rapid, and reliable method when compared with previous methods.     

Determination of Triazoles in Tea Samples Using Dispersive Solid Phase Extraction Combined with Dispersive Liquid–Liquid Microextraction Followed by Liquid Chromatography–Tandem Mass Spectrometry

In this study, dispersive solid phase extraction (DSPE) combined with dispersive liquid–liquid microextraction (DLLME) method was developed for the determination of triazole fungicide residues in tea samples. DSPE with ODS C₁₈, primary secondary amine, and florisil as sorbents was applied to clean up and minimize matrix interference from tea samples; it was followed with the enrichment of target compounds in the DLLME procedure and detection with liquid chromatography–tandem mass spectrometry (LC-MS/MS). The effects of various experimental parameters on the DSPE and DLLME procedures were studied systematically, such as the kinds and volume of sorbents, extraction and dispersive solvents, and extraction time. Under optimum conditions, the method was validated in a tea matrix. The matrix-matched calibration curves of three triazoles had good linearity in the range of 0.0125–50 μg kg^?1, and the linear regression coefficients (r) ranged from 0.9998 to 0.9999. The limits of quantification (S/N?=?10) for penconazole, tebuconazole, and triadimenfon were 4.0, 7.8, and 31.6 ng kg^?1, respectively. The intra-day and inter-day relative standard deviations varied from 3.6 to 18.6 %. Recoveries in three concentration levels were between 91 and 118 %. The obtained results show that the proposed DSPE-DLLME-LC-MS method has the potential to analyze trace fungicides in a complex sample matrix.     

Analysis of Pesticides in Tomato Combining QuEChERS and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography

A new sample preparation procedure combining QuEChERS and dispersive liquid–liquid microextraction (DLLME) was optimized for the determination at trace levels of 13 pesticides from different chemical families (i.e. 2,4-D, acetamiprid, bentazone, cymoxanil, deltamethrin, dicamba, diuron, foramsulfuron, mesotrione, metalaxyl-M, methomyl, pyraclostrobin and tembotrione) in tomato by high-performance liquid chromatography with diode array detection. Target pesticides from tomato samples were isolated by liquid partitioning with acetonitrile and salts and cleaned up by dispersive solid-phase extraction (d-SPE); the analytes were concentrated in trichloromethane by the DLLME procedure. The disperser solvent from DLLME was used at the same time as carrier of analytes form extraction in QuEChERS method. The main factors affecting sample cleanup by d-SPE in QuEChERS and DLLME yield were optimized by means of an experimental design. Under the optimum conditions, good linearity was obtained, the recoveries of pesticides in tomato samples at spiking levels between 0.01 and 1.00 mg/kg ranged from 86 to 116 % (for foramsulfuron and cymoxanil, respectively). Precision was within 15.0 % (RSD) except at the LQ for tembotrione, which was 17.4 %. Limits of quantification achieved (ranging from 0.0058 to 0.15 mg/kg) were below the maximum residue limits established by the European Union.     

Development of a Dispersive Liquid–Liquid Microextraction Method for the Determination of α-Tocopherol in Pigmented Wheat by High-Performance Liquid Chromatography

A dispersive liquid–liquid microextraction (DLLME) method coupled to high-performance liquid chromatography was developed for the analysis of α-tocopherol in grain samples. The DLLME parameters including the type and volume of extractants, the volume of disperser and the addition of salt were examined. The optimized DLLME procedure consisted in the formation of a cloudy solution promoted by the fast addition to the sample (5 mL of saponified sample solution diluted with 5 mL of water) of a mixture of carbon tetrachloride (extraction solvent, 80 μL) and ethanol (dispersive solvent, 200 μL) without the addition of salt, followed by shaking for 5 min and centrifuging for 3 min at 5,000 rpm. Intra- and inter-day repeatability expressed as % RSD were 3.5 and 7.6 %, respectively. The limit of detection and the limit of quantification were 1.9 and 6.3 μg?L^?1. The comparison of this method with the national standardized extraction method, supercritical carbon dioxide extraction, accelerated solvent extraction, and conventional heat-reflux extraction indicates that the DLLME was accurate (no significant differences at the 0.05 % probability level), high efficient, low organic solvent-consuming, and low cost. This procedure was successfully applied to 42 samples of 14 types of purple wheat, for which the content of α-tocopherol exhibited a significantly negative correlation with the pigment content measured by a spectrophotometer. The recovery rates ranged from 90.5 to 103.7 %.     

