Optimization Of Dispersive Liquid-liquid Microextraction Research Articles

Univariate optimization of dispersive liquid-liquid microextraction for preconcentration of lead from environmental matrices, Samawah region prior to quantification using flame atomic absorption spectroscopy

Univariate optimization of dispersive liquid-liquid microextraction for preconcentration of lead from environmental matrices, Samawah region prior to quantification using flame atomic absorption spectroscopy

Multivariate optimization of dispersive liquid-liquid microextraction using ionic liquid for the analysis of ultraviolet filters in natural waters

In this work, a vortex-assisted dispersive liquid-liquid microextraction method, using an ionic liquid as the extracting solvent was developed, for the simultaneous analysis of three UV filters in different water samples. The extracting and dispersive solvents were selected in a univariate way. Then, the parameters such as the volume of the extracting and dispersive solvents, pH and ionic strength were evaluated using a full experimental design 24, followed by Doehlert matrix. The optimized method consisted of 50 μL of extracting solvent (1-octyl-3-methylimidazolium hexafluorophosphate), 700 μL of dispersive solvent (acetonitrile) and pH of 4.5. When combined with high-performance liquid chromatography, the method limit of detection ranged from 0.3 to 0.6 μg L−1, enrichment factors between 81 and 101%, and the relative standard deviation between 5.8 and 10.0%. The developed method demonstrated effectiveness in concentrating UV filters in both river and seawater samples, being a simple and efficient option for this type of analysis.

Thin-Layer Chromatography: an Efficient Technique for the Optimization of Dispersive Liquid-Liquid Microextraction.

Thin-layer chromatography (TLC) is an often omitted analytical technique due to its lower sensitivity and separation capacity. Even in the era of high-performance liquid chromatography (HPLC), thin-layer chromatography still offers many advantages, such as simplicity, rapidity, and cost-effectiveness, which predict TLC to be the first-choice method for the laborious optimization process requiring analysis of numerous samples. In this work, a thin-layer chromatography method with chemical and densitometric detection was used to optimize a dispersive liquid-liquid microextraction (DLLME) process for the extraction and preconcentration of estradiol in human urine. The chromatographic system consisted of silica gel plates as the stationary phase and toluene-ethanol (9:1; v/v) mixture as the developing solvent. The plates were dyed with 10% phosphomolybdic acid reagent and sequentially evaluated densitometrically at λ = 430 nm. In the context of DLLME optimization, parameters including the type and volume of extraction and dispersive solvents, centrifugation, salt addition and extraction time, were studied. The proposed DLLME-TLC method was successfully applied to the determination of estradiol in real human urine samples.

Optimization of dispersive liquid-liquid microextraction (DLLME) method for determination of 2, 4-D and MCPA in water by HPLC with using Box-Behnken design

Optimization of dispersive liquid-liquid microextraction (DLLME) method for determination of 2, 4-D and MCPA in water by HPLC with using Box-Behnken design

Multivariate optimization of dispersive liquid-liquid microextraction for the determination of paclobutrazol and triflumizole in water by GC-MS.

A new analytical method based on dispersive liquid-liquid microextraction with gas chromatography mass spectrometry has been optimized for the simultaneous determination of paclobutrazol and triflumizole in tap water and wastewater samples. A two-level, full-factorial design that allowed the study of main effects and factor interactions was applied to analyze the influence on microextraction process by chloroform, ethanol, potassium iodide and hand shaking period. The extraction conditions selected were 200μL of chloroform, 3.0mL of ethanol, 2.0g of potassium iodide and 15s of hand shaking. The limits of detection obtained for triflumizole and paclobutrazol under optimum conditions were 0.97 and 0.29ng/mL, respectively. Calibration plots of both analytes were linear over a wide concentration range, and good precision was observed for replicate measurements. Applicability and accuracy of the method were determined by performing spiked recovery tests. Appreciable recovery results were obtained for municipal wastewater and matrix matching was used to obtain close to 100% recovery for tap water.

