Low-density Organic Solvent Research Articles

Microwave-Assisted Extraction/Dispersive Liquid–Liquid Microextraction Coupled with DSI-GC-IT/MS for Analysis of Essential Oil from Three Species of Cardamom

A novel method of microwave-assisted extraction coupled with polyethylene Pasteur-pipette-based dispersive liquid–liquid microextraction applying low-density organic solvent (MAE-LDS-DLLME) was successfully developed for extraction and preconcentration of essential oil from three species of cardamom (Semen Alpiniae Katsumadai, Fructus Amomi Rotundus, and Semen Myristicae). The essential oil was analyzed by gas chromatography-ion trap/mass spectrometry (GC-IT/MS) using a ChromatoProbe direct sample introduction (DSI) device. The effects of various parameters affecting the extraction process, such as the type of extraction solvent and dispersive solvent, ionic strength, microwave power, and irradiation time, were investigated thoroughly and optimized. The optimal conditions were extraction solvent of toluene, dispersive solvent of methanol, microwave power of 80 W, irradiation time of 4.0 min, plant material amount of 0.1 g, and no addition of salt. Compared with hydrodistillation, MAE-DLLME-DSI-GC–MS is a simple, rapid, low-cost, efficient, and environmentally friendly method, and the essential oil contains higher amounts of oxygenated compounds, which play an important and valuable role in terms of their contribution to the fragrance of the essential oil. In this work, we also studied the main components of the three varieties of cardamom. Qualitative and quantitative differences in the components of the three essential oils were found to be present. Based on comparison of the main bioactive compounds of essential oil, a significant difference was found between Semen Alpiniae Katsumadai or Fructus Amomi Rotundus and Semen Myristicae. This study also provides a new approach for quality assessment of traditional Chinese medicines.

Rapid analysis of triclosan in water samples using an in-tube ultrasonication assisted emulsification microextraction coupled with gas chromatography-electron capture detection

In this study, a new in-tube based ultrasound-assisted emulsification microextraction (IT-USAEME) technique coupled with gas chromatography-micro-electron capture detection (GC-μECD) was developed for the efficient and rapid analysis of triclosan in environmental water samples. In this extraction procedure, the aqueous sample was taken in an indigenously fabricated home-made glass extraction device (an 8 mL glass tube inbuilt with a self-scaled capillary tip) and extraction solvent (low density organic solvent) was added to it followed by ultrasonication. After extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus making the collection and measurement of the upper organic solvent layer simple and convenient. Parameters affecting the extraction efficiency such as selection of extraction solvent, extraction solvent volume, ultrasonication time, pH and ionic strength were thoroughly investigated and optimized. Under optimal conditions, the method showed good linearity in the concentration range from 20–2000 ng L−1 with a correlation coefficient of 0.9982 for the target analyte. The limit of detection was 4 ng L−1 and the enrichment factor obtained was 331. The method was validated with real water samples and the relative recoveries of environmental water samples ranged between 91.2 and 97.3% and relative standard deviations ranged between 2.8 and 5.4%, making the proposed method highly reliable. Moreover, the present approach avoids the usage of chlorinated organic extraction solvents and derivatization processes for triclosan determination. The proposed method provides a simple, rapid, sensitive, low cost, easy to handle (in-tube set-up for USAEME) and eco-friendly procedure to determine triclosan in aqueous samples.

Homogeneous Liquid–Liquid Extraction (HoLLE) <i>via</i> Flotation Combined with Gas Chromatography–Flame Ionization Detection as a Very Simple, Rapid and Sensitive Method for the Determination of Fenitrothion in Water Samples

Homogeneous liquid-liquid extraction via flotation assistance (HoLLE-FA) and gas chromatography-flame ionization detection (GC-FID) was presented for the extraction and determination of fenitrothion in water samples. In this work, a rapid, simple and efficient HoLLE-FA method was developed based on applying low-density organic solvents without employing centrifugation. A special extraction cell was designed to facilitate the collection of low-density solvent extraction in the determination of fenitrothion in water samples. The water sample solution was added into an extraction cell that contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. Under the optimum conditions, the method performance was studied in terms of the linear dynamic range (LDR from 1.0 up to 100 μg L⁻¹), linearity (r² > 0.998), and precision (repeatability < 8.0%). Also, limit of detection (LOD) of 0.4 μg L⁻¹ was obtained for fenitrothion. The applicability of the HoLLE-FA method was evaluated by the extraction and determination of fenitrothion in three different water samples.

