Ionic Liquid Dispersive Liquid-liquid Microextraction Research Articles

Optimization of [P6,6,6,14 +]3[GdCl6 3−] magnetic ionic liquid assisted dispersive liquid-liquid microextraction for selective and sensitive determination of cadmium in environmental water and food

A simple and green hydrophobic magnetic ionic-liquid assisted dispersive liquid-liquid microextraction (MIL-DLLME) was optimized for the determination of trace cadmium (Cd (II)) in environmental and food samples by flame atomic absorption spectrophotometer. To achieve selective and sensitive extraction of Cd (II), four MILs were prepared and tested. Extraction parameters of the MIL-DLLME including pH, type and volume of the MIL, type and volume of dispersive solvent, extraction cycle, ionic strength and sample volume were investigated in detail and optimized by Box–Behnken design. Under optimum conditions, matrix effect, recovery study, intra-day and inter-day precision were performed for the MIL-DLLM. The analytical characteristics such as limit of detection, limit of quantification and pre-concentration factor were 0.17, 0.56 and 125 ng mL−1, respectively. The validation of the MIL-DLLME was evaluated by analysis of reference materials. Moreover, the accuracy of the results in the analysis of real samples was evaluated by standard addition and quantitative recoveries (91 ± 5–101 ± 2%) were achieved. The results obtained in the analysis of both reference materials and real samples showed that the MIL-DLLME has a selective applicability for cadmium.

Ionic Liquid-Dispersive Micro-Extraction and Detection by High Performance Liquid Chromatography-Mass Spectrometry for Antifouling Biocides in Water.

A simple analytical method was developed and evaluated for the determination of two antifouling biocides using an ionic liquid-dispersive liquid-liquid micro-extraction (IL-DLLME) and a high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis. Irgarol 1051 and Sea-Nine 211 were extracted from deionized water, lake water, and seawater using IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) and ethyl acetate as the extraction solvent and the dispersion solvent. Several factors were considered, including the type and volume of extraction and dispersive solvent, IL amount, sample pH, salt effect, and cooling temperature. The developed method resulted in a recovery range of 78.7-90.3%, with a relative standard deviation (RSD, n = 3) less than 7.5%. The analytes were enriched greater than 40-fold, and the limits of detection (LOD) for two antifouling biocides were 0.01-0.1 μg L-1. The method was effectively applied for the analysis of real samples of freshwater as well as samples of seawater.

Application of a reversed-phase ionic liquid dispersive liquid-liquid microextraction method for the extraction and preconcentration of domoic acid from urine samples

A simple and efficient sample extraction and preconcentration method based on reversed-phase ionic liquid dispersive liquid-liquid microextraction (RP-IL-DLLME) had been developed and used to quantify the domoic acid in human urine samples. The analysis was performed by ultra-performance liquid chromatography and photodiode array detection. During the procedure, hydrophilic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim] BF4 as dispersive solvent and NaOH solution was chosen as extraction solvent. Some important parameters in the method were investigated to get high enrichment factors. Under optimal conditions, the linearity of the method was in the range of 0.1–10 ng mL−1 and the correlation coefficient was above 0.9996. The relative standard deviations (RSDs) of the developed methods for intra-day (n = 5) and inter-day (n = 5) precision ranged from 1.9 to 3.9%. Meanwhile, limit of detection (LOD) was 0.03 ng mL−1(S/N = 3) and that of quantification (LOQ) was 0.1 ng mL−1(S/N = 10) with the enrichment factors (EF) being 230. Eventually, the proposed method was successfully applied to the determination of Dominic acid in human urine samples.

In-syringe ionic liquid-dispersive liquid-liquid microextraction coupled with HPLC for the determination of trans,trans-muconic acid in human urine sample.

trans,trans-Muconic acid has been widely used as a biomarker in biological monitoring of benzene-exposed workers during routine occupational health services. In the present study, a novel microextraction technique, in-syringe ionic liquid-dispersive liquid-liquid microextraction, was implemented for preconcentration of trans,trans-muconic acid followed by analytical determination by high-performance liquid chromatography with ultraviolet detection. Moreover, the important variables affecting the performance of applied microextraction technique including needle diameter, volume of the spiked sample, volume of the ionic liquid, salt addition, rotation speed of centrifugation, centrifuge time, and ultrasonic time were optimized by experimental design. A good linear relationship was observed at the range of 0.032-10μg/mL between the peak area and the concentration levels (R2 =0.9997). The limit of detection and extraction recovery for trans,trans-muconic acid were 0.011μg/mL and>96.2%, respectively. This method provided easy and rapid analysis of low amounts of trans,trans-muconic acid in human urine with simple equipment.