Optimized Dispersive Liquid–Liquid Microextraction and Determination of Sorbic Acid and Benzoic Acid in Beverage Samples by Gas Chromatography

A new rapid method for direct determination of trace levels of sorbic and benzoic acids was developed by dispersive liquid–liquid microextraction and gas chromatography with flame ionization detection. In the proposed approach, the separation procedure of sorbic and benzoic acids was performed on a general chromatographic column without any prior derivatization processes. Some effective parameters on the microextraction recovery were studied and optimized utilizing multilevel factorial and central composite experimental designs. The best concurrent extraction efficiency acquired using ethanol and chloroform as dispersive and extraction solvents. Central composite design (CCD) resulted in the optimized values of microextraction parameters as follows: 1.0 mL of dispersive and 0.1 mL of extraction solvents, ionic salt concentration of 50 g?L^?1 at pH 4. Under optimum conditions, the calibration curve was linear over the range 0.5–20 mg L^?1. Relative standard deviation was 11% and 13% for five repeated determinations for sorbic and benzoic acids, respectively. Limits of detection were acquired as 0.2 mg L^?1 for sorbic acid and 0.5 mg L^?1 for benzoic acid. The average recoveries were 31% and 39% for sorbic and benzoic acids, respectively. The method was successfully applied to the determination of sorbic and benzoic acids as preservatives in beverage samples.     

Combined Use of Liquid–Liquid Microextraction and Carbon Nanotube Reinforced Hollow Fiber Microporous Membrane Solid-Phase Microextraction for the Determination of Triazine Herbicides in Water and Milk Samples by High-Performance Liquid Chromatography

A simple, efficient and environmentally friendly method for the extraction and determination of five triazine herbicides in water and milk samples was developed by simultaneous liquid–liquid microextraction and carbon nanotube reinforced hollow fiber microporous membrane solid-phase microextraction coupled with high-performance liquid chromatography–diode array detection. The parameters that affect the extraction efficiencies, including the type and concentration of multi-walled carbon nanotube, type of membrane solvent and desorption solvent, the type and volume of the extraction solvent in sample solution, extraction time and temperature, the pH of sample solution, stirring rate, and ionic strength were investigated and optimized. Under the optimum conditions, the method shows a good linearity within a range of 0.5–200 ng mL⁻¹ for water samples and 1–200 ng mL⁻¹ for milk samples, with the correlation coefficients (r) varying from 0.9991 to 0.9998 and from 0.9989 to 0.9994, respectively. The limits of detection were in the range between 0.08 and 0.15 ng mL⁻¹ for water samples and 0.3 and 0.5 ng mL⁻¹ for milk samples, while the relative standard deviations varied from 4.6% to 6.9% and from 5.3% to 7.7%, respectively. The recoveries of the target analytes at spiking levels of 5.0 and 50.0 ng mL⁻¹ were in the range from 86.6% to 106.8% for water samples and from 81.3% to 97.4% for milk samples. The results demonstrated that the developed method was an efficient pretreatment and enrichment procedure for the determination of triazine pesticides in real water and milk samples.     

Dispersive Liquid–Liquid Microextraction Combined With Micellar Electrokinetic Chromatography for the Determination of Some Photoinitiators in Fruit Juice

A fast and simple technique composed of dispersive liquid–liquid microextraction (DLLME) and micellar electrokinetic chromatography (MEKC) with diode array detector (DAD) was developed for the determination of multi-photoinitiators in fruit juice. Seven photoinitiators were separated in MEKC using a 25 mM borate buffer of pH 8.0, containing 24 mM sodium dodecyl sulfate (SDS), 10 mM β-cyclodextrin (β-CD), and 12.5 % acetonitrile (v/v). A CD-modified MEKC made this method more suitable for the determination of isopropylthioxanthone (ITX) isomers including 2-IXT and 4-ITX than the recently prescribed methods. A DLLME procedure was used as an offline preconcentration strategy. The satisfactory recoveries obtained by DLLME spiked at two spiked levels ranged from 85.6 to 124.7 % with relative standard deviations (RSDs) below 14 %. The limits of quantification (LOQs) ranged from 2.1 to 6.0 μg kg^?1.     

Fast Preconcentration of Pesticide Residues in Oilseeds by Combination of QuEChERS with Dispersive Liquid–Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry

A fast, efficient, and simple method for determination of pesticide residues in pumpkin seeds has been developed combining QuEChERS and dispersive liquid–liquid microextraction (DLLME) followed by gas chromatography and mass spectrometry (GC-MS). Parameters affecting the DLLME performance such as solvent selection and volume of extractive and dispersive solvent, salt effect, and extraction time were studied. Under the selected conditions (50 μL extractive solvent chloroform, 1 mL QuEChERS extract, and 3 mL water), the developed method was validated. Linearity was evaluated at nine concentrations in the broad range of 0.1–500 μg/kg with correlation coefficients from 0.9842 to 0.9972. The relative standard deviations at lowest calibration level varied from 0.3 to 22 %. Under the optimum conditions, an enrichment factor was 6–17-fold and detection limits 0.01–12.17 μg/kg were achieved. Finally, the developed and validated method was successfully applied for the extraction and determination of pesticide residues in 16 real samples with 2 positive findings below maximum residue limits (MRL). Limits of detection (LODs) of the proposed method are below the MRLs established by the European Union.     