Injection-ultrasound-assisted emulsification microextraction based on using low-density organic solvent followed by high-performance liquid chromatography for the determination of pyrethroids in water samples

A highly efficient, simple and rapid method, injection-ultrasound-assisted emulsification microextraction based on using low-density organic solvents followed by high-performance liquid chromatography-ultraviolet detection, was developed for the determination of trace level pyrethroids in water samples. Various parameters influencing the extraction efficiency, such as type of extractant, extractant volume, ultrasonic time, centrifugation time and salt addition, were studied and optimized by two methods: the single factor experiment and the Box-Behnken design. Under the optimum conditions, great enrichment factors (678-713) and good recoveries (92.48-97.31%) were obtained for the extraction and analysis of artificial water samples. Linearity of the method for three pyrethroids was in the range of 0.11-218 μg L(-1) for fenpropathrin, and 0.07-136 μg L(-1) for fenvalerate and permethrin, respectively, with correlation coefficients ranging from 0.9994 to 0.9999. The limits of detection for the target analytes were 12.13 to 20.16 ng L(-1), and the limits of quantification were 40.43 to 67.19 ng L(-1). The recoveries of the three pyrethroids from actual water samples at three spiked levels were in the range of 83.25 to 103.3% with relative standard deviation RSDs less than 7.40%.

Homogeneous liquid–liquid microextraction via flotation assistance for rapid and efficient determination of polycyclic aromatic hydrocarbons in water samples

In this work, a rapid, simple and efficient homogeneous liquid–liquid microextraction via flotation assistance (HLLME-FA) method was developed based on applying low density organic solvents without no centrifugation. For the first time, a special extraction cell was designed to facilitate collection of the low-density solvent extraction in the determination of four polycyclic aromatic hydrocarbons (PAHs) in water samples followed by gas chromatography-flame ionization detector (GC-FID). The effect of different variables on the extraction efficiency was studied simultaneously using experimental design. The variables of interest in the HLLME-FA were selected as extraction and homogeneous solvent volumes, ionic strength and extraction time. Response surface methodology (RSM) was applied to investigate the optimum conditions of all the variables. Using optimized variables in the extraction process, for all target PAHs, the detection limits, the precisions and the linearity of the method were found in the range of 14–41μgL−1, 3.7–10.3% (RSD, n=3) and 50–1000μgL−1, respectively. The proposed method has been successfully applied to the analysis of four target PAHs in the water samples, and satisfactory results were obtained.

Vortex‐assisted liquid–liquid microextraction combined with gas chromatography‐mass spectrometry for the determination of organophosphate pesticides in environmental water samples and wines

A simple vortex-assisted liquid-liquid microextraction protocol followed by GC-MS is proposed for the determination of 12 organophosphate pesticides residues in environmental water samples and wines. The sample pretreatment employs the usage of low-density organic solvent. The parameters affecting the extraction efficiency (type and volume of organic extraction solvent, sample pH, ionic strength, extraction time, and centrifugation speed) were carefully examined. A mild emulsification process was involved by the addition of 40 μL toluene into 10 mL sample followed by sequential vortex-based agitation and manual shaking for 3 min. Following the extraction, the pesticide-rich organic solvent was recovered by centrifugation at 4000 rpm for 5 min. A fraction of the floated toluene was then collected and analyzed by GC-MS in SIM mode. Under the optimized conditions, the enrichment factor ranged between 65 and 389. Satisfactory linearity was observed for all pesticides tested with correlation coefficients higher than 0.9945 while the LODs were in the range of 2-11 ng L(-1) . The main advantages of the proposed method are the simplicity of operation, rapidity, low cost, and high sensitivity.