Application of constrained mixture design and Doehlert matrix in the optimization of dispersive liquid-liquid microextraction assisted by ultrasound for preconcentration and determination of cadmium in sediment and water samples by FAAS

A dispersive liquid-liquid microextraction assisted by ultrasound (USADLLME) with 5-(4-Dimethylaminobenzylidene)Rhodanine procedure has been developed for preconcentration of cadmium in water and sediment samples by flame atomic absorption spectrometry (FAAS). The proportions of mixture composed of disperser, extractor solvents and complexing reagent was optimized using a constrained mixture design. The variables pH, concentration of NaCl and sonication time were optimized using a Doehlert matrix. The precision of method expressed as relative standard deviation (RSD) of 2.92 and 3.38% for 50 and 20μgL−1, respectively, the detection limit was 0.23μgL−1 and the limit of quantification of 0.76μgL−1. The accuracy was confirmed by the analysis of certified reference materials (Drinking Water Standard APS 1071, Fresh Water Sediment 3 RTC 016, Oyster Tissue NIST 1566b, Tomato Leaves NIST 1773a), the Spike test showed recoveries between 90 and 110%. The method was applied to river water, drinking water and sediment, the concentration of cadmium ranged from 1.46–4.60μgL−1 for water samples and from 0.90 to 1.23μgg−1 for sediment samples.

Response surface methodology for the optimization of dispersive liquid-liquid microextraction of chloropropanols in human plasma.

Chloropropanols are processing toxicants with a potential risk to human health due to the increased intake of processed foods. A rapid and efficient method for the determination of three chloropropanols in human plasma was developed using ultrasound-assisted dispersive liquid-liquid microextraction. The method involved derivatization and extraction in one step followed by gas chromatography with tandem mass spectrometry analysis. Parameters affecting extraction, such as sample pH, ionic strength, type and volume of dispersive and extraction solvents were optimized by response surface methodology using a pentagonal design. The linear range of the method was 5-200 ng/mL for 1,3-dichloro-2-propanol, 10-200 ng/mL for 2,3-dichloro-2-propanol and 10-400 ng/mL for 3-chloropropane-1,2-diol with the determination coefficients between 0.9989 and 0.9997. The limits of detection were in the range of 0.3-3.2 ng/mL. The precision varied from 1.9 to 10% relative standard deviation (n = 9). The recovery of the method was between 91 and 101%. Advantages such as low consumption of organic solvents and short time of analysis make the method suitable for the biomonitoring of chloropropanols.

Optimization of Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop of Endocrine Disrupting Compounds in Liquid Food Samples Using Response Surface Plot Method

Optimization of Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop of Endocrine Disrupting Compounds in Liquid Food Samples Using Response Surface Plot Method

Optimization of dispersive liquid-liquid microextraction with central composite design for preconcentration of chlordiazepoxide drug and its determination by HPLC-UV

A simple, rapid, and sensitive method based on dispersive liquid-liquid microextraction combined with HPLC-UV detection applied for the quantification of chlordiazepoxide in some real samples. The effect of different extraction conditions on the extraction efficiency of the chlordiazepoxide drug was investigated and optimized using central composite design as a conventional efficient tool. Optimum extraction condition values of variables were set as 210 μL chloroform, 1.8 mL methanol, 1.0 min extraction time, 5.0 min centrifugation at 5000 rpm min(-1), neutral pH, 7.0% w/v NaCl. The separation was reached in less than 8.0 min using a C18 column using isocratic binary mobile phase (acetonitrile/water (60:40, v/v)) with flow rate of 1.0 mL min(-1) The linear response (r(2) > 0.998) was achieved in the range of 0.005-10 μg mL(-1) with detection limit 0.0005 μg mL(-1) The applicability of this method for simultaneous extraction and determination of chlordiazepoxide in four different matrices (water, urine, plasma, and chlordiazepoxide tablet) were investigated using standard addition method. Average recoveries at two spiking levels were over the range of 91.3-102.5% with RSD < 5.0% (n = 3). The obtained results show that dispersive liquid-liquid microextraction combined with HPLC-UV is a fast and simple method for the determination of chlordiazepoxide in real samples.