Evaluation of Dispersive Liquid–Liquid Microextraction–HPLC–UV for Determination of Deoxynivalenol (DON) in Wheat Flour

A fast and simple method for the extraction of deoxynivalenol (DON) from wheat flour using dispersive liquid–liquid microextraction (DLLME) followed by high-performance liquid chromatography–UV detection has been developed and compared with immunoaffinity column cleanup (IAC) process. The influence of several important parameters on the extraction efficacy was studied. Under optimized conditions, a linear calibration curve was obtained in the range of 50–1,000 μg/L. Average recoveries of DON from spiked wheat samples at levels of 500 μg/kg for DLLME and IAC ranged from 72.9?±?1.6 and 85.5?±?3.1, respectively. A good correlation was found for spiked samples between DLLME and IAC methods. The limit of detection was 125 and 50 μg/kg for DLLME and IAC method, respectively. Advantages of DLLME method with respect to the IAC have been pointed out.     

A Miniaturized Preconcentration Method Based on Dispersive Liquid–Liquid Microextraction for the Spectrophotometric Determination of Aziridine in Food Simulants

In this work a simple, rapid and sensitive method using dispersive liquid–liquid microextraction (DLLME) combined with UV–Vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of aziridine in food simulants. The method is based on derivatization of aziridine with Folin's reagent (1,2-naphthoquione-4-sulphonic acid) and extraction of color product using DLLME technique. Some important parameters, such as reaction conditions, and type and volume of extraction solvent and disperser solvent were studied and optimized. Under optimum conditions, a linear calibration curve in the range of 2.0–350 ng mL^?1 of aziridine was obtained. Detection limit based on 3S_b was 1.0 ng mL^?1, and the relative standard deviation for 50 ng mL^?1 of aziridine was 2.49c (n?=?7). The proposed method was applied for the determination of aziridine in food simulants.     

QuEChERS in Combination with Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction Based on Solidification of Floating Organic Droplet Method for the Simultaneous Analysis of Six Fungicides in Grape

A method for simultaneous analysis of six fungicides in grape was developed by using ultrasound-assisted dispersive liquid–liquid microextraction based on solidification of floating organic droplet method (UA-DLLME-SFO) combined with high-performance liquid chromatography equipped with UV detector (HPLC-UV). The extractant was obtained from grape samples using the modified QuEChERS (acronym of quick, easy, cheap, effective, rugged, and safe) method. Then the target fungicides were rapidly transferred from the acetonitrile extract to the phase of 100 μL of 1-undecanol, which is of low density, low toxicity, and proper melting point near room temperature using UA-DLLME-SFO. Experimental parameters affecting the extraction efficiency were studied and optimized. Under the optimum conditions, recovery tests were carried out at three different concentrations. The average recoveries ranged from 72.5 % to 100.6 % with relative standard deviations of 0.8 % to 7.3 % (n?=?5). The limits of quantifications of the method for all the target fungicides varied from 0.5 to 5 mg?kg^?1, which were lower than the MRLs established by Codex Alimentarius Commission and USA. Compared with the conventional method, the proposed method is easy, fast, economic, and less toxic and avoids conventional concentration methods like rotary evaporation and nitrogen stream drying.     

A Novel Cationic Surfactant-Assisted Switchable Solvent-Based Dispersive Liquid–Liquid Microextraction for Determination for Orange II in Food Samples

In this research, a new and green procedure based on the cationic surfactant-assisted switchable solvent-based dispersive liquid–liquid microextraction (CS-SS-DLLME) with UV-vis spectrophotometry was used for the extraction and determination of the Orange II dye in food samples. The main feature of the switchable solvent is the simple and reversible conversion of polarity protonated triethylammonium carbonate (P-TEA-C, ionic) to triethylamine (TEA, nonionic) by adding NaOH. This extraction method is based on hydrophilicity switchable solvent and ion pair effect of cationic surfactant. Simplicity, high-performance extraction, rapidity of the process, increase of stability, and reduction of the extractive phase volatility are other advantages of the proposed method. The parameters including the extraction and preconcentration of Orange II were studied and optimized. Under optimal conditions, the calibration curve was linear within the range of 2–450 μg/L and the detection limit was 0.9 μg/L and the relative standard deviation (RSD) for 80 μg/L of Orange II was 1.68%. This developed method was used successfully for the determination of Orange II in food samples.     

