Determination of organic compounds in water using dispersive liquid-liquid microextraction
TL;DR: The ability of DLLME technique in the extraction of other organic compounds such as organochlorine pesticides, organophosphorus pesticides and substituted benzene compounds were studied.
About: This article is published in Journal of Chromatography A.The article was published on 2006-05-26. It has received 2959 citations till now. The article focuses on the topics: Extraction (chemistry) & Aqueous two-phase system.
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TL;DR: In this article, a quantitative structure-property relationship (QSPR) model based on atom-type electrotopological state (Estate) indices has been developed for predicting the dispersive liquid-liquid microextraction (DLLME) enrichment effect for aromatic organics by using 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF6]) ionic liquid as extractant.
Abstract: In this work, a quantitative structure–property relationship (QSPR) model based on atom-type electrotopological state (E-state) indices has been developed for predicting the dispersive liquid–liquid microextraction (DLLME) enrichment effect for aromatic organics by using 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIM][PF6]) ionic liquid as extractant. The enrichment factors of the aromatic organics obtained through DLLME-IL process were used as the dependent variable of the multiple linear regression (MLR) equation. The E-state indices of those organic compounds which combined together both electronic and topological characteristics of the analyzed molecules were used as molecular structure descriptors and the independent variable of the equation. The squared correlation coefficient R2 for the MLR was 0.992 for the training set of 33 compounds. For the test set of 8 compounds, the linear regression coefficient was R2 = 0.985. The results of this study showed that it can successfully predict enrichment factors of [OMIM][PF6] in DLLME by using atom-type E-state indices, which can provide one more way for predicting the ability of ionic liquid to extract organic compounds based on their molecular structures.
1 citations
TL;DR: In this article , a Quadruple isotope dilution (QID) method with three calibration mixtures (A*B-x, x=1,2,3) and one sample mixture (AB) was performed to enhance the method accuracy and precision.
Abstract: This study proposed a precise/accurate analytical method for the paracetamol (PCT) determination in human serum/urine matrices. PCT was simultaneously derivatized and preconcentrated by dispersive liquid-liquid microextraction (DLLME). Benzoyl chloride dissolved in dichloromethane was used as derivatization agent in the extraction solvent. Quadruple isotope dilution (QID) method with three calibration mixtures (A*B-x, x=1,2,3) and one sample mixture (AB) was performed to enhance the method accuracy and precision. In our research laboratory, paracetamol benzoate-d3 (PCT benzoate-d3) was synthesized and used as isotopically labelled substance (B) to conduct QID method. After the combination of QID and DLLME-GC-MS systems, percent recovery results for human serum/urine matrices were found to be 99.3–101.0 % and 98.8–99.9 %, respectively.
1 citations
TL;DR: A green coacervative microextraction method with solidification of floating surfactant droplets (CAME-SFD) was developed for the preconcentration and determination of glibenclamide in environmental water samples followed by fluorescence detection as discussed by the authors.
1 citations
17 Mar 2017
TL;DR: In this article, a vortex assisted low density based dispersive liquid-liquid microextraction followed by high performance liquid chromatography with ultraviolet detector has been developed for the determination of three pesticides including chlorflurenol-methyl, chlorfenvinphos, and diazinon from environmental water samples.
Abstract: In this study, vortex-assisted low density based dispersive liquid-liquid microextraction followed by high performance liquid chromatography with ultraviolet detector has been developed for the determination of three pesticides including chlorflurenol-methyl, chlorfenvinphos, and diazinon from environmental water samples. Different parameters influencing the extraction efficiency such as the type and volume of extraction and disperser solvent, sample pH, salt addition as well as vortex and centrifugation time were investigated and the optimal conditions were obtained. Under the optimum conditions, the calibration curves were linear in the concentration range of 8.5–100, 3.1–100 and 36.5–600 ng/mL for chlorflurenol-Methyl, chlorfenvinphos and diazinon, respectively, with coefficient of determination (r) of 0.993 or better. The limits of detection and quantification of the analytes, which were determined at 3 and 10 signal-to-noise ratio (S/N) ranged from 0.9–11 and 3.1–36.8 ng/mL, respectively. The proposed method has been successfully applied to the analysis of real water samples. The relative recoveries (%RR) studied at two spiking concentration levels were ranging from 76–108%, with the corresponding relative standard deviation (%RSD) ranging from 1.9–9.9%. The results of study demonstrated that the proposed method is efficient for extraction and/or preconcentration of the three pesticides prior to quantitative determination utilizing HPLC–UV/Vis instrument.
1 citations
Cites background or methods from "Determination of organic compounds ..."
...It was first reported in 2006 by Rezaee and coworkers [20] and since then, it has shown enormous application for extraction and/or preconcentration of various organic and inorganic pollutants from...
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...Thus, in the last three decades, several, new, novel modified sample preparation methods involving superior advantages including simplicity, quickness, low cost, high recoveries, high preconcentration factor, minimal toxic organic solvent consumption and reduced wastes, over the traditional methods: liquid-liquid extraction (LLE) [20] and solid phase extraction (SPE) [21, 22] have been developed and utilized for analysis of pesticide residues in various matrices including environmental waters [12, 20, 28-30]....