A simple solvent collection technique for a dispersive liquid–liquid microextraction of parabens from aqueous samples using low‐density organic solvent

A simple technique for the collection of an extraction solvent lighter than water after dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection was developed for the determination of four paraben preservatives in aqueous samples. After the extraction procedure, low-density organic solvent together with some little aqueous phase was separated by using a disposable glass Pasteur pipette. Next, the flow of the aqueous phase was stopped by successive dipping the capillary tip of the pipette into anhydrous Na(2)SO(4). The upper organic layer was then removed simply with a microsyringe and injected into the high-performance liquid chromatography system. Experimental parameters that affect the extraction efficiency were investigated and optimized. Under optimal extraction conditions, the extraction recoveries ranged from 25 to 86%. Good linearity with coefficients with the square of correlation coefficients ranging from 0.9984 to 0.9998 was observed in the concentration range of 0.001-0.5 μg/mL. The relative standard deviations ranged from 4.1 to 9.3% (n = 5) for all compounds. The limits of detection ranged from 0.021 to 0.046 ng/mL. The method was successfully applied for the determination of parabens in tap water and fruit juice samples and good recoveries (61-108%) were achieved for spiked samples.

Application of ultrasound-assisted emulsification microextraction based on applying low-density organic solvent for the determination of organochlorine pesticides in water samples

In this study, a polyethylene Pasteur pipette-based ultrasound-assisted emulsification microextraction (USAEME) applying low-density organic solvent was successfully developed for the extraction of trace levels of organochlorine pesticides (OCPs) in water samples and followed by gas chromatography–mass spectrometry (GC–MS) analysis. In this approach, a polyethylene Pasteur squeeze-type pipette was employed as a convenient extraction device and ultrasound radiation was applied to accelerate the emulsification of low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OCPs in water samples. Thirty microliters of extraction solvent (isooctane), of lower density than water, were injected into the aqueous sample solution held in the pipette. The latter was then immersed in an ultrasound water bath to form an emulsion. After 30s extraction, phase separation was achieved by centrifugation. The upper layer (isooctane) was collected and analyzed by GC–MS. No disperser solvent was required in this procedure. Significantly, fast analysis and high extraction efficiency were achieved. Another feature of the procedure was the use of the pipette as the extraction device, which permitted less dense than water organic solvent to be used as extraction solvent. This method broadens the applicability of USAEME to a wider range of solvent. Additionally, carry-over problems were avoided with the use of the disposable pipette. Parameters affecting the efficiency of polyethylene Pasteur pipette-based USAEME, such as the extraction solvent, extraction solvent volume, extraction and centrifugation time, ionic strength and extraction temperature were investigated. Under the optimum conditions, the proposed method provided good enrichment factors (EFs) in the range of 128 and 328, with relative standard deviations (RSDs) ranging from 2.7% to 12.4%. The limits of detection were in the range of 0.8 and 10ng/L depending on the analytes. The linearities were between 0.01 and 50μg/L for hexachlorobenzene, dieldrin, endrin and o,p′-DDD, 0.05–25μg/L for heptachlor, and 0.005–50μg/L for p,p′-DDE. Finally, the polyethylene Pasteur pipette-based USAEME was successfully used for the fast determination of OCPs in river and tap water samples. The proposed method provides a simple, convenient, rapid, sensitive, cost-effective, and environmentally friendly process for the determination of OCPs in water samples.

Dispersive liquid–liquid microextraction using extraction solvents lighter than water combined with high performance liquid chromatography for determination of synthetic antioxidants in fruit juice samples

A simple, rapid and sensitive sample pretreatment technique, termed dispersive liquid–liquid microextraction (DLLME), was developed as an extraction methodology to determine two synthetic phenolic antioxidants (SPAs), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), in various fruit juice samples prior to high performance liquid chromatography (HPLC). The extraction method is based on replacing the extraction solvent in the ordinary DLLME, namely the chlorinated organic solvent, with low-density organic solvents such as hexane, ethyl acetate, octanol and 2-ethyl-1-hexanol in the ternary component solvent (aqueous solution:extracting solvent:disperser solvent) system. Several factors affecting the microextraction efficiency, such as type and volume of extraction and dispersive solvents, pH of the sample solution, extraction time, ionic strength and extraction temperature, were investigated. Under the optimum conditions, the method yielded a linear calibration curve ranging from 10 to 2500μgL−1 for BHA and 2 to 2500μgL−1 for BHT, with determination coefficients (R2) varying from 0.9993 to 0.9989. Enrichment factors for BHA and BHT were 208 and 203, and limits of detection were 2.5 and 0.9μgL−1, respectively. The relative standard deviation percent (RSD%) for the extraction and determination at 10 and 100μgL−1 levels of target antioxidants was less than 4.7% (n=7). Finally, the designed method was successfully applied for the preconcentration and determination of the studied SPAs in different fruit juice samples, and satisfactory results were obtained.

