Formation Of Cloudy Solution Research Articles

Determination of triazine herbicides in juice samples by microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography.

A novel microextraction method, termed microwave-assisted ionic liquid/ionic liquid dispersive liquid-liquid microextraction, has been developed for the rapid enrichment and analysis of triazine herbicides in fruit juice samples by high-performance liquid chromatography. Instead of using hazardous organic solvents, two kinds of ionic liquids, a hydrophobic ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate) and a hydrophilic ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), were used as the extraction solvent and dispersion agent, respectively, in this method. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of 1-hexyl-3-methylimidazolium hexafluorophosphate dispersed entirely into sample solution with the help of 1-butyl-3-methylimidazolium tetrafluoroborate. In addition, an ion-pairing agent (NH4 PF6 ) was introduced to improve recoveries of the ionic liquid phase. Several experimental parameters that might affect the extraction efficiency were investigated. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 5.00-250.00μg/L, with the correlation coefficients of 0.9982-0.9997. The practical application of this effective and green method is demonstrated by the successful analysis of triazine herbicides in four juice samples, with satisfactory recoveries (76.7-105.7%) and relative standard deviations (lower than 6.6%). In general, this method is fast, effective, and robust to determine triazine herbicides in juice samples.

Ultrasound-assisted temperature-controlled ionic liquid dispersive liquid-phase microextraction combined with reversed-phase liquid chromatography for determination of organophosphorus pesticides in water samples.

A rapid and sensitive ultrasound-assisted temperature-controlled ionic liquid (IL) dispersive liquid-phase microextraction (UTILDLPME) combined with reversed-phase liquid chromatography-ultraviolet (RPLC-UV) was developed for the determination of five organophosphorus pesticides (OPPs; azinphos-methyl, chloropyriphos, parathion-methyl, diazinon, and phosalone) in water samples. Parameters including IL type, IL volume, ionic strength, sonication time, heating/cooling temperature, centrifugal time, and speed were investigated. The extraction procedure was induced by the formation of cloudy solution, which was composed of 75 μL of 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM]PF6 ) dispersed entirely into 5 mL sample solution with the assistance of ultrasound for 3 min and temperature at 40°C. Under optimal conditions, linearity of the five OPPs was obtained in the range of 0.09-200 ng/mL with correlation coefficients of 0.998 or more. Limits of detection and limits of quantitation ranged from 0.01 to 0.1 ng/mL and from 0.05 to 0.4 ng/mL, respectively. Compared with conventional microextraction techniques, the proposed UTILDLPME exhibited the highest extraction efficiency ranging between 90 and 98% for targeted OPPs. Furthermore, the proposed UTILDLPME/RPLC was successfully applied to different water samples (tap, well, and lake water) showing relative recoveries ranging from 96.9 to 103.2%. Therefore, UTILDLPME/RPLC-UV could be a simple, rapid, sensitive, and efficient routine technique for determination of OPPs in water.

Miniaturized ionic liquid dispersive liquid–liquid microextraction in a coupled-syringe system combined with UV for extraction and determination of danazol in danazol capsule and mice serum

In this study, for the first time, a coupled 1-mL microsyringe system was utilized to perform a miniaturized ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) method. Danazol was extracted and determined via the developed method followed by micro-volume ultraviolet spectroscopy (UV). The extraction process was carried out by the injection of extraction solvent ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] into sample solution (syringe A), and then rapid shoot the solution into syringe B. After that the shooting was repeated several times at a rate of 1cycle/s. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C8mimPF6] dispersed entirely into sample solution with the help of shooting without any dispersive solvent, ultrasonication or high temperature. Several important parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, the limit of detection (LOD) was 0.055μg/mL (capsule) or 0.054μg/mL (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.62-25μg/mL. The proposed method was successfully applied to danazol capsule and the real mice serum samples and good spiked recoveries in the range of 90.5–103.4% were obtained. The obtained results of this work were in good agreement with the results of HPLC.