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...efficiency of the target analyte into the organic phase [9, 20]....
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...After extracting, the fine droplets containing the analyes are separated by centrifugation for the subsequent analysis [20, 2831]....
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...These techniques include liquid chromatography (LC) with ultraviolet (UV) detector [8], diode array detectors (DAD) [9-12] and mass spectrometry detector (MS) [13, 14, 15]; gas chromatography (GC) with detectors such as flame ionization detection (FID) [5, 16], flame photometric detector (FPD) [ 17, 18], nitrogen-phosphorus detection (NPD) [18], MS [16, 20, 21, 22], and tandem MS (MS/MS) [23]; micellar electrokinetic chromatography with ultraviolet/visible detector (MEKC-UV) [24] and laser-induced fluorescence detection [25]....
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References
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4,485 citations
TL;DR: An analytical technique is described which combines solvent extraction with gas chromatographic (GC) analysis in a simple and inexpensive apparatus involving very little solvent consumption and is in good agreement with a convective-diffusive kinetic model.
Abstract: An analytical technique is described which combines solvent extraction with gas chromatographic (GC) analysis in a simple and inexpensive apparatus involving very little solvent consumption. A small drop (8 μL) of a water-immiscible organic solvent, containing an internal standard, is located at the end of a Teflon rod which is immersed in a stirred aqueous sample solution. After the solution has been stirred for a prescribed period of time, the probe is withdrawn from the aqueous solution, and the organic phase is sampled with a microsyringe and injected into the GC for quantification. The observed rate of solvent extraction is in good agreement with a convective−diffusive kinetic model. Analytically, the relative standard deviation of the method is 1.7% for a 5.00-min extraction of the analyte 4-methylacetophenone into n-octane.
1,191 citations
TL;DR: This unique microextraction system is simple and flexible, permits automated backwashing, consumes only microquantities of organic solvents, and is capable of being coupled with other analytical systems.
Abstract: An organic microdrop (∼1.3 μL) is suspended inside a flowing aqueous drop from which the analyte is extracted. The drop-in-drop system is achieved by a multitube assembly. The aqueous phase is continuously delivered to the outer drop and is aspirated away from the bottom meniscus of the drop. After the sampling/extraction period, a wash solution replaces the sample/reagent in the aqueous layer, resulting in a clear outer aqueous drop housing a colored organic drop containing the extracted material. This also results in an automatic backwash. The color intensity of the organic drop, related to the analyte concentration, is monitored by a light-emitting diode based absorbance detector. After the analytical cycle, the organic drop is removed and replaced by a new one. The performance of the system is illustrated with the determination of sodium dodecyl sulfate (a methylene blue active substance) extracted as an ion pair into chloroform. This unique microextraction system is simple and flexible, permits autom...
697 citations
TL;DR: In this article, two modes of liquid-phase microextraction (LPME) were developed for capillary gas chromatography, i.e., static and dynamic LPME, which involve the use of very small amounts of organic solvent in a conventional microsyringe.
Abstract: Two modes of liquid-phase microextraction (LPME) were developed for capillary gas chromatography. Both methodologies, i.e., static LPME and dynamic LPME, involve the use of very small amounts of organic solvent (<2 μL) in a conventional microsyringe. The performance of the two techniques is demonstrated in the determination of two chlorobenzenes extracted into a single drop of toluene by the use of a 10-μL syringe. Static LPME provided some enrichment (∼12-fold), good reproducibility (9.7%), and simplicity but suffered relatively long extraction time (15 min). Dynamic LPME provided higher (∼27-fold) enrichment within much shorter extraction time (∼3 min), and relatively poorer precision (12.8%), primarily due to repeated manual manipulation. Both methods allow the direct transfer of extracted analytes into a gas chromatograph.
648 citations
TL;DR: In this article, the authors measured the amount of a sample compound extracted into a 1-μL drop of n-octane suspended in a stirred aqueous solution from the tip of a microsyringe needle.
Abstract: The amount of a sample compound extracted into a 1-μL drop of n-octane suspended in a stirred aqueous solution from the tip of a microsyringe needle is measured by gas chromatography (GC) as a function of time. The observed extraction rate curve is first order and yields the overall mass transfer coefficient for the sample compound, βo. For a given compound, βo varies linearly with stirring rate. Among the four compounds malathion, 4-methylacetophenone, 4-nitrotoluene, and progesterone, at a given stirring rate, βo is linearly proportional to the diffusion coefficient of the compound (Daq). This supports the film theory of convective−diffusive mass transfer, as opposed to the penetration theory. The relative standard deviation of the GC signal for 4-methylacetophenone after a 1.00 min extraction at 1500 rpm is 1.5%, which suggests that the system exhibits excellent potential as a tool for rapid analysis by solvent extraction/GC.
531 citations