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Sample records for surfactant-enhanced emulsification microextraction

  1. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction.

    PubMed

    Yang, Zhong-Hua; Lu, Yue-Le; Liu, Yu; Wu, Tong; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2011-10-07

    A novel sample pre-treatment technique, based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction (VSLLME), followed by gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of seven organophosphorus pesticides (OPPs) in wine and honey samples. In the VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which was used as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The main parameters relevant to this method were investigated and the optimum conditions were established: 15 μL chlorobenzene was used as extraction solvent, 0.2 mmol L(-1) Triton X-114 was selected as the surfactant, the extraction time was fixed at 30s, 3% sodium chloride was added and the extraction process was performed under the room temperature. Under the optimum conditions, limits of detections (LODs) were varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSD, n=6) ranged from 2.3% and 8.9%. The linearity was obtained by five points in the concentration range of 0.1-50.0 μg L(-1). Correlation coefficients (r) varied from 0.9969 to 0.9991. The enrichment factors (EFs) were in a range of 282-309. Finally, the proposed method has been successfully applied to the determination of target analytes in real samples. The recoveries of the target analytes in wine and honey samples were between 81.2% and 108.0%.

  2. Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of Cd and Ni in tea and water samples.

    PubMed

    Ezoddin, Maryam; Taghizadeh, Tayebeh; Majidi, Behrooz

    2014-01-01

    A microextraction method based on ultrasound-assisted surfactant-enhanced emulsification using solidification of a floating organic droplet (UASEME-SFO) was evaluated for simultaneous determination of Cd and Ni in water and tea samples followed by flame atomic absorption spectrometry. In the UASEME-SFO technique, Triton X-100 was used as an emulsifier to accelerate the emulsification of the extraction solvent into a sample solution and hasten the mass transfer of the analytes. Analytes form a complex and are extracted into 1-dodecanol which was used as an extraction solvent. Some parameters such as type and volume of the extraction solvent, the type and concentration of the surfactant, ultrasound extraction time, reagent concentration, centrifuge conditions and salt concentration were investigated. Under optimum conditions, calibration curves were linear in the range of 0.3-100 and 0.6-180 microg L(-1) with detection limits of 0.11 and 0.20 microg L(-1) for Cd and Ni, respectively. The accuracy of the method was confirmed by parallel analyses using the certified reference material of water and tea samples. The recoveries of the analytes in tea leaves, tea infusions and water samples were in the range of 96.5-105.1%.

  3. Low-density solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction and its application.

    PubMed

    Yang, Zhong-Hua; Liu, Dong-Hui; Zhao, Wen-ting; Wu, Tong; Zhou, Zhi-Qiang; Wang, Peng

    2013-03-01

    For the first time, the low-density solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction, followed by GC-flame photometric detection has been developed for the determination of eight organophosphorus pesticides in aqueous samples. A small volume of organic extraction solvent (toluene) was dispersed into the aqueous samples by the assistance of surfactant and vortex agitator. The extraction was performed in a special disposable polyethylene pipette, allowing using the reagents with lower density than water as extraction solvents. The influence parameters were systemically investigated and optimized: toluene (30 μL) and Triton X-100 (0.2 mmol/L) were used as the extraction solvent and the surfactant, respectively, and the extraction was performed for 1 min under room temperature without adding sodium chloride. Under the optimum conditions, the validation parameters such as the RSD (n = 6; 2.1-11.3%), LOD (0.005 and 0.05 μg/L), and linear range (0.1-50.0 μg/L with correlation coefficients (0.9958-0.9992) showed the method was satisfying. The proposed method has been successfully applied to the determination of the organophosphorus pesticides in real samples with recoveries between 82.8 and 100.2%.

  4. Determination of phthalate esters in liquor samples by vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction followed by GC-MS.

    PubMed

    Leng, Geng; Chen, Wenjin; Zhang, Mingfang; Huang, Fang; Cao, Qiming

    2014-03-01

    A novel method using vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction has been developed for the extraction of phthalate esters (PAEs) in Chinese liquor samples prior to analysis by GC-MS. In the proposed method, a high-density extraction solvent (carbon tetrachloride) was dispersed into samples with the aid of a surfactant (Triton X-100) and vortex agitation, resulting in a short extraction equilibrium (30 s). After centrifugation, a single microdrop of solvent was easily collected for GC-MS analysis. Key factors that affected the extraction efficiency were optimized. Under the optimum conditions, linearity was found in the range from 0.05 to 50 μg/L. Coefficients of determination varied from 0.9938 to 0.9971. LODs, based on an S/N of 3, ranged from 4.9 to 13 ng/L. Enrichment factors varied from 140 to 184. Reproducibility and recoveries were assessed by testing a series of three liquor samples that were spiked with different concentration levels. Finally, the proposed method was successfully applied to the determination of PAEs in 16 Chinese liquor samples. In this work, high-density-solvent vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction was applied for the first time for the extraction of PAEs in Chinese liquor samples and was proved to be simple, rapid, and sensitive.

  5. Vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction for the determination of carbamates in juices by micellar electrokinetic chromatography tandem mass spectrometry.

    PubMed

    Moreno-González, David; Huertas-Pérez, José F; García-Campaña, Ana M; Gámiz-Gracia, Laura

    2015-07-01

    A new method based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction has been developed for the extraction of carbamate pesticides in juice samples prior to their determination by micellar electrokinetic chromatography coupled to tandem mass spectrometry. This sample treatment allowed the satisfactory extraction and the extract clean-up of 25 carbamates from different fruit and vegetal juices (banana, tomato, and peach). In this study, the addition of ammonium perfluorooctanoate in the aqueous sample in combination with vortex agitation, provided very clean extracts with short extraction times. Under optimized conditions, recoveries of the proposed method for these pesticides from fortified juice samples ranged from 81% to 104%, with relative standard deviations lower than 15%. Limits of quantification were between 2.3µgkg(-)(1) and 4.7µgkg(-)(1), showing the high sensitivity of this fast and simple method.

  6. Development of a home-made extraction device for vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with lighter than water organic solvents.

    PubMed

    Yang, Zhong-Hua; Wang, Peng; Zhao, Wen-ting; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2013-07-26

    We have developed a novel vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction using the low density solvent for the determination of eight organophosphorus pesticides (OPPs) in water samples. The key point of this method is the application of a special home-made extraction device. The influence parameters relevant to this method were systemically investigated and the optimum conditions were as follow: 35μL of toluene was used as extraction solvent and 0.2mmol L-1 Triton X-100 was chosen as the surfactant to enhance the emulsification. Under the optimum experimental conditions, the limit of detections (LODs) of the method was ranged between 0.01 and 0.05μgL(-1) and the relative standard deviations (RSDs) were 2.9-8.1%. The calibration curve was linear in the range of 0.1-50.0μgL(-1), with the correlation coefficients (r) varying from 0.9949 to 0.9991. Finally, the developed method has been successfully applied to the determination of eight organophosphorus pesticides in river, reservoir and well water samples with recoveries between 82.1% and 98.7%.

  7. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction for the determination of triazine herbicides in water samples by microemulsion electrokinetic chromatography.

    PubMed

    Li, Ran-Hong; Liu, Dong-Hui; Yang, Zhong-Hua; Zhou, Zhi-Qiang; Wang, Peng

    2012-07-01

    A novel method based on the combination of microemulsion electrokinetic chromatography (MEEKC) and vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction (VSLLME) was developed for the determination of five triazine herbicides (simazine, atrazine, ametryn, prometryn, and terbutryn) in water samples. The five triazine herbicides were baseline separated by using the microemulsion buffer containing a 10 mmol/L borate buffer at pH 9.5, 2.5% (w/v) SDS as surfactant, 0.8% (w/v) ethyl acetate as oil phase, and 6.0% (w/v) 1-butanol as cosurfactant. The optimum extraction conditions of VSLLME were as follows: 100 μL chloroform was used as extraction solvent, 5.0 × 10⁻⁵ mol/L Tween-20 was chosen as the surfactant to enhance the emulsification, and the extraction process was carried out by vortex mixing for 3 min. Under these optimum experimental conditions, the calibration curve was linear in the range of 2.0-200.0 ng/mL, with the correlation coefficients (r²) varying from 0.9927 to 0.9958. The detection limits of the method varied from 0.41 to 0.62 ng/mL. The purposed method was applied to the determination of five triazine herbicides in real water samples, and the recoveries were between 80.6 and 107.3%.

  8. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction of biogenic amines in fermented foods before their simultaneous analysis by high-performance liquid chromatography.

    PubMed

    Donthuan, Jaruwan; Yunchalard, Sirinda; Srijaranai, Supalax

    2014-11-01

    A simple, rapid, sensitive, and environmentally friendly method, based on modified dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography was developed for the simultaneous determination of five biogenic amines in fermented food samples. Biogenic amines were derivatized with 9-fluorenylmethyl chloroformate, extracted by vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction, and then analyzed by high-performance liquid chromatography. Five biogenic amine compounds were separated within 30 min using a C18 column and gradient elution with acetonitrile and 1% acetic acid. Factors influencing the derivatization and extraction efficiency such as type and volume of extraction solvent, type, and concentration of surfactant, pH, salt addition, and vortex time were optimized. Under the optimum conditions, the method provided the enrichment factors in the range of 161-553. Good linearity was obtained from 0.002-0.5 mg/L for cadaverine and tyramine, 0.003-1 mg/L for tryptamine and histamine, and 0.005-1 mg/L for spermidine with coefficient of determination (R(2) ) > 0.992. The limits of detection ranged from 0.0010 to 0.0026 mg/L. The proposed method was successfully applied to analysis of biogenic amines in fermented foods such as fermented fish (plaa-som), wine and beer where good recoveries were obtained in the range of 83.2-112.5%

  9. Ionic-liquid-based, manual-shaking- and ultrasound-assisted, surfactant-enhanced emulsification microextraction for the determination of three fungicide residues in juice samples.

    PubMed

    Chen, Xiaochu; You, Xiangwei; Liu, Fengmao; Hou, Fan; Zhang, Xu

    2015-01-01

    A novel manual-shaking- and ultrasound-assisted surfactant-enhanced emulsification microextraction method was developed for the determination of three fungicides in juice samples. In this method, the ionic liquid, 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, instead of a volatile organic solvent was used as the extraction solvent. The surfactant, NP-10, was used as an emulsifier to enhance the dispersion of the water-immiscible ionic liquid into an aqueous phase, which accelerated the mass transfer of the analytes. Organic dispersive solvent typically required in common dispersive liquid-liquid microextraction methods was not necessary. In addition, manual shaking for 15 s before ultrasound to preliminarily mix the extraction solvent and the aqueous sample could greatly shorten the time for dispersing the ionic liquid into aqueous solution by ultrasound irradiation. Several experimental parameters affecting the extraction efficiency, including type and volume of extraction solvent, type and concentration of surfactant, extraction time, and pH, were optimized. Under the optimized conditions, good linearity with the correlation coefficients (γ) higher than 0.9986 and high sensitivity with the limit of detection ranging from 0.4 to 1.6 μg/L were obtained. The average recoveries ranged from 61.4 to 86.0% for spiked juice, with relative standard deviations from 1.8 to 9.7%. The proposed method was demonstrated to be a simple, fast, and efficient method for the analysis of the target fungicides in juice samples.

  10. Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

    PubMed

    Peng, Guilong; He, Qiang; Lu, Ying; Mmereki, Daniel; Pan, Weiliang; Tang, Xiaohui; Zhou, Guangming; Mao, Yufeng; Su, Xaioxuan

    2016-04-01

    A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The influences of analytical parameters, including extraction solvent type and its volume, surfactant type and its volume, pH, concentration of chelating agent, salt effect and extraction time were investigated. Under the optimized conditions, a good relative standard deviation of 3.69% at 10 ng L(-1) was obtained. The calibration graph showed a linear pattern in the ranges of 5-30 ngL(-1), with a limit of detection of 0.76 ng L(-1). The linearity was obtained by five points in the concentration range of 5-30 ngL(-1). The enrichment factor was 320. The procedure was applied to wastewater and river water, and the accuracy was assessed through the analysis of the recovery experiments.

  11. Binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar.

    PubMed

    Chen, Xiaochu; Zhang, Xu; Liu, Fengmao; Hou, Fan

    2017-02-01

    A binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5-200 μg/L. The limits of quantification of the method were in the range of 2-5 μg/L. The relative standard deviations for interday assays were 1.7-11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments.

  12. Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop combined with high performance liquid chromatography for determination of naproxen and nabumetone.

    PubMed

    Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh; Abbasi, Bijan

    2015-12-18

    A novel, rapid, simple and green vortex-assisted surfactant-enhanced emulsification microextraction method based on solidification of floating organic drop was developed for simultaneous separation/preconcentration and determination of ultra trace amounts of naproxen and nabumetone with high performance liquid chromatography-fluorescence detection. Some parameters influencing the extraction efficiency of analytes such as type and volume of extractant, type and concentration of surfactant, sample pH, KCl concentration, sample volume, and vortex time were investigated and optimized. Under optimal conditions, the calibration graph exhibited linearity in the range of 3.0-300.0ngL(-1) for naproxen and 7.0-300.0ngL(-1) for nabumetone with a good coefficient of determination (R(2)>0.999). The limits of detection were 0.9 and 2.1ngL(-1). The relative standard deviations for inter- and intra-day assays were in the range of 5.8-10.1% and 3.8-6.1%, respectively. The method was applied to the determination of naproxen and nabumetone in urine, water, wastewater and milk samples and the accuracy was evaluated through recovery experiments.

  13. Vortex-assisted surfactant-enhanced emulsification microextraction combined with LC-MS/MS for the determination of glucocorticoids in water with the aid of experimental design.

    PubMed

    Asati, Ankita; Satyanarayana, G N V; Patel, Devendra K

    2017-04-01

    An efficient and inexpensive method using vortex-assisted surfactant-enhanced emulsification microextraction (VASEME) based on solidification of floating organic droplet coupled with ultraperformance liquid chromatography-tandem mass spectrometry is proposed for the analysis of glucocorticoids in water samples (river water and hospital wastewater). VASEME was optimized by the experimental validation of Plackett-Burman design and central composite design, which has been co-related to experimental design. Plackett-Burman design showed that factors such as vortex time, surfactant concentration, and pH significantly affect the extraction efficiency of the method. Method validation was characterized by an acceptable calibration range of 1-1000 ng L(-1), and the limit of detection was in the range from 2.20 to 8.12 ng L(-1) for glucocorticoids. The proposed method was applied to determine glucocorticoids in river water and hospital wastewater in Lucknow, India. It is reliable and rapid and has potential application for analysis of glucocorticoids in environmental aqueous samples. Graphical Abstract Low density based extraction of gluococorticoids by using design of experiment.

  14. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet combined with HPLC for the determination of neonicotinoid pesticides.

    PubMed

    Vichapong, Jitlada; Burakham, Rodjana; Srijaranai, Supalax

    2013-12-15

    A microextraction procedure based on vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet (VSLLME-SFO) for preconcentration of neonicotinoid pesticides, including acetamiprid, clotianidin, nitenpyram, imidacloprid, and thiamethoxam, has been developed. In VSLLME-SFO process, the addition of surfactant (as an emulsifier), could be enhance the mass-transfer from the aqueous solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous by vortex process. Other experimental parameters affected the extraction efficiency, including the kind and concentration of salt, concentration and volume of HCl, kind and concentration of surfactant and its volume, kind and volume of extraction solvent, vortex time and the centrifugation extraction time, were also optimized. The optimum extraction conditions of VSLLME-SFO were 10.00 mL of sample, 0.3% (w/v) Na2SO4, 50 µL of 0.050 mol L(-1) SDS, 1.0 mol L(-1) HCl (400 µL), 150 µL of octanol, vortex time 1 min and centrifugation time 10 min. The sediment phase was analyzed by subjecting it to HPLC using a mobile phase of 25% acetonitrile in water, at a flow rate of 1.0 mL min(-1), and photodiode array detection at 254 nm. Under the optimum extraction conditions, high enrichment factors (20-100 fold) and low limit of detection (0.1-0.5 μg L(-1)) could be obtained. This method provided high sensitivity, low toxic organic solvents used, and simplicity of the extraction processes. The proposed method was successfully applied in the analysis of neonicotinoids in fruit juice and water samples.

  15. Application of Ultrasound-Assisted Surfactant-Enhanced Emulsification Microextraction Based on Solidification of Floating Organic Droplets and High Performance Liquid Chromatography for Preconcentration and Determination of Alprazolam and Chlordiazepoxide in Human Serum Samples.

    PubMed

    Goudarzi, Nasser; Amirnavaee, Monavar; Arab Chamjangali, Mansour; Farsimadan, Sahar

    2017-03-03

    An improved microextraction method is proposed on the basis of ultrasound-assisted surfactant-enhanced emulsification and solidification of a floating organic droplet procedure combined with high performance liquid chromatography for the preconcentration and quantification of alprazolam (ALP) and chlordiazepoxide (CHL) present in a number of human serum samples. Several parameters affecting the extraction efficiency were investigated by the Plackett -Burman factorial design as the screening design. Then the response surface methodology based on the Box-Behnken design was used to optimize the effective parameters in the proposed procedure. The limits of detection for the proposed method were found to be 3.0 and 3.1 ng mL-1 for CHL and ALP, respectively. The calibration curves obtained for the method were linear in the ranges of 10.0-3,500.0 and 10.0-3,000.0 ng mL-1 for CHL and ALP, respectively, with a good determination coefficient. The recoveries of the drugs in the spiked human serum samples were above 93.0%. The developed method was successfully applied to the analysis of these studied drugs in human serum samples. The pre-treatment of the serum samples was performed using acetonitrile to remove the proteins. The proposed procedure was an accurate and reliable one for the determination and preconcentration of these drugs in blood samples.

  16. Vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet combined with flame atomic absorption spectrometry for the fast determination of cadmium in water samples.

    PubMed

    Peng, Guilong; Lu, Ying; He, Qiang; Mmereki, Daniel; Tang, Xiaohui; Zhong, Zhihui; Zhao, Xiaolong

    2016-01-01

    A novel vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with solidification of floating organic droplet (VSLLME-SFO) was developed for the fast, simple and efficient determination of cadmium (Cd) in water samples followed by flame atomic absorption spectrometry (FAAS). In the VSLLME-SFO process, the addition of surfactant (as an emulsifier), could enhance the mass transfer from the aqueous solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous phase under vigorous shaking with the vortex. In this paper, we investigated the influences of analytical parameters, including pH, extraction solvent type and its volume, surfactant type and its volume, concentration of chelating agent, salt effect and vortex time, on the extraction efficiency of Cd. Under the optimized conditions, the limit of detection was 0.16 μg/L. The analyte enrichment factor was 37.68. The relative standard deviation was 3.2% (10 μg/L, n = 10) and the calibration graph was linear, ranging from 0.5 to 30 μg/L. The proposed method was successfully applied for the analysis of ultra-trace Cd in river water and wastewater samples.

  17. Extraction and determination of sulfonylurea herbicides in water and soil samples by using ultrasound-assisted surfactant-enhanced emulsification microextraction and analysis by high-performance liquid chromatography.

    PubMed

    Ghobadi, Masoomeh; Yamini, Yadollah; Ebrahimpour, Behnam

    2015-02-01

    An ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) with low-density extraction solvents was developed for the extraction of sulfonylurea herbicides from water and soil samples prior to high-performance liquid chromatography coupled with ultraviolet detection (HPLC-UV). In this technique, a surfactant was used as emulsifier which could enhance the dispersion of water-immiscible extraction solvent into aqueous phase and was favorable for the mass-transfer of the analytes from aqueous phase to organic phase. The target analytes were extracted into an extraction phase (Aliquat-336 in 1-octanol) and dispersed in an aqueous solution. After extraction and phase separation, the organic solvent on top of the solution was withdrawn into a syringe and 20 µL of it was injected into a HPLC instrument for analysis. Influential factors in extraction were investigated and optimized. Under optimum experimental conditions, calibration curve was linear in the concentration range from 1 to 100 µg/L, with coefficients of estimation (R(2) values) varying from 0.9928 to 0.9952, and satisfactory repeatabilities (4.7

  18. Ultrasound-assisted surfactant-enhanced emulsification microextraction based on the solidification of a floating organic droplet used for the simultaneous determination of six fungicide residues in juices and red wine.

    PubMed

    You, Xiangwei; Wang, Suli; Liu, Fengmao; Shi, Kaiwei

    2013-07-26

    A novel ultrasound-assisted surfactant-enhanced emulsification microextraction technique based on the solidification of a floating organic droplet followed by high performance liquid chromatography with diode array detection was developed for simultaneous determination of six fungicide residues in juices and red wine samples. The low-toxicity solvent, 1-dodecanol, was used as an extraction solvent. For its low density and proper melting point near room temperature, the extractant droplet was collected easily by solidifying it at a low temperature. The surfactant, Tween 80, was used as an emulsifier to enhance the dispersion of the water-immiscible extraction solvent into an aqueous phase, which hastened the mass-transfer of the analytes. Organic dispersive solvent typically required in common dispersive liquid-liquid microextraction methods was not used in the proposed method. Some parameters (e.g., the type and volume of extraction solvent, the type and concentration of surfactant, ultrasound extraction time, salt addition, and volume of samples) that affect the extraction efficiency were optimized. The proposed method showed a good linearity within the range of 5μgL(-1)-1000μgL(-1), with the correlation coefficients (γ) higher than 0.9969. The limits of detection for the method ranged from 0.4μgL(-1) to 1.4μgL(-1). Further, this simple, practical, sensitive, and environmentally friendly method was successfully applied to determine the target fungicides in juice and red wine samples. The recoveries of the target fungicides in red wine and fruit juice samples were 79.5%-113.4%, with relative standard deviations that ranged from 0.4% to 12.3%.

  19. Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop followed by electrothermal atomic absorption spectrometry for speciation of antimony (ΙΙΙ, V).

    PubMed

    Eftekhari, Mohammad; Chamsaz, Mahmoud; Arbab-Zavar, Mohammad Hossein; Eftekhari, Ali

    2015-01-01

    Vortex-assisted surfactant-enhanced emulsification microextraction based on solidification of floating organic drop (VASEME-SFO) was used for preconcentration and speciation of antimony (ΙΙΙ, V) followed by electrothermal atomic absorption spectrometry (ETAAS). In this procedure, Triton X-114 was used as emulsifier and 1-undecanol was used as extraction solvent. This method is based on the complexation of Sb(ΙΙΙ) with dithizone (as complexing agent) at pH 2 and extraction of the resulting hydrophobic complex into the extraction solvent (1-undecanol) with vortex-assisted liquid phase microextraction, whereas Sb(V) remained in solution. Sb(ΙΙΙ) in extraction solvent was directly analyzed by ETAAS after dilution with ethanol, and Sb(V) was calculated by subtracting Sb(ΙΙΙ) from the total antimony after reducing Sb(V) to Sb(ΙΙΙ) by L-cysteine. Under the optimized condition, the calibration curve was linear in the range of 0.4-8 μg L(-1) of Sb(ΙΙΙ) with a correlation coefficient of 0.9995. The detection limit based on three times of the standard deviation of the blank (n = 8) was 0.09 μg L(-1). The validation and the recovery of the proposed method were performed by the analysis of a certified reference material and spike method. The obtained results were in very good agreements with certified values. The proposed method was successfully applied for the determination of antimony species at trace levels in different water samples.