Optimization of vortex-assisted ionic liquid dispersive liquid–liquid microextraction by experimental design prior to hydride generation atomic absorption spectrometry for determination of selenium species in food, beverage and water samples

We applied novel vortex-assisted ionic liquid dispersive liquid-liquid microextraction (VA-IL-DLLME) method to preconcentration and extraction of Se(IV) ions from water, beverage and food samples. The method was optimized using central composite design combined with the response surface analysis. After extraction, inorganic selenium species (total Se, Se(IV) and Se(VI)) were determined by hydride generation atomic absorption spectrometry. 1-n-Octyl-3-methylimidazolium bis(trifluoromethane)-sulfonamide [C8mim NTf2] and tetrahydrofuran were used as the extraction and dispersive solvents, respectively. Applied vortex assisted the extractant dispersion and accelerated the mass transfer process. Obtained optimum conditions for microextraction procedure are as follows: mass of [C8mim NTf2], pH, extraction time and THF volume should be equal to 85 mg, 6.8, 15 min and 730 μL, respectively. Under these conditions, we observed linear range, limit of detection and enrichment factor equal to 5−500ng L−1, 1.5 ng L−1 and 120, respectively. We also fount linear regression coefficients in the dependence between Absorbance and Se(IV) concentration: Absorbance = 0.0652 CSe(IV) + 0.0185. We added 200 μg kg−1 of Se(IV) to selected food samples and 100 ng L−1 of Se(IV) to selected waters and beverages. Relative standard deviations and recovery values were within the ranges of 2.4–3.5 % and 92.7÷103.4 %, respectively. The optimized VA-IL-DLLME method reported here provides high extraction efficiency, fast extraction and lower detection limit without a heating step than alternative microextraction methods. This method also requires environmental solvents for determination and preconcentration of trace Se species in the selected samples. In addition, the reported VA-IL-DLLME procedure is the first method which use [C8mim NTf2] as extraction solvent for the preconcentration and separation of Se(IV) ions.

Determination of Butachlor and Fipronil in Liquid Milk Using Ionic Liquid Dispersive Liquid-Liquid Microextraction Coupled with Ultra-High Performance Liquid Chromatography

A novel method for the determination of butachlor and fipronil in liquid milk has been developed using ionic liquid dispersive liquid-liquid microextraction coupled with ultra-high performance liquid chromatography (UHPLC). The optimum extraction conditions were determined to be 60 μL of 1-octyl-3-methyl imidazole six fluorine phosphate extraction solvent, 1000 μL of acetonitrile as the dispersing solvent, vortex extraction time of 3 min, centrifugation for 5 min at room temperature at 10 000 rpm. After extraction, 30 μL of extraction solvent was obtained from the sample for UHPLC analysis. It was shown that good linearity was obtained with butachlor and fipronil concentrations from 5 to 1000 μg/kg with correlation coefficient of 0.999. The average recoveries were in the range of 90 to 104% at spiked levels from 10 to 50 μg/kg with intra-day relative standard deviations lower than 3.7% (n = 6) and inter-day relative standard deviations lower than 6.1% (n = 3). The limits of detection were 0.5 and 0.3 μg/kg for butachlor and fipronil, respectively.

Determination of Very Low Concentration of Bisphenol A in Toys and Baby Pacifiers Using Dispersive Liquid-Liquid Microextraction by In Situ Ionic Liquid Formation and High-Performance Liquid Chromatography.