Meigs’ syndrome

In this study, for the first time, a coupled 1-mL microsyringe system was utilized to perform a miniaturized ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) method. Danazol was extracted and determined via the developed method followed by micro-volume ultraviolet spectroscopy (UV). The extraction process was carried out by the injection of extraction solvent ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] into sample solution (syringe A), and then rapid shoot the solution into syringe B. After that the shooting was repeated several times at a rate of 1 cycle/s. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C8mimPF6] dispersed entirely into sample solution with the help of shooting without any dispersive solvent, ultrasonication or high temperature. Several important parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, the limit of detection (LOD) was 0.055 μg/mL (capsule) or 0.054 μg/mL (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.62-25 μg/mL. The proposed method was successfully applied to danazol capsule and the real mice serum samples and good spiked recoveries in the range of 90.5–103.4% were obtained. The obtained results of this work were in good agreement with the results of HPLC.

Application of surfactant assisted dispersive liquid–liquid microextraction as an efficient sample treatment technique for preconcentration and trace detection of zonisamide and carbamazepine in urine and plasma samples

A simple, rapid, and efficient method, based on surfactant assisted dispersive liquid–liquid microextraction (SA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of zonisamide and carbamazepine in biological samples. A conventional cationic surfactant called cethyltrimethyl ammonium bromide (CTAB) was used as a disperser agent in the proposed approach. 1.5mL of CTAB (0.45mmolL−1) (disperser solvent) containing 50.0μL of 1-octanol (extraction solvent) was injected rapidly into the 7.0mL of water or diluted plasma or urine. A cloudy solution (water, 1-octanol, and CTAB) was formed in the test tube. After formation of cloudy solution, the mixture was centrifuged and 20μL of collected phase was injected into HPLC for subsequent analysis. Some parameters such as the type and volume of the extraction solvent, the type and concentration of surfactant, pH, ionic strength and centrifugation time were evaluated and optimized. Under optimum extraction conditions, the limits of detections (LODs) were 2.1 and 1.5μgL−1 (based on 3Sb/m) for urine samples, and 2.3 and 1.6μgL−1 for plasma samples. Linear dynamic range of 5–300 and 5–200μgL−1 were obtained for zonisamide and carbamazepine in all samples. Finally, the applicability of the proposed method was evaluated by extraction and determination of the drugs in urine and plasma samples.

Determination of Estrogens in Water Samples by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with High Performance Liquid Chromatography

Using 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6MIM][PF6]) ionic liquid as extraction solvent, five estrogens including estrone (E1), 17β-estradiol (E2), estriol (E3), 17α -ethynylestradiol (EE2), and diethylstilbestrol (DES) in water samples were determined by dispersive liquid-liquid microextraction (DLLME) followed by high performance liquid chromatography with a photodiode array detector and a fluorescence detector (HPLC-DAD-FLD). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C6MIM][PF6] dispersed entirely into the sample solution with the help of a disperser solvent (acetone). Parameters including both extraction and disperser solvents and their volumes, extraction and centrifugal time, sample pH, and salt effect were investigated and optimized. Under the optimized conditions, 110–349 fold enrichment factors of analytes were obtained. The calibration curves were linear in the concentration range of 0.2–100 µg L−1 for E2, E3, and EE2 detected with FLD, and 1–100 µg L−1 for E1 and DES detected with DAD. The correlation coefficient of the calibration curve was between 0.9990 and 0.9997. The limits of detection (LOD, S/N = 3) for the five estrogens were in the range of 0.08–0.5 µg L−1. The relative standard deviations (RSD) for six replication experiments at the concentration of 5.0 µg L−1 were ≤5.7%. The proposed method was applied to the analysis of three water samples from different sources (river water, waste water, and sea water). The relative recoveries of spiked water samples are satisfied with 89.3–102.4% and 88.7–105.2% at two different concentration levels of 5.0 and 50.0 µg L−1, respectively.

Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid–liquid microextraction for the determination of sulfonamides in infant formula milk powder using high-performance liquid chromatography

Ultrasound-assisted ionic liquid/ionic liquid-dispersive liquid–liquid microextraction (UA-IL/IL-DLLME) high-performance liquid chromatography was developed and applied to the extraction, separation and determination of sulfonamides in infant formula milk powder samples. The hydrophobic IL and hydrophilic IL were used as extraction solvent and dispersion solvent, respectively. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C6MIM][PF6] dispersed entirely into sample solution with help of [C4MIM][BF4]. The purification of sample and concentration of target analytes were performed simultaneously. The introduction of ion-pairing agent (NH4PF6) was beneficial to the improvement of recoveries for IL phase and analytes. The experimental parameters of the UA-IL/IL-DLLME, including concentration of [C6MIM][PF6] and [C4MIM][BF4] in sample solution, ultrasound extraction time, pH value of sample solution and amount of ion-pairing agent (NH4PF6), were evaluated. The limits of detection for sulfamerazine, sulfamethizole, sulfachlorpyridazine, sulfamonomethoxine, sulfmethoxazole and sulfisoxazole were 2.94, 9.26, 16.7, 5.28, 3.35 and 6.66μgkg−1, respectively. When the present method was applied to the analysis of infant formula milk powder samples, the recoveries of the analytes ranged from 90.4% to 114.8% and relative standard deviations were lower than 7.5%. The proposed method was compared with the ionic liquid-homogeneous liquid–liquid microextraction, ionic liquid-ultrasound-assisted emulsification–microextraction and ionic liquid-temperature-controlled-DLLME. The results indicated that the proposed method is effective for the extraction of the sulfonamides in milk powder samples.

Determination of nalidixic acid using dispersive liquid-liquid microextraction followed by HPLC-UV

Summary A fast, simple, and sensitive sample preparation procedure based on dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography and ultraviolet (HPLC-UV) detection was developed for the determination of nalidixic acid in a human urine sample. A mixture of extraction solvent (35 μL carbon tetrachloride) and disperser solvent (1.0 mL acetonitrile) were rapidly injected into an aqueous sample (5.0 mL) for the formation of cloudy solution; the analyte in the sample was extracted into the fine droplets of carbon tetrachloride. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was determined by HPLC-UV. The influence of several important parameters on extraction efficiency of nalidixic acid was evaluated. Under optimized experimental conditions, the calibration graph was linear in the concentration range of 1–800 μg L−1 with the coefficient of determination being 0.9994. The limits of detection and ...

Rapid and sensitive determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography

A rapid and sensitive method has been developed for the determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography. This method involves the use of an appropriate mixture of extraction solvent (8.0 µL tetrachloroethylene) and disperser solvent (1.0 mL acetonitrile) for the formation of cloudy solution in 5.0 mL aqueous sample containing biphenyl and biphenyl oxide. After extraction, phase separation was performed by centrifugation and biphenyl and biphenyl oxide in sedimented phase (5.0 ± 0.3 µL) were determined by gas chromatography-flame ionisation (GC-FID) system. Type of extraction and disperser solvents and their volumes, salt effect on the extraction recovery of biphenyl and biphenyl oxide from aqueous solution have been investigated. Under the optimum conditions and without salt addition, the enrichment factors for biphenyl and biphenyl oxide were 819 and 785, while the extraction recovery were 81.9% and 78.5%, respectively. The linear range was (0.125–100 µg L−1) and limit of detection was (0.015 µg L−1) for both analytes. The relative standard deviation (RSD, n = 4) for 5.0 µg L−1 of analytes were 8.4% and 6.7% for biphenyl and biphenyl oxide, respectively. The relative recoveries of biphenyl and biphenyl oxide from sea, river water and refined water (Paksan company) samples at spiking level of 5.0 µg L−1 were between 85.0% and 100 %.