  20. Low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction combined with gas chromatography-mass spectrometry for the fast determination of phthalate esters in bottled water.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2013-01-25

    For the first time, a novel low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction (LDS-VSLLME) was developed for the fast, simple and efficient determination of six phthalate esters (PEs) in bottled water samples followed by gas chromatography-mass spectrometry (GC-MS). In the extraction procedure, the aqueous sample solution was injected into a mixture of extraction solvent (toluene) and surfactant (cetyltrimethyl ammonium bromide), which were placed in a glass tube with conical bottom, to form an emulsion by the assistance of vortex agitation. After extraction and phase separation by centrifugation, and removal of the spent sample, the toluene extract was collected and analyzed by GC-MS. The addition of surfactant enhanced the dispersion of extraction solvent in aqueous sample and was also favorable for the mass transfer of the analytes from the aqueous sample to the extraction solvent. Moreover, using a relatively less toxic surfactant as the emulsifier agent overcame the disadvantages of traditional organic dispersive solvents that are usually highly toxic and expensive and might conceivably decrease extraction efficiency to some extent since they are not as effective as surfactants themselves in generating an emulsion. With the aid of surfactant and vortex agitation to achieve good organic extraction solvent dispersion, extraction equilibrium was achieved within 1 min, indicating it was a fast sample preparation technique. Another prominent feature of the method was the simple procedure to collect a less dense than water solvent by a microsyringe. After extraction and phase separation, the aqueous sample was removed using a 5-mL syringe, thus leaving behind the extract, which was retrieved easily. This novel method simplifies the use of low-density solvents in DLLME. Under the optimized conditions, the proposed method provided good linearity in the range of 0.05-25 μg/L, low limits of detection (8-25 ng

  1. Comparison of air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction for polycyclic aromatic hydrocarbons determination in hookah water.

    PubMed

    Rajabi, Maryam; Bazregar, Mohammad; Daneshfar, Ali; Asghari, Alireza

    2015-07-01

    In this work, two disperser-free microextraction methods, namely, air-agitated liquid-liquid microextraction and ultrasound-assisted emulsification microextraction are compared for the determination of a number of polycyclic aromatic hydrocarbons in aqueous samples, followed by gas chromatography with flame ionization detection. The effects of various experimental parameters upon the extraction efficiencies of both methods are investigated. Under the optimal conditions, the enrichment factors and limits of detection were found to be in the ranges of 327-773 and 0.015-0.05 ng/mL for air-agitated liquid-liquid microextraction and 406-670 and 0.015-0.05 ng/mL for ultrasound-assisted emulsification microextraction, respectively. The linear dynamic ranges and extraction recoveries were obtained to be in the range of 0.05-120 ng/mL (R(2) ≥ 0.995) and 33-77% for air-agitated liquid-liquid microextraction and 0.05-110 ng/mL (R(2) ≥ 0.994) and 41-67% for ultrasound-assisted emulsification microextraction, respectively. To investigate this common view among some people that smoking hookah is healthy due to the passage of smoke through the hookah water, samples of both the hookah water and hookah smoke were analyzed.

  2. Ultrasound-assisted emulsification microextraction for the determination of ephedrines in human urine by capillary electrophoresis with direct injection. Comparison with dispersive liquid-liquid microextraction.

    PubMed

    Alshana, Usama; Göğer, Nilgün G; Ertaş, Nusret

    2012-08-01

    Ultrasound-assisted emulsification microextraction and dispersive liquid-liquid microextraction were compared for extraction of ephedrine, norephedrine, and pseudoephedrine from human urine samples prior to their determination by capillary electrophoresis. Formation of a microemulsion of the organic extract with an aqueous solution (at pH 3.2) containing 10% methanol facilitated the direct injection of the final extract into the capillary. Influential parameters affecting extraction efficiency were systematically studied and optimized. In order to enhance the sensitivity further, field-amplified sample injection was applied. Under optimum extraction and stacking conditions, enrichment factors of up to 140 and 1750 as compared to conventional capillary zone electrophoresis were obtained resulting in limits of detection of 12-33 μg/L and 1.0-2.8 μg/L with dispersive liquid-liquid microextraction and ultrasound-assisted emulsification microextraction when combined with field-amplified sample injection. Calibration graphs showed good linearity for urine samples by both methods with coefficients of determination higher than 0.9973 and percent relative standard deviations of the analyses in the range of 3.4-8.2% for (n = 5). The results showed that the use of ultrasound to assist microextraction provided higher extraction efficiencies than disperser solvents, regarding the hydrophilic nature of the investigated analytes.

  3. Determination of melamine in soil samples using surfactant-enhanced hollow fiber liquid phase microextraction followed by HPLC–UV using experimental design

    PubMed Central

    Sarafraz Yazdi, Ali; Raouf Yazdinezhad, Samaneh; Heidari, Tahereh

    2014-01-01

    Surfactant-enhanced hollow fiber liquid phase (SE-HF-LPME) microextraction was applied for the extraction of melamine in conjunction with high performance liquid chromatography with UV detection (HPLC–UV). Sodium dodecyl sulfate (SDS) was added firstly to the sample solution at pH 1.9 to form hydrophobic ion-pair with protonated melamine. Then the protonated melamine–dodecyl sulfate ion-pair (Mel–DS) was extracted from aqueous phase into organic phase immobilized in the pores and lumen of the hollow fiber. After extraction, the analyte-enriched 1-octanol was withdrawn into the syringe and injected into the HPLC. Preliminary, one variable at a time method was applied to select the type of extraction solvent. Then, in screening step, the other variables that may affect the extraction efficiency of the analyte were studied using a fractional factorial design. In the next step, a central composite design was applied for optimization of the significant factors having positive effects on extraction efficiency. The optimum operational conditions included: sample volume, 5 mL; surfactant concentration, 1.5 mM; pH 1.9; stirring rate, 1500 rpm and extraction time, 60 min. Using the optimum conditions, the method was analytically evaluated. The detection limit, relative standard deviation and linear range were 0.005 μg mL−1, 4.0% (3 μg mL−1, n = 5) and 0.01–8 μg mL−1, respectively. The performance of the procedure in extraction of melamine from the soil samples was good according to its relative recoveries in different spiking levels (95–109%). PMID:26644934

  4. Dissolved carbon dioxide flotation: an effective way for phase separation in emulsification microextraction method.

    PubMed

    Molaei, Saeideh; Saleh, Abolfazl; Ghoulipour, Vanik; Seidi, Shahram

    2015-04-03

    Dissolved carbon dioxide flotation after emulsification microextraction (DCF-EME) technique coupled with gas chromatography-electron capture detection (GC-ECD) was introduced for preconcentration and determination of six organochlorine pesticides (OCPs) in seawater samples. DCF-EME method is based on the rapid and simple phase separation of low density organic solvent from the aqueous phase via introducing of a saturated NaHCO3 solution (9.6% w/v) into the acidified sample solution (0.1M of HCl) containing analytes. Thanks to the in situ generation of carbon dioxide (CO2) bobbles intensified by ultrasound radiation, the dispersed extraction solvent was collected to the surface of the aqueous sample and then was narrowed to the capillary part of a special home-made extraction cell for facile retrieving. Under the optimal conditions, the limits of detection were at the range of 2.6-9.2 ng L(-1) and preconcentration factors were varied between 271 and 307 for different OCPs. The applicability of the developed method was evaluated by the extraction and determination of the target analytes from Caspian seawater samples.

  5. Ultrasound-assisted emulsification-microextraction for the sensitive determination of ethyl carbamate in alcoholic beverages.

    PubMed

    Liao, Qie Gen; Li, Wei Hong; Luo, Lin Guang

    2013-08-01

    A method based on ultrasound-assisted emulsification-microextraction (USAEME) was proposed in this contribution for the determination of ethyl carbamate (EC) in alcoholic beverages using gas chromatography coupled to triple quadrupole mass spectrometry. To achieve the determination of EC in alcoholic beverages, the influences on the extraction efficiency of type and volume of extraction solvent, temperature, ionic strength, alcohol content, and extraction time were studied, once the extraction solvent had been selected. The optimized conditions were 200.0 μL of chloroform at 30 °C during 5 min with 15% (m/v) sodium chloride addition. The detection limit, relative standard deviations, linear range, and recoveries under the optimized conditions were 0.03 μg L(-1), 4.2-6.1%, 0.1-50.0 μg L(-1), and 80.5-87.9%, respectively. Moreover, the feasibility of the present method was also validated by real samples. To the best of our knowledge, this is the first time that USAEME has been applied to determine a strongly hydrophilic compound in alcoholic beverages.

  6. A new coupling of spectrophotometric determination with ultrasound-assisted emulsification dispersive liquid-liquid microextraction of trace silver

    NASA Astrophysics Data System (ADS)

    Wen, Xiaodong; Kong, Lamei; Chen, Meihui; Deng, Qingwen; Zhao, Xia; Guo, Jie

    2012-11-01

    In this work, a new coupling of spectrophotometric determination with preconcentration method named as ultrasound-assisted emulsification dispersive liquid-liquid microextraction (UAE-DLLME) for trace silver was firstly established. Disperser solvent in traditional DLLME was substituted by ultrasound-assisted emulsification, which could afford more effective emulsification and make the extraction method greener. The extraction was accomplished efficiently in only 3 min during ultrasound-assisted emulsification. Compared to traditional DLLME, the established pretreatment was simpler, greener and more effective. The UAE-DLLME technique was effectively coupled with ordinary spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The factors influencing UAE-DLLME, such as concentration of chelating agent, kind and volume of extractant, pH, conditions of phase separation, ultrasound extraction time and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for silver was 0.45 μg L-1, with sensitivity enhancement factor (EF) of 35. The established method was applied to the determination of trace silver in real and certified reference samples with satisfactory analytical results.

  7. A new coupling of spectrophotometric determination with ultrasound-assisted emulsification dispersive liquid-liquid microextraction of trace silver.

    PubMed

    Wen, Xiaodong; Kong, Lamei; Chen, Meihui; Deng, Qingwen; Zhao, Xia; Guo, Jie

    2012-11-01

    In this work, a new coupling of spectrophotometric determination with preconcentration method named as ultrasound-assisted emulsification dispersive liquid-liquid microextraction (UAE-DLLME) for trace silver was firstly established. Disperser solvent in traditional DLLME was substituted by ultrasound-assisted emulsification, which could afford more effective emulsification and make the extraction method greener. The extraction was accomplished efficiently in only 3 min during ultrasound-assisted emulsification. Compared to traditional DLLME, the established pretreatment was simpler, greener and more effective. The UAE-DLLME technique was effectively coupled with ordinary spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The factors influencing UAE-DLLME, such as concentration of chelating agent, kind and volume of extractant, pH, conditions of phase separation, ultrasound extraction time and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for silver was 0.45 μg L(-1), with sensitivity enhancement factor (EF) of 35. The established method was applied to the determination of trace silver in real and certified reference samples with satisfactory analytical results.

  8. Simultaneous determination of cork taint and Brett character responsible compounds in wine using ultrasound-assisted emulsification microextraction with solidification of floating organic drop.

    PubMed

    Pizarro, C; Sáenz-González, C; Pérez-del-Notario, N; González-Sáiz, J M

    2012-08-03

    In this study, ultrasound-assisted emulsification microextraction combined with solidification of floating organic drop method (USAEME-SFOD) has been proposed as a novel approach for the sensitive determination of haloanisoles and volatile phenols in wines. For this purpose, the influence of the different parameters affecting the procedure (type and volume of extraction solvent, temperature, time and ionic strength) was evaluated in order to optimise the efficiency of the process. Subsequently, the linearity, detection and quantification limits, precision, recoveries and applicability to real samples were studied, obtaining excellent method performance results. Moreover, USAEME-SFOD was compared with other liquid-liquid microextraction methods such as dispersive liquid-liquid microextraction (DLLME) and ultrasound-assisted emulsification microextraction (USAEME). This comparison study proved the suitability of USAEME-SFOD as an alternative to previously reported methods for the simultaneous determination of cork taint and Brett character responsible compounds in wines.

  9. Novel coupling of surfactant assisted emulsification dispersive liquid-liquid microextraction with spectrophotometric determination for ultra trace nickel

    NASA Astrophysics Data System (ADS)

    Deng, Qingwen; Chen, Meihui; Kong, Lamei; Zhao, Xia; Guo, Jie; Wen, Xiaodong

    2013-03-01

    In this work, dispersive liquid-liquid microextraction (DLLME) was improved and the preconcentration method named as surfactant assisted emulsification dispersive liquid-liquid microextraction (SAE-DLLME) was established for ultra trace nickel preconcentration and spectrophotometric determination. Non-ionic surfactant Triton X-100 (TX-100) was used as emulsifier and Triton X-114 (TX-114) was investigated as comparison. Disperser solvent was substituted by surfactant, which could afford more effective emulsification and make the extraction relatively greener. The extraction was accomplished efficiently in only 1 min during manual shaking. Compared to traditional DLLME, the developed SAE-DLLME pretreatment was simple, rapid and effective. The improved extraction technique was firstly coupled with traditional spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The influence factors relevant to SAE-DLLME including extraction parameters and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for nickel was 0.24 μg L-1, with sensitivity enhancement factor (EF) of 23.

  10. Novel coupling of surfactant assisted emulsification dispersive liquid-liquid microextraction with spectrophotometric determination for ultra trace nickel.

    PubMed

    Deng, Qingwen; Chen, Meihui; Kong, Lamei; Zhao, Xia; Guo, Jie; Wen, Xiaodong

    2013-03-01

    In this work, dispersive liquid-liquid microextraction (DLLME) was improved and the preconcentration method named as surfactant assisted emulsification dispersive liquid-liquid microextraction (SAE-DLLME) was established for ultra trace nickel preconcentration and spectrophotometric determination. Non-ionic surfactant Triton X-100 (TX-100) was used as emulsifier and Triton X-114 (TX-114) was investigated as comparison. Disperser solvent was substituted by surfactant, which could afford more effective emulsification and make the extraction relatively greener. The extraction was accomplished efficiently in only 1 min during manual shaking. Compared to traditional DLLME, the developed SAE-DLLME pretreatment was simple, rapid and effective. The improved extraction technique was firstly coupled with traditional spectrophotometer to improve the analytical performance and expand the application of spectrophotometric determination. The influence factors relevant to SAE-DLLME including extraction parameters and instrumental conditions, were studied in detail. Under the optimal conditions, the limit of detection (LOD) for nickel was 0.24 μg L(-1), with sensitivity enhancement factor (EF) of 23.

  11. Polytetrafluoroethylene physisorption-assisted emulsification microextraction as a cleanup and preconcentration step in the gas chromatography determination of aliphatic hydrocarbons in marine sediment samples.

    PubMed

    Molaei, Saeideh; Saleh, Abolfazl; Ghoulipour, Vanik; Seidi, Shahram

    2017-02-01

    For the first time, the application of polytetrafluoroethylene powder as an extractant phase collector or holder in liquid-phase microextraction has been developed. For this purpose, the analytical performances of two different ways of applying polytetrafluoroethylene powder in microextraction methods including polytetrafluoroethylene physisorption-assisted emulsification microextraction and dispersive liquid-phase microextraction via polytetrafluoroethylene extractant phase holders have been compared for analysis of aliphatic hydrocarbons in aqueous phases. Under the same conditions, the former showed better extraction efficiencies over the latter and as a result, it was applied as preconcentration and cleanup step in the analysis of aliphatic hydrocarbons in sediment samples followed by gas chromatography analysis. The linearity of the polytetrafluoroethylene physisorption-assisted emulsification microextraction method was obtained over a range of 3.7 and 2000 ng/g (R(2) > 0.993). The relative standard deviations were less than 6.5% (n = 3). The limits of detection and quantification obtained by this method were 1.1-9.0 and 3.7-30 ng/g, respectively, indicating that satisfactory results were achieved by the procedure.

  12. Development of ultrasound-assisted emulsification microextraction for determination of thiocynate ion in human urine and saliva samples.

    PubMed

    Hashemi, Mahdi; Daryanavard, Seyed Mosayeb; Abdolhosseini, Sana

    2013-02-15

    Ultrasound-assisted emulsification microextraction (USAE-ME) procedure coupled with UV-vis spectrophotometric measurement has been developed for determination of thiocyanate ion (SCN(-)) in water and biological fluids samples. The method is based on protonation of SCN(-) ions in acidic medium and extraction of thiocyanic acid into fine droplets of chloroform as an extraction solvent contains rhodamine B (RhB). The RhB was protonated in presence of thiocynanic acid to form highly colored ion-pair complex of [thiocynate][RhBH(+)] in chloroform, which used for subsequent spectrophotometric determination of SCN(-) ions. Experimental parameters for both spectrophotometric reaction and USAE-ME procedure have been optimized. Under optimized conditions the calibration curve for SCN(-) showed good linearity in the range of 38.0-870.0ngmL(-1) (R(2)=0.9967). The limit of detection (S/N=3) and preconcentration factor were 5.0ngmL(-1) and 40, respectively. Relative standard deviation for determination of 200ngmL(-1) of SCN(-) was 2.8% (n=5). The proposed method has been successfully applied for determination of SCN(-) ion in tap water, mineral bottled water and human saliva and urine samples with an average recovery of 99.2%.

  13. Development of ultrasound-assisted emulsification microextraction based on solidification of a floating organic droplet for determination of organochlorine pesticides in water samples.

    PubMed

    Shu, Bin; Yang, Zhaoguang; Lee, Hsiaowan; Qiu, Bo; Li, Haipu

    2016-02-01

    An ultrasound-assisted emulsification microextraction based on the solidification of a floating organic droplet followed by gas chromatography with electron capture detection was developed for the simultaneous determination of 13 organochlorine pesticides in water samples. In the proposed method, ultrasound was applied to achieve the emulsification without addition of any dispersive solvent. In consequence, the volume of extraction phase remained unaffected by the ion strength of aqueous phase and high extraction recoveries were obtained. It was also found that dilution of the floating phase with acetone was necessary for preventing peak splitting in chromatogram. Under optimal conditions, the proposed method provided good sensitivity (the detection limits of organochlorine pesticides ranged from 1.3 to 3.9 ng/L) and good repeatability of extraction (below 6.5%, n = 5). The recoveries in reservoir and river water samples were between 75.8% and 96.9%.

  14. Ionic liquid-based ultrasound-assisted emulsification microextraction coupled with high performance liquid chromatography for the determination of four fungicides in environmental water samples.

    PubMed

    Liang, Pei; Wang, Fang; Wan, Qin

    2013-02-15

    A highly efficient and environmentally friendly sample preparation method termed ionic liquid-based ultrasound-assisted emulsification microextraction (IL-USAEME) combined with high performance liquid chromatography has been developed for the determination of four fungicides (azoxystrobin, diethofencarb, pyrimethanil and kresoxim-methyl) in water samples. In this novel approach, ionic liquid (IL) was used as extraction solvent in place of the organic solvent used in conventional USAEME assay, and there is no need for using organic dispersive solvent which is typically required in the common dispersive liquid-liquid microextraction method. Various parameters that affect the extraction efficiency, such as the kind and volume of IL, ultrasound emulsification time, extraction temperature and salt addition were investigated and optimized. Under the optimum extraction condition, the linearities of calibration curves were in the range from 3 to 5000 ng mL(-1) for target analytes with the correlation coefficient higher than 0.9992. The enrichment factors and the limits of detection were in the range of 88-137 and 0.73-2.2 ng mL(-1), depending on the analytes. The environmental water samples were successfully analyzed using the proposed method, and the relative recoveries at fortified levels of 50 and 100 ng mL(-1) were in the range of 83.9%-116.2%.

  15. Orthogonal array optimization of ultrasound-assisted emulsification-microextraction for the determination of chlorinated phenoxyacetic acids in river water.

    PubMed

    Lin, Shu-Ling; Fuh, Ming-Ren

    2010-05-21

    Orthogonal array design (OAD) was utilized for the first time to optimize the experimental conditions of ultrasound-assisted emulsification-microextraction (USAEME) for determining chlorinated phenoxyacetic acids (CPAs) in river water samples. The use of ultrasound facilitates the mass transfer of CPAs from an aqueous phase into a water-immiscible organic extraction solvent (dichloromethane, DCM) without adding dispersive solvent to form numerous microdroplets. The water-immiscible extractant was collected by centrifugation, dried under low pressure, reconstituted in methanol-water mixture (1:1), and injected into a HPLC system for the determination of CPAs. The linear range was 2-1000 ng mL(-1) (2, 5, 10, 50, 200, 500 and 1000 ng mL(-1)) for each analyte and the relative standard deviations of CPAs among the seven different concentrations were in the range of 1.5-17.0% (n=3). The detection limits (signal-to-noise ratio of 3) of CPAs ranged from 0.67 to 1.50 ng mL(-1). The ranges of intra-day precision (n=3) for CPAs at the levels of 5 and 200 ng mL(-1) were 3.6-11.9% and 5.3-9.5%, respectively. The range of inter-day precision (n=3) at 5 and 200 ng mL(-1) were 1.4-7.7% and 8.5-12.2%, respectively. The applicability of USAEME for environmental analysis was demonstrated by determining CPAs in river water. The recoveries of CPAs from five-spiked river water samples at 10 and 200 ng mL(-1) were 96.3-112.5% and 94.8-109.4%, respectively. The maximum contaminant level (MCL) of 2,4-D in drinking water and the tolerance of residues in food for p-CPA are 70 and 200 microg L(-1), respectively, according to the US EPA regulations. These contaminant levels fall in the linear range investigated in this study. In addition, this USAEME method provided detection limits lower than their contaminant levels, which made USAEME an effective sample preparation method for determining organic environmental contaminants, such as CPAs, in river water samples with little consumption of

  16. Ultrasound-assisted emulsification microextraction with simultaneous derivatization coupled to fibre optics-based cuvetteless UV-vis micro-spectrophotometry for formaldehyde determination in cosmetic samples.

    PubMed

    Lavilla, Isela; Cabaleiro, Noelia; Pena, Francisco; de la Calle, Inmaculada; Bendicho, Carlos

    2010-07-26

    In this work, ultrasound-assisted emulsification microextraction in combination with fibre optics-based cuvetteless UV-vis micro-spectrophotometry has been proposed as a novel method for the determination of formaldehyde in water-based cosmetics such as shampoo, conditioner and shower gel. The use of a powerful cup-horn sonoreactor allows simultaneous extraction and derivatization of the samples without any pre-treatment. The type and volume of organic extractant solvent, need for a disperser solvent, sonication conditions (sonication time and amplitude), ionic strength and centrifuging time have been carefully studied. Matrix effects were also evaluated. The European official method for quantification of formaldehyde in cosmetic products was used for comparison purposes. An important improvement in sensitivity and sample throughput as well as miniaturization was achieved. A limit of detection of 0.02 microg g(-1) of formaldehyde and a repeatability expressed as relative standard deviation of 5.9% were obtained.

  17. Solvent-based de-emulsification dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry for determination of trace organochlorine pesticides in environmental water samples.

    PubMed

    Zacharis, Constantinos K; Tzanavaras, Paraskevas D; Roubos, Konstantinos; Dhima, Kico

    2010-09-17

    In this work, we propose solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME) as a simple, rapid and efficient sample pretreatment technique for the extraction and preconcentration of organochlorine pesticides (OCPs) from environmental water samples. Separation and analysis of fifteen OCPs was carried out by gas chromatography-mass spectrometry (GC/MS). Parameters affecting the extraction efficiency were systematically investigated. The detection limits were in the range of 2-50 ng L(-1) using selective ion monitoring (SIM). The precision of the proposed method, expressed as relative standard deviation, varied between 3.5 and 10.2% (n=5). Results from the analysis of spiked environmental water samples at the low-ppb level met the acceptance criteria set by the EPA.

  18. Sonication-assisted emulsification microextraction combined with vortex-assisted porous membrane-protected micro-solid-phase extraction using mixed zeolitic imidazolate frameworks 8 as sorbent.

    PubMed

    Ge, Dandan; Lee, Hian Kee

    2012-11-09

    Mixed zeolitic imidazolate framework 8 (ZIF-8) (nanometer and micron-sized) material were synthesized and applied as sorbent to sonication-assisted emulsification microextraction coupled to vortex-assisted porous membrane-protected micro-solid-phase extraction (SAE-VA-μ-SPE) of polycyclic aromatic hydrocarbons (PAHs) from water samples. Better extraction results was obtained by using the mixed sorbent for the extraction of PAHs from aqueous samples, than either nanometer or micron-sized ZIF-8 separately. The developed method proved to be a time-saving, highly efficient (total extraction procedure was less than 10 min), accurate and robust method for water sample pretreatment. Parameters influencing the extraction efficiency such as desorption solvent, extraction solvent volume, emulsification time, desorption time and salt concentration were investigated and optimized. The limits of detection from gas chromatography-mass spectrometric analysis of six PAHs after SAE-VA-μ-SPE ranged between 0.004 and 0.011 ng/ml. The linear ranges were from 0.05 to 50 ng/ml, and the correlation coefficient was higher than 0.9943. The proposed method provides an interesting and innovative approach of combining different microscale sample preparation methods to solve analytical problems that are not easily addressed by the individual procedure alone.

