Dispersive Liquid-phase Microextraction Research Articles

Gas-assisted dispersive liquid-phase microextraction using ionic liquid as extracting solvent for spectrophotometric speciation of copper

Gas-assisted dispersive liquid-phase microextraction (GA-DLPME) has been developed for preconcentration and spectrophotometric determination of copper ion in different water samples. The ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate and argon gas, respectively, were used as the extracting solvent and disperser. The procedure was based on direct reduction of Cu(II) to Cu(I) by hydroxylamine hydrochloride, followed by extracting Cu(I) into ionic liquid phase by using neocuproine as the chelating agent. Several experimental variables that affected the GA-DLPME efficiency were investigated and optimized. Under the optimum experimental conditions (IL volume, 50µL; pH, 6.0; acetate buffer, 1.5molL−1; reducing agent concentration, 0.2molL−1; NC concentration, 120µgmL−1; Ar gas bubbling time, 6min; argon flow rate, 1Lmin−1; NaCl concentration, 6% w/w; and centrifugation time, 3min), the calibration graph was linear over the concentration range of 0.30–2.00µgmL−1 copper ion with a limit of detection of 0.07µgmL−1. Relative standard deviation for five replicate determinations of 1.0µgmL−1 copper ion was found to be 3.9%. The developed method was successfully applied to determination of both Cu(I) and Cu(II) species in water samples.

Determination of Traces of Ni, Cu, and Zn in Wastewater and Alloy Samples by Flame-AAS after Ionic Liquid-Based Dispersive Liquid Phase Microextraction

A procedure has been developed for simultaneous separation/preconcentration of copper, nickel, and zinc based on in situ ionic liquid-based dispersive liquid-liquid microextraction method as a prior step to their determination by flame atomic absorption spectrometry. The analytes reacted with sodium diethyl dithiocarbamate at pH 7 to form hydrophobic chelates, which were separated and preconcentrated in the ionic liquid phase. The method is fast, simple, accurate, and environmentally friendly. The parameters affecting the extraction efficiency of the proposed method such as the pH of sample solution, centrifugation time, type and volume of the dispersive solvent, and the salt effect were studied. Enrichment factors of 61.8, 61.2, and 40.0 and detection limits of 0.79, 0.93, and 0.71 µg L-1 were obtained for copper, nickel, and zinc, respectively. The relative standard deviations based on six replicate measurements were between 1.0 and 2.7%. The method was successfully applied to the extraction and determination of these metals in wastewater and alloy samples.

Reflection scanometry as a new detection technique in temperature-controlled ionic liquid-based dispersive liquid phase microextraction

Coupling temperature-controlled ionic liquid-based dispersive liquid phase microextraction with reflection scanometry as a new detection technique for colored liquid solutions.

Trace determination of manganese(II) by temperature-controlled/assisted ionic liquid-based dispersive liquid-phase microextraction and electrothermal atomic absorption spectrometry

A microextraction method, namely temperature-controlled/assisted ionic liquid-based dispersive liquid-phase microextraction (DLPME) for manganese(II) determination in environmental water samples is presented. Manganese(II) was extracted from aqueous solution into an ionic liquid (IL) after complexation with 1-(2-thiazolylazo)-2-naphthol (TAN) and directly introduced for electrothermal atomic absorption spectrometry (ETAAS) determination. Several factors that might affect ETAAS signal and extraction efficiency, such as pyrolysis and atomization temperature; and pH adjustment, concentration of TAN, extraction time, volume of IL and stirring rate were studied. Within optimal experimental conditions, the detection limit (3σ), the quantification limit (10σ), the enrichment factor and the relative standard deviation for five replicate determinations at 0.5 μg L−1 of manganese(II) were calculated as 0.023 μg L−1, 0.076 μg L−1, 58.7 and 6.3 %, respectively. The presented method was also successfully applied to the determination of manganese(II) in real samples. The main benefits of the method are simplicity, low cost, rapidity, high recovery, powerful extraction efficiency and the proposed approach is free of volatile organic solvents.