Determination of Thiamphenicol in Honey by Dispersive Liquid--Liquid Microextraction with High-Performance Liquid Chromatography

Dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-variable wavelength detector (HPLC-VWD) was developed for extraction and determination of thiamphenicol (THA) in honey. A mixture of extraction solvent (30 microL 1,1,2,2-tetrachloroethane) and dispersive solvent (1.0 mL of acetonitrile) was rapidly injected into 5.00 mL sample solution for the formation of cloudy solution. The analyte in the sample was extracted into the fine droplets of C(2)H(2)Cl(4). After extraction, phase separation was performed by centrifugation, and the enriched analyte in the sedimented phase was determined by HPLC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time, sample solution pH, sample volume, and salt effect, were investigated and optimized. Under the optimum extraction condition, the method yielded a linear calibration curve in the concentration range from 3 to 2000 microg/kg for target analyte. The enrichment factors for THA was 87.9, and the limit of detection (S/N = 3) was 0.1 microg/kg. The relative standard deviation for the extraction of 10 microg/kg of THA was 6.2% (n = 6). The main advantages of DLLME-HPLC method are simplicity of operation, rapidity, low cost, high enrichment factor, high recovery, good repeatability, and extraction solvent volume at the microL level. Honey samples were successfully analyzed using the proposed method.

Ionic liquid-based dispersive liquid–liquid microextraction followed high-performance liquid chromatography for the determination of organophosphorus pesticides in water sample

Using 1-octyl-3-methylimidazolium hexafluorophosphate ([C 8MIM][PF 6]) ionic liquid as extraction solvent, organophosphorus pesticides (OPPs) (parathion, phoxim, phorate and chlorpyifos) in water were determined by dispersive liquid–liquid microextraction (DLLME) combined with high-performance liquid chromatography (HPLC). The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C 8MIM][PF 6] dispersed entirely into sample solution with the help of disperser solvent (methanol). Parameters including extraction solvent and its volume, disperser solvent and its volume, extraction time, centrifugal time, salt addition, extraction temperature and sample pH were investigated and optimized. Under the optimized conditions, up to 200-fold enrichment factor of analytes and acceptable extraction recovery (>70%) were obtained. The calibration curves were linear in the concentration range of 10.5–1045.0 μg L −1 for parathion, 10.2–1020.0 μg L −1 for phoxim, 54.5–1089.0 μg L −1 for phorate and 27.2–1089.0 μg L −1 for chlorpyifos, respectively. The limits of detection calculated at a signal-to-noise ratio of 3 were in the range of 0.1–5.0 μg L −1. The relative standard deviations for seven replicate experiments at 200 μg L −1 concentration level were less than 4.7%. The proposed method was applied to the analysis of four different sources water samples (tap, well, rain and Yellow River water) and the relative recoveries of spiked water samples are 99.9–115.4%, 101.8–113.7% and 87.3–117.6% at three different concentration levels of 75, 200 and 1000 μg L −1, respectively.

LC Determination of Chloramphenicol in Honey Using Dispersive Liquid–Liquid Microextraction

A novel method, dispersive liquid–liquid microextraction coupled with liquid chromatography-variable wavelength detector (LC-VWD), has been developed for the determination of chloramphenicol (CAP) in honey. A mixture of extraction solvent (30 μL 1,1,2,2-tetrachloroethane) and dispersive solvent (1.00 mL acetonitrile) were rapidly injected by syringe into a 5.0 mL real sample for the formation of cloudy solution, the analyte in the sample was extracted into the fine droplets of C2H2Cl4. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was determined by LC-VWD. Some important parameters, such as the kind and volume of extraction solvent and dispersive solvent, extraction time, sample solution pH, sample volume and salt effect were investigated and optimized. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 3 to 2,000 μg kg−1 for target analyte. The enrichment factor for CAP was 68.2, and the limit of detection (S/N = 3) were 0.6 μg kg−1. The relative standard deviation (RSD) for the extraction of 10 μg kg−1 of CAP was 4.3% (n = 6). The main advantages of method are high speed, high enrichment factor, high recovery, good repeatability and extraction solvent volume at μL level. Honey samples were successfully analyzed using the proposed method.