  19. Development of liquid phase microextraction based on manual shaking and ultrasound-assisted emulsification method for analysis of organochlorine pesticides in aqueous samples.

    PubMed

    Wei, Shuo-Yang; Leong, Mei-I; Li, Yee; Huang, Shang-Da

    2011-12-23

    A novel method using sample preparation method, "ultrasound-assisted emulsification microextraction" (USAEME) with manual shaking, coupled with gas chromatography using and an electron capture detector (GC-ECD) was developed for the analysis of organochlorine pesticides (OCPs) in aqueous samples. The apparatus is simple and easy to operate. After manual shaking for 10s, ultrasound was used to accelerate emulsification of the organic solvent (1-decanol) in aqueous solution. Only 10 μL of the low-toxicity extraction solvent is used in this method; no dispersive solvent is required and the total extraction time is ∼4 min. Manual shaking before ultrasound-assisted emulsification enhances the extraction efficiency by >100%. The effects of horizontal and vertical orientation as well as the location of the sample within the ultrasonic bath were studied. After centrifugation, we used an improved solvent collection system (ISCS) to reduce the amount of extraction solvent required. A 1 μL sample of the extract was injected into the GC column. Under optimum conditions, the linear range of the method is 5-2500 ngL(-1) for most of the OCPs, and the limit of detection of the method ranged from 0.6 to 2.9 ngL(-1).The relative recoveries ranged from 75 to 107% for sea water and from 70 to 99% for field fresh water. The method, which provides good enrichment factors, low LODs and minimization of the consumption of organic solvent, provides a rapid, simple and environment-friendly procedure for determining OCPs in aqueous samples.

  20. Ultrasound-Assisted Emulsification Microextraction Based on Solidification Floating Organic Drop Trace Amounts of Manganese Prior to Graphite Furnace Atomic Absorption Spectrometry Determination

    PubMed Central

    Mohadesi, Alireza; Falahnejad, Masoumeh

    2012-01-01

    In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn+2 at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50–10.0 ng mL−1 with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL−1 was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

  1. Ionic liquid-based totally organic solvent-free emulsification microextraction coupled with high performance liquid chromatography for the determination of three acaricides in fruit juice.

    PubMed

    Zhang, Jiaheng; Liang, Zhe; Guo, Hao; Gao, Peng; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

    2013-10-15

    A novel, totally organic solvent-free emulsification microextraction (TEME) technique using ionic liquids (ILs) is proposed in this study. Seven bis(trifluoromethylsulfonyl)imide ionic liquids were synthesized. After comparing the physicochemical properties of the ionic liquids and their application to microextraction experiments, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6MIM][NTf2]), which has moderate surface tension and viscosity, was selected as the extraction solvent. The dispersion of ILs and mass transfer were accelerated by ultrasound irradiation and temperature control processes. Therefore, no dispersive organic solvent was needed. Several variables, such as ionic liquid volume, duration of the ultrasound extraction, dispersion temperature, ionic strength and centrifugation time were investigated and optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.1-600 μg L(-1) for chlorfenapyr and fenpyroximate and 0.5-600 μg L(-1) for spirodiclofen, with correlation coefficients of 0.9994-0.9999. The enrichment factors were between 261 and 285. The limits of detection (LODs) were 0.02-0.06 μg L(-1). Real fruit juice samples (at fortified levels of 10 μg L(-1) and 30 μg L(-1)) were successfully analyzed using the proposed method. The relative recoveries and enrichment factors were in the range of 92-104%.

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

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2012-08-24

    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

  3. In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry.

    PubMed

    Shokri, Masood; Beiraghi, Asadollah; Seidi, Shahram

    2015-08-19

    For the first time, a simple and efficient in situ emulsification microextraction method using a dicationic ionic liquid followed by magnetic assisted physisorption was presented to determine trace amounts of lead. In this method, 400 μL of 1.0 mol L(-1) lithium bis (trifluoromethylsulfonyl) imide aqueous solution, Li[NTf2], was added into the sample solution containing 100 μL of 1.0 mol L(-1) 1,3-(propyl-1,3-diyl) bis (3-methylimidazolium) chloride, [pbmim]Cl2, to form a water immiscible ionic liquid, [pbmim][NTf2]2. This new in situ formed dicationic ionic liquid was applied as the acceptor phase to extract the lead-ammonium pyrrolidinedithiocarbamate (Pb-APDC) complexes from the sample solution. Subsequently, 30 mg of Fe3O4 magnetic nanoparticles (MNPs) were added into the sample solution to collect the fine droplets of [pbmim][NTf2]2, physisorptively. Finally, MNPs were eluted by acetonitrile, separated by an external magnetic field and the obtained eluent was subjected to micro-sampling flame atomic absorption spectrometry (FAAS) for further analysis. Comparing with other microextraction methods, no special devices and centrifugation step are required. Parameters influencing the extraction efficiency such as extraction time, pH, concentration of chelating agent, amount of MNPs and coexisting interferences were studied. Under the optimized conditions, this method showed high extraction recovery of 93% with low LOD of 0.7 μg L(-1). Good linearity was obtained in the range of 2.5-150 μg L(-1) with determination coefficient (r(2)) of 0.9921. Relative standard deviation (RSD%) for seven repeated measurements at the concentration of 10 μg L(-1) was 4.1%. Finally, this method was successfully applied for determination of lead in some water and plant samples.

  4. Ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction coupled with capillary electrophoresis for the determination of parabens in personal care products.

    PubMed

    Ma, Teng; Li, Zheng; Jia, Qiong; Zhou, Weihong

    2016-07-01

    We developed a CE and ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction method for the determination of four parabens (methyl paraben, ethyl paraben, propyl paraben, and butyl paraben) in personal care products including mouthwash and toning lotion. In the proposed extraction procedure, ionic liquid (IL, 1-octyl-3-methylimidazolium hexafluorophosphate) was used as extraction solvent, moreover, no disperser solvent was needed. Parameters affecting the extraction efficiency including volume of IL, heating temperature, ultrasonic time, extraction time, sample pH, ionic strength, and centrifugation time were optimized. Under the optimized conditions, the method was found to be linear over the range of 3-500 ng/mL with coefficient of determination (R(2) ) in the range of 0.9990-0.9998. The LODs and LOQs for the four parabens were 0.45-0.72 ng/mL and 1.50-2.40 ng/mL, respectively. Intraday and interday precisions (RSDs, n = 5) were in the range of 5.4-6.8% and 7.0-8.7%, respectively. The recoveries of parabens at different spiked levels ranged from 71.9 to 119.2% with RSDs less than 9.5%.

  5. Measurement of selected polychlorinated biphenyls (PCBs) in water via ultrasound assisted emulsification-microextraction (USAEME) using low-density organic solvents.

    PubMed

    Yurdakok-Dikmen, Begum; Kuzukiran, Ozgur; Filazi, Ayhan; Kara, Erdem

    2016-04-01

    Despite bans and restrictions for their adverse health effects including endocrine disruption, due to their stability in the environment, polychlorinated biphenyls (PCBs) are still of concern for their residues in several matrices. This study employed low-density ultrasound-assisted emulsification-microextraction (USAEME) to measure selected PCBs (28, 52, 101, 118, 138, 153, and 180) in water samples for gas chromatography-mass spectrometry analysis. Among tested solvents (isooctane, chloroform, hexane, and cyclohexane), 200 μL isooctane resulted in the highest yield for a 10 mL sample. The optimized method was validated and yielded recoveries of 87.29-92.83% with the limit of detection and limit of quantification (LOQ) values 3-12 ng/L and 10-40 ng/L, respectively. Twelve tap water samples collected in September 2014 were screened using this simple, rapid, and validated method. PCB concentrations in two samples were above the LOQ values; one sample contained 1,380 ng/L of PCB 118, 530 ng/L of PCB 138, and 152 ng/L of PCB 153, and the other contained 444 ng/L of PCB 138. Despite the city water supply being clean and the municipality employing all available measures to ensure clean water supply, the general public must be made aware of the regular maintenance of local water pipelines and storage tanks for the prevention of PCB contamination.

  6. Water-based slow injection ultrasound-assisted emulsification microextraction for the determination of deoxynivalenol and de-epoxy-deoxynivalenol in maize and pork samples.

    PubMed

    Li, Songqing; Li, Yanshen; Wang, Ying; Zhou, Wenfeng; Gao, Haixiang; Zhang, Suxia

    2013-05-01

    A novel water-based slow injection ultrasound-assisted emulsification microextraction (SI-USAEME) method followed by ultra-high performance liquid chromatography-tandem mass spectrometry analysis was developed for the rapid pretreatment and determination of deoxynivalenol (DON) and its metabolite, de-epoxy-deoxynivalenol (DOM-1), in maize and pork samples. After optimization, the method recoveries for DON and DOM-1 ranged from 73 to 85 % with intraday and interday variations less than 9.4 and 9.2 %, respectively. The limits of detection for DON were 4.2 μg kg(-1) in maize and 6.2 and 5.9 μg kg(-1) for DON and DOM-1, respectively, in pork. In addition, an immunoaffinity column (IAC) was prepared. A study comparing the IAC cleanup method, the solid-phase extraction (SPE) cleanup method, and the proposed SI-USAEME method was presented. The water-based SI-USAEME method could become a simple, low-cost alternative to the conventional IAC and SPE method. The method was successfully applied to the analysis of commercial maize and pork products.

  7. Determination of personal care products and hormones in leachate and groundwater from Polish MSW landfills by ultrasound-assisted emulsification microextraction and GC-MS.

    PubMed

    Kapelewska, Justyna; Kotowska, Urszula; Wiśniewska, Katarzyna

    2016-01-01

    Determination of the endocrine disrupting compounds (EDCs) in leachate and groundwater samples from the landfill sites is very important because of the proven harmful effects of these compounds on human and animal organisms. A method combining ultrasound-assisted emulsification microextraction (USAEME) and gas chromatography-mass spectrometry (GC-MS) was developed for simultaneous determination of seven personal care products (PCPs): methylparaben (MP), ethylparaben (EP), propylparaben (PP), buthylparaben (BP), benzophenone (BPh), 3-(4-methylbenzylidene)camphor (4-MBC), N,N-diethyltoluamide (DEET), and two hormones: estrone (E1) and β-estradiol (E2) in landfill leachate and groundwater samples. The limit of detection (LOD)/limit of quantification (LOQ) values in landfill leachate and groundwater samples were in the range of 0.003-0.083/0.009-0.277 μg L(-1) and 0.001-0.015/0.002-0.049 μg L(-1), respectively. Quantitative recoveries and satisfactory precision were obtained. All studied compounds were found in the landfill leachates from Polish municipal solid waste (MSW) landfills; the concentrations were between 0.66 and 202.42 μg L(-1). The concentration of pollutants in groundwater samples was generally below 0.1 μg L(-1).

  8. Speciation of antimony(III) and antimony(V) by electrothermal atomic absorption spectrometry after ultrasound-assisted emulsification of solidified floating organic drop microextraction.

    PubMed

    Wen, Shengping; Zhu, Xiashi

    2013-10-15

    A simple, sensitive and efficient method of ultrasound-assisted emulsification of solidified floating organic drop microextraction (USE-SFODME) coupled to electrothermal atomic absorption spectrometry for the speciation of antimony at different oxidation state Sb(III)/Sb(V) in environmental samples was established. In this method, the hydrophobic complex of Sb(III) with sodium diethyldithiocarbamate (DDTC) is extracted by 1-undecanol at pH 9.0, while Sb(V) remains in aqueous phase. Sb(V) content can be calculated by subtracting Sb(III) from the total antimony after reducing Sb(V) to Sb(III) by l-cysteine. Various factors affecting USE-SFODME including pH, extraction solvent and its volume, concentration of DDTC, sonication time, and extraction temperature were investigated. Under the optimized conditions, the calibration curve was linear in the range from 0.05 to 10.0 ng mL(-1), with the limit of detection (3σ) 9.89 ng L(-1) for Sb(III). The relative standard deviation for Sb(III) was 4.5% (n=9, c=1.0 ng mL(-1)). This method was validated against the certified reference materials (GSB 07-1376-2001, GBW07441), and applied to the speciation of antimony in environmental samples (soil and water samples) with satisfactory results.

  9. Surfactant-enhanced alkaline flooding for light oil recovery. Annual report, 1992--1993

    SciTech Connect

    Wasan, D.T.

    1994-08-01

    In this report, the authors present the results of experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, the authors have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil, and (4) developed a technique to study water-in-oil emulsion film properties.

  10. Analysis of phenolic pollutants in human samples by high performance capillary electrophoresis based on pretreatment of ultrasound-assisted emulsification microextraction and solidification of floating organic droplet.

    PubMed

    Wang, Huili; Yan, Hao; Wang, Chengjun; Chen, Fan; Ma, Meiping; Wang, Wenwei; Wang, Xuedong

    2012-08-31

    A novel, simple and rapid method, termed ultrasound-assisted emulsification microextraction and solidification of floating organic droplet (UAEM-SFO) coupled to high performance capillary electrophoresis (HPCE), was developed for preconcentration and analysis of five phenolic compounds (PCs) in human urine and blood samples. The proposed method is based on microextraction of target analytes in less-toxic organic solvent under assistance of ultrasound. A micro-droplet of less-toxic organic solvent floating on the surface of liquid samples in a sealed vial can be dispersed into sample solutions under the ultrasound frequency, solidified under ice bath, collected with a medicine spatula, molten at ambient temperature, and finally subjected to HPCE analysis. The parameters of UAEM-SFO procedure including type and volume of extraction solvent, extraction temperature, time of ultrasound-assisted extraction and centrifugation, sample pH, and ionic strength were optimized. The influence parameters on HPCE resolution such as pH, concentration of running buffer, applied voltage and injection time were also investigated. This method requires only 40 μL of 2-dodecanol extraction solvent and 8 min of pretreatment time. The enrichment factors of analytes were in the range of 114-172 and extraction recoveries (69-86%) were obtained. Good linearity was achieved for five analytes in the range of 0.05-100 μg L⁻¹ and the correlation coefficients ranged from 0.9934 to 0.9999. The limits of detection were 0.01 μg L⁻¹ for triclosan (TCS) and biophenol A (BPA), and 0.02 μg L⁻¹ for pentachlorophenol (PCP), 2,4-dichlorophenol (2,4-DCP) and 4-nonylphenol (4-NP) in urine samples, and 0.02 μg L⁻¹ for TCS and BPA, 0.04 μg L⁻¹ for PCP, 2,4-DCP and 4-NP in blood samples. The developed UAEM-SFO-HPCE method has a great potential in routine residual analysis of trace PCs in biological samples.

  11. Emulsification liquid-liquid microextraction based on deep eutectic solvent: An extraction method for the determination of benzene, toluene, ethylbenzene and seven polycyclic aromatic hydrocarbons from water samples.

    PubMed

    Khezeli, Tahere; Daneshfar, Ali; Sahraei, Reza

    2015-12-18

    In this study, for the first time, a simple, inexpensive and sensitive method named emulsification liquid-liquid microextraction based on deep eutectic solvent (ELLME-DES) was used for the extraction of benzene, toluene, ethylbenzene (BTE) and seven polycyclic aromatic hydrocarbons (PAHs) from water samples. In a typical experiment, 100μL of DES (as water-miscible extraction solvent) was added to 1.5mL of sample solution containing target analytes. A homogeneous solution was formed immediately. Injection of 100μL of THF (as emulsifier agent) into homogeneous solution provided a turbid state. After extraction, phase separation (aqueous phase/DES rich phase) was performed by centrifugation. DES rich phase was withdrawn by a micro-syringe and submitted to isocratic reverse-phase HPLC with UV detection. Under optimum conditions obtained by response surface methodology (RSM) and desirability function (DF), the calibration graphs were linear in the concentration range from 10 to 200μg/L for benzene, 10-400μg/L for toluene, 1-400μg/L for ethylbenzene, biphenyl, chrysene and fluorene, and 0.1-400μg/L for anthracene, benzo[a]pyrene, phenanthrene and pyrene. The coefficients of determination (r(2)) and limits of detection were 0.9924-0.9997 and 0.02-6.8μg/L, respectively. This procedure was successfully applied to the determination of target analytes in spiked water samples. The relative mean recoveries ranged from 93.1 to 103.3%.

  12. Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry.

    PubMed

    Ahmadvand, Mohammad; Sereshti, Hassan; Parastar, Hadi

    2015-09-25

    In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a comprehensive analysis, multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was used for resolution, identification and quantification of the target PAHs in the presence of uncalibrated interferences. The regression coefficients and relative errors (REs, %) of calibration curves of the PAHs were in the satisfactory range of 0.9971-0.9999 and 1.17-6.59%, respectively. Furthermore, analytical figures of merit (AFOM) for univariate and second-order calibrations were obtained and compared. As an instance, the limit of detections (LODs) of target PAHs were in the range of 1.87-18.9 and 0.89-6.49ngmL(-1) for univariate and second-order calibration, respectively. Finally, the proposed strategy was used for determination of target PAHs in real water samples (tap and hookah waters). The relative recoveries (RR) and the relative standard deviations (RSDs) were 68.4-109.80% and 2.15-6.93%, respectively. It was concluded that combination of multivariate chemometric methods with USAEME-GC-MS can be considered as a new insight for the analysis of target analytes in complex sample matrices.

  13. A sensitive emulsification liquid phase microextraction coupled with on-line phase separation followed by HPLC for trace determination of sulfonamides in water samples.

    PubMed

    Ebrahimpour, Behnam; Yamini, Yadollah; Rezazadeh, Maryam

    2015-01-01

    For the first time, ion-pair based emulsification liquid phase microextraction coupled with a novel approach for phase separation followed by high performace liquid chromatgraphy (HPLC) was utilized for trace determination of sulfonamides in water samples. After the formation of ion-pair complex with a cationic surfactant, sulfonamides were extracted into the drops of dispersed organic extracting solvent. Then, the cloudy solution was passed through an in-line filter located in a suitable holder and was separated based on emulsion filtration. By changing the HPLC valve position, the filter was laid in the mobile phase path, and the extraction phase was eluted by the mobile phase and introduced into the separation column for analysis. The effects of important parameters, such as type of extraction solvent, type of ion-pair agent and its concentration, pH of sample solution, ionic strength, and volume of extraction phase, on the extraction efficiency, were investigated and optimized. Under optimal conditions, the linear range, limits of detection, and precision (relative standard deviations) were 0.3-100, 0.1-0.3 μg L(-1), and 4.7-5.8%, respectively. Preconcentration factors (PFs) for the compounds studied were obtained in the range of 268-664. These PFs correspond to extraction recoveries in the range of 41-97%. The sample throughput of the method was 3 samples per hour, regarding 20 min analysis time for a single procedure. Finally, the method was successfully applied to determine the selected sulfonamides in some water samples.

  14. Determination of molybdenum in plants by vortex-assisted emulsification solidified floating organic drop microextraction and flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Oviedo, Jenny A.; Fialho, Lucimar L.; Nóbrega, Joaquim A.

    2013-08-01

    A fast and sensitive procedure for extraction and preconcentration of molybdenum in plant samples based on solidified floating organic drop microextraction combined with flame atomic absorption spectrometry and discrete nebulization was developed. 8-Hydroxyquinoline (8-HQ) was used as complexing agent. The experimental conditions established were: 0.5% m v- 1 of 8-HQ, 60 μL of 1-undecanol as the extractant phase, 2 min vortex extraction time, centrifugation for 2 min at 2000 rpm, 10 min into an ice bath and discrete nebulization by introducing 200 μL of solution. The calibration curve was linear from 0.02 to 4.0 mg L- 1 with a limit of detection of 4.9 μg L- 1 and an enhancement factor of 67. The relative standard deviations for ten replicate measurements of 0.05 and 1.0 mg L- 1 Mo were 6.0 and 14.5%, respectively. The developed procedure was applied for determining molybdenum in corn samples and accuracy was proved using certified reference materials.

  15. Novel solvent-free microwave-assisted extraction coupled with low-density solvent-based in-tube ultrasound-assisted emulsification microextraction for the fast analysis of organophosphorus pesticides in soils.

    PubMed

    Su, Yi-Song; Yan, Cheing-Tong; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

    2013-07-01

    A novel and rapid solventless microwave-assisted extraction coupled with low-density solvent-based in-tube ultrasound-assisted emulsification microextraction has been developed for the efficient determination of nine organophosphorus pesticides in soils by GC analysis with microelectron capture detection. A specially designed, homemade glass tube inbuilt with a scaled capillary tube was used as an extraction device to collect and measure the separated extractant phase easily. Parameters affecting the efficiencies of the developed method were thoroughly investigated. From experimental results, the following conditions were selected for the extraction of organophosphorus pesticides from 1.0 g of soil sample to 5 mL of aqueous solution under 226 W of microwave irradiation for 2.5 min followed by ultrasound-assisted emulsification microextraction with 20 μL toluene for 30 s and then centrifugation at 3200 rpm for 3 min. Detections were linear in the range of 0.25-10 ng/g with detection limits between 0.04 and 0.13 ng/g for all target analytes. The applicability of the method to real samples was assessed on agricultural contaminated soils and the recoveries ranged between 91.4 and 101.3%. Compared to other methods, the present method was shown to be highly competitive in terms of sensitivity, cost, eco-friendly nature, and analysis speed.

  16. Surfactant-enhanced alkaline flooding for light oil recovery. [Annual report], 1993--1994

    SciTech Connect

    Wasan, D.T.

    1995-03-01

    In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (2) investigated the kinetics of oil removal from a silica surface, and (3) developed a theoretical interfacial activity model for determining equilibrium interfacial tension. The results of the studies conducted during the course of this project are presented.

  17. Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, April 1, 1995--June 30, 1995

    SciTech Connect

    Wasan, D.T.

    1995-09-01

    The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested.

  18. SIMULATION OF SURFACTANT-ENHANCED AQUIFER REMEDIATION

    EPA Science Inventory

    Surfactant-enhanced aquifer remediation (SEAR) is currently under active investigation as one of the most promising alternatives to conventional pump-and-treat remediation for aquifers contaminated by dense nonaqueous phase organic liquids. An existing three-dimensional finite-di...

  19. Centrifugeless ultrasound-assisted emulsification microextraction based on salting-out phenomenon followed by high-performance liquid chromatography for the simple determination of phthalate esters in aqueous samples.

    PubMed

    Mirparizi, Ehsan; Rajabi, Maryam; Bazregar, Mohammad; Asghari, Alireza

    2017-03-20

    A fast, sensitive, and centrifugeless ultrasound-assisted emulsification microextraction followed by high performance liquid chromatography method is developed for the determination of some phthalate esters in aqueous samples. In this method, a simple approach is followed for elimination of the centrifugation step in dispersive liquid-liquid microextraction using an organic solvent whose melting point is near the ambient temperature, consumption of the extracting solvent is efficiently reduced, and the overall extraction time was found to be only 7 min. The variables affecting the method are optimized. Under the optimal experimental conditions (75 μL of 1-undecanol, a flow rate of 2.0 mL min(-1) , and an ultrasound irradiation of 1 min), the proposed method exhibits good preconcentration factors (52-97), low limits of detection (1.0-5.0 ng mL(-1) ), and linearities in the range of 5-1500 ng mL(-1) (r(2) ≥ 0.995). Finally, the method is successfully applied to the analysis of phthalate esters in the drinking and river water samples. To study the probable release of the phthalate esters from a polyethylene container into boiling water, the boiling water exposed to the polyethylene container was analyzed by the proposed method. This article is protected by copyright. All rights reserved.

  20. Surfactant-enhanced alkaline flooding field project

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  1. Surfactant-enhanced alkaline flooding for light oil recovery. Final report 1994--1995

    SciTech Connect

    Wasan, D.T.

    1995-12-01

    In this report, the authors present the results of their experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, the authors have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil, and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are summarized.

  2. Surfactant-enhanced alkaline flooding for light oil recovery. Final report

    SciTech Connect

    Wasan, D.T.

    1996-05-01

    In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12. 0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are discussed.

  3. A new 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid based ultrasound-assisted emulsification microextraction for the determination of organic ultraviolet filters in environmental water samples.