Bisphenol A (BPA) is a chemical compound used in the manufacturing of plastics and resins whose presence in the body in low concentrations can cause serious health problems. Due to this, there is a growing interest in the scientific community to develop analytical methods that allow quantifying trace concentrations of BPA in different types of samples. The determination of this compound in toys made of plastics that can be manipulated by children leads to an extra concern, because it is possible for BPA to enter the body by introducing these toys into the mouth. This work presents a novel procedure to the quickly and easily quantification of trace levels of BPA in samples of toys and pacifiers according to the current demanding regulations. The determination of very low levels of BPA was carried out by ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) followed by high-performance liquid chromatography (HPLC). The formation in situ of the ionic liquid (IL) 1-octyl-3-methylimidazolium bis((trifluoromethane)sulfonyl)imide ([C8MIm] [NTf2]), was achieved by mixing 1-octyl-3-methylimidazolium chloride ([C8MIm]Cl) and lithium bis(trifluoromethanesulfonyl)imide ([NTf2]Li) aqueous solutions, reaching an instant dispersion whose cloud of microdrops allows the total extraction of BPA in the IL from aqueous solutions. After centrifugation, BPA concentration in the sedimented phase was determined by HPLC. The optimal experimental conditions for the microextraction and determination of BPA in the IL were studied. The total extraction was achieved at pH 4, heating the sample at 30 °C for 5 min, using 100 µL of IL precursor volume, and spinning after the formation of dispersion at 3000 rpm for 10 min. The enrichment factor (EF) and detection limit (LOD) reached with the procedure were 299 and 0.19 µg L−1, respectively. The relative standard deviation for ten replications at the 0.5 µg L−1 level was 5.2%. Recovery studies showed a mean value for BPA recovery percentage in the samples of 99%. Additionally, a hybrid model was applied to characterize the extraction kinetics. This simple, low cost and fast method simplifies traditional microextraction techniques, representing an outstanding alternative.

A simple preconcentration method for highly sensitive determination of Pb in bee products by magnetic ionic liquid dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

A highly efficient preconcentration method based on the dispersive liquid-liquid microextraction technique (DLLME), that incorporated a magnetic ionic liquid (MIL) as extractant and electrothermal atomic absorption spectrometry (ETAAS) detection, was developed to determine Pb at ultra-trace levels in different bee products. Initially, the analyte was chelated with 1,5-diphenylcarbazide in 2 mol L-1 HCl and extracted by 150 μL of trihexyl(tetradecyl)phosphonium tetrachloromanganate (II) ([P6,6,6,14]2MnCl4). Subsequently, the extractant phase was separated by a magnet and an aliquot was injected into the graphite furnace of ETAAS. Phase separation was possible without a centrifugation step by using a MIL, thus reducing the analysis time and simplifying the proposed method. Under optimal experimental conditions, an extraction efficiency of 97% and a sensitivity enhancement factor of 107 were obtained. A detection limit (LOD) of 3 ng L-1 with a relative standard deviation of 3.6% (at 100 ng L-1 Pb, n = 10) and a linear range of 10-3000 ng L-1 were obtained. This work reports the first application of the MIL [P6,6,6,14]2MnCl4 along with the DLLME technique for the determination of Pb at trace levels in different bee products, such as honey, mead, honey vinegar and honey beer.

Magnetic nanoparticle-assisted in situ ionic liquid dispersive liquid-liquid microextraction of pyrethroid pesticides in urine samples

Dispersive liquid–liquid microextraction (DLLME) based on Fe3O4 magnetic nanoparticle-assisted in situ ionic liquid was developed as a novel method for the pretreatment of pyrethroid pesticides (flumethrin, bifenthrin and silafluofen) in urine samples. [N4,4,4,4]Cl and Na[N(CN)2] formed a ionic liquid ([N4,4,4,4][N(CN)2]), which provides an alternative to highly toxic solvents; moreover, high extraction recoveries and enrichment factors were achieved. The extraction parameters affecting the extraction recoveries were investigated. Under optimum conditions, the analytical method showed a good linear response, with correlation coefficient (R2) values ranging from 0.9994 to 0.9996. The enrichment factor, limit of detection and recovery were 108–125, 2.7–5.0 μg L−1 and 88.0–101.1%, respectively. Therefore, this green and simple method is suitable for the microextraction of pyrethroid pesticides in urine samples. It is valuable to establish a sensitive method for monitoring trace levels of pyrethroids, which could contribute to the use of rapid and green sample preparation procedures in urine samples.

Determination of Escitalopram in Biological Samples by Dispersive Liquid-Liquid Microextraction Combined with GC-MS/MS.