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Olive and Refined Pomace Olive Oils with Modified Low Temperature and Ultrasound-Assisted Liquid–Liquid Extraction Method Followed by the HPLC/FLD

The cleanup method of modified low temperature was compared with the standardized method of modified ultrasound-assisted liquid–liquid (UALL) extraction for the analysis of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil and refined pomace olive oil. The modified UALL extraction consisted in purification on C₁₈ reversed-phase, Florisil-bonded-phase and NH₂ cartridges, and modified low-temperature extraction was followed by alumina-N and NH₂ solid-phase extraction (SPE) cartridges. Both methods are followed by reversed-phase high-performance liquid chromatography with fluorescence detection. The chromatograms of the final extracts showed lower interferences in both of the methods. The solvent consumption and cost for the modified UALL method were higher than those of the modified low temperature, and also, it needed more equipment, but its analysis time was less. The limit of detection and limit of quantitation of the modified UALL method were 0.16–0.97 and 0.57–2.93 μg kg^?1, respectively, and for the modified low temperature, they were 0.09–1.97 and 0.29–5.99 μg kg^?1, respectively. The PAH recoveries for the modified UALL extraction method ranged from 75.0 to 111.0 % (RSD?=?3–8 %), and for the modified low temperature, they ranged from 81.5 to 113.8 % (RSD?=?3–10 %).     

Ion-Pair-Based Air-Assisted Liquid–Liquid Microextraction for the Extraction and Preconcentration of Phthalic Acids from Aqueous Samples

In the present study, a rapid, simple, and highly efficient sample preparation method based on ion-pair air-assisted liquid–liquid microextraction using a low-density extraction solvent followed by high performance liquid chromatography–diode array detection has been developed for the extraction, preconcentration, and determination of three phthalic acids (phthalic acid, iso-phthalic acid, and terephthalic acid) in aqueous samples. In this method, a mixture of tri-butyl amine (as an ion-pair reagent) and toluene (as an extraction solvent) is transferred into an aqueous sample solution. Fine organic solvent droplets are formed by aspirating and dispersing of the mixture via syringe needle. After that, the formed ion-pairs are extracted into toluene, and after centrifuging, the obtained collected phase is transferred into a microtube and is evaporated to dryness under a stream of nitrogen at room temperature. The residue is re-dissolved in mobile phase and injected into the separation system for analysis. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.09–0.24 and 0.29–0.78 ng mL^?1, respectively. Extraction recoveries and enrichment factors were from 88 to 98 % and 443 to 491, respectively. Relative standard deviations for the extraction of 5 ng mL^?1 of each analyte were less than 8.4 % for intra-day (n?=?6) and inter-days (n?=?5) precisions. Finally, different aqueous samples were successfully analyzed using the proposed method, and the target analytes were determined in some of them at ng mL^?1 level.     

Determination of Sulfite in Water and Dried Fruit Samples by Dispersive Liquid–Liquid Microextraction Combined with UV–Vis Fiber Optic Linear Array Spectrophotometry

A simple and rapid dispersive liquid?Cliquid microextraction (DLLME) method was applied to preconcentrate sulfite ions from aqueous samples as a prior step to its determination by fiber optic-linear array detection spectrophotometry. The procedure is based on the color reaction of sulfite with o-phthaldialdehyde (OPA) in the presence of ammonia to form isoindole and extraction of the formed isoindole derivative using the DLLME technique. The conditions for the microextraction performance were investigated and optimized. The calibration graph was linear in the range of 2?C100???g?L^?1with a detection limit of 0.2???g?L^?1. The relative standard deviation for five replicate measurements of 10 and 50???g?L^?1of sulfite were 2.8 and 2.0?%, respectively. Under the optimized conditions, the enrichment factor of ~133 was obtained from a sample volume of 10?mL. The proposed method was successfully applied to the sulfite determination in drinking water and in food samples.     