    PubMed

    Ge, Dandan; Lee, Hian Kee

    2012-08-17

    A novel microextraction approach termed ionic liquid based ultrasound-assisted emulsification microextraction (IL-USAEME) combined with high-performance liquid chromatography-ultraviolet (HPLC-UV) was developed for the preconcentration and detection of organic ultraviolet (UV) filters in environmental water samples. An ionic liquid (IL) was used in place of an organic solvent as in conventional USAEME. In the study, orthogonal array designs (OAD) were employed for the optimization of the extraction parameters: type of IL, pH of the sample, extraction volume, ultrasonic time and salt concentration. In the first step, a mixed level OAD matrix, OA(16) (4(1) × 2(12)) was employed for the initial optimization. Based on the results of the first step, an ultra-hydrophobic IL, 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate was chosen as the IL extractant and sample pH was set at a value of 3. Ultrasonic time, extraction volume and salt concentration were further optimized in the second step by an OA(16) (4(5)) matrix. Under the latter optimized conditions, calibration curves with coefficients of estimation higher than 0.997 over the concentration range of 5 and 1000 ng/ml, and the relative standard deviations for six replicates of the extraction from 2.6 to 6.6% were obtained. The limits of detection for four organic UV filters were between 0.5 and 1 ng/ml. The validated technique was applied to the analysis of organic UV filters in environmental water samples.

  4. Zeolite imidazolate frameworks 8 as sorbent and its application to sonication-assisted emulsification microextraction combined with vortex-assisted porous membrane-protected micro-solid-phase extraction for fast analysis of acidic drugs in environmental water samples.

    PubMed

    Ge, Dandan; Lee, Hian Kee

    2012-09-28

    A novel and fast procedure, sonication-assisted emulsification microextraction combined with vortex-assisted porous membrane protected micro-solid-phase extraction (SAEME-VA-μ-SPE), was developed for the gas chromatography-mass spectrometric determination of acidic drugs from environmental water samples. One advantage of the new procedure is that any solvent immiscible with water can be used as extractant solvent of SAEME and any solid sorbent can be used for μ-SPE in the SAEME-VA-μ-SPE process. In the present work, zeolite imidazolate framework 8 (ZIF-8) was employed as extraction sorbent for μ-SPE and 1-octanol as extractant solvent for SAEME. ZIF-8 has very good thermal, chemical and water stability, which make it a suitable material for the extraction of trace analytes from aqueous samples. Under the optimized extraction conditions, the developed method exhibited low limits of detection (0.01-0.04 ng/ml), good linearity (with r² between 0.9965 and 0.9993) from 0.5 to 50 ng/ml and satisfactory repeatability (between 4.1% and 7.6%). In essence SAEME-VA-μ-SPE is a combination of two different and efficient miniaturized techniques. It was demonstrated to be a fast, accurate, and convenient pretreatment procedure for trace analysis of environmental water samples.

  5. Determination of nitrophenols using ultrahigh pressure liquid chromatography and a new manual shaking-enhanced, ultrasound-assisted emulsification microextraction method based on solidification of a floating organic droplet.

    PubMed

    Chung, Ren-Je; Leong, Mei-I; Huang, Shang-Da

    2012-07-13

    Nitrophenols are toxic compounds in the wastewater. In the proposed method, a new technique using a manual shaking-enhanced, ultrasound-assisted emulsification microextraction (MS-USAEME) method based on solidification of a floating organic droplet combined with ultrahigh pressure liquid chromatography (UHPLC) has been developed for the extraction and determination of nitrophenols in aqueous samples. In this method, the low toxicity extraction solvent 1-undecanol was used to extract the nitrophenols. After centrifugation, ice bath was used to solidify the floating extraction solvent, using microtubes to collect the floated extraction solvent and diluting with 30 μL of dimethyl sulfoxide, then injecting into the UHPLC for further analysis. The relative standard deviations (RSD) were 6-12%, enrichment factors (EFs) were 62-500, the relative recoveries (RR) of this method were 80-110% for spiked lake water samples. The detection limits of this method were 0.5-3.0 μg L⁻¹ for spiked lake water and 0.6-3.2 μg L⁻¹ for spiked agriculture water. The further performance of the proposed method was gauged by analyzing field samples.

  6. Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, October 1--December 30, 1994

    SciTech Connect

    Wasan, D.T.

    1994-12-31

    The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested. The problem of characterizing emulsions in porous media is very important in enhanced oil recovery applications. This is usually accomplished by externally added or insitu generated surfactants that sweep the oil out of the reservoir. Emulsification of the trapped oil is one of the mechanisms of recovery. The ability to detect emulsions in the porous medium is therefore crucial to designing profitable flood systems. The capability of microwave dielectric techniques to detect emulsions in porous medium is demonstrated by mathematical modelling and by experiments. This quarter the dielectric properties of porous media are shown to be predicted adequately by treating it an an O/W type dispersion of sand grains in water. Dielectric measurements of emulsion flow in porous media show that dielectric techniques may be applied to determine emulsion characteristics in porous media. The experimental observations were confirmed by theoretical analysis.

  7. Surfactant-enhanced alkaline flooding for light oil recovery. [Quarterly] report, March 31--June 30, 1993

    SciTech Connect

    Wasan, D.T.

    1993-09-01

    The overall objective of this project is to develop a very cost- effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested. Last quarter we have investigated the mechanisms responsible for spontaneous emulsification in alkali/acidic crude oil systems with and without added surfactant. We have observed that the roll cell size and formation time depend strongly on the pH and ionic strength of the alkaline solution. For a particular roll cell size, the addition of surfactant causes the cells to take longer to form, causing an interfacial resistance to mass transfer and making the interface more rigid. We have shown that interfacial turbulence is a necessary but not sufficient condition for spontaneous emulsification. Low interfacial tension is also a necessary condition. This quarter a microwave interferometric procedure was developed for the determination of low water content (0. 5 to 10 vol%) of water-in-oil macroemulsions. The apparatus operates at a frequency of 23.48 GHz in the K-band microwave region. The procedure is based on the large differences in dielectric properties between water and oil, and it utilizes the variation in phase shift as sample path length is varied. Measurements are accurate to within 0.5 vol% water.

  8. Optimization of modified dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the simultaneous preconcentration and determination of nitrazepam and midazolam drugs: An experimental design.

    PubMed

    Goudarzi, Nasser; Farsimadan, Sahar; Chamjangali, Mansour Arab; Bagherian, Ghadam Ali

    2015-05-01

    A simple, sensitive, and rapid microextraction method, namely, ultrasound-assisted surfactant-enhanced emulsification microextraction based on the solidification of floating organic droplet method coupled with high-performance liquid chromatography was developed for the simultaneous preconcentration and determination of nitrazepam and midazolam. The significant parameters affecting the extraction efficiency were considered using Plackett-Burman design as a screening method. To obtain the optimum conditions with consideration of the selected significant variables, a Box-Behnken design was used. The microextraction procedure was performed using 29.1 μL of 1-undecanol, 1.36% (w/v) of NaCl, 10.0 μL of sodium dodecyl sulfate (25.0 μg mL(-1)), and 1.0 μL of Tween80 (25.0 μg mL(-1)) as an emulsifier in an extraction time of 20.0 min at pH 7.88. In order to investigate the validation of the developed method, some validation parameters including the linear dynamic range, repeatability, limit of detection, and recoveries were studied under the optimum conditions. The detection limits of the method were 0.017 and 0.086 ng mL(-1) for nitrazepam and midazolam, respectively. The extraction recovery percentages for the drugs studied were above 91.0 with acceptable relative standard deviation. The proposed methodology was successfully applied for the determination of these drugs in a number of human serum samples.

  9. SURFACTANT ENHANCED AQUIFER REMEDIATION WITH SURFACTANT REGENERATION/REUSE

    EPA Science Inventory

    A demonstration of surfactant-enhanced aquifer remediation was conducted during the spring of 1999 at Marine Corps Base, Camp LeJeune, NC. A PCE-DNAPL zone was identified and delineated by extensive soil sampling in 1997, and was further characteized by a partitioning interwell t...

  10. Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

    PubMed Central

    Mohanty, Sagarika; Jasmine, Jublee

    2013-01-01

    Surfactant enhanced bioremediation (SEB) of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL) pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs). Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review. PMID:24350261

  11. Surfactant-enhanced alkaline flooding field project. Annual report, Revision

    SciTech Connect

    French, T.R.

    1991-10-01

    The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

  12. Surfactant-enhanced low-pH alkaline flooding

    SciTech Connect

    Peru, D.A. and Co., Columbia, MD . Research Div.); Lorenz, P.B. )

    1990-08-01

    This paper reports sodium bicarbonate investigated as a potential alkaline agent in surfactant-enhanced alkaline flooding because it has very little tendency to dissolve silicate minerals. In experiments performed with Wilmington, CA, crude oil and three types of surfactants, the bicarbonate/surfactant combination caused a marked lowering of interfacial tension (IFT). Bicarbonate protected the surfactant against divalent cations and reduced adsorption of surfactant and polymer on various minerals. Coreflood test confirm that sodium bicarbonate plus surfactant can be an effective alternative to the high-pH flooding process.

  13. Surfactant-enhanced alkaline flooding for light oil recovery. Quarterly report, January 1--March 31, 1994

    SciTech Connect

    Wasan, D.T.

    1994-06-01

    The overall objective of this project is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12.0) for ultimate spontaneous emulsification and ultra-low tension. In addition, the novel concept of pH gradient design to optimize flood water conditions will be tested. Last quarter we investigated the phase behavior and the regions where in the middle phase occurs. The optimum phase was found to go through a maximum with pH, sodium concentration and surfactant concentration. The optimum pH is about 12.0 to 13.5, the optimum sodium concentration is about 0.513 mol/liter, and the optimum surfactant concentration is about 0.2%. The effect of surfactant type was also investigated. Petrostep B-105 was found to give the most middle phase production. This quarter, we investigated the contact angle of Long Beach oil, Adena oil, and a model oil on a solid glass surface in contact with an aqueous alkaline solution both with and without added preformed surfactant. The contact angle with Long Beach and Adena oils showed oil-wet conditions, whereas the model oil showed both oil-wet and water-wet conditions depending on the pH of the aqueous phase. The addition of surfactant to the alkaline solution resulted in making the system less oil-wet. Spreading of the oil on the glass surface was observed in all three systems investigated.

  14. Surfactant enhanced ricinoleic acid production using Candida rugosa lipase.

    PubMed

    Goswami, Debajyoti; Sen, Ramkrishna; Basu, Jayanta Kumar; De, Sirshendu

    2010-01-01

    In this study, ricinoleic acid was produced on surfactant enhanced castor oil hydrolysis using Candida rugosa lipase. The most effective surfactant was Span 80. Employing fractional factorial design, the most suitable temperature and surfactant concentration were found to be 31 degrees C and 0.257% (w/w in buffer) respectively whereas pH, enzyme concentration, buffer concentration and agitation were identified as the most significant independent variables. A 2(4) full factorial central composite design was applied and the optimal conditions were found to be pH 7.0, enzyme concentration 7.42 mg/g oil, buffer concentration 0.20 g/g oil and agitation 1400 rpm with the maximum response of 76% in 4 h. The most important variable was pH, whereas enzyme and buffer concentrations also showed pronounced effect on response. This is the first report on the application of response surface methodology for optimizing surfactant enhanced ricinoleic acid production using C. rugosa lipase.

  15. Surfactant-enhanced alkaline flooding with weak alkalis

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1991-02-01

    The objective of Project BE4B in FY90 was to develop cost-effective and efficient chemical flooding formulations using surfactant-enhanced, lower pH (weak) alkaline chemical systems. Chemical systems were studied that mitigate the deleterious effects of divalent ions. The experiments were conducted with carbonate mixtures and carbonate/phosphate mixtures of pH 10.5, where most of the phosphate ions exist as the monohydrogen phosphate species. Orthophosphate did not further reduce the deleterious effect of divalent ions on interfacial tension behavior in carbonate solutions, where the deleterious effect of the divalent ions is already very low. When added to a carbonate mixture, orthophosphate did substantially reduce the adsorption of an atomic surfactant, which was an expected result; however, there was no correlation between the amount of reduction and the divalent ion levels. For acidic oils, a variety of surfactants are available commercially that have potential for use between pH 8.3 and pH 9.5. Several of these surfactants were tested with oil from Wilmington (CA) field and found to be suitable for use in that field. Two low-acid crude oils, with acid numbers of 0.01 and 0.27 mg KOH/g of oil, were studied. It was shown that surfactant-enhanced alkaline flooding does have merit for use with these low-acid crude oils. However, each low-acid oil tested was found to behave differently, and it was concluded that the applicability of the method must be experimentally determined for any given low-acid crude oil. 19 refs., 10 figs. 4 tabs.

  16. SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY EVALUATION VERSUCHSEININCHTUNG ZUR GRUNDWASSER-UND ALTLASTENSANIERUNG (VEGAS) FACILITY, STUTTGART, GERMANY

    EPA Science Inventory

    This innovative technology evaluation report (ITER) summarized the results of an evaluation of a surfactant-enhanced extraction technology. This evaluation was conducted under a bilateral agreement between the United States (U.S.) Environmental Protection Agency (EPA) Superfund ...

  17. Surfactant-enhanced remediation of organic contaminated soil and water.

    PubMed

    Paria, Santanu

    2008-04-21

    Surfactant based remediation technologies for organic contaminated soil and water (groundwater or surface water) is of increasing importance recently. Surfactants are used to dramatically expedite the process, which in turn, may reduce the treatment time of a site compared to use of water alone. In fact, among the various available remediation technologies for organic contaminated sites, surfactant based process is one of the most innovative technologies. To enhance the application of surfactant based technologies for remediation of organic contaminated sites, it is very important to have a better understanding of the mechanisms involved in this process. This paper will provide an overview of the recent developments in the area of surfactant enhanced soil and groundwater remediation processes, focusing on (i) surfactant adsorption on soil, (ii) micellar solubilization of organic hydrocarbons, (iii) supersolubilization, (iv) density modified displacement, (v) degradation of organic hydrocarbon in presence surfactants, (vi) partitioning of surfactants onto soil and liquid organic phase, (vii) partitioning of contaminants onto soil, and (viii) removal of organics from soil in presence of surfactants. Surfactant adsorption on soil and/or sediment is an important step in this process as it results in surfactant loss reduced the availability of the surfactants for solubilization. At the same time, adsorbed surfactants will retained in the soil matrix, and may create other environmental problem. The biosurfactants are become promising in this application due to their environmentally friendly nature, nontoxic, low adsorption on to soil, and good solubilization efficiency. Effects of different parameters like the effect of electrolyte, pH, soil mineral and organic content, soil composition etc. on surfactant adsorption are discussed here. Micellar solubilization is also an important step for removal of organic contaminants from the soil matrix, especially for low aqueous

  18. Surfactant-enhanced sodium bicarbonate flooding. Project OE6

    SciTech Connect

    Peru, D.A.

    1986-08-01

    Three anionic and four nonionic surfactants were tested for their emulsification behavior with TRONACRAB (sodium bicarbonate) and Wilmington crude oil. Three of the surfactants were found to enhance the solubilization of oil in the brine phase in the presence of TRONACARB according to the screening guide established in this study. Interfacial tension measurements were made on the most promising systems. The results support the hypothesis that a synergistic relationship can exist between low concentrations of synthetic surfactant and TRONACRAB. In batch experiments using kaolinite and in a linear coreflood using consolidated Berea sandstone, TRONACRAB reduced adsorption of surfactant by up to 93%. TRONACARB was less effective in preventing adsorption onto crushed Berea sandstone probably due to an unusually high amount of ferrodolomite (calcium magnesium carbonate with iron impurities). The following conclusion have been made from the results of this work. (1) Addition of water-soluble synthetic surfactants to brines containing TRONACARB enhances the aqueous solubility of surfactants formed in situ. (2) The greatest solubilization of oil into the brine phase occurs when TRONACARB is used with synthetic surfactant. (3) The use of TRONACARB in combination with synthetic surfactants results in ultralow interfacial tension upon contact with the oil phase. (4) TRONACARB decreases the temperature at which ninionics can solubilize oil effectively (lower IFT). The use of nonionics at lower temperatures will reduce adsorption significantly. (5) TRONACARB is as useful as higher pH alkaline agents in preventing adsoprtion of anionic surfactants. 12 refs., 10 figs., 4 tabs.

  19. Beyond dispersive liquid-liquid microextraction.

    PubMed

    Leong, Mei-I; Fuh, Ming-Ren; Huang, Shang-Da

    2014-03-28

    Dispersive liquid-liquid microextraction (DLLME) and other dispersion liquid-phase microextraction (LPME) methods have been developed since the first DLLME method was reported in 2006. DLLME is simple, rapid, and affords high enrichment factor, this is due to the large contact surface area of the extraction solvent. DLLME is a method suitable for the extraction in many different water samples, but it requires using chlorinated solvents. In recent years, interest in DLLME or dispersion LPME has been focused on the use of low-toxicity solvents and more conveniently practical procedures. This review examines some of the most interesting developments in the past few years. In the first section, DLLME methods are separated in two categories: DLLME with low-density extraction solvent and DLLME with high-density extraction solvent. Besides these methods, many novel special devices for collecting low-density extraction solvent are also mentioned. In addition, various dispersion techniques with LPME, including manual shaking, air-assisted LPME (aspirating and injecting the extraction mixture by syringe), ultrasound-assisted emulsification, vortex-assisted emulsification, surfactant-assisted emulsification, and microwave-assisted emulsification are described. Besides the above methods, combinations of DLLME with other extraction techniques (solid-phase extraction, stir bar sorptive extraction, molecularly imprinted matrix solid-phase dispersion and supercritical fluid extraction) are introduced. The combination of nanotechnique with DLLME is also introduced. Furthermore, this review illustrates the application of DLLME or dispersion LPME methods to separate and preconcentrate various organic analytes, inorganic analytes, and samples.

  20. An overview of liquid phase microextraction approaches combined with UV-Vis spectrophotometry.

    PubMed

    Dehghani Mohammad Abadi, Malihe; Ashraf, Narges; Chamsaz, Mahmoud; Shemirani, Farzaneh

    2012-09-15

    Ultraviolet and visible spectrophotometer has become a popular analytical instrument in the modern day laboratories. However, the low concentrations of many analytes in samples make it difficult to directly measure them by UV-Vis spectrophotometry. This overview focuses on the combinations of microvolume UV-Vis spectrophotometry with miniaturized approaches to sample preparation, namely, single drop microextraction (SDME), dispersive liquid-liquid microextraction (DLLME), cold induced aggregation microextraction (CIAME), in situ solvent formation microextraction (ISSFME), ultrasound assisted emulsification microextraction (USAEME), solidified floating organic drop microextraction (SFODME), and hollow fiber based liquid phase microextraction (HF-LPME) to improve both the selectivity and sensitivity. Integration of these techniques provides unique advantages which include availability, simplicity of operation, low cost, speed, precision and accuracy; hence making them a powerful tool in chemical analysis.

  1. SURFACTANT-ENHANCED SOLUBILIZATION OF RESIDUAL DODECANE IN SOIL COLUMNS - 2. MATHEMATICAL MODELING

    EPA Science Inventory

    A mathematical model is developed to describe surfactant-enhanced solubilization of nonaqueous-phase liquids (NAPLs) in porous media. The model incorporates aqueous-phase transport equations for organic and surfactant components as well as a mass balance for the organic phase. Ra...

  2. FIELD DEMONSTRATION STUDIES OF SURFACTANT-ENHANCED SOLUBILIZATION AND MOBILIZATION AT HILL AIR FORCE BASE, UTAH

    EPA Science Inventory

    Surfactant-enhanced subsurface remediation can dramatically improve contaminant removal rates compared to the traditional pump-and-treat technology. Surfactants can be used to significantly enhance the solubilization of non-aqueous phase liquids (NAPL) constituents, or they can b...

  3. Removal of PAHs with surfactant-enhanced soil washing: influencing factors and removal effectiveness.

    PubMed

    Peng, Sheng; Wu, Wei; Chen, Jiajun

    2011-02-01

    PAH removal with surfactant enhanced washing was investigated through a series of laboratory tests to examine the effect of stirring speed, washing time, surfactant concentration, liquid/solid ratio, temperature, and on-and-off mode. The first four factors show significant influence on the PAH removal while the latter two do not. Total removal ratio and a new proposed parameter, solubilization percentage, are used to evaluate the effectiveness quantitatively.

  4. Application of Optimized Vortex-Assisted Surfactant-Enhanced DLLME for Preconcentration of Thymol and Carvacrol, and Their Determination by HPLC-UV: Response Surface Methodology.

    PubMed

    Ghaedi, Mehrorang; Roosta, Mostafa; Khodadoust, Saeid; Daneshfar, Ali

    2015-08-01

    A novel vortex-assisted surfactant-enhanced dispersive liquid-liquid microextraction combined with high-performance liquid chromatography (VASEDLLME-HPLC) was developed for the determination of thymol and carvacrol (phenolic compound). In this method, the extraction solvent (CHCl3) was dispersed into the aqueous samples via a vortex agitator and addition of the surfactant (Triton X-100). The preliminary experiments were undertaken to select the best extraction solvent and surfactant. The influences of effective variables were investigated using a Plackett-Burman 2(7-4) screening design and then, the significant variables were optimized by using a central composite design combined with desirability function. Working under optimum conditions specified as: 140 µL CHCl3, 0.08% (w/v, Triton X-100), 3 min extraction time, 6 min centrifugation at 4,500 rpm, pH 7, 0.0% (w/v) NaCl permit achievement of high and reasonable linear range over 0.005-4.0 mg L(-1) with R(2) = 0.9998 (n = 10). The separation of thymol and carvacrol was achieved in <14 min using a C18 column and an isocratic binary mobile phase acetonitrile-water (55:45, v/v) with a flow rate of 1.0 mL min(-1). The VASEDLLME is applied for successful determination of carvacrol and thymol in different thyme and pharmaceutical samples with relative standard deviation <4.7% (n = 5).

  5. Anionic surfactants enhance click reaction-mediated protein conjugation with ubiquitin.

    PubMed

    Schneider, Daniel; Schneider, Tatjana; Aschenbrenner, Joos; Mortensen, Franziska; Scheffner, Martin; Marx, Andreas

    2016-03-01

    The Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC) has become increasingly important in the conjugation chemistry of biomolecules. For example, it is an efficient and convenient method to generate defined ubiquitin-protein conjugates. Here, we investigate the effect of surfactants on the efficiency of CuAAC for chemical protein ubiquitylation. We found that anionic surfactants enhance conjugate formation by up to 10-fold resulting in high yields even at low (i.e., micromolar) concentrations of the reactants. Notably, the herein investigated conjugates are functional and thus properly folded.

  6. Remediation of Nitrobenzene Contaminated Soil by Combining Surfactant Enhanced Soil Washing and Effluent Oxidation with Persulfate

    PubMed Central

    Yan, Jingchun; Gao, Weiguo; Qian, Linbo; Han, Lu; Chen, Yun; Chen, Mengfang

    2015-01-01

    The combination of surfactant enhanced soil washing and degradation of nitrobenzene (NB) in effluent with persulfate was investigated to remediate NB contaminated soil. Aqueous solution of sodium dodecylbenzenesulfonate (SDBS, 24.0 mmol L-1) was used at a given mass ratio of solution to soil (20:1) to extract NB contaminated soil (47.3 mg kg-1), resulting in NB desorption removal efficient of 76.8%. The washing effluent was treated in Fe2+/persulfate and Fe2+/H2O2 systems successively. The degradation removal of NB was 97.9%, being much higher than that of SDBS (51.6%) with addition of 40.0 mmol L-1 Fe2+ and 40.0 mmol L-1 persulfate after 15 min reaction. The preferential degradation was related to the lone pair electron of generated SO4•−, which preferably removes electrons from aromatic parts of NB over long alkyl chains of SDBS through hydrogen abstraction reactions. No preferential degradation was observed in •OH based oxidation because of its hydrogen abstraction or addition mechanism. The sustained SDBS could be reused for washing the contaminated soil. The combination of the effective surfactant-enhanced washing and the preferential degradation of NB with Fe2+/persulfate provide a useful option to remediate NB contaminated soil. PMID:26266532

  7. Visualization of surfactant enhanced NAPL mobilization and solubilization in a two-dimensional micromodel

    SciTech Connect

    ZHONG,LIRONG; MAYER,ALEX; GLASS JR.,ROBERT J.