Objective To establish a method for determination of escitalopram in biological samples by ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry （GC-MS/MS） and provide evidences for forensic determination of cases related to escitalopram. Methods The 1-hexyl-3-methylimidazolium hexafluorophosphate （[C6MIM][PF6]） was selected as an extract solvent to process biological samples. Ultrasound-assisted extraction was used on the samples. Then the samples were detected by GC-MS/MS. Results The linear range of escitalopram in blood and liver were 5.56-1 111.10 ng/mL and 0.025-5.00 mg/g, respectively. The correlation coefficient （r） were greater than 0.999, limit of detection （LOD） were 4.00 ng/mL and 2.00 μg/g, limit of quantitation （LOQ） were 14.00 ng/mL and 6.00 μg/g, respectively. The extraction recovery rates were all greater than 50%, the interday and intraday precision were less than 20%. Escitalopram was detected in blood and liver samples from the actual poisoning case by this method with a content of 1.26 μg/mL and 0.44 mg/g, respectively. Conclusion The ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with GC-MS/MS is environment friendly, rapid, has good enriching effect and consumes less organic solvent and can be used for forensic determination of escitalopram related cases.

Simultaneous determination of sulfonamides in milk: In-situ magnetic ionic liquid dispersive liquid-liquid microextraction coupled with HPLC.

Four novel organic magnetic ionic liquids were synthesized and characterized. A new method of in-situ magnetic ionic liquid dispersive liquid-liquid microextraction coupled with HPLC was established to simultaneously separate, preconcentrate and determine trace amount of sulfonamides in milk samples for the first time. In this work, extraction procedure was free of volatile organic solvent. Extraction equilibrium was immediately achieved without further operation such as vortex shaking. Magnetic separation of two phases was effectively achieved by applying external magnetic field without need of centrifugation. Furthermore, only a very small amount of inorganic salts were generated. This is the first time to realize all these advantages in an analytical method. Under the optimal conditions, satisfactory enrichment factors, precisions, linear range and low limit of detection and quantitation were acquired. The validated method was successfully applied in the simultaneous analysis of 5 sulfonamides in real milk samples.

Ultra-trace Cr preconcentration in honey samples by magnetic ionic liquid dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

An analytical method based on the dispersive liquid-liquid microextraction (DLLME) technique, using a magnetic ionic liquid (MIL) as an extraction phase, was developed for ultra trace Cr determination in honey samples. The elemental detection was performed by electrothermal atomic absorption spectrometry (ETAAS). In the developed method both centrifugation and complexation of the analyte were not required. The Cr(III) species was extracted by the MIL trihexyl(tetradecyl)phosphonium ([P6,6,6,14]FeCl4) after the formation of [CrCl2(H2O)4]Cl. The MIL phase was separated by a magnetic rod, diluted in CHCl3 and Cr was determined by ETAAS. Under optimized experimental conditions, an extraction efficiency of 98% and a sensitivity enchancement factor of 105 were achieved. A detection limit (LOD) of 5 ng L−1 Cr and relative standard deviation of 3.5% (at 50 ng L−1 Cr and n = 10) were obtained. Also, the linear range of the calibration curve was from 15 ng L−1 to 180 ng L−1. The method was applied for Cr determination in honey samples of different shades.

Advances in dispersive liquid-liquid microextraction and its application to analysis of biological samples

Dispersive liquid-liquid microextraction (DLLME) is a mini-extraction technology with merits of low cost, environment friendliness, and high extraction efficiency; moreover, this method is easy to operate and requires only a short operation time. In this paper, several extraction models, including normal dispersive liquid-liquid microextraction, ionic liquid dispersive liquid-liquid microextraction, and ultrasound-assisted dispersive liquid-liquid microextraction, are reviewed according to the type of extraction solvents and dispersive methods. This paper also summarizes the application of DLLME to the analysis of biological samples in the last five years.

Determination of pyrethroid residues in herbal tea using temperature-controlled ionic liquid dispersive liquid-liquid microextraction by high performance liquid chromatography

A simple and effective method for determining five pyrethroid residues in herbal tea by ultrasound-enhanced temperature-controlled (UETC) ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) coupled with high performance liquid chromatography-diode array detection (HPLC-DAD) was developed. The use of ultrasonication and heating improved the ability of the ionic liquid to extract the analytes. Various parameters that affect the extraction efficiency were investigated and optimized using single factor experiments and response surface design. The optimum conditions of the experiment were 121 µL of [HMIM][PF6] (extraction solvent), 794 µL of acetonitrile (dispersive solvent), a heating temperature of 40°C, a sonication time of 3.6 min and a pH of 2.9. Under optimized conditions, the linearity was in the range of 0.05–5 mg L−1 with correlation coefficients above 0.9993. The limits of detection and quantification were 1.25–1.35 µg L−1 and 5 µg L−1, respectively. The mean recoveries of the five pyrethroids ranged from 74.02% to 109.01%, with RSDs below 9.04%. The proposed method was reliable for the analysis of pyrethroids in Chinese herbal tea.