Determination of the Nicotine Content in Solanaceae Vegetables by Solid-Phase Extraction Coupled with Ultra High-Performance Liquid Chromatography–Tandem Mass Spectrometry

A validated method based on solid-phase extraction and ultra high-performance liquid chromatography–triple quadrupole tandem mass spectrometry, with electrospray ionization operated in the positive ion mode and multiple reaction monitoring, was developed for the determination of nicotine in Solanaceae vegetables. Sample preparation involved liquid–solid extraction, centrifugation, filtration, and solid-phase extraction. Two kinds of solid-phase extraction adsorbents, based on different retention mechanisms, were investigated. Relatively higher recoveries were obtained with a hydrophilic–lipophilic-balanced cartridge. A deuterated internal standard was used for quantification. The limit of quantification (LOQ) of nicotine in different vegetables was found to be between 0.07 and 0.5 μg/kg. The nicotine levels in the vegetable samples were above the LOQs. The method described here is thus suitable for the analysis of large sample batches, because it provides accurate quantification, high sensitivity and rapid chromatographic separation with facile preparation. The solid-phase extraction cartridges and organic solvents used in this work are easy to obtain, enabling the application of this method in most analytical laboratories.     

On-line Solid-Phase Extraction Coupled to Liquid Chromatography–Ion Trap Tandem Mass Spectrometry for Determination of Penicillins in Catfish

A highly selective method was developed for the simultaneous determination of eight penicillins in catfish using automated on-line solid-phase extraction coupled to liquid chromatography–tandem mass spectrometry (XLC–MS/MS). The type of cartridge, equilibration sample volume, volume of solvent to carry the sample into the cartridge, and elution times were studied in order to optimize the XLC operating conditions. MS/MS conditions were also adjusted for better peak resolution. The present method was validated in agreement with the criteria of Commission Decision 2002/657/EC, showing a linear range from 2 to 350 μg kg⁻¹ and regression coefficient higher than 0.995 for the studied penicillins. Decision limits, calculated in the case of substances with no permitted limit, were lower than 0.6 μg kg⁻¹, and detection capability values were lower than 2.0 μg kg⁻¹. Samples spiked at 2.0, 10.0, and 50.0 μg kg⁻¹ showed high recovery (72–92%) and precision values lower than 20% except for amoxicillin. The present method was also applied for the analysis of penicillins in 30 catfish samples bought in local markets.     

Development of Multiresidue Analysis for 21 Synthetic Colorants in Meat by Microwave-Assisted Extraction–Solid-Phase Extraction–Reversed-Phase Ultrahigh Performance Liquid Chromatography

A novel ultrahigh performance liquid chromatographic method is developed for analysis of 21 synthetic colorants with different acid–base property, solubility, and polarity. The meat samples were extracted by microwave-assisted extraction followed by cleanup with solid-phase extraction. The effective separation of the colorants in meat matrixes was achieved, and no interfering peaks could be detected at the retention time of the analytes. The calibration curves showed good linearity with correlation coefficients of 0.9940–0.9999. The limits of quantification were 0.48–7.19 μg/kg. The average recovery of the 21 analytes from meat samples spiked with 25 and 75 μg?kg^?1 was 61.29–116.1 % with relative standard deviation (RSD) of <11 %. For blank beef sausage spiked with 50 μg?kg^?1 for each analyte, the intraday precision (as RSD) for 21 analytes was 1.45–9.21 % for six determinations within a day. This method has the advantages of being rapid, sensitive, accurate, and with high-throughput and can be applied for multiresidue analysis of meat samples, including six allowable azo food colorants, ten banned azo food colorants, four banned triphenylmethanes, and rhodamin B food colorant.     

Vortex-Assisted Liquid–Liquid Microextraction Combined with HPLC for the Simultaneous Determination of Five Phthalate Esters in Liquor Samples

A vortex-assisted liquid–liquid microextraction (VALLME) method using hexanoic acid as extractant followed by high-performance liquid chromatography–diode array detection was developed for the extraction and determination of five phthalate esters (PAEs) including bis-methylglycol ester (DMEP), benzyl butyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-n-butyl phthalate (DBP), and di-n-octyl phthalate (DNOP) from liquor samples. In this method, hexanoic acid was employed as extraction solvent, because its density is lower than water. And vortex mixing was utilized as a mild emulsification procedure to reduce emulsification time and improve the effect of extraction. Under the studied conditions, five phthalate esters were successfully separated within 20 min and the limits of detection were 2.3 ng mL^?1 for DMEP, 1.1 ng mL^?1 for BBP, 1.9 ng mL^?1 for DCHP, 1.2 ng mL^?1 for DBP, and 1.5 ng mL^?1 for DNOP, respectively. Recoveries of the PAEs spiked into liquor samples were ranged from 89 to 93 %. The precisions of the proposed method were varied from 1.6 to 2.6 % (RSD). The VALLME method has been proved to have the potential to be applied to the preconcentration of the target analytes. Moreover, the method is simple, high sensitivity, consumes much less solvent than traditional methods and environmental friendly.