    2000-03-08

    Surfactant-enhanced aquifer remediation is an emerging technology for aquifers contaminated with nonaqueous phase liquids (NAPLs). A two-dimensional micromodel and image capture system were applied to observe NAPL mobilization and solubilization phenomena. In each experiment, a common residual NAPL field was established, followed by a series of mobilization and solubilization experiments. Mobilization floods included pure water floods with variable flow rates and surfactant floods with variations in surfactant formulations. At relatively low capillary numbers (N{sub ca}<10{sup {minus}3}), the surfactant mobilization floods resulted in higher NAPL saturations than for the pure water flood, for similar N{sub ca}.These differences in macroscopic saturations are explained by differences in micro-scale mobilization processes. Solubilization of the residual NAPL remaining after the mobilization stage was dominated by the formation of dissolution fingers, which produced nonequilibrium NAPL solubilization. A macroemulsion phase also as observed to form spontaneously and persist during the solubilization stage of the experiments.

  8. SURFACTANT ENHANCED RECOVERY OF TETRACHLOROETHYLENE FROM A POROUS MEDIUM CONTAINING LOW PERMEABILITY LENSES. 2. NUMERICAL SIMULATION. (R825409)

    EPA Science Inventory

    Abstract

    A numerical model of surfactant enhanced solubilization was developed and applied to the simulation of nonaqueous phase liquid recovery in two-dimensional heterogeneous laboratory sand tank systems. Model parameters were derived from independent, small-scale, ...

  9. A comparison of various modes of liquid-liquid based microextraction techniques: determination of picric acid.

    PubMed

    Burdel, Martin; Šandrejová, Jana; Balogh, Ioseph S; Vishnikin, Andriy; Andruch, Vasil

    2013-03-01

    Three modes of liquid-liquid based microextraction techniques--namely auxiliary solvent-assisted dispersive liquid-liquid microextraction, auxiliary solvent-assisted dispersive liquid-liquid microextraction with low-solvent consumption, and ultrasound-assisted emulsification microextraction--were compared. Picric acid was used as the model analyte. The determination is based on the reaction of picric acid with Astra Phloxine reagent to produce an ion associate easily extractable by various organic solvents, followed by spectrophotometric detection at 558 nm. Each of the compared procedures has both advantages and disadvantages. The main benefit of ultrasound-assisted emulsification microextraction is that no hazardous chlorinated extraction solvents and no dispersive solvent are necessary. Therefore, this procedure was selected for validation. Under optimized experimental conditions (pH 3, 7 × 10(-5) mol/L of Astra Phloxine, and 100 μL of toluene), the calibration plot was linear in the range of 0.02-0.14 mg/L and the LOD was 7 μg/L of picric acid. The developed procedure was applied to the analysis of spiked water samples.

  10. Multi objective optimization of the setup of a surfactant-enhanced DNAPL remediation.

    PubMed

    Schaerlaekens, Jan; Carmeliet, Jan; Feyen, Jan

    2005-04-01

    Surfactant-enhanced aquifer remediation (SEAR) is widely considered a promising technique to remediate dense nonaqueous phase liquid (DNAPL) contaminations in-situ. The costs of a SEAR remediation are important and depend mostly on the setup of the remediation. Costs can be associated with the installation of injection and extraction wells, the required time of the remediation (and thus labor costs, lease of installations, and energy), the extracted water volume (the purification of the extracted water), and the injected surfactant amount. A cost-effective design of the remediation setup allows an optimal use of resources. In this work, a SEAR remediation was simulated for a hypothetical typical DNAPL contamination. A constrained multi-objective optimization of the model was applied to obtain a Pareto set of optimal remediation strategies with different weights for the two objectives of the remediation: (i) the maximal removal of DNAPL mass (ii) with a minimal total cost. A relatively sharp Pareto front was found, showing a considerable tradeoff between DNAPL removal and total remediation costs. These Pareto curves can help decision makers select an optimal remediation strategy in terms of cost and remediation efficiency depending on external constraints such as the available budget and obligatory remediation goals.

  11. Surfactant-Enhanced Desorption and Biodegradation of Polycyclic Aromatic Hydrocarbons in Contaminated Soil

    PubMed Central

    Zhu, Hongbo; Aitken, Michael D.

    2010-01-01

    We evaluated two nonionic surfactants, one hydrophobic (Brij 30) and one hydrophilic (C12E8), for their ability to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil after it had been treated in an aerobic bioreactor. The effects of each surfactant were evaluated at doses corresponding to equilibrium aqueous-phase concentrations well above the surfactant’s critical micelle concentration (CMC), slightly above the CMC, and below the CMC. The concentrations of all 3- and 4-ring PAHs were significantly lower in the soil amended with Brij 30 at the two lower doses compared to controls, whereas removal of only the 3-ring PAHs was significantly enhanced at the highest Brij 30 dose. In contrast, C12E8 did not enhance PAH removal at any dose. In the absence of surfactant, <5% of any PAH desorbed from the soil over an 18-d period. Brij 30 addition at the lowest dose significantly increased the desorption of most PAHs, whereas the addition of C12E8 at the lowest dose actually decreased the desorption of all PAHs. These findings suggest that the effects of the two surfactants on PAH biodegradation could be explained by their effects on PAH bioavailability. Overall, this study demonstrates that the properties of the surfactant and its dose relative to the corresponding aqueous-phase concentration are important factors in designing systems for surfactant-enhanced bioremediation of PAH-contaminated soils in which PAH bioavailability is limited. PMID:20586488

  12. Surfactant-enhanced desorption and biodegradation of polycyclic aromatic hydrocarbons in contaminated soil.

    PubMed

    Zhu, Hongbo; Aitken, Michael D

    2010-10-01

    We evaluated two nonionic surfactants, one hydrophobic (Brij 30) and one hydrophilic (C(12)E(8)), for their ability to enhance the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil after it had been treated in an aerobic bioreactor. The effects of each surfactant were evaluated at doses corresponding to equilibrium aqueous-phase concentrations well above the surfactant's critical micelle concentration (CMC), slightly above the CMC, and below the CMC. The concentrations of all 3- and 4-ring PAHs were significantly lower in the soil amended with Brij 30 at the two lower doses compared to controls, whereas removal of only the 3-ring PAHs was significantly enhanced at the highest Brij 30 dose. In contrast, C(12)E(8) did not enhance PAH removal at any dose. In the absence of surfactant, <5% of any PAH desorbed from the soil over an 18 day period. Brij 30 addition at the lowest dose significantly increased the desorption of most PAHs, whereas the addition of C(12)E(8) at the lowest dose actually decreased the desorption of all PAHs. These findings suggest that the effects of the two surfactants on PAH biodegradation could be explained by their effects on PAH bioavailability. Overall, this study demonstrates that the properties of the surfactant and its dose relative to the corresponding aqueous-phase concentration are important factors in designing systems for surfactant-enhanced bioremediation of PAH-contaminated soils in which PAH bioavailability is limited.

  13. Cosolubilization synergism occurrence in codesorption of PAH mixtures during surfactant-enhanced remediation of contaminated soil.

    PubMed

    Liang, Xujun; Guo, Chuling; Wei, Yanfu; Lin, Weijia; Yi, Xiaoyun; Lu, Guining; Dang, Zhi

    2016-02-01

    Surfactant-enhanced remediation (SER) has been widely applied in decontaminating PAH-polluted soil. Most researches focus on evaluating washing efficiency without considering pollutants' mutual interaction. This study aims to investigate cosolubilization effect between phenanthrene (Phe) and pyrene (Pyr) in nonionic surfactant Triton X-100 (TX100) solution on their codesorption performance from soil. Cosolubilization experiment showed that, when cosolubilized, solubility of Phe and Pyr in TX100 increased by 15.38% and 18.19%, respectively, as quantified by the deviation ratio of molar solubilization ratio in single and binary solute solubilization systems. The synergism may be due to the enlarged micelle volume caused by PAHs solubilized in the shell region of the micelle. The cosolubilization effect was further observed in the soil washing process. The strengthened TX100 solubilization capacity towards Phe and Pyr could increase the two PAHs' codesorption efficiency from soil, accompanied by synergistic extent of 6-15%. However, synergism in codesorption was weaker than that observed in the cosolubilization system, which may be related to surfactant loss to soil and PAH partition into soil organic matter and the sorbed surfactants. The improved remediation performance during codesorption of mixed PAHs implies the significance of combining PAHs' mutual interaction into evaluating SER, which may reduce the surfactant washing concentration and save remediation cost.

  14. DEMONSTRATION OF PILOT-SCALE PERVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. II. HOLLOW FIBER MEMBRANE MODULES

    EPA Science Inventory

    Pilot-scale demonstration of pervaporation-based removal of volatile organic compounds from a surfactant enhanced aquifer remediation (SEAR) fluid has been conducted at USEPA's Test & Evaluation Facility using hollow fiber membrane modules. The membranes consisted of microporous...

  15. Membrane emulsification to produce perfume microcapsules

    NASA Astrophysics Data System (ADS)

    Pan, Xuemiao

    Microencapsulation is an efficient technology to deliver perfume oils from consumer products onto the surface of fabrics. Microcapsules having uniform size/mechanical strength, may provide better release performance. Membrane emulsification in a dispersion cell followed by in-situ polymerization was used to prepare narrow size distribution melamine-formaldehyde (MF) microcapsules containing several types of oil-based fragrances or ingredients. Investigated in this study are the parameters impacting to the size and size distribution of the droplets and final MF microcapsules. A pilot plant-scale cross-flow membrane system was also used to produce MF microcapsules, demonstrating that the membrane emulsification process has potential to be scaled up for industrial applications. In this study, health and environmental friendly poly (methyl methacrylate) (PMMA) microcapsules with narrow size distribution were also prepared for the first time using the dispersion cell membrane emulsification system. Characterization methods previously used for thin-shell microcapsules were expanded to analyse microcapsules with thick shells. The intrinsic mechanical properties of thick shells were determined using a micromanipulation technique and finite element analysis (FEM). The microcapsules structure was also considered in the determination of the permeability and diffusivity of the perfume oils in good solvents..

  16. Performance of sonication and microfluidization for liquid-liquid emulsification.

    PubMed

    Maa, Y F; Hsu, C C

    1999-05-01

    The purpose of this research was to evaluate and compare liquid-liquid emulsions (water-in-oil and oil-in-water) prepared using sonication and microfluidization. Liquid-liquid emulsions were characterized on the basis of emulsion droplet size determined using a laser-based particle size analyzer. An ultrasonic-driven benchtop sonicator and an air-driven microfluidizer were used for emulsification. Sonication generated emulsions through ultrasound-driven mechanical vibrations, which caused cavitation. The force associated with implosion of vapor bubbles caused emulsion size reduction and the flow of the bubbles resulted in mixing. An increase in viscosity of the dispersion phase improved the sonicator's emulsification capability, but an increase in the viscosity of the dispersed phase decreased the sonicator's emulsification capability. Although sonication might be comparable to homogenization in terms of emulsification efficiency, homogenization was relatively more effective in emulsifying more viscous solutions. Microfluidization, which used a high pressure to force the fluid into microchannels of a special configuration and initiated emulsification via a combined mechanism of cavitation, shear, and impact, exhibited excellent emulsification efficiency. Of the three methodologies, sonication generated more heat and might be less suitable for emulsion systems involving heat-sensitive materials. Homogenization is in general a more effective liquid-liquid emulsification method. The results derived from this study can serve as a basis for the evaluation of large-scale liquid-liquid emulsification in the microencapsulation process.

  17. Preparation of polyurea capsules using electrocapillary emulsification.

    PubMed

    Sakai, Hideki; Tanaka, Keisuke; Fukushima, Hiroshi; Tsuchiya, Koji; Sakai, Kenichi; Kondo, Tamotsu; Abe, Masahiko

    2008-10-15

    Polyurea capsules have been prepared using the electrocapillary emulsification method in order to control the particle size within the submicron range. The polyurea capsules have been synthesized via the interfacial polycondensation between tetraethylenepentamine (TEP) dissolved in an aqueous phase and toluenediisocyanate (TDI) dissolved in a mixture of cyclohexane and chloroform. The oil phase contains a lipophilic nonionic surfactant (sorbitan sesquioleate, SO-15) as an emulsion stabilizer. Scanning electron microscope (SEM) observations reveal that the capsule size is decreased as (i) the amount of the aqueous phase injected into the oil phase is decreased and (ii) the dropping rate of the aqueous phase is decreased. Indeed, the mole ratio of the two monomers makes a significant impact on the capsule size. Under the best experimental condition examined in this study, we obtained polyurea capsules with a diameter of approximately 200nm, which should be useful in developing bioreactors or carriers.

  18. Nano-encapsulated PCM via Pickering Emulsification

    NASA Astrophysics Data System (ADS)

    Wang, Xuezhen; Zhang, Lecheng; Yu, Yi-Hsien; Jia, Lisi; Sam Mannan, M.; Chen, Ying; Cheng, Zhengdong

    2015-08-01

    We designed a two-step Pickering emulsification procedure to create nano-encapsulated phase changing materials (NEPCMs) using a method whose simplicity and low energy consumption suggest promise for scale-up and mass production. Surface-modified amphiphilic zirconium phosphate (ZrP) platelets were fabricated as the Pickering emulsifiers, nonadecane was chosen as the core phase change material (PCM), and polystyrene, the shell material. The resultant capsules were submicron in size with remarkable uniformity in size distribution, which has rarely been reported. Differential scanning calorimetry (DSC) characterization showed that the capsulation efficiency of NEPCMs, and they were found to be thermal stable, as characterized by the DSC data for the sample after 200 thermal cycles. NEPCMs exhibit superior mechanical stability and mobility when compared with the well-developed micro-encapsulated phase change materials (MEPCMs). NEPCMs find useful applications in thermal management, including micro-channel coolants; solar energy storage media; building temperature regulators; and thermal transfer fabrics.

  19. Efficiency of surfactant-enhanced desorption for contaminated soils depending on the component characteristics of soil-surfactant--PAHs system.

    PubMed

    Zhou, Wenjun; Zhu, Lizhong

    2007-05-01

    The sorption of surfactants onto soils has a significant effect on the performance of surfactant enhanced desorption. In this study, the efficiency of surfactants in enhancing desorption for polycyclic aromatic hydrocarbons (PAHs) contaminated soils relative to water was evaluated with a term of relative efficiency coefficient (REC). Since the sorption of surfactants onto soils, surfactants only enhanced PAH desorption when REC values were larger than 1 and the added surfactant concentration was greater than the corresponding critical enhance desorption concentration (CEDC), which was defined as the corresponding surfactant concentration with REC=1. A model was utilized to describe and predict the REC and CEDC values for PAH desorption. The model and experimental results indicated that the efficiency of surfactants in enhancing PAH desorption showed strong dependence on the soil composition, surfactant structure and PAH properties. These results are of practical interest for the selection of surfactant to optimize soil remediation technologies.

  20. DEMONSTRATION OF PILOT-SCALE PREVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. I. SPIRAL WOUND MEMBRANE MODULES

    EPA Science Inventory

    During the summer of 1996, a pilot-scale demonstration of a surfactant enhanced aquifer remediation (SEAR) process for removal of dense non-aqueous phase liquids (DNAPLs) from soils was conducted at Hill Air Force Base in Layton, Utah. Five thousand gallons of the extracted DNAP...

  1. Nano-encapsulated PCM via Pickering Emulsification

    PubMed Central

    Wang, Xuezhen; Zhang, Lecheng; Yu, Yi-Hsien; Jia, Lisi; Sam Mannan, M.; Chen, Ying; Cheng, Zhengdong

    2015-01-01

    We designed a two-step Pickering emulsification procedure to create nano-encapsulated phase changing materials (NEPCMs) using a method whose simplicity and low energy consumption suggest promise for scale-up and mass production. Surface-modified amphiphilic zirconium phosphate (ZrP) platelets were fabricated as the Pickering emulsifiers, nonadecane was chosen as the core phase change material (PCM), and polystyrene, the shell material. The resultant capsules were submicron in size with remarkable uniformity in size distribution, which has rarely been reported. Differential scanning calorimetry (DSC) characterization showed that the capsulation efficiency of NEPCMs, and they were found to be thermal stable, as characterized by the DSC data for the sample after 200 thermal cycles. NEPCMs exhibit superior mechanical stability and mobility when compared with the well-developed micro-encapsulated phase change materials (MEPCMs). NEPCMs find useful applications in thermal management, including micro-channel coolants; solar energy storage media; building temperature regulators; and thermal transfer fabrics. PMID:26278332

  2. Study on mechanism of wet air oxidation of emulsification wastewater.

    PubMed

    Tang, Wen W; Zeng, Xin P; Xiao, Yao M; Gu, Guo W

    2009-04-01

    Wet air oxidation (WAO) can effectively be used to treat high-concentration, non-biodegradable emulsification wastewater that contains nonionic matters. Gas chromatograph analysis of emulsification wastewater after oxidation indicated that a catalyst increased production of fatty acids but could not promote its oxidation between 160 and 180 degrees C. When the temperature was greater than or equal to 220 degrees C, the catalyst not only increased production of fatty acids initially but effectively promoted its oxidation in later stages and significantly reduced the concentration of residual surfactants. Experiments proved that fatty acids (especially acetic acid) were the primary intermediate products and that oxidation of these acids was the rate-limiting step. During the process of catalytic WAO of emulsification wastewater, active oxygen molecules attacked organic matters resulting in production of fatty acids, ketone, alcohol, hydrocarbon, and oligo-polyether through radical chain reactions.

  3. Researches and applications of the ultrasonic emulsifications and dispersions.

    PubMed

    Quanlu, Li; Yinhong, Zhang; Jing, Wu

    2013-11-01

    This paper defines power ultrasonics and their two important directions: Ultrasonic emulsification and dispersion from a practical point of view, brief reports on recent research results are ultrasonic emulsification to be used for the preparation of composite electrorheological fluid, and ultrasonic dispersion to be used dispersion as a new type cold cloud catalytic agent metaldehyde [CH3CH]4-6 (this is used for artificial rain), etc., and produce good results or gain progress. Then, the principle and applications of power ultrasonics (including magnetostriction type ultrasonic transducer and piezoelectric type ultrasonic transducer) in the emulsification or dispersion, are pointed out. Also, ultrasonic extensive applications in chemistry, materials, and life sciences are briefly introduced.

  4. The effect of polymer-surfactant interaction on the rheological properties of surfactant enhanced alkaline flooding formulations

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1993-02-01

    Surfactant-enhanced, lower pH (weak) alkaline chemicals are effective for mobilizing residual oil. Polymer is used for mobility control because if mobility control is lost, then oil recovery is reduced. The ability to maintain mobility control during surfactant-alkaline flooding can be adversely affected by chemical interaction. In this work, interaction between polymers and surfactants was shown to be affected by pH, ionic strength, crude oil, and the properties of the polymers and surfactants. Polymer-surfactant interaction (phase separation, precipitation, and viscosity loss) occurred between most of the polymers and surfactants that were tested. Polymer-surfactant interaction is difficult to eliminate, and no method was found for completely eliminating interaction. Polymer-surfactant interaction occurred at optimal salinity and below optimal salinity. Polymer-surfactant interaction had an adverse effect on polymer rheology; however, the adverse effect of interaction on polymer rheology was lessened when oil was present. Increasing the pH of chemical systems further reduced the adverse effects of interaction on polymer rheology.

  5. Removal of As, Cd, Cu, Ni, Pb, and Zn from a highly contaminated industrial soil using surfactant enhanced soil washing

    NASA Astrophysics Data System (ADS)

    Torres, Luis G.; Lopez, Rosario B.; Beltran, Margarita

    Surfactant enhanced soil washing (SESW) was applied to an industrial contaminated soil. A preliminary characterization of the soil regarding the alkaline-earth metals, Na, K, Ca and Mg took values of 2866, 2036, 2783 and 4149 mg/kg. The heavy metals As, Cd, Cu, Pb, Ni and Zn, had values of 4019, 14, 35582, 70, 2603, and 261 mg/kg, respectively. When using different surfactants, high removal of Cu, Ni and Zn were found, and medium removals for Pb, As and Cd. In the case of these three metals, tap water removed more than the surfactant solutions, except for the case of As. There were surfactants with average removals (this is, the removal for all the metals studied) of 67.1% (Tween 80), 64.9% (Surfacpol 14104) and 61.2% (Emulgin W600). There were exceptional removals using Texapon N-40 (83.2%, 82.8% and 86.6% for Cu, Ni and Zn), Tween 80 (85.9, 85.4 and 81.5 for Cd, Zn and Cu), Polafix CAPB (79%, 83.2% and 49.7% for Ni, Zn and As). The worst results were obtained with POLAFIX LO with a global removal of 45%, well below of the average removal with tap water (50.2%).All removal efficiencies are reported for a one step washing using 0.5% surfactant solutions, except for the case of mezquite gum, where a 0.1% solution was employed.

  6. Efficient emulsification of viscous oils at high drop volume fraction.

    PubMed

    Tcholakova, Slavka; Lesov, Ivan; Golemanov, Konstantin; Denkov, Nikolai D; Judat, Sonja; Engel, Robert; Danner, Thomas

    2011-12-20

    It is shown experimentally in this study that the increase of drop volume fraction can be used as an efficient tool for emulsification of viscous oils in turbulent flow. In a systematic series of experiments, the effects of drop volume fraction and viscosity of the dispersed phase on the mean, d(32), and maximum, d(V95), diameters of the drops, formed during emulsification, are quantified. The volume fraction, Φ, of the dispersed oily phase is varied between 1% and 90%, and oils with viscosity varying between 3 and 10,000 mPa.s are studied. All experiments are performed at sufficiently high surfactant concentration, as to avoid possible drop-drop coalescence during emulsification. The analysis of the experimental data shows that there is a threshold drop volume fraction, Φ(TR), at which a transition from inertial turbulent regime into viscous turbulent regime of emulsification occurs, due to the increased overall viscosity of the emulsion. At Φ < Φ(TR), d(32) and d(V95) depend weakly on Φ and are well described by known theoretical expression for emulsification in inertial turbulent regime (Davies, Chem. Eng. Sci. 1985, 40, 839), which accounts for the effects of oil viscosity and interfacial tension. At Φ > Φ(TR), both d(32) and polydispersity of the formed emulsions decrease very significantly with the increase of Φ (for the oils with η(D) > 10 mPa.s). Thus, very efficient emulsification of the viscous oils is realized. Very surprisingly, a third regime of emulsification is observed in the range of concentrated emulsions with Φ > 75%, where the mean drop size and emulsion polydispersity are found experimentally to be very similar for all oils and surfactants studied-an experimental fact that does not comply with any of the existing models of drop breakup during emulsification. Possible mechanistic explanations of this result are discussed. The experimental data for semiconcentrated and concentrated emulsions with Φ > Φ(TR) are described by a simple

  7. Phaco-emulsification causes the formation of cavitation bubbles.

    PubMed

    Svensson, B; Mellerio, J

    1994-09-01

    There have been reports of complications arising from damage to non-lenticular ocular tissue during the increasingly popular procedure of cataract extraction with phaco-emulsification. One cause of this damage might be the formation of cavitation bubbles. Such bubbles are known to produce free radicals and shock waves. This paper demonstrates directly the formation of cavitation bubbles at the tip of the phaco-probe. It also shows the importance of a smooth probe profile in reducing bubble formation. Recommendations are made for probe and tip design and for the use of minimum power during the surgical procedure of phaco-emulsification.

  8. Drivers and applications of integrated clean-up technologies for surfactant-enhanced remediation of environments contaminated with polycyclic aromatic hydrocarbons (PAHs).