Simultaneous determination of amphetamine and related compounds in human urine using ultrasound-assisted emulsification microextraction and gas chromatography

3,4-methylenedioxymethylamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyethylamphetamine (MDEA) and 3,4-methylenedioxypropylamphetamine (MDPA) were extracted from human urine by using ultrasound-assisted emulsification microextraction (USAEME) method based on applying low density organic solvents followed by gas chromatographic analysis with flame ionization detection. Fourteen microliters of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing a sample without salt addition that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. In order to improve the extraction efficiency, experimental parameters affecting the extraction efficiency, including type and volume of extraction solvent, pH value of sample, extraction time and temperature were investigated. Under the optimal conditions, the linear dynamic range was in the range of 0.5–500 μg L−1 for MDEA and MDPA and 1.0–500 μg L−1 for MDA and MDMA with limits of detection (LODs) in the range of 0.2 to 0.4 μg L−1. The results indicate that the developed method is rapid, accurate and sensitive and can be used for the simultaneous determination of MDA, MDMA, MDEA and MDPA in urine samples.

Extraction and determination of biphenyl and biphenyl oxide in water samples by using ultrasound-assisted emulsification microextraction-gas chromatography-flame ionization detection

In this article, a fast, simple and efficient method for determination of biphenyl and biphenyl oxide in water samples was developed using an ultrasound-assisted emulsification microextraction (USAEME) method based on applying low density organic solvents. 14 μL of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample without salt addition that was located inside an ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Under the optimum conditions, enrichment factors (EFs) of 883 and 1066 for biphenyl and biphenyl oxide, respectively, were obtained. The method performance was studied in terms of linear dynamic range (LDRs from 0.5 μg L−1 to 200 μg L−1 for both analytes), linearity (r2 ≥ 0.995) and precision (repeatability ≤ 8%). Also, we obtained limits of detection (LODs) of 0.1 μg L−1 for biphenyl and biphenyl oxide. The applicability of the USAEME method was evaluated by the extraction and determination of biphenyl and biphenyl oxide from different water samples.

Application of ultrasound-assisted emulsification microextraction followed by gas chromatography for determination of organophosphorus pesticides in water and soil samples

In the present study a fast, simple and efficient method for determination of organophosphorus pesticides (OPPs) in water and soil samples was developed by using ultrasound assisted emulsification microextraction (USAEME) based on applying low density organic solvents. Fourteen microlitres of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene (about 4 μL) was injected into a gas chromatographic instrument equipped with a flame ionization detector for analysis. Under the optimum conditions, preconcentration factors of 2390 and 1390 were obtained for diazinon and chlorpyrifos respectively. The method performance was studied in terms of linear dynamic range (LDRs from 0.01 μg L−1 to 100 μg L−1), linearity (r2 ≥ 0.9984), precision (repeatability ≤ 8.7%), and extraction percentage (79.9 and 46.3%). Also, limits of detections of 0.01 and 0.1 μg L−1 were obtained for diazinon and chlorpyrifos respectively. The applicability of the USAEME method was evaluated by the extraction and determination of OPPs from some natural water and soil samples.

Comparison of ultrasound-assisted emulsification and dispersive liquid–liquid microextraction methods for the speciation of inorganic selenium in environmental water samples using low density extraction solvents