Preconcentration and determination of nickel (II) and copper (II) ions, in vegetable oils by [TBP] [PO4] IL-based dispersive liquid–liquid microextraction technique, and flame atomic absorption spectrophotometry

The present research is a novel enrichment method based on ionic liquid dispersive liquid-liquid micro-extraction that was combined with flame atomic absorption spectroscopy to determine the concentration of Cu2+ and Ni2+ ions in vegetable oil samples at trace levels. The ionic liquid [TBP] [PO4] and chloroform were used as the extraction and dispersive solvent respectively. Canola oil containing oil-soluble standard of Cu2+ or Ni2+ ions as the model compound was used. Under optimum conditions the linear ranges were 1–100 and 1−200 μg/kg for Cu2+ and Ni2+ respectively with correlation coefficient (R2) of 0.99. The relative standard deviation (RSD, n = 5) for Cu2+ and Ni2+ at a concentration of 20 μg/kg was 2.2 % and 3.2 % respectively. The LOD (3 s) and LOQ (10 s) were 0.35 ppb and 1.2 ppb; and 0.77 ppb and 2.57 ppb for Cu2+ and Ni2+ respectively.

Analysis of Zinc and Chromium in Grain Samples Using Ionic Liquid-Based Ultrasound-Assisted Microextraction Followed by Flame-AAS After Microwave Digestion

A simple, rapid and eco-friendly microextraction method was developed for the determination and preconcentration of zinc (Zn) and chromium (Cr) from grain products by ultrasonic-assisted ionic liquid dispersive liquid-liquid microextraction (UA-IL-DLLME) combined with flame atomic absorption spectrometry (FAAS). Quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one dihydrate) was used for the complexation of Zn(II) and Cr(III) ions at different pHs. The 1-hexyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl]imide ([Hmim][NTf2] and acetonitrile were used as extraction solvent and dispersive solvent, respectively. To provide quantitative extraction of analytes, important experimental variables such as pH of sample solution, temperature, ultrasonic time, amount of chelating agent, amount of ionic liquid, type and amount of dispersive solvent, and interference effect were extensively studied and optimized. The detection limits and operating ranges for Zn(II) and Cr(III) using the optimized conditions were 7.5, 25-450 and 2.4, 8-300μgL-1, respectively. For the validation of the proposed method, the certified reference material was tested using the standard addition method. After microwave digestion analysis of grain products, relative standard deviations (RSDs%) and recoveries were ranged from 1.2 to 2.3% and from 91.2 to 103.7%, respectively. The UA-IL-DLLME method has been successfully applied for the determination of Zn and Cr in grain samples (chickpea, broad bean, pea, beans, and wheat).

Ionic-liquid-based microextraction method for the determination of silver nanoparticles in consumer products.

A simple method to determine hazardous silver nanoparticles (AgNPs) based on ionic liquid (IL) dispersive liquid-liquid microextraction and back-extraction is described. This approach involves AgNP stabilization using a cationic surfactant followed by extraction from the sample matrix by means of an IL as an extraction phase. Certain ILs have high affinity for metals, and preliminary experiments showed that those ILs consisting of imidazolium cation efficiently extracted AgNPs in the presence of a cationic surfactant and a chelating agent. Afterward, histamine was used as a dispersing agent to promote phase transfer of differently coated AgNPs from the IL in aqueous solution to be subsequently analyzed by UV-visible spectrometry. The analytical procedure allows AgNPs to be recovered from the sample matrix in an aqueous medium, the enrichment factor being up to 4, preserving both AgNP size and AgNP shape as demonstrated by transmission electron microscopy images and the localized surface plasmon resonance band characteristic of each AgNP. The present method exhibited a linear response for AgNPs in the range from 3 to 20 μg/mL, the limit of detection being 0.15 μg/mL. Method efficiency was assessed in spiked orange juice and face cream, yielding recoveries ranging from 75.7% to 96.6%. The method was evaluated in the presence of other nanointerferents (namely, gold nanoparticles). On the basis of diverse electrophoretic mobilities and surface plasmon resonance bands for metal nanoparticles, capillary electrophoresis was used to prove the lack of interaction of the target AgNPs with gold nanoparticles during the whole protocol; thus, interferents do not affect AgNP determination. As a consequence, the analytical approach described has great potential for the analysis of engineered nanosilver in consumer products. Graphical abstract Simple protocol for the determination of silver nanoparticles (AgNPs) based on dispersive liquid-liquid extraction with a specific short alkyl side chain ionic liquid and their quantitative detection with a UV-visible spectrometer. HMIM•PF6 1-hexyl-3-methylimidazolium hexafluorophosphate, NP nanoparticle, SPR surface plasmon resonance.