    PubMed

    Liang, Xujun; Guo, Chuling; Liao, Changjun; Liu, Shasha; Wick, Lukas Y; Peng, Dan; Yi, Xiaoyun; Lu, Guining; Yin, Hua; Lin, Zhang; Dang, Zhi

    2017-03-29

    Surfactant-enhanced remediation (SER) is considered as a promising and efficient remediation approach. This review summarizes and discusses main drivers on the application of SER in removing polycyclic aromatic hydrocarbons (PAHs) from contaminated soil and water. The effect of PAH-PAH interactions on SER efficiency is, for the first time, illustrated in an SER review. Interactions between mixed PAHs could enhance, decrease, or have no impact on surfactants' solubilization power towards PAHs, thus affecting the optimal usage of surfactants for SER. Although SER can transfer PAHs from soil/non-aqueous phase liquids to the aqueous phase, the harmful impact of PAHs still exists. To decrease the level of PAHs in SER solutions, a series of SER-based integrated cleanup technologies have been developed including surfactant-enhanced bioremediation (SEBR), surfactant-enhanced phytoremediation (SEPR) and SER-advanced oxidation processes (SER-AOPs). In this review, the general considerations and corresponding applications of the integrated cleanup technologies are summarized and discussed. Compared with SER-AOPs, SEBR and SEPR need less operation cost, yet require more treatment time. To successfully achieve the field application of surfactant-based technologies, massive production of the cost-effective green surfactants (i.e. biosurfactants) and comprehensive evaluation of the drivers and the global cost of SER-based cleanup technologies need to be performed in the future.

  9. Investigation of surfactant-enhanced mass removal and flux reduction in 3D correlated permeability fields using magnetic resonance imaging.

    PubMed

    Zhang, Changyong; Werth, Charles J; Webb, Andrew G

    2008-09-10

    Magnetic resonance imaging (MRI) was used to visualize the NAPL source zone architecture before and after surfactant-enhanced NAPL dissolution in three-dimensional (3D) heterogeneously packed flowcells characterized by different longitudinal correlation lengths: 2.1 cm (aquifer 1) and 1.1 cm (aquifer 2). Surfactant flowpaths were determined by imaging the breakthrough of a paramagnetic tracer (MnCl(2)) analyzed by the method of moments. In both experimental aquifers, preferential flow occurred in high permeability materials with low NAPL saturations, and NAPL was preferentially removed from the top of the aquifers with low saturation. Alternate flushing with water and two surfactant pulses (5-6 pore volumes each) resulted in approximately 63% of NAPL mass removal from both aquifers. However, overall reduction in mass flux (Mass Flux 1) exiting the flowcell was lower in aquifer 2 (68%) than in aquifer 1 (81%), and local effluent concentrations were found to increase by as high as 120 times at local sampling ports from aquifer 2 after surfactant flushing. 3D MRI images of NAPL revealed that NAPL migrated downward and created additional NAPL source zones in previously uncontaminated areas at the bottom of the aquifers. The additional NAPL source zones were created in the direction transverse to flow in aquifer 2, which explains the higher mass flux relative to aquifer 1. Analysis using a total trapping number indicates that mobilization of NAPL trapped in the two coarsest sand fractions is possible when saturation is below 0.5 and 0.4, respectively. Results from this study highlight the potential impacts of porous media heterogeneity and NAPL source zone architecture on advanced in-situ flushing technologies.

  10. Surfactant-enhanced bioremediation

    SciTech Connect

    Churchill, P.F.; Dudley, R.J.; Churchill, S.A.

    1995-12-31

    This study was undertaken to examine the effect of three structurally related, non-ionic surfactants, Triton X-45, Triton X-100 and Triton X-165, as well as the oleophilic fertilizer, Inipol EAP 22, on the rate of biodegradation of phenanthrene by pure bacterial cultures. Each surfactant dramatically increased the apparent aqueous solubility of phenanthrene. Model studies were conducted to investigate the ability of these surfactants to enhance the rate of transport and uptake of polycyclic aromatic hydrocarbons into bacterial cells, and to assess the impact that increasing the aqueous solubility of hydrocarbons has on their rate of biodegradation. The results indicate that increasing the apparent aqueous solubility of hydrocarbons can lead to enhanced biodegradation rates by two Pseudomonas saccharophila strains. However, the experiments also suggest that some surfactants can inhibit aromatic hydrocarbon biodegradation by certain bacteria. The data also support the hypothesis that surface-active components present in the oleophilic fertilizer formulation, Inipol EAP 22, may have significantly contributed to the positive results reported in tests of remedial agent impact on bioremediation, which was used as a supplemental clean-up technology on Exxon Valdez crude oil-contaminated Alaskan beaches.

  11. Surfactant Enhanced DNAPL Removal

    DTIC Science & Technology

    2001-08-01

    or the permeability contrast (i.e., degree of heterogeneity) that is present in the DNAPL zone. To solubilize DNAPL with surfactants, a sufficient...with respect to the effects of permeability and heterogeneity upon the costs of SEAR: as permeability decreases and/or the degree of heterogeneity...not be an issue for surfactant recovery at all sites. The degree to which MEUF will concentrate the calcium is a function of the surfactant itself

  12. Pickering Emulsification to Mass Produce Nanoencapsulated Phase-change-material

    NASA Astrophysics Data System (ADS)

    Wang, Xuezhen; Zhang, Lecheng; Yu, Yi-Hsien; Mannan, S. Sam; Chen, Ying; Cheng, Zhengdong; Cheng's Group Team, Dr.

    2015-03-01

    Phase changing materials (PCM) have useful applications in thermal management. However, mass production of micro and nano encapsulated PCM has been a challenge. Here, we present a simple and scalable method via a two-step Pickering emulsification method. We have developed interface active nanoplates by asymmetric modification of nanoplates of layered crystal materials. Nanoencapsulated PCM is realized with exfoliated monolayer nanoplates surfactants using very little energy input for emulsification. Further chemical reactions are performed to convert the emulsions into core-shell structures. The resulted capsules are submicron in size with remarkable uniformity in size distribution. DSC characterization showed that the capsulation efficiency of NEPCM was 58.58% and were thermal stable which was characterized by the DSC data for the sample after 200 thermal cycling.

  13. Development and application of ultrasound-assisted microextraction to analysis of fenitrothion in environmental samples.

    PubMed

    Takahashi, Fumiki; Kobayashi, Kanya; Jin, Jiye

    2016-10-01

    A microextraction technique based on ultrasonic emulsification and demulsification was developed for detecting pesticides at trace levels in environmental water samples. In this ultrasound-assisted microextraction (UAME), chloroform was emulsified with an aqueous sample solution containing trace fenitrothion (MEP) by ultrasonic irradiation (48 kHz) for 5 min. The emulsion was then demulsified by ultrasonic irradiation (2.4 MHz) for 10 min. This resulted in phase separation of the water and chloroform without centrifugation. The demulsified chloroform was collected by a microsyringe and submitted to gas chromatography-mass spectrometry. In conventional extraction with mechanical stirring, the extraction recovery (ER) of MEP was strongly dependent on the sample/chloroform volume ratio. However, in UAME, the ER was independent of the volume ratio and the ER was >80 % when the enrichment factor was 40. In UAME, MEP was rapidly extracted into the chloroform because of the large specific surface areas of the small chloroform droplets in the oil-in-water (O/W) emulsion. This gave a high extraction efficiency for MEP. UAME is a simple method requiring only a change in the ultrasound frequency and with no pretreatment steps that could contaminate the sample. The suitability of UAME was demonstrated by application to the detection of trace levels of pesticides in a spiked water sample from a fish tank. Graphical abstract Schematic diagram of the ultrasound-assisted microextraction (UAME) method.

  14. Some Physicochemical Remarks on Spontaneous Emulsification of Vitreal Tamponades

    PubMed Central

    dell'Omo, Roberto; Zeppa, Lucio; Bufalo, Gennaro; Cardone, Michele; Romano, Mario; Ambrosone, Luigi

    2014-01-01

    The importance of gravitational instability in determining the emulsification of vitreal tamponades is discussed. Theoretical results and numerical simulations indicate that the spontaneous formation of water-silicon oil is a rare event and that the very low concentration of surface active agents cannot justify the systematic formation of emulsions. The gravitational instabilities seem to play the main role. Our theoretical results seem in agreement with the experimental evidences; furthermore they indicate a future research line for the improvement of endotamponades. Indeed, the use of biodegradable antifoam may avoid the formation of bubbles and delay the formation of emulsions. PMID:25133159

  15. Effects of high hydrostatic pressure and chemical reduction on the emulsification properties of gum arabic.

    PubMed

    Ma, Fanyi; Bell, Alan E; Davis, Fred J; Chai, Yunxi

    2015-04-15

    Gum arabic is widely used in the food industry as an additive, both as a thickener and an emulsifier. This study has compared the emulsification properties of two types of gums, KLTA (Acacia senegal) and GCA (Acacia seyal), both in their native/untreated forms and after exposure to high pressure (800 MPa). Further studies were undertaken to chemically modify the disulphide linkages present and to investigate the effects of their reduction on the diffusion of the carbohydrate materials. The emulsification properties of the gum samples were examined by determining the droplet size distribution in a "model" oil-in-water system. Results showed that high pressure treatment and chemical reduction of gums changed the emulsification properties of both gums. The high molecular weight component in arabinogalactan-proteins (AGP/GP), and more "branched" carbohydrates present in gum arabic, may be responsible for the emulsification properties of GCA gum, indicating that the emulsification mechanisms for KLTA and GCA were different.

  16. Emulsification in novel ultrasonic cavitation intensifying bag reactors.

    PubMed

    van Zwieten, Ralph; Verhaagen, Bram; Schroën, Karin; Fernández Rivas, David

    2017-05-01

    Cavitation Intensifying Bags (CIBs), a novel reactor type for use with ultrasound, have been recently proposed as a scaled-up microreactor with increased energy efficiencies. We now report on the use of the CIBs for the preparation of emulsions out of hexadecane and an SDS aqueous solution. The CIBs have been designed in such a way that cavitation effects created by the ultrasound are increased. It was found that the CIBs were 60 times more effective in breaking up droplets than conventional bags, therewith showing a proof of principle for the CIBs for the preparation of emulsions. Droplets of 0.2μm could easily be obtained. To our knowledge, no other technology results in the same droplet size more easily in terms of energy usage. Without depending on the wettability changes of the membrane, the CIBs score similarly as membrane emulsification, which is the most energy friendly emulsification method known in literature. Out of the frequencies used, 37kHz was found to require the lowest treatment time. The treatment time decreased at higher temperatures. While the energy usage in the current non-optimised experiments was on the order of 10(7)-10(9)J/m(3), which is comparable to that of a high-pressure homogenizer, we expect that the use of CIBs for the preparation of fine emulsions can still be improved considerably. The process presented can be applied for other uses such as water treatment, synthesis of nanomaterials and food processing.

  17. Enhanced oil recovery by surfactant-enhanced volumetric sweep efficiency: First annual report for the period September 30, 1985-September 30, 1986. [Sandpacks

    SciTech Connect

    Harwell, J H; Scamehorn, J F

    1987-05-01

    Surfactant-enhanced volumetric sweep efficiency is a novel EOR method which utilizes precipitation/coacervation of surfactants to plug the most permeable regions of the reservoir, improving the efficiency of a waterflooding operation. This technique does not rely on reduction of interfacial tension between aqueous and oleic phases to enhance oil recovery. Therefore, even though surfactants are involved, this new technique is not a substitute or improvement on classical surfactant flooding; however, it has the potantial to compete with polymer flooding as an alternative sweep efficiency improvement method. In surfactant-enhanced volumetric sweep efficiency, a slug containing one kind of surfactant is injected into the reservoir, followed by a brine spacer. This is followed by injection of a second kind of surfactant which has lower adsorption than the first surfactant used. Anionic and cationic surfactants are one possible combination for this application. These may form either a precipitate or a coacervate upon mixing. Phase boundaries for some specific systems of this type have been determined over a wide range of conditions and a model developed to describe this behavior. Another possibility is the use of nonionic surfactants, which may form coacervate under proper conditions. The adsorption behavior of mixtures of anionic and nonionic surfactants was measured to aid in modeling the chromatographic effects with these surfactants in the reservoir. Studies with sandpacks of different permeabilities in parallel configuration using mixtures of anionic and cationic surfactants have demonstrated the capability of this method to reduce flow rates through a more permeable sandpack more than that through a less permeable sandpack. 4 refs., 23 figs., 8 tabs.

  18. Tandem dispersive liquid-liquid microextraction as an efficient method for determination of basic drugs in complicated matrices.

    PubMed

    Bazregar, Mohammad; Rajabi, Maryam; Yamini, Yadollah; Saffarzadeh, Zahra; Asghari, Alireza

    2016-01-15

    A simple and efficient approach is introduced for the improvement of the clean-up and applicability of the dispersive liquid-liquid microextraction (DLLME) method in complicated matrices. For this purpose, two dispersive microextraction methods were combined, and the tandem dispersive liquid-liquid microextraction (TDLLME) method was provided. At first, using the ultrasound-assisted emulsification microextraction (USAEME) method, the tricyclic anti-depressant (TCA) drugs nortriptyline, imipramine, and amitriptyline, as the model compounds, contained in an aqueous sample solution (8.0 mL), were extracted into an organic solvent (35 μL). Then by utilizing the air-agitated liquid-liquid microextraction (AALLME) method, these analytes were simply back-extracted into 50 μL of an aqueous acceptor phase. By performing this convenient extraction method, a high sample clean-up was obtained; the overall extraction time was 7 min. The back-extraction step could be performed in less than 2 min, and very simple tools were required for this purpose. The response surface methodology (RSM) was used for the optimization of the experimental parameters so that the volumes 95 and 50 μL were obtained for the organic solvent and the acceptor phase, respectively, and the pH values of 11.25 and 1.75 were obtained for the donor and acceptor phases, respectively, as the optimal extraction conditions. Under the optimized conditions, TDLLME-HPLC-UV provided a good linearity in the range of 2.5-5000 ng mL(-1), low limits of detection (0.7-1.0 ng mL(-1)), good extraction repeatabilities (relative standard deviations below 6.2%, n=5), and enrichment factors (EFs) of 50-101. Finally, the developed method was successfully used for the determination of the mentioned drugs in the wastewater and human plasma samples.

  19. Dispersive suspended microextraction.

    PubMed

    Yang, Zhong-Hua; Liu, Yu; Lu, Yue-Le; Wu, Tong; Zhou, Zhi-Qiang; Liu, Dong-Hui

    2011-11-14

    A novel sample pre-treatment technique termed dispersive suspended microextraction (DSME) coupled with gas chromatography-flame photometric detection (GC-FPD) has been developed for the determination of eight organophosphorus pesticides (ethoprophos, malathion, chlorpyrifos, isocarbophos, methidathion, fenamiphos, profenofos, triazophos) in aqueous samples. In this method, both extraction and two phases' separation process were performed by the assistance of magnetic stirring. After separating the two phases, 1 μL of the suspended phase was injected into GC for further instrument analysis. Varieties of experiment factors which could affect the experiment results were optimized and the following were selected: 12.0 μL p-xylene was selected as extraction solvent, extraction speed was 1200 rpm, extraction time was 30 s, the restoration speed was 800 rpm, the restoration time was 8 min, and no salt was added. Under the optimum conditions, limits of detections (LODs) varied between 0.01 and 0.05 μg L(-1). The relative standard deviation (RSDs, n=6) ranged from 4.6% to 12.1%. The linearity was obtained by five points in the concentration range of 0.1-100.0 μg L(-1). Correlation coefficients (r) varied from 0.9964 to 0.9995. The enrichment factors (EFs) were between 206 and 243. In the final experiment, the developed method has been successfully applied to the determination of organophosphorus pesticides in wine and tap water samples and the obtained recoveries were between 83.8% and 101.3%. Compared with other pre-treatment methods, DSME has its own features and could achieve satisfied results for the analysis of trace components in complicated matrices.

  20. Microencapsulated probiotics using emulsification technique coupled with internal or external gelation process.

    PubMed

    Song, Huiyi; Yu, Weiting; Gao, Meng; Liu, Xiudong; Ma, Xiaojun

    2013-07-01

    Alginate-chitosan microcapsules containing probiotics (Yeast, Y235) were prepared by emulsification/external gelation and emulsification/internal gelation techniques respectively. The gel beads by external gelation showed asymmetrical structure, but those by internal gelation showed symmetrical structure in morphology. The cell viability was approximately 80% for these two techniques. However, during cell culture process, emulsification/internal gelation microcapsules showed higher cell growth and lower cell leakage. Moreover, the survival rate of entrapped low density cells with culture (ELDCwc) increased obviously than that directly entrapped high density cells (dEHDC) and free cells when keeping in simulated gastrointestinal conditions. It indicated the growth process of cells in microcapsule was important and beneficial to keep enough active probiotics under harmful environment stress. Therefore, the emulsification/internal gelation technique was the preferred method for application in food or biotechnological industries.

  1. Ultrasonic emulsification of food-grade nanoemulsion formulation and evaluation of its bactericidal activity.

    PubMed

    Ghosh, Vijayalakshmi; Mukherjee, Amitava; Chandrasekaran, Natarajan

    2013-01-01

    Basil oil (Ocimum basilicum) nanoemulsion was formulated using non-ionic surfactant Tween80 and water by ultrasonic emulsification method. Process of nanoemulsion development was optimized for parameters such as surfactant concentration and emulsification time to achieve minimum droplet diameter with high physical stability. Surfactant concentration was found to have a negative correlation with droplet diameter, whereas emulsification time had a positive correlation with droplet diameter and also with intrinsic stability of the emulsion. Stable basil oil nanoemulsion with droplet diameter 29.3 nm was formulated by ultrasonic emulsification for 15 min. Formulated nanoemulsion was evaluated for antibacterial activity against Escherichia coli by kinetics of killing experiment. Fluorescence microscopy and FT-IR results showed that nanoemulsion treatment resulted alteration in permeability and surface features of bacterial cell membrane.

  2. Analysis of triazine herbicides using an up-and-down-shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Chen, Pai-Shan; Haung, Wan-Yun; Huang, Shang-Da

    2014-04-01

    In dispersive liquid-liquid microextraction, a few hundred microliters to a few milliliters of water-miscible dispersive solvent are commonly used to assist emulsification in aqueous samples. In the present study, a consistent and automatic up-and-down-shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) that does not require a dispersive solvent was developed. The enrichment factors (EFs) of the targets obtained using the automatic shaker were 361-1391 for UDSA-DLLME, 51-77 for ultrasonication, and 298-922 for vortexing. The linearity of the method was in the range 0.2-200μgL(-1), and its limit of detections was within 0.02-0.04μgL(-1). The intraday and interday relative standard deviations ranged from 5.7 to 10.0% and 5.5 to 10.3%, respectively. The relative recoveries of river and lake samples spiked with 2.0μgL(-1) of triazines were 94.2-102.2% and 98.5-104.1%, respectively. The technique provided high repeatability and recovery. No matrix interference from river and lake water was observed. The method also achieved high EFs compared with those obtained through other emulsification methods such as vortexing and ultrasonication. UDSA-DLLME is an alternative sample preparation technique with good performance.

  3. Microfluidic EDGE emulsification: the importance of interface interactions on droplet formation and pressure stability

    NASA Astrophysics Data System (ADS)

    Sahin, Sami; Bliznyuk, Olesya; Rovalino Cordova, Ana; Schroën, Karin

    2016-05-01

    The fact that interactions of components with interfaces can influence processes is well-known; e.g. deposit accumulation on heat exchangers and membrane fouling lead to additional resistances against heat and mass transfer, respectively. In microfluidic emulsification, the situation is even more complex. Component accumulation at the liquid/liquid interface is necessary for emulsion stability, while undesired at the solid/liquid interface where it may change wettability. For successful emulsification both aspects need to be controlled, and that is investigated in this paper for o/w emulsification with microfluidic EDGE devices. These devices were characterised previously, and can be used to detect small wettability changes through e.g. the pressure stability of the device. We used various oil/emulsifier combinations (alkanes, vegetable oil, surfactants and proteins) and related droplet size and operational pressure stability to component interactions with the solid surface and liquid interface. Surfactants with a strong interaction with glass always favour emulsification, while surfactants that have week interactions with the surface can be replaced by vegetable oil that interacts strongly with glass, resulting in loss of emulsification. Our findings clearly show that an appropriate combination of construction material and emulsion components is needed to achieve successful emulsification in microfluidic EDGE devices.

  4. Microfluidic EDGE emulsification: the importance of interface interactions on droplet formation and pressure stability

    PubMed Central

    Sahin, Sami; Bliznyuk, Olesya; Rovalino Cordova, Ana; Schroën, Karin

    2016-01-01

    The fact that interactions of components with interfaces can influence processes is well-known; e.g. deposit accumulation on heat exchangers and membrane fouling lead to additional resistances against heat and mass transfer, respectively. In microfluidic emulsification, the situation is even more complex. Component accumulation at the liquid/liquid interface is necessary for emulsion stability, while undesired at the solid/liquid interface where it may change wettability. For successful emulsification both aspects need to be controlled, and that is investigated in this paper for o/w emulsification with microfluidic EDGE devices. These devices were characterised previously, and can be used to detect small wettability changes through e.g. the pressure stability of the device. We used various oil/emulsifier combinations (alkanes, vegetable oil, surfactants and proteins) and related droplet size and operational pressure stability to component interactions with the solid surface and liquid interface. Surfactants with a strong interaction with glass always favour emulsification, while surfactants that have week interactions with the surface can be replaced by vegetable oil that interacts strongly with glass, resulting in loss of emulsification. Our findings clearly show that an appropriate combination of construction material and emulsion components is needed to achieve successful emulsification in microfluidic EDGE devices. PMID:27230981

  5. Scaling-up parameters for site restoration process using surfactant-enhanced soil washing coupled with wastewater treatment by Fenton and Fenton-like processes.

    PubMed

    Bandala, Erick R; Cossio, Horacio; Sánchez-Lopez, Adriana D; Córdova, Felipe; Peralta-Herández, Juan M; Torres, Luis G

    2013-01-01

    Estimation of scaling-up parameters for a site restoration process using a surfactant-enhanced soil washing (SESW) process followed by the application of advanced oxidation processes (Fenton and photo-Fenton) was performed. For the SESW, different parameters were varied and the soil washing efficiency for pesticide (2,4-D) removal assessed. The resulting wastewater was treated using the Fenton reaction in the absence and presence of ultraviolet (UV) radiation for pesticide removal. Results showed that agitation speed of 1550 rpm was preferable for the best pesticide removal from contaminated soil. It was possible to wash contaminated soils with different soil concentrations; however the power drawn was higher as the soil concentration increased. Complete removal of the pesticide and the remaining surfactant was achieved using different reaction conditions. The best degradation conditions were for the photo-Fenton process using [Fe(II)] = 0.3 mM; [H2O2] = 4.0 mM where complete 2,4-D and sodium dodecylsulfate (SDS) removal was observed after 8 and 10 minutes of reaction, respectively. Further increase in the hydrogen peroxide or iron salt concentration did not show any improvement in the reaction rate. Kinetic parameters, i.e. reaction rate constant and scaling-up parameters, were determined. It was shown that, by coupling both processes (SESW and AOPs), it is possible the restoration of contaminated sites.

  6. Correlation between DNAPL distribution area and dissolved concentration in surfactant enhanced aquifer remediation effluent: a two-dimensional flow cell study

    SciTech Connect

    Wu, Bin; Li, Huiying; Du, Xiaoming; Zhong, Lirong; Yang, Bin; Du, Ping; Gu, Qingbao; Li, Fasheng

    2016-02-01

    During the process of surfactant enhanced aquifer remediation (SEAR), free phase dense non-aqueous phase liquid (DNAPL) may be mobilized and spread. The understanding of the impact of DNAPL spreading on the SEAR remediation is not sufficient with its positive effect infrequently mentioned. To evaluate the correlation between DNAPL spreading and remediation efficiency, a two-dimensional sandbox apparatus was used to simulate the migration and dissolution process of 1,2-DCA (1,2-dichloroethane) DNAPL in SEAR. Distribution area of DNAPL in the sandbox was determined by digital image analysis and correlated with effluent DNAPL concentration. The results showed that the effluent DNAPL concentration has significant positive linear correlation with the DNAPL distribution area, indicating the mobilization of DNAPL could improve remediation efficiency by enlarging total NAPL-water interfacial area for mass transfer. Meanwhile, the vertical migration of 1,2-DCA was limited within the boundary of aquifer in all experiments, implying that by manipulating injection parameters in SEAR, optimal remediation efficiency can be reached while the risk of DNAPL vertical migration is minimized. This study provides a convenient visible and quantitative method for the optimization of parameters for SEAR project, and an approach of rapid predicting the extent of DNAPL contaminant distribution based on the dissolved DNAPL concentration in the extraction well.