Herein, ultrasound-assisted emulsification microextraction (USAEME) and dispersive liquid–liquid microextraction (DLLME) methods based on applying low-density organic solvents have been critically compared for the speciation of inorganic selenium, Se(IV) (selenite) and Se(VI) (selenate) in environmental water samples by gas chromatography-flame ionization detection (GC-FID). At pH 2 and T = 75 °C for 7 min, only Se(IV) was able to form the piazselenol complex with 4-nitro- o-phenylenediamine. Piazselenol was extracted using an extraction solvent and was injected into a GC-FID instrument for the determination of Se(IV). Conveniently, Se(VI) remained in the aqueous phase. Total inorganic selenium was determined after the reduction of Se(VI) to Se(IV) and prior to the above procedures. The Se(VI) concentration was calculated as the difference between the measured total inorganic selenium and Se(IV) content. The effect of various experimental parameters on the efficiencies of the two methods and their optimum values were studied with the aid of response surface methodology and experimental design. Under the optimal conditions, the limit of detections (LODs) for Se(IV) obtained by USAEME-GC-FID and DLLME-GC-FID were 0.05 and 0.11 ng mL −1, respectively. The relative standard deviations (RSDs, n = 6) for the measurement 10 ng mL −1 of Se(IV) were 5.32% and 4.57% with the enrichment factors of 2491 and 1129 for USAEME-GC-FID and DLLME-GC-FID, respectively. Both methods were successfully applied to the analysis of inorganic selenium in different environmental water samples and certified reference material (NIST SRM 1643e).

Improved solvent collection system for a dispersive liquid–liquid microextraction of organochlorine pesticides from water using low‐density organic solvent

In this study, the organochlorine pesticides (OCPs) levels in lake and tap water samples were determined by a dispersive liquid-liquid microextraction method using a low-density organic solvent and an improved solvent collection system (DLLME-ISCS). This method used a very small volume of a solvent of low toxicity (11 μL of 1-nonanol and 400 μL of methanol) to extract OCPs from 10 mL water samples prior to the analysis by GC. After centrifugation in the dispersive liquid-liquid microextraction, there was a liquid organic drop floating between the water surface and the glass wall of the centrifuge tube. The liquid organic drop (with some water phase) was transferred into a microtube (3 mm×15 mm) with a syringe. The organic and aqueous phases were separated in the microtube immediately. Then, 1 μL of the organic solvent (which was in the upper portion of liquid in the microtube) was easily collected by a syringe and injected into the GC-ECD system for the analysis. Under optimum conditions, the linear range of this method was 5-5000 ng/L for most of the analytes. The correlation coefficient was higher than 0.997. Enrichment factors ranged from 1309 to 3629. The relative recoveries ranged from 73 to 119% for lake water samples. The LODs of the method ranged from 0.7 to 9.4 ng/L. The precision of the method ranged from 1.0 to 10.8% for lake water.

Directly suspended droplet microextraction with in injection-port derivatization coupled to gas chromatography–mass spectrometry for the analysis of polyphenols in herbal infusions, fruits and functional foods

A miniaturized liquid-phase extraction procedure based on directly suspended droplet microextraction is proposed for determining different classes of polyphenols. A derivatization reaction by means of in injection-port reaction with bis(trimethylsilyl)trifluoroacetamide is carried out to convert the polar non-volatile polyphenols into volatile derivatives. The separation and detection is carried out by coupling gas chromatography with mass spectrometry in the selected ion monitoring mode. The procedure uses undecanone, a low density organic solvent, and several factors influencing the extraction, collection efficiency and derivatization reaction are optimized. Excellent linearity was obtained for the range studied (0.05–500 ng mL −1). The limits of detection are between 0.011 and 0.13 ng mL −1, depending on the compound, and the limits of quantification between 0.037 and 0.43 ng mL −1. The sensitivity and detection limits for polyphenols using the DSDME sample pretreatment method were very low. Enrichment factors are between 413 and 578. The recoveries obtained for spiked samples are satisfactory for all the compounds. The coupled miniaturized method is applied to the sensitive determination of both cis- and trans-resveratrol isomers, piceatannol, catechin, epicatechin, quercetin and fisetin in herbal infusions, fruits, juices and functional foods.