In situ ionic liquid dispersive liquid-liquid microextraction combined with ultra high performance liquid chromatography for determination of neonicotinoid insecticides in honey samples.

An efficient in situ ionic liquid dispersive liquid-liquid microextraction followed by ultra-performance liquid chromatography was developed to determine four neonicotinoid insecticides in wild and commercial honey samples. In this method, a hydrophobic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, formed by in situ reaction between potassium hexafluorophosphate and 1-butyl-3-methylimidazolium bromide in sample solution, was used as the extraction solvent. In comparison with the traditional dispersive liquid-liquid microextraction method, the developed method required no dispersive solvent. To achieve high extraction efficiency and enrichment factor, the effects of various experimental parameters were studied in detail. Under the optimized conditions, the limits of detection and quantification were in the ranges of 0.30-0.62 and 1.20-2.50μg/L, respectively. The method showed high enrichment factors (74-115) with the recoveries between 81.0 and 103.4%. The proposed method was finally applied to different wild and commercial honey samples.

Ionic liquid dispersive liquid-liquid microextraction combined with LC-UV-Vis for the fast and simultaneous determination of cortisone and cortisol in human saliva samples

Ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) was used for the first time for the extraction and preconcentration of cortisone and cortisol from human saliva samples. This approach allows the determination of both compounds by liquid chromatography (LC) with ultra-violet/visible (UV/Vis) detection at physiological levels. The IL 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6] and methanol (MeOH) were used as extraction and dispersive solvents, respectively. The parameters that affect extraction (ionic strength, pH, amount of IL, volume of dispersive solvent, vortex and centrifugation time) were optimized. Limits of detection were 0.11 (cortisone) and 0.16 μg L−1 (cortisol) and enrichment factors of 5.0 (cortisol) and 6.3 (cortisone) were achieved. Recoveries from 83.3 ± 1.6 to 115.8 ± 3.0% were obtained for the extraction of the target analytes in spiked human saliva samples. Intraday and interday precision, expressed as relative standard deviation, was below 4.2 and 7.8% for cortisone and cortisol, respectively. The method was successfully applied to the determination of cortisone and cortisol in saliva from healthy volunteers (n = 9) in the morning and in the evening. The method is simple, faster, and more environmentally friendly than the current ones.

Comparison of three different dispersive liquid-liquid microextraction modes performed on their most usual configurations for the extraction of phenolic, neutral aromatic, and amino compounds from waters.

In this work we seek clues to select the appropriate dispersive liquid-liquid microextraction mode for extracting three categories of compounds. For this purpose, three common dispersive liquid-liquid microextraction modes were compared under optimized conditions. Traditional dispersive liquid-liquid microextraction, in situ ionic liquid dispersive liquid-liquid microextraction, and conventional ionic liquid dispersive liquid-liquid microextraction using chloroform, 1-butyl-3-methylimidazolium tetrafluoroborate, and 1-hexyl-3-methylimidazolium hexafluorophosphate as the extraction solvent, respectively, were considered in this work. Phenolic, neutral aromatic, and amino compounds (each category included six members) were studied as analytes. The analytes in the extracts were determined by high-performance liquid chromatography with UV detection. For the analytes with polar functionalities, the in situ ionic liquid dispersive liquid-liquid microextraction mode mostly led to better results. In contrast, for neutral hydrocarbons without polar functionalities, traditional dispersive liquid-liquid microextraction using chloroform produced better results. In this case, where dispersion forces were the dominant interactions in the extraction, the refractive index of solvent and analyte predicted the extraction performance better than the octanol/water partition coefficient. It was also revealed that none of the methods were successful in extracting hydrophilic analytes (compounds with the log octanol/water partition coefficient<2). The results of this study could be helpful in selecting a dispersive liquid-liquid microextraction mode for the extraction of various groups of compounds.