  7. The effect of polymer-surfactant interaction on the rheological properties of surfactant enhanced alkaline flooding formulations. [Phase separation, precipitation and viscosity loss

    SciTech Connect

    French, T.R.; Josephson, C.B.

    1993-02-01

    Surfactant-enhanced, lower pH (weak) alkaline chemicals are effective for mobilizing residual oil. Polymer is used for mobility control because if mobility control is lost, then oil recovery is reduced. The ability to maintain mobility control during surfactant-alkaline flooding can be adversely affected by chemical interaction. In this work, interaction between polymers and surfactants was shown to be affected by pH, ionic strength, crude oil, and the properties of the polymers and surfactants. Polymer-surfactant interaction (phase separation, precipitation, and viscosity loss) occurred between most of the polymers and surfactants that were tested. Polymer-surfactant interaction is difficult to eliminate, and no method was found for completely eliminating interaction. Polymer-surfactant interaction occurred at optimal salinity and below optimal salinity. Polymer-surfactant interaction had an adverse effect on polymer rheology; however, the adverse effect of interaction on polymer rheology was lessened when oil was present. Increasing the pH of chemical systems further reduced the adverse effects of interaction on polymer rheology.

  8. In situ, field-scale evaluation of surfactant-enhanced DNAPL recovery using a single-well, ``push-pull'' test

    SciTech Connect

    Istok, J.D.; Field, J.A.

    1999-10-01

    The overall goal of this project was to further develop the single-well, ``push-pull'' test method as a feasibility assessment and site-characterization tool for studying the fundamental fate and transport behavior of injected surfactants and their ability to solubilize and mobilize dense nonaqueous phase liquids (DNAPLs) in the subsurface. The specific objectives were to develop a modified push-pull test for use in identifying and quantifying the effects of sorption, precipitation, and biodegradation on the fate and transport of injected surfactants, use the developed test method to quantify the effects of these processes on the ability of injected surfactants to solubilize and mobilize residual phase trichloroethane (TCE), and demonstrate the utility of the developed test method for performing site characterization and feasibility studies for surfactant-enhanced DNAPL recovery systems in the field. The results from the intermediate-scale laboratory experiments conducted for this project indicate that the single-well, push-pull test method can provide quantitative information on the effectiveness of injected surfactants in enhancing DNAPL solubilization in natural aquifer sediments. Specifically, the results of this research demonstrate the ability of the single-well, push-pull test to characterize the behavior of multi-component surfactants in the presence of natural aquifer sediment under laboratory and in-situ field conditions.

  9. Surfactant-enhanced spectrofluorimetric determination of total aflatoxins from wheat samples after magnetic solid-phase extraction using modified Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Manafi, Mohammad Hanif; Allahyari, Mehdi; Pourghazi, Kamyar; Amoli-Diva, Mitra; Taherimaslak, Zohreh

    2015-07-01

    The extraction and preconcentration of total aflatoxins (including aflatoxin B1, B2, G1, and G2) using magnetic nanoparticles based solid phase extraction (MSPE) followed by surfactant-enhanced spectrofluorimetric detection was proposed. Ethylene glycol bis-mercaptoacetate modified silica coated Fe3O4 nanoparticles as an efficient antibody-free adsorbent was successfully applied to extract aflatoxins from wheat samples. High surface area and strong magnetization properties of magnetic nanoparticles were utilized to achieve high enrichment factor (97), and satisfactory recoveries (92-105%) using only 100 mg of the adsorbent. Furthermore, the fast separation time (less than 10 min) avoids many time-consuming cartridge loading or column-passing procedures accompany with the conventional SPE. In determination step, signal enhancement was performed by formation of Triton X-100 micelles around the analytes in 15% (v/v) acetonitrile-water which dramatically increase the sensitivity of the method. Main factors affecting the extraction efficiency and signal enhancement of the analytes including pH of sample solution, desorption conditions, extraction time, sample volume, adsorbent amount, surfactant concentration and volume and time of micelle formation were evaluated and optimized. Under the optimum conditions, wide linear range of 0.1-50 ng mL-1 with low detection limit of 0.03 ng mL-1 were obtained. The developed method was successfully applied to the extraction and preconcentration of aflatoxins in three commercially available wheat samples and the results were compared with the official AOAC method.

  10. Cross-Interface Emulsification for Generating Size-Tunable Droplets.

    PubMed

    Xu, Peng; Zheng, Xu; Tao, Yi; Du, Wenbin

    2016-03-15

    We report cross-interface emulsification (XiE), a simple method for the generation of monodisperse droplets of controllable volumes from picoliter to nanoliter. A device is set up in which a fused-silica capillary is vibrating across the surface of the continuous phase (mineral oil) in a reservoir, and the flow of the dispersed phase (aqueous solution) in the capillary is segmented into monodisperse droplets at the air/oil interface. We find that the volume of droplets is mainly dominated by the flow rate and vibrating frequency and not significantly influenced by other factors, such as the viscosity of the continuous phase and dispersed phase, the inner diameter of the capillary (20-100 μm), or the shape of the tip (tapered or flat). These features reflect high robustness, flexibility, and precision of XiE for on-demand volume control of droplets. The droplets automatically assemble into planar monolayer droplet arrays (PMDA) in flat-bottomed microwells of 96-well plates, offering excellent convenience for imaging of droplets. As a representative application, we carry out digital loop-mediated isothermal amplification using PMDAs with multivolume droplets for the absolute quantification of nucleic acids. Our results demonstrate that XiE is simple and controllable for the production of monodisperse size-tunable droplets, and it offers opportunities for common laboratories, even without microfabrication facilities, to perform digital quantification, single cell analysis, and other biochemical assays with high throughput.

  11. Emulsification Characteristics Using a Dynamic Woven Metal Microscreen Membrane

    PubMed Central

    Sabouni, Rana; Gomaa, Hassan G.; Liu, Jiangshan; Zhu, Jesse

    2016-01-01

    An oscillatory emulsification system for the production of oil in water emulsions using a commercially available low-cost woven metal microscreen (WMMS) is investigated. The system allows for independent control of both the oscillation frequencies and amplitudes such that it provides two degrees of freedom for controlling the emulsion properties. The investigations included the production of both surfactant and particle-stabilized emulsions. The average droplet size was found to decrease when both the oscillation frequency and amplitude was increased. For surfactant-stabilized emulsions, using bi-surfactants in both the continuous and dispersed phases resulted in a smaller droplet size due to lower interfacial tension. For particle-stabilized emulsions, both the hydrodynamics of the system and the hydrophobic and hydrophilic nature of the stabilizing particles influenced the interfacial properties at the oil–water interface, which in turn affected the final droplet size and distribution with potential droplet breakage. In absence of the latter, a simple torque balance model can be used to reasonably predict the average emulsion droplet size. PMID:27331821

  12. Manufacture of large uniform droplets using rotating membrane emulsification.

    PubMed

    Vladisavljević, Goran T; Williams, Richard A

    2006-07-01

    A new rotating membrane emulsification system using a stainless steel membrane with 100 microm laser drilled pores was used to produce oil/water emulsions consisting of 2 wt% Tween 20 as emulsifier, paraffin wax as dispersed oil phase and 0.01-0.25 wt% Carbomer (Carbopol ETD 2050) as stabilizer. The membrane tube, 1 cm in diameter, was rotated inside a stationary glass cylinder, diameter of 3 cm, at a constant speed in the range 50-1500 rpm. The oil phase was introduced inside the membrane tube and permeated through the porous wall moving radially into the continuous phase in the form of individual droplets. Increasing the membrane rotational speed increased the wall shear stress which resulted in a smaller average droplet diameter being produced. For a constant rotational speed, the average droplet diameter increased as the stabilizer content in the continuous phase was lowered. The optimal conditions for producing uniform emulsion droplets were a Carbomer content of 0.1-0.25 wt% and a membrane rotational speed of 350 rpm, under which the average droplet diameter was 105-107 microm and very narrow coefficients of variation of 4.8-4.9%. A model describing the operation is presented and it is concluded that the methodology holds potential as a manufacturing protocol for both coarse and fine droplets and capsules.

  13. Microfluidic step-emulsification in a cylindrical geometry

    NASA Astrophysics Data System (ADS)

    Chakraborty, Indrajit; Leshansky, Alexander M.

    2016-11-01

    The model microfluidic device for high-throughput droplet generation in a confined cylindrical geometry is investigated numerically. The device comprises of core-annular pressure-driven flow of two immiscible viscous liquids through a cylindrical capillary connected co-axially to a tube of a larger diameter through a sudden expansion, mimicking the microfluidic step-emulsifier (1). To study this problem, the numerical simulations of axisymmetric Navier-Stokes equations have been carried out using an interface capturing procedure based on coupled level set and volume-of-fluid (CLSVOF) methods. The accuracy of the numerical method was favorably tested vs. the predictions of the linear stability analysis of core-annular two-phase flow in a cylindrical capillary. Three distinct flow regimes can be identified: the dripping (D) instability near the entrance to the capillary, the step- (S) and the balloon- (B) emulsification at the step-like expansion. Based on the simulation results we present the phase diagram quantifying transitions between various regimes in plane of the capillary number and the flow-rate ratio. MICROFLUSA EU H2020 project.

  14. Ensemble of Surrogates-based Optimization for Identifying an Optimal Surfactant-enhanced Aquifer Remediation Strategy at Heterogeneous DNAPL-contaminated Sites

    NASA Astrophysics Data System (ADS)

    Lu, W., Sr.; Xin, X.; Luo, J.; Jiang, X.; Zhang, Y.; Zhao, Y.; Chen, M.; Hou, Z.; Ouyang, Q.

    2015-12-01

    The purpose of this study was to identify an optimal surfactant-enhanced aquifer remediation (SEAR) strategy for aquifers contaminated by dense non-aqueous phase liquid (DNAPL) based on an ensemble of surrogates-based optimization technique. A saturated heterogeneous medium contaminated by nitrobenzene was selected as case study. A new kind of surrogate-based SEAR optimization employing an ensemble surrogate (ES) model together with a genetic algorithm (GA) is presented. Four methods, namely radial basis function artificial neural network (RBFANN), kriging (KRG), support vector regression (SVR), and kernel extreme learning machines (KELM), were used to create four individual surrogate models, which were then compared. The comparison enabled us to select the two most accurate models (KELM and KRG) to establish an ES model of the SEAR simulation model, and the developed ES model as well as these four stand-alone surrogate models was compared. The results showed that the average relative error of the average nitrobenzene removal rates between the ES model and the simulation model for 20 test samples was 0.8%, which is a high approximation accuracy, and which indicates that the ES model provides more accurate predictions than the stand-alone surrogate models. Then, a nonlinear optimization model was formulated for the minimum cost, and the developed ES model was embedded into this optimization model as a constrained condition. Besides, GA was used to solve the optimization model to provide the optimal SEAR strategy. The developed ensemble surrogate-optimization approach was effective in seeking a cost-effective SEAR strategy for heterogeneous DNAPL-contaminated sites. This research is expected to enrich and develop the theoretical and technical implications for the analysis of remediation strategy optimization of DNAPL-contaminated aquifers.

  15. Dispersion of oil into water using lecithin-Tween 80 blends: The role of spontaneous emulsification.

    PubMed

    Riehm, David A; Rokke, David J; Paul, Prakash G; Lee, Han Seung; Vizanko, Brent S; McCormick, Alon V

    2017-02-01

    Lecithin-rich mixtures of the nontoxic surfactants lecithin and Tween 80 are effective marine oil spill dispersants, but produce much higher oil-water interfacial tension than other, comparably effective dispersants. This suggests interfacial phenomena other than interfacial tension influence lecithin-Tween 80 dispersants' effectiveness. The interface between seawater and dispersant-crude oil mixtures was studied using light microscopy, cryogenic scanning electron microscopy, and droplet coalescence tests. Lecithin:Tween 80 ratio was varied from 100:0 to 0:100 and wt% dispersant in the oil was varied from 1.25 to 10wt%. Tween 80-rich dispersants cause oil-into-water spontaneous emulsification, while lecithin-rich dispersants primarily cause water-into-oil spontaneous emulsification. Possible mechanisms for this spontaneous emulsification are discussed, in light of images of spontaneously emulsifying interfaces showing no bursting microstructures, interfacial gel, or phase inversion, and negligible interfacial turbulence. Dispersant loss into seawater due to oil-into-water spontaneous emulsification may explain why Tween 80-rich dispersants are less effective than lecithin-rich dispersants with comparable interfacial tension, although longer droplet coalescence times observed for Tween 80-rich, self-emulsifying dispersant-oil mixtures may mitigate the effects of dispersant leaching. Conversely, surfactant retention in oil via lecithin-rich dispersants' water-into-oil emulsification may explain why lecithin-Tween 80 dispersants are as effective as dispersants containing other surfactant blends which produce lower interfacial tension.

  16. Solid phase microextraction field kit

    DOEpatents

    Nunes, Peter J.; Andresen, Brian D.

    2005-08-16

    A field kit for the collection, isolation and concentration of trace amounts of high explosives (HE), biological weapons (BW) and chemical weapons (CW) residues in air, soil, vegetation, swipe, and liquid samples. The field kit includes a number of Solid Phase Microextraction (SPME) fiber and syringe assemblies in a hermetically sealed transportation container or tubes which includes a sampling port, a number of extra SPME fiber and syringe assemblies, the fiber and syringe assemblies including a protective cap for the fiber, and an extractor for the protective cap, along with other items including spare parts, protective glove, and an instruction manual, all located in an airtight container.

  17. Emulsification-Induced Homohelicity in Racemic Helical Polymer for Preparing Optically Active Helical Polymer Nanoparticles.

    PubMed

    Zhao, Biao; Deng, Jinrui; Deng, Jianping

    2016-04-01

    Optically active nano- and microparticles have constituted a significant category of advanced functional materials. However, constructing optically active particles derived from synthetic helical polymers still remains as a big challenge. In the present study, it is attempted to induce a racemic helical polymer (containing right- and left-handed helices in equal amount) to prefer one predominant helicity in aqueous media by using emulsifier in the presence of chiral additive (emulsification process). Excitingly, the emulsification process promotes the racemic helical polymer to unify the helicity and directly provides optically active nanoparticles constructed by chirally helical polymer. A possible mechanism is proposed to explain the emulsification-induced homohelicity effect. The present study establishes a novel strategy for preparing chirally helical polymer-derived optically active nanoparticles based on racemic helical polymers.

  18. Ultrasound-assisted temperature-controlled ionic-liquid dispersive liquid-phase microextraction method for simultaneous determination of anethole, estragole, and para-anisaldehyde in different plant extracts and human urine: a comparative study.

    PubMed

    Rajabi, Maryam; Haji-Esfandiari, Sudabeh; Barfi, Behruz; Ghanbari, Hanieh

    2014-07-01

    In this study, the performances of four ionic-liquid-based microextraction methods, ionic-liquid-based dispersive liquid-liquid microextraction (IL-DLLME), ionic-liquid-based ultrasound-assisted emulsification microextraction (IL-USA-ME), temperature-controlled ionic-liquid dispersive liquid-phase microextraction (TC-IL-DLME), and ultrasound-assisted temperature-controlled ionic-liquid dispersive liquid-phase microextraction (USA-TC-IL-DLME), were investigated for extraction of three bioactive compounds (anethole, estragole, and anisaldehyde) from different plant extracts and human urine. Anethole and estragole were chosen because they can alter cellular processes positively or negatively, and an efficient method is needed for their extraction and sensitive determination in the samples mentioned. Because there is no previous report on the separation of anethole and estragole (structural isomers), first, simultaneous gradient elution and flow programming were used. The microextraction methods were then applied and compared for analysis of these compounds in plant extracts and human urine by use of high-performance liquid chromatography (HPLC). The effect of conditions on extraction efficiency was studied and under the optimum conditions, the best enrichment factors (58-64), limits of detection (14-18 ng mL(-1)), limits of quantification (47-60 ng mL(-1)), and recovery (94.4-101.7 %) were obtained by use of USA-TC-IL-DLME. The optimized conditions were used to determine anethole, estragole, and para-anisaldehyde in fennel, anise, and tarragon extracts and in human urine.

  19. Surfactant-Enhanced DNAPL Removal

    DTIC Science & Technology

    2001-08-24

    DNAPL SOURCE REMEDIATION AT SITE 88, MARINE CORPS BASE CAMP LEJEUNE vii AATDF AFCEE AFB AFP4 AQT B bgs CERCLA CITT em cmc cp cu d de DE&S DNAPL DoD...liquid meter(s) medium, middle Marine Corps Base maximum contaminant level millidarcies micellar-enhanced ultrafiltration unit minute(s) multi-level...present in the subsurface adjacent to a dry-cleaning facility operated by the Marine Corps Base (MCB) Camp Lejeune, North Carolina. The contaminant was

  20. Emulsification Of Eutectic Salt Mixtures In Fluid Vehicles

    NASA Astrophysics Data System (ADS)

    Vanderhoff, J. W.; El-Aasser, M. S.; Hawkins, T. W.

    1988-05-01

    High-internal-phase-volume emulsions of 75 volt 3/18/79 potassium iodide/sodium iodide/ urea model eutectic salt mixture in 83.5/16.5 Sartomer R-45HT hydroxy-terminated polybutadi-ene/Nujol mineral oil binder mixture were prepared at 60°C using water-in-oil emulsifiers and cured with isophorone diisocyanate or Desmodur N-100. The Nujol mineral oil enhanced the emulsification with a negligible reduction in the tensile properties of the cured elastomer. The average emulsion droplet sizes were ca. 200 nm initially, but increased slowly during curing to 500-1000 nm. The coalescence of the emulsion droplets followed the second-order dependence predicted by the von Smoluchowski diffusion-controlled flocculation; the rate constants were 1.05x10-18 and 9.58x10-18 cc/droplet-sec for dirnethyldioctadecylammonium bromide and Span 85 sorbitan trioleate, respectively. The isophorone diisocyanate reacted with emulsifiers containing primary hydroxyl or amine groups, to give unstable emulsions or no emulsions at all. Dimethyldioctadecylammonium bromide with no primary hydroxyl or amine groups, however, did not react with isocyanates and gave stable emulsions. The reaction of the R-45HT hydroxy-terminated polybutadiene with isophorone diisocyanate followed the expec-ted second-order kinetics with a rate constant of 3.42x10-4 liters/mole-sec at 60°C. The tensile properties of the cured elastomers and emulsions generally increased with increasing NCO/OH ratio up to 1.6/1.0. With increasing volume fraction of dispersed phase, the maximum stress (tensile strength) decreased, the maximum strain (percent elongation) increased, and the initial modulus (tensile modulus) decreased, in contrast to the behavior of conventional filled polymer systems; however, the maximum stresses were in accord with theoretical values for a filled polymer in which the filler particles bear no load, the initial moduli were in accord with the predictions of an isostrain model, and the maximum strain increased

  1. Fabrication of starch-based microparticles by an emulsification-crosslinking method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch-based microparticles (MPs) fabricated by a water-in-water (w/w) emulsification-crosslinking method could be used as a controlled-release delivery vehicle for food bioactives. Due to the processing route without the use of toxic organic solvents, it is expected that these microparticles can be...

  2. Nanoemulsions prepared by a low-energy emulsification method applied to edible films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Catastrophic phase inversion (CPI) was used as a low-energy emulsification method to prepare oil-in-water (O/W) nanoemulsions in a lipid (Acetem)/water/nonionic surfactant (Tween 60) system. CPIs in which water-in-oil emulsions (W/O) are transformed into oil-in-water emulsions (O/W) were induced by ...

  3. Lecithin-Based Nano-emulsification Improves the Bioavailability of Conjugated Linoleic Acid.

    PubMed

    Heo, Wan; Kim, Jun Ho; Pan, Jeong Hoon; Kim, Young Jun

    2016-02-17

    In this study, we investigated the effects of lecithin-based nano-emulsification on the heat stability and bioavailability of conjugated linoleic acid (CLA) in different free fatty acid (FFA) and triglyceride (TG) forms. CLA nano-emulsion in TG form exhibited a small droplet size (70-120 nm) compared to CLA nano-emulsion in FFA form (230-260 nm). Nano-emulsification protected CLA isomers in TG form, but not in free form, against thermal decomposition during the heat treatment. The in vitro bioavailability test using monolayers of Caco-2 human intestinal cells showed that nano-emulsification increased the cellular uptake of CLA in both FFA and TG forms. More importantly, a rat feeding study showed that CLA content in small intestinal tissues or plasma was higher when CLA was emulsified, indicating an enhanced oral bioavailability of CLA by nano-emulsification. These results provide important information for development of nano-emulsion-based delivery systems that improve thermal stability and bioavailability of CLA.

  4. Vortex-assisted liquid-liquid microextraction of octylphenol, nonylphenol and bisphenol-A.

    PubMed

    Yiantzi, Evangelia; Psillakis, Elefteria; Tyrovola, Konstantina; Kalogerakis, Nicolas

    2010-03-15

    A new and fast equilibrium-based solvent microextraction technique termed vortex-assisted liquid-liquid microextraction (VALLME) has been developed and used for the trace analysis of octylphenol, nonylphenol and bisphenol-A in water and wastewater samples. According to VALLME, dispersion of microvolumes of a low density extractant organic solvent into the aqueous sample is achieved by using for the first time vortex mixing, a mild emulsification procedure. The fine droplets formed could extract target analytes towards equilibrium faster because of the shorter diffusion distance and larger specific surface area. Upon centrifugation the floating extractant acceptor phase restored its initial single microdrop shape and was used for high-performance liquid chromatographic analysis. Different experimental parameters were controlled and the optimum conditions found were: 50 microl of octanol as the extractant phase; 20 ml aqueous donor samples; a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; centrifugation for 2 min at 3500 rpm; no ionic strength or pH adjustment. The calculated calibration curves gave high levels of linearity yielding correlation coefficients (r(2)) greater than 0.9935. The repeatability and reproducibility of the proposed method were found to be good and the limits of the detection were calculated in the low microg l(-1) level ranging between 0.01 and 0.07 microg l(-1). Matrix effects were determined by applying the proposed method to spiked tap, river water and treated municipal wastewater samples. The proposed method was finally applied to the determination of target pollutants in real wastewater effluent samples using the standard addition method.

  5. Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.

    PubMed

    Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria

    2014-02-21

    Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ∼0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption.

  6. Mechanisms of Neutral and Anionic Surfactant Sorption to Solid-Phase Microextraction Fibers.

    PubMed

    Haftka, Joris J-H; Hammer, Jort; Hermens, Joop L M

    2015-09-15

    Octanol-water partitioning (Kow) is considered a key parameter for hydrophobicity and is often applied in the prediction of the environmental fate and exposure of neutral organic compounds. However, surfactants can create difficulties in the determination of Kow because of emulsification of both water and octanol phases. Moreover, not only is sorption behavior of ionic surfactants related to hydrophobicity, but also other interactions are relevant in sorption processes. A different approach to develop parameters that can be applied in predictive modeling of the fate of surfactants in the environment is therefore required. Distribution between solid-phase microextraction (SPME) fibers and water was used in this study to measure the affinity of surfactants to a hydrophobic phase. Fiber-water sorption coefficients of alcohol ethoxylates, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates were determined at pH 7 by equilibration of the test analytes between fiber and water. Distribution between fiber and water of anionic compounds with pKa ∼ 5 (i.e., alkyl carboxylates) was dominated by the neutral fraction. Anionic surfactants with pKa ≤ 2 (i.e., alkyl sulfates and alkyl sulfonates) showed strong nonlinear distribution to the fiber. The fiber-water sorption coefficients for alcohol ethoxylates and alkyl sulfates showed a linear trend with bioconcentration factors from the literature. Fiber-water sorption coefficients are promising as a parameter to study the effects of hydrophobicity and other potential interactions on sorption behavior of neutral and anionic surfactants.