Liquid–liquid microextraction methods based on ultrasound-assisted emulsification and single-drop coupled to gas chromatography–mass spectrometry for determining strobilurin and oxazole fungicides in juices and fruits

Two procedures are proposed based on ultrasound-assisted emulsification and single-drop liquid–liquid microextraction for the sensitive determination of seven strobilurin and six oxazole fungicides in fruits and juice samples. Both miniaturized techniques are coupled to gas chromatography with mass spectrometry in the selected ion monitoring mode, GC–MS(SIM). The procedures use low density organic solvents, and several factors influencing the emulsification, extraction and collection efficiency are optimized. The detection limits obtained at a signal-to-noise ratio of 3 are below the MRLs set by the European Commission. Enrichment factors are between 140–1140 for the first technique used and 80–1600 for the latter. The recoveries obtained for spiked samples are satisfactory for all compounds. The methods are validated according to the Commission Decision 2002/657/EC. Different fruit and juices are analyzed by the proposed method and none of the samples contained fungicide residues above the detection limits.

Determination of organophosphorous pesticides in water using in-syringe ultrasound-assisted emulsification and gas chromatography with electron-capture detection

An in-syringe ultrasound-assisted emulsification microextraction (USAEME) was developed for the extraction of organophosphorus pesticides (OPPs) from water samples. The OPPs subsequently analyzed gas chromatography (GC) using a microelectron capture detector (μECD). Ultrasound radiation was applied to accelerate the emulsification of μL-level low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OPPs in the sample preparation for GC-μECD. Parameters affecting the efficiency of USAEME, such as the extraction solvent, solvent volume, pH, salt-addition, and extraction time were thoroughly investigated. Based on experimental results, OPPs were extracted from a 5 mL aqueous sample by the addition of 20 μL toluene as the extraction solvent, followed by ultrasonication for 30 s, and then centrifugation for 3 min at 3200 rpm, offered the best extraction efficiency. Detections were linear in the concentration of 0.01–1 μg/L with detection limits between 1 ng/L and 2 ng/L for OPPs. Enrichment factors ranged from 330 to 699. Three spiked aqueous samples were analyzed, and recovery ranged from 90.1% to 104.7% for farm-field water, and 90.1% to 101.8% for industrial wastewater. The proposed method provides a simple, rapid, sensitive, inexpensive, and eco-friendly process for determining OPPs in water samples.

Ultrasound-assisted emulsification microextraction method based on applying low density organic solvents followed by gas chromatography analysis for the determination of polycyclic aromatic hydrocarbons in water samples

In this study, a fast, simple and efficient ultrasound-assisted emulsification microextraction (USAEME) method was successfully developed based on applying low density organic solvents. Fourteen microliters of toluene was injected slowly into a 12 mL home-designed centrifuge glass vial containing an aqueous sample that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated toluene (about 4 μL) was injected into a gas chromatographic system equipped with a flame ionization detector (GC-FID) for analysis. Some polycyclic aromatic hydrocarbons (PAHs) were selected as model compounds for developing the method and evaluating its performance and to compare the efficiency of the proposed method with previously reported techniques. Several factors influencing the emulsification, extraction and collection efficiency such as the nature and volume of organic solvent, emulsification–extraction temperature, ionic strength and equilibrium and centrifugation times were investigated and optimized. Under the optimum conditions, preconcentration factors (PFs) in a range of 1776–2714 were obtained. The performance of the proposed method was studied in terms of linear dynamic range (LDRs from 0.05 to 100 μg L −1), linearity ( R 2 ≥ 0.994), precision (repeatability: RSD% ≤ 7.9, reproducibility: RSD% ≤ 14.6) and extraction percents (59.2–90.5%). Limits of detection (LODs) in the range of 0.02–0.05 μg L −1 were obtained for different PAHs. The applicability of the proposed method was evaluated by the extraction and determination of PAHs from several natural water samples.

Liquid mixing driven motions of floating macroscopic objects

Dropping miscible and low-density organic solvents into water generates translational and rotational motions of floating objects including oil droplets, polymer half spheres, and model boats. The moving speed of the boat at different loads and the force produced by solvent drops are measured. In contrast to motions driven by surface tension of monolayer, the liquid mixing driven motion can be dynamically steered without restriction and continued provided the supply is maintained and the amount of water is large enough. Such motions are the result of Marangoni instability in binary liquid-liquid systems with intentionally produced concentration gradients behind the floating objects.

A procedure for the micro-phase extraction of lipophilic drugs from biological fluids with low-density organic solvents.

A procedure for the micro-phase extraction of lipophilic drugs from biological fluids with low-density organic solvents.