Application of ionic liquid-based dispersive liquid phase microextraction for highly sensitive simultaneous determination of three endocrine disrupting compounds in food packaging

Ionic liquid (IL) dispersive liquid–liquid microextraction (DLLME) method was successfully developed for extracting three endocrine disrupting compounds (EDCs) (bisphenol A, bisphenol AF and bisphenol AP) from the food packaging. 1-Octyl-3-methylimidazoliumhexafluorophosphate ([C8MIM][PF6]) was selected as extraction solution. The extraction procedure did not require a dispersive solvent. Three EDCs extraction kinetics were found to be very fast and the equilibrium was attained within 3.0min following the pseudo-first-order model. The H-bonding and hydrophobic interactions play an important role in the partitioning of EDCs into IL from aqueous solution. The recovered IL could be reused for three runs without significant loss of extraction efficiencies. The spiked recoveries of three targets in food packaging were in the range of 97.8–103.1%. The limits of detection ranged from 0.50 to 1.50ngmL−1 (S/N=3). As a result, this method has been successfully applied for the sensitive detection of three EDCs in real samples.

Determination of trace mercury in water based on N-octylpyridinium ionic liquids preconcentration and stripping voltammetry

A novel method for determination of trace mercury in water is developed. The method is performed by extracting mercury firstly with ionic liquids (ILs) and then detecting the concentration of mercury in organic media with anodic stripping voltammetry. Liquid-liquid extraction of mercury(II) ions by four ionic liquids with N-octylpyridinium cations ([OPy]+) was studied. N-octylpyridinium tetrafluoroborate and N-octylpyridinium trifluoromethylsulfonate were found to be efficient and selective extractant for mercury. Temperature controlled dispersive liquid phase microextraction (TC-DLPME) technique was utilized to improve the performance of preconcentration. After extraction, precipitated IL was diluted by acetonitrile buffer and mercury was detected by differential pulse stripping voltammetry (DPSV) with gold disc electrode. Mercury was enriched by 17 times while interfering ions were reduced by two orders of magnitude in the organic media under optimum condition. Sensitivity and selectivity for electrochemical determination of mercury were improved by using the proposed method. Tap, pond and waste water samples were analyzed with recoveries ranging from 81% to 107% and detection limit of 0.05μg/L.

Nano polypyrrole-coated magnetic solid phase extraction followed by dispersive liquid phase microextraction for trace determination of megestrol acetate and levonorgestrel

The aim of the present work is combination of the advantages of magnetic solid phase extraction (MSPE) and dispersive liquid phase microextraction (DLLME) followed by filtration-based phase separation. A new pretreatment method was developed for trace determination of megestrol acetate and levonorgestrel by liquid chromatography/ultraviolet detection in biological and wastewater samples. After magnetic solid phase extraction, the eluent of MSPE was used as the disperser solvent for DLLME. Emulsion resulted from DLLME procedure was passed through the in-line filter for phase separation. Finally the retained analytes in the filter was washed with mobile phase of liquid chromatography and transferred to the column for separation. This approach offers the preconcentration factors of 3680 and 3750 for megestrol acetate and levonorgestrel, respectively. This guarantees determination of the organic compounds at trace levels. The important parameters influencing the extraction efficiency were studied and optimized. Under the optimal extraction conditions, a linear range of 0.05–50ngmL−1 (R2>0.998) and limit of detection of 0.03ngmL−1 were obtained for megestrol acetate and levonorgestrel. Under optimal conditions, the method was successfully applied for determination of target analytes in urine and wastewater samples and satisfactory results were obtained (RSDs<6.8%).

Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid-phase microextraction coupled with ultra-high performance liquid chromatography and ultraviolet detection.

A hydroxyl-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid-phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H-bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0-1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0-1000 μg/L for estriol. The detection limits were in the range of 1.7-3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples.

Dispersive liquid-phase microextraction for determination of phthalates in water

A technique for phthalate extraction from water samples has been proposed. This technique is based on the preconcentration of target substances using the dispersive liquid-phase microextraction with subsequent determination of these substances using a gas chromatograph with flame ionization detector. Under the optimal conditions of microextraction (involving 0.25 cm3 of acetonitrile and 0.05 cm3 of chloroform in 10% NaCl solution for water sample volume of 8 cm3) concentration factors of phthalates amount to 360–393 at their extraction degree of 91–98%, while the detection limit can reach 3–8 μg/dm3. The proposed technique is characterized by a high accuracy and reproducibility.

Analysis of Methamphetamine in Human Urine Using Ionic Liquid Dispersive Liquid-Phase Microextraction Combined with HPLC

A specific and sensitive method using ionic liquid dispersive liquid-phase microextraction coupled with high-performance liquid chromatography was developed and applied in the analysis of methamphetamine in human urine. In this experiment, 1-butyl-3-methylimidazolium bis (trifluoromethyl) imide ([BMIM]TF2N) was selected as the extraction solvent and parameters affecting the extraction efficiency such as the volume of ionic liquid, percentage of dispersant, dissolving temperature, extraction time, sample pH, centrifuging time and salting-out effect have been investigated in detail. Under optimized conditions, good linear relationship of methamphetamine was obtained in the range 0.04–20.00 μg mL−1, the correlation coefficient (r) was 0.9987, the limit of detection and limit of quantitation were 0.01 and 0.04 μg mL−1, respectively, and the enrichment factor was 44. The results showed that the method was simple, time-saving, special, clean, sensitive and it could be applied in the analgesics analysis of forensic trace evidences and addicted cases.

Дисперсійна мікроекстракція для концентрування аліфатичних альдегідів С1 –С5 у формі похідних o-(2,3,4,5,6-пентафторбензил) гідроксиламіну

Дисперсійна мікроекстракція для концентрування аліфатичних альдегідів С1 –С5 у формі похідних o-(2,3,4,5,6-пентафторбензил) гідроксиламіну

Solvent selection in ultrasonic-assisted emulsification microextraction: Comparison between high- and low-density solvents by means of novel type of extraction vessel

There are numerous published reports about dispersive liquid phase microextraction of the wide range of substances, however, till now no broadly accepted systematic and purpose oriented selection of extraction solvent has been proposed. Most works deal with the optimization of available solvents without adequate pre-consideration of properness. In this study, it is tried to compare the performances of low- and high-density solvents at the same conditions by means of novel type of extraction vessel with head and bottom conical shape. Extraction efficiencies of seven basic pharmaceutical compounds using eighteen common organic solvents were studied in this work. It was much easier to work with high-density solvents and they mostly showed better performances. This work shows that although exact predicting the performance of the solvents is multifaceted case but the pre-consideration of initial selection of solvents with attention to the physiochemical properties of the desired analytes is feasible and promising. Finally, the practicality of the method for extraction from urine and plasma samples was investigated.

Combination of ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the determination of triazine herbicides in water samples

Abstract A temperature-controlled ionic liquid dispersive liquid-phase microextraction in combination with high performance liquid chromatography was developed for the enrichment and determination of triazine herbicides such as cyanazine, simazine, and atrazine in water samples. 1-Octyl-3-methylimidazolium hexafluorophosphate ([C 8 MIM][PF 6 ]) was selected as the extraction solvent. Several experimental parameters were optimized. Under the optimal conditions, the linear range for cyanazine was in the concentration range of 0.5–80 μg/L and the linear range for simazine and atrazine was in the range of 1.0–100 μg/L. The limit of detection (LOD, S/N = 3) was in the ranges of 0.05–0.06 μg/L, and the intra day and inter day precision (RSDs, n = 6) was in the ranges of 3.2%–6.6% and 4.8%–8.9%, respectively. Four real water samples were analyzed with the developed method, and the experimental results showed that the spiked recoveries were satisfactory. All these exhibited that the developed method was a valuable tool for monitoring such pollutants.

Preconcentration and determination of bisphenol A, naphthol and dinitrophenol from environmental water samples by dispersive liquid-phase microextraction and HPLC

This paper describes a new, rapid and reliable determination method for bisphenol A, 1-naphthol, 2-naphthol and 2,4-dinitrophenol using dispersive liquid-phase microextraction prior to high-performance liquid chromatography. In this method chlorobenzene was used as the extraction solvent and acetone was used as the disperser solvent. The parameters, which may influence the extraction efficiency such as the types and volumes of extraction solvent and disperser solvent, extraction time, sample pH, centrifugation time and salting-out effect, have been investigated. Under optimal conditions, there was a good linear relationship in the concentration range 0.25–50, 0.5–100, 0.75–150, and 1.5–300 μg L−1 for 2,4-dinitrophenol, 2-naphthol, 1-naphthol and bisphenol A, respectively. The limits of detection based on the ratio of signal-to-noise were equal to three (LODs, S/N = 3) in the range 0.11–0.62 μg L−1. Precision of the proposed method (RSDs, n = 6) were in the range 2.6–9.3%. The experimental results demonstrated that the present method lowered the LOQs compared to that of most existing methods and provided a simple and rapid analytical procedure. The analysis of real water samples spiked with two different concentrations resulted in good spiked recoveries in the range 86.8–118%. These results indicated that the proposed method would be competitive for the analysis of phenols.

Room Temperature Ionic Liquid-Based Dispersive Liquid Phase Microextraction for the Separation/Preconcentration of Trace Cd2+ as 1-(2-pyridylazo)-2-naphthol (PAN) Complex from Environmental and Biological Samples and Determined by FAAS

The current work develops a new green methodology for the separation/preconcentration of cadmium ions (Cd(2+)) using room temperature ionic liquid-dispersive liquid phase microextraction (RTIL-DLME) prior to analysis by flame atomic absorption spectrometry with microsample introduction system. Room temperature ionic liquids (RTIL) are considered "Green Solvents" for their thermally stable and non-volatile properties, here 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] was used as an extractant. The preconcentration of Cd(2+) in different waters and acid digested scalp hair samples were complexed with 1-(2-pyridylazo)-2-naphthol and extracted into the fine drops of RTILs. Some significant factors influencing the extraction efficiency of Cd(2+) and its subsequent determination, including pH, amount of ligand, volume of RTIL, dispersant solvent, sample volume, temperature, and incubation time were investigated in detail. The limit of detection and the enhancement factor under the optimal conditions were 0.05 μg/L and 50, respectively. The relative standard deviation of 100 μg/L Cd(2+) was 4.3 %. The validity of the proposed method was checked by determining Cd(2+) in certified reference material (TM-25.3 fortified water). The sufficient recovery (>98 %) of Cd(2+) with the certified value. The mean concentrations of Cd in lake water 13.2, waste water 15.7 and hair sample 16.8 μg/L, respectively and the developed method was applied satisfactorily to the preconcentration and determination of Cd(2+) in real samples.

Quantitative analysis of piroxicam using temperature-controlled ionic liquid dispersive liquid phase microextraction followed by stopped-flow injection spectrofluorimetry

BackgroundPiroxicam (PXM) belongs to the wide class of non-steroidal anti-inflammatory drugs (NSAIDs). PXM has been widely applied in the treatment of rheumatoid arthritis, gonarthrosis, osteoarthritis, backaches, neuralgia, mialgia. In the presented work, a green and benign sample pretreatment method called temperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) was followed with stopped-flow injection spectrofluorimetry (SFIS) for quantitation of PXM in pharmaceutical formulations and biological samples.MethodsTemperature-controlled ionic liquid dispersive liquid phase microextraction (TCIL-DLPME) was applied as an environmentally friendly sample enrichment method to extract and isolate PXM prior to quantitation. Dispersion of 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) ionic liquid (IL) through the sample aqueous solution was performed by applying a relatively high temperature. PXM was extracted into the extractor, and after phase separation, PXM in the final solution was determined by stopped-flow injection spectrofluorimetry (SFIS).Results and Major ConclusionDifferent factors affecting the designed method such as IL amount, diluting agent, pH and temperature were investigated in details and optimized. The method provided a linear dynamic range of 0.2-150 μg l-1, a limit of detection (LOD) of 0.046 μg l-1 and a relative standard deviation (RSD) of 3.1%. Furthermore, in order to demonstrate the analytical applicability of the recommended method, it was applied for quantitation of PXM in real samples.

Dispersive liquid-phase microextraction in combination with HPLC for the enrichment and rapid determination of benzoylurea pesticides in environmental water samples

Benzoylurea (BU) insecticides have contributed greatly to the output of crops. Their residue in the environment put serious threats on human health and environmental safety. In this study, we have established a new, rapid, and reliable method for the monitoring of typical BU insecticides such as diflubenzuron, flufenoxuron, triflumuron, and chlorfluazuron with dispersive liquid-liquid microextraction prior to HPLC. Chlorobenzene and ethanol were employed as the extraction solvent and disperser solvent, respectively. The possible parameters which would influence the extraction efficiency such as the kinds and volumes of extraction and disperser solvents, extraction time, sample pH, centrifuging time, and salting-out effect were optimized in detail. Under the optimal conditions, the linear range of proposed method was in the range of 1.0-70 μg/L. The detection limits varied from 0.24 to 0.82 μg/L and the precision of the method was <6.5% (RSD, n = 6). The proposed method was validated with real water samples and satisfactory spiked recoveries were achieved. All these results indicate that the proposed method is a low cost, easy to operate, efficient, and sensitive method for the analysis of BU insecticides in water samples.

Ionic liquid-based dispersive liquid–liquid microextraction for determination of trace amounts of iron in water, rock and human blood serum samples

A green and sensitive dispersive liquid-phase microextraction procedure based on room-temperature ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) for preconcentration and determination of total iron in real samples prior to flame atomic absorption spectrometry was developed. 2-Mercaptopyridine-N-oxide (pyrithione) and ethanol were used as complexing agent and dispersive solvent in the proposed method, respectively. The factors influencing the extraction were optimized. Under optimum conditions, the enhancement factor of 15 was obtained from only 11.35 mL of aqueous phase. The linear dynamic range and the detection limit were 10.0–700 and 2.4 μg L−1, respectively. The relative standard deviation (RSD) for ten replicate measurements of 500 μg L−1 of iron is 3.1 %. The developed method has been successfully applied for the determination of iron in water samples, human blood serum and rock certified reference material with high efficiency.

A rapid shaking-based ionic liquid dispersive liquid phase microextraction for the simultaneous determination of six synthetic food colourants in soft drinks, sugar- and gelatin-based confectionery by high-performance liquid chromatography

A novel and simple rapid shaking-based method of ionic liquid dispersive liquid phase microextraction for the determination of six synthetic food colourants (Tartrazine, Amaranth, Sunset Yellow, Allura Red, Ponceau 4R, and Erythrosine) in soft drinks, sugar- and gelatin-based confectionery was established. High-performance liquid chromatography coupled with an ultraviolet detector was used for the determinations. The extraction procedure did not require a dispersive solvent, heat, ultrasonication, or additional chemical reagents. 1-Octyl-3-methylimidazolium tetrafluoroborate ([C8MIM][BF4]) was dispersed in an aqueous sample solution as fine droplets by manual shaking, enabling the easier migration of analytes into the ionic liquid phase. Factors such as the [C8MIM][BF4] volume, sample pH, extraction time, and centrifugation time were investigated. Under the optimum experimental conditions, the proposed method showed excellent detection sensitivity with limits of detection (signal-to-noise ratio=3) within 0.015–0.32ng/mL. The method was also successfully used in analysing real food samples. Good spiked recoveries from 95.8%–104.5% were obtained.

Trace Determination of Cadmium Ions by Flame Atomic Absorption Spectrometry after Pre-Concentration Using Temperature-Controlled Ionic Liquid Dispersive-Liquid Phase Microextraction

This paper is about an improved temperature-controlled ionic liquid dispersive liquid-phase microextraction method for pre-concentration of cadmium ions prior to determination by flame atomic absorption spectrometry. In this study, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) was used as extraction solvent. Cadmium complexed with dithizone, and then entered into the dispersed ionic liquid droplets at 40 oC. Some parameters affecting the extraction efficiency such as the volume of [C4MIM][PF6], dissolving temperature, sample pH, centrifuging time and salt effect have been investigated in detail. The calibration graph was linear in the range of 2-250 ng mL-1, the limit of detection (3Sb) was 0.62 ng mL-1. The enhancement factor was found to be 48.4 and the relative standard deviation (RSD) for 10 replicate determinations of 50 ng mL-1 Cd was 2.7%. The developed method successfully applied to the determination of cadmium in several real samples.