  7. Optimization of parameters in the emulsification process by two different methods.

    PubMed

    Carlotti, M E; Pattarino, F; Gasco, M R; Brusasca, P

    1993-12-01

    Synopsis An O/W emulsion with a lipopeptidic emulsifier was optimized by means of two different methods, specifically by experimental design and by selective variation of the parameters. Two optimized emulsions were obtained; they had similar values of emulsification (time and rate of homogenization) and amounts of components. Résumé Une émulsion O/E, avec un lipopeptide comme tensioactif, a été optimisée par deux méthodes d'optimisation différentes, notamment par l'experimental design et par la variation selective de certain paramètres. Deux émulsions optimisées ont été ainsi obtenues: ces émulsions ont des valeurs d'emulsification (temp et vitesse d'homogénéisation) et des quantités des composantes très proches.

  8. A Mutant Strain of a Surfactant-Producing Bacterium with Increased Emulsification Activity

    NASA Astrophysics Data System (ADS)

    Liu, Qingmei; Yao, Jianming; Pan, Renrui; Yu, Zengliang

    2005-06-01

    As reported in this paper, a strain of oil-degrading bacterium Sp-5-3 was determined to belong to Enterobacteriaceae, which would be useful for microbial enhanced oil recovery (MEOR). The aim of our study was to generate a mutant using low energy N+ beam implantation. With 10 keV of energy and 5.2 × 1014 N+/cm2 of dose - the optimum condition, a mutant, S-34, was obtained, which had nearly a 5-fold higher surface and a 13-fold higher of emulsification activity than the wild type. The surface activity was measured by two methods, namely, a surface tension measuring instrument and a recording of the repulsive circle of the oil film; the emulsification activity was scaled through measuring the separating time of the oil-fermentation mixture. The metabolic acid was determined as methane by means of gas chromatography.

  9. Controlled microfluidic emulsification of oil in a clay nanofluid: Role of salt for Pickering stabilization

    NASA Astrophysics Data System (ADS)

    Gholamipour-Shirazi, A.; Carvalho, M. S.; Fossum, J. O.

    2016-07-01

    Research on emulsions is driven by their widespread use in different industries, such as food, cosmetic, pharmaceutical and oil recovery. Emulsions are stabilized by suitable surfactants, polymers, solid particles or a combination of them. Microfluidic emulsification is the process of droplet formation out of two or more liquids under strictly controlled conditions, without pre-emulsification step. Microfluidic technology offers a powerful tool for investigating the properties of emulsions themselves. In this work stable oil in water emulsions were formed with hydrophilic Laponite RD® nanoparticles adsorbed at the interface of the oil phase and aqueous clay nanofluid in a T junction microfluidic chip. Emulsion stability up to at least 40 days could be observed.

  10. Emulsification at the Liquid/Liquid Interface: Effects of Potential, Electrolytes and Surfactants.

    PubMed

    Chowdhury, Mehrin; Kataky, Ritu

    2016-01-04

    Emulsification of oils at liquid/liquid interfaces is of fundamental importance across a range of applications, including detergency. Adsorption and partitioning of the anionic surface active ions at the interface between two immiscible solutions is known to cause predictable chaos at the transfer potential region of the surfactant. In this work, the phenomenon that leads to the chaotic behaviour shown by sodium dodecylbenzene sulfonate (SDBS) at the water/1,2-dichloroethane interface is applied to commercial surfactants and aqueous/glyceryl trioleate interface. Electrochemical methods, electrocapillary curves, optical microscopy and conductivity measurements demonstrated that at 1.5 mm of SDBS, surfactants are adsorbed at the interface and assemble into micelles, leading to interfacial instability. As the concentration of the anionic surfactant was enhanced to 8 and 13.4 mm, the Marangoni effect and the interfacial emulsification became more prominent. The chaotic behaviour was found to be dependent on the surfactant concentration and the electrolytes present.

  11. Grafting amphiphilic brushes onto halloysite nanotubes via a living RAFT polymerization and their Pickering emulsification behavior.

    PubMed

    Hou, Yifan; Jiang, Junqing; Li, Kai; Zhang, Yanwu; Liu, Jindun

    2014-02-20

    Amphiphilic brushes of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) are grafted onto halloysite nanotubes (HNTs) via a surface reversible addition-fragmentation chain transfer (RAFT) living polymerization through anchoring R group in RAFT agent S-1-dodecyl-S'-(R,R'-dimethyl-R″-acetic acid) trithiocarbonates (DDMAT). The characterization of TGA, TEM, and GPC show that amphiphilic brushes are successfully grafted onto HNTs in a living manner. To verify the amphiphilicity of HNTs grafted with block copolymers, their Pickering emulsification behavior in water/soybean oil diphase mixture is studied. The results show that modified HNTs can emulsify water/soybean oil diphase mixture and the emulsification performance is dependent on microstructure of amphiphilic brushes such as hydrophilic/hydrophobic segment size and sequence.

  12. Advances in membrane emulsification. Part A: recent developments in processing aspects and microstructural design approaches.

    PubMed

    Spyropoulos, Fotis; Lloyd, David M; Hancocks, Robin D; Pawlik, Aleksandra K

    2014-03-15

    Modern emulsion processing technology is strongly influenced by the market demands for products that are microstructure-driven and possess precisely controlled properties. Novel cost-effective processing techniques, such as membrane emulsification, have been explored and customised in the search for better control over the microstructure, and subsequently the quality of the final product. Part A of this review reports on the state of the art in membrane emulsification techniques, focusing on novel membrane materials and proof of concept experimental set-ups. Engineering advantages and limitations of a range of membrane techniques are critically discussed and linked to a variety of simple and complex structures (e.g. foams, particulates, liposomes etc.) produced specifically using those techniques.

  13. Linking Findings in Microfluidics to Membrane Emulsification Process Design: The Importance of Wettability and Component Interactions with Interfaces

    PubMed Central

    Schroën, Karin; Ferrando, Montse; de Lamo-Castellví, Silvia; Sahin, Sami; Güell, Carme

    2016-01-01

    In microfluidics and other microstructured devices, wettability changes, as a result of component interactions with the solid wall, can have dramatic effects. In emulsion separation and emulsification applications, the desired behavior can even be completely lost. Wettability changes also occur in one phase systems, but the effect is much more far-reaching when using two-phase systems. For microfluidic emulsification devices, this can be elegantly demonstrated and quantified for EDGE (Edge-base Droplet GEneration) devices that have a specific behavior that allows us to distinguish between surfactant and liquid interactions with the solid surface. Based on these findings, design rules can be defined for emulsification with any micro-structured emulsification device, such as direct and premix membrane emulsification. In general, it can be concluded that mostly surface interactions increase the contact angle toward 90°, either through the surfactant, or the oil that is used. This leads to poor process stability, and very limited pressure ranges at which small droplets can be made in microfluidic systems, and cross-flow membrane emulsification. In a limited number of cases, surface interactions can also lead to lower contact angles, thereby increasing the operational stability. This paper concludes with a guideline that can be used to come to the appropriate combination of membrane construction material (or any micro-structured device), surfactants and liquids, in combination with process conditions. PMID:27187484

  14. Preparation of gelatin microbeads with a narrow size distribution using microchannel emulsification.

    PubMed

    Iwamoto, Satoshi; Nakagawa, Kei; Sugiura, Shinji; Nakajima, Mitsutoshi

    2002-01-01

    The purpose of this study was to prepare monodisperse gelatin microcapsules containing an active agent using microchannel (MC) emulsification, a novel technique for preparing water-in-oil (W/O) and oil-in-water (O/W) emulsions. As the first step in applying MC emulsification to the preparation of monodisperse gelatin microcapsules, simple gelatin microbeads were prepared using this technique. A W/O emulsion with a narrow size distribution containing gelatin in the aqueous phase was created as follows. First, the aqueous disperse phase was fed into the continuous phase through the MCs at 40 degrees C (operating pressure: 3.9 kPa). The emulsion droplets had an average particle diameter of 40.7 microm and a relative standard deviation of 5.1%. The temperature of the collected emulsion was reduced and maintained at 25 degrees C overnight. The gelatin microbeads had a smooth surface after overnight gelation; the average particle diameter was calculated to be 31.6 microm, and the relative standard deviation, 7.3%. The temperature was then lowered to 5 degrees C by rapid air cooling and finally dried. The gelatin beads were dried and could be resuspended well in iso-octane. They had an average particle diameter of 15.6 microm, and a relative standard deviation of 5.9%. Using MC emulsification, we were able to prepare gelatin microbeads with a narrow size distribution. Since this emulsification technique requires only a low-energy input, it may create desirable experimental conditions for microencapsulation of unstable substances such as peptides and proteins. This method is promising for making monodisperse microbeads.

  15. Fabricating polyacrylamide microbeads by inverse emulsification to mimic the size and elasticity of living cells.

    PubMed

    Labriola, Nicholas R; Mathiowitz, Edith; Darling, Eric M

    2016-12-20

    Inverse emulsification was used to fabricate polyacrylamide (PAAm) microbeads with size and elastic properties similar to typical, mammalian cells. These biomimicking microbeads could be fluorescently stained and functionalized with a collagen type-I coating, post-polymerization, for tracking bead locations and promoting cell recognition/binding, respectively. By occupying a previously unfilled range of sizes and mechanical properties, these microbeads may find unique use in both biomedical and materials applications.

  16. Statistical Analysis of Optimal Ultrasound Emulsification Parameters in Thistle-Oil Nanoemulsions.

    PubMed

    Miastkowska, Małgorzata A; Banach, Marcin; Pulit-Prociak, Jolanta; Sikora, Elżbieta S; Głogowska, Agata; Zielina, Michał

    2017-01-01

    Thistle oil (INCI: Silybum marianum seed oil) is known as an anti-oxidant, moisturizing and skin regenerating cosmetic raw material. Nanoemulsions are a new form of cosmetic product showing very good user properties (ease of spreading over the skin with no greasy feeling). Moreover, due to their structure, they can also transport both hydrophilic and hydrophobic active substances to the skin. The aim of this work was the preparation and characterization of nanoemulsions, based on thistle oil. The non-ionic surfactants polysorbate 80 (PEG-20 sorbitan monooleate), decyl glucoside, and a polyglyceryl-4 ester blend were applied to stabilize the nanosystems. All formulations were obtained by a high energy method, using an ultrasonic device (Labsonic U, an ultrasound homogenizer). Variations in the emulsification parameters were tested, including surfactants concentration, pre-emulsification time, ultrasound power and sonication time. On the basis of statistical analysis (experimental design, cluster analysis, classification and regression trees) the best emulsification process parameters were determined. In order to verify the results of statistical analysis, once more an experimental study was conducted. The results obtained confirmed that statistical analysis can be a useful method in determining the conditions for obtaining stable nanoemulsions with desired properties. Formulations obtained with the use of Silybum marianum seed oil were characterized by long-term stability, a low polydispersity index, low viscosity and an average droplet size less than 200 nm.

  17. Probing insulin bioactivity in oral nanoparticles produced by ultrasonication-assisted emulsification/internal gelation

    PubMed Central

    Lopes, Marlene A; Abrahim-Vieira, Bárbara; Oliveira, Claudia; Fonte, Pedro; Souza, Alessandra M T; Lira, Tammy; Sequeira, Joana A D; Rodrigues, Carlos R; Cabral, Lúcio M; Sarmento, Bruno; Seiça, Raquel; Veiga, Francisco; Ribeiro, António J

    2015-01-01

    Alginate–dextran sulfate-based particles obtained by emulsification/internal gelation technology can be considered suitable carriers for oral insulin delivery. A rational study focused on the emulsification and particle recovery steps was developed in order to reduce particles to the nanosize range while keeping insulin bioactivity. There was a decrease in size when ultrasonication was used during emulsification, which was more pronounced when a cosurfactant was added. Ultrasonication add-on after particle recovery decreased aggregation and led to a narrower nanoscale particle-size distribution. Insulin encapsulation efficiency was 99.3%±0.5%, attributed to the strong pH-stabilizing electrostatic effect between insulin and nanoparticle matrix polymers. Interactions between these polymers and insulin were predicted using molecular modeling studies through quantum mechanics calculations that allowed for prediction of the interaction model. In vitro release studies indicated well-preserved integrity of nanoparticles in simulated gastric fluid. Circular dichroism spectroscopy proved conformational stability of insulin and Fourier transform infrared spectroscopy technique showed rearrangements of insulin structure during processing. Moreover, in vivo biological activity in diabetic rats revealed no statistical difference when compared to nonencapsulated insulin, demonstrating retention of insulin activity. Our results demonstrate that alginate–dextran sulfate-based nanoparticles efficiently stabilize the loaded protein structure, presenting good physical properties for oral delivery of insulin. PMID:26425087

  18. Does the emulsification procedure influence freezing and thawing of aqueous droplets?

    NASA Astrophysics Data System (ADS)

    Hauptmann, Astrid; Handle, Karl F.; Baloh, Philipp; Grothe, Hinrich; Loerting, Thomas

    2016-12-01

    Here we investigate the freezing and thawing properties of aqueous solutions in oil emulsions, with a particular focus on investigating the influence of the oil and surfactant and the stirring time of the emulsion. Specifically, we employ optical cryomicroscopy in combination with differential scanning calorimetry to study the phase behavior of emulsified 25 wt. % ammonium sulfate droplets in the temperature range down to 93 K. We conclude that the nucleation temperature does not vary with oil-surfactant combination, that is, homogeneous nucleation is probed. However, incomplete emulsification and non-unimodal size distribution of dispersed droplets very often result in heterogeneous nucleation. This in turn affects the distribution of freeze-concentrated solution and the concentration of the solid ice/ammonium sulfate mixture and, thus, the phase behavior at sub-freezing temperatures. For instance, the formation of letovicite at 183 K critically depends on whether the droplets have frozen heterogeneously or homogeneously. Hence, the emulsification technique can be a very strong technique, but it must be ensured that emulsification is complete, i.e., a unimodal size distribution of droplets near 15 μm has been reached. Furthermore, phase separation within the matrix itself or uptake of water from the air may impede the experiments.

  19. Centrifugal step emulsification applied for absolute quantification of nucleic acids by digital droplet RPA.

    PubMed

    Schuler, Friedrich; Schwemmer, Frank; Trotter, Martin; Wadle, Simon; Zengerle, Roland; von Stetten, Felix; Paust, Nils

    2015-07-07

    Aqueous microdroplets provide miniaturized reaction compartments for numerous chemical, biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for the fast and easy production of monodisperse droplets. Homogenous droplets with pre-selectable diameters in a range from 120 μm to 170 μm were generated with coefficients of variation of 2-4% and zero run-in time or dead volume. The droplet diameter depends on the nozzle geometry (depth, width, and step size) and interfacial tensions only. Droplet size is demonstrated to be independent of the dispersed phase flow rate between 0.01 and 1 μl s(-1), proving the robustness of the centrifugal approach. Centrifugal step emulsification can easily be combined with existing centrifugal microfluidic unit operations, is compatible to scalable manufacturing technologies such as thermoforming or injection moulding and enables fast emulsification (>500 droplets per second and nozzle) with minimal handling effort (2-3 pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute quantification of Listeria monocytogenes DNA concentration standards with a total analysis time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with processing times of about 2 hours, the overall processing time of digital analysis was reduced by more than a factor of 4.

  20. Water-in-oil emulsification in a non-uniform alternating electric field

    NASA Astrophysics Data System (ADS)

    Choi, Suhwan; Saveliev, Alexei

    2015-11-01

    The emulsification of a water microdroplet placed in castor oil was performed using a non-uniform alternating electric field formed in the pin-to-plate geometry. A non-uniform electric field of ~40 kV/mm alternating with a frequency of 6.7 kHz was generated near the pin electrode. The applied frequency exceeded charge relaxation frequency of castor oil (0.3 Hz) and was below charge relaxation frequency of deionized water (7.8 kHz) used in the experiments. The emulsification process was captured with a CCD camera. The emulsification process started with entrainment of the water droplet in the high electric filed region near the pin electrode under the dielectrophoretic force. Upon touching the pin, the microdroplet was disintegrated in numerous channels and secondary droplets. The process continued by entrainment of secondary droplets and continuous size reduction. Three droplet breakup mechanisms were identified: drop elongation and capillary breakup, ac electrospraying of individual droplets, chain and bridge formation and decay. The quasi-steady narrow size distribution of emulsified water droplets with diameters close to 1 μm was formed after a few minutes. The generated emulsion was confined near the needle electrode due to the dielectrophoretic force. The emulsion had a well-defined boundary with a shape resembling a pendant drop suspended on the pin electrode.

  1. Ionic-liquid-based surfactant-emulsified microextraction procedure accelerated by ultrasound radiation followed by high-performance liquid chromatography for the simultaneous determination of antidepressant and antipsychotic drugs.

    PubMed

    Zare, Fahimeh; Ghaedi, Mehrorang; Daneshfar, Ali

    2015-03-01

    In the present work, an efficient and environmental friendly method of ionic-liquid-based emulsified microextraction procedure accelerated by ultrasound radiation has been developed. Subsequently, its performance was compared with dispersive liquid-liquid microextraction and ultrasound-assisted surfactant-based emulsification microextraction methods. The optimization of experimental conditions was carried out by combination of central composite design and response surface methodology. The optimum conditions of variables were set as follows: 50 μL of 1-hexyl-3-methylimidazolium hexafluorophosphate (extracting solvent), 10 min ultrasound time, and 10 min vortex time for agitating 6 mL sample solution in pH 3 in the presence of 4 mg sodium dodecyl sulfate without addition of salt and 200 μL of methanol as diluent solvent. Under these conditions, the responses are linear for doxepin and perphenazine in the range of 0.3-1000 and 5-1000 μg/L, respectively. The limits of detection were 0.1 μg/L for doxepin and 1 μg/L for perphenazine. Relative standard deviations were lower than 3.5 for the determination of both species. Finally, the method was used for the preconcentration and determination of doxepin and perphenazine in urine sample with relative recoveries in the range of 89-98%.

  2. A Simple Organic Solvent-Free Liquid-Liquid Microextraction Method for the Determination of Potentially Toxic Metals as 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol Complex from Food and Biological Samples.

    PubMed

    Barfi, Behruz; Rajabi, Maryam; Asghari, Alireza

    2016-04-01

    An organic solvent-free method was developed to extract some potentially toxic metals, as complexed with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol, from different real samples prior to their determination by microsampling flame atomic absorption spectrometry. The method, named ionic liquid-based ultrasound-enhanced air-assisted liquid-liquid microextraction (IL-USE-AALLME), is based upon withdrawing and pushing out a mixture of an aqueous sample and an IL (as the extraction solvent) for several times into a conical test tube using a single syringe, placed in an ultrasound bath (as the enhancing mass transfer agent) during the extraction process. Different effective parameters were studied, and at the optimized conditions, limits of detection, linear dynamic ranges, and enrichment factors were ranged from 0.9 to 2.2 μg L(-1), 3.0 to 1023 μg L(-1), and 20 ± 2 to 22 ± 2, respectively. After optimization, the method was successfully applied to determine Pb(2+), Cu(2+), Co(2+), Ni(2+), and Cr(3+) in different biological (hair and nail), vegetable (coriander, parsley, and tarragon), fruit juice (apple, orange, and peach), and water (tap, mineral, and wastewater) samples. The proposed method was compared with two other IL-based and disperser solvent-free methods (i.e., IL-based air-assisted liquid-liquid microextraction and IL-based ultrasound-assisted emulsification microextraction) to demonstrate its performance.

  3. Microextraction sample preparation techniques in biomedical analysis.

    PubMed

    Szultka, Malgorzata; Pomastowski, Pawel; Railean-Plugaru, Viorica; Buszewski, Boguslaw

    2014-11-01

    Biologically active compounds are found in biological samples at relatively low concentration levels. The sample preparation of target compounds from biological, pharmaceutical, environmental, and food matrices is one of the most time-consuming steps in the analytical procedure. The microextraction techniques are dominant. Metabolomic studies also require application of proper analytical technique for the determination of endogenic metabolites present in biological matrix on trace concentration levels. Due to the reproducibility of data, precision, relatively low cost of the appropriate analysis, simplicity of the determination, and the possibility of direct combination of those techniques with other methods (combination types on-line and off-line), they have become the most widespread in routine determinations. Additionally, sample pretreatment procedures have to be more selective, cheap, quick, and environmentally friendly. This review summarizes the current achievements and applications of microextraction techniques. The main aim is to deal with the utilization of different types of sorbents for microextraction and emphasize the use of new synthesized sorbents as well as to bring together studies concerning the systematic approach to method development. This review is dedicated to the description of microextraction techniques and their application in biomedical analysis.

  4. New developments in microextraction techniques in bioanalysis. A review.

    PubMed

    Ocaña-González, Juan Antonio; Fernández-Torres, Rut; Bello-López, Miguel Ángel; Ramos-Payán, María

    2016-01-28

    In recent years, the interest in new extraction methods with lower sample volume requirements, simpler equipment and handling, and lower reagent consumption, has led to the development of a series of microextraction methods based on extraction phases in the microliter order. Nowadays, many references can be found for several of these methods, which imply a wide range of applications referred to both the analyte and the sample nature. In this paper, recent developments in both well-established microextraction techniques (solid phase microextraction, hollow-fiber liquid phase microextraction, dispersive liquid-liquid microextraction, etc.) and recently appeared microextraction procedures (nanoextraction systems, microchip devices, etc.) for the clinical analysis of biological samples will be reviewed and discussed.

  5. Application of ionic liquid in liquid phase microextraction technology.

    PubMed

    Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

    2012-11-01

    Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction.

  6. Optimization of two different dispersive liquid-liquid microextraction methods followed by gas chromatography-mass spectrometry determination for polycyclic aromatic hydrocarbons (PAHs) analysis in water.

    PubMed

    Tseng, Wan-Chi; Chen, Pai-Shan; Huang, Shang-Da

    2014-03-01

    Novel sample preparation methods termed "up-and-down shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME)" and "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)" coupled with gas chromatography-mass spectrometry (GC-MS) have been developed for the analysis of 11 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. For UDSA-DLLME, an up-and-down shaker-assisted emulsification was employed. Extraction was complete in 3min. Only 14 μL of 1-heptanol was required, without a dispersive solvent. Under the optimum conditions, the linear range was 0.08-100 µg L(-1), and the LODs were in the range 0.022-0.060 µg L(-1). The enrichment factors (EFs) ranged from 392 to 766. Relative recoveries were between 84% and 113% for river, lake, and field water. In WLSEME, 9 μL of 1-nonanol as extraction solvent and 240 μL of 1 mg L(-1) Triton X-100 as surfactant were mixed in a microsyringe to form a cloudy emulsified solution, which was then injected into the samples. Compared with other surfactant-assisted emulsion methods, WLSEME uses much less surfactant. The linear range was 0.08-100 µg L(-1), and the LODs were 0.022-0.13 µg L(-1). The EFs ranged from 388 to 649. The relative recoveries were 86-114% for all three water specimens.

  7. Water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction for the determination of organochlorine pesticides in aqueous samples.

    PubMed

    Li, Yee; Chen, Pai-Shan; Huang, Shang-Da

    2013-07-26

    A novel sample preparation method, "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)", coupled with gas chromatography using an electron capture detector (GC-ECD) was developed for the analysis of the organochlorine pesticides (OCPs), heptachlor, α-endosulfan, 4,4-DDE, 2,4-DDD and endrin, in aqueous samples. A microsyringe is used to withdrew and discharge 10-12μL of the extraction solvent and 60-120μL of water as the dispersed solvent (containing 1mgL(-1), Tween 80) 4 times within 10s to form a cloudy emulsified solution in the syringe. This is then injected into an 8mL aqueous sample spiked with all above OCPs. Dodecyl acetate and 2-dodecanol were both selected as extraction solvents to optimize their conditions separately. The total extraction time was about 0.5min. Under optimum conditions, using dodecyl acetate (12μL) as extraction solvent, the linear range of the method was 10-1000ngL(-1) for all OCPs, and the the limits of detection (LODs) ranged from 1 to 5ngL(-1). The absolute recoveries and relative recoveries were from 20.8 to 43.5% and 83.2 to 109.8% for lake water, and 19.9-49.2% and 85.4-115.9% for seawater respectively. In the second method, 2-dodecanol as extraction solvent, the linear range was from 5 to 5000ngL(-1) for the target compounds, and the LODs were between 0.5 and 2ngL(-1). The absolute recoveries and relative recoveries ranged from 25.7 to 42.2% and 96.3-111.2% for sea water, and 22.4-41.9% and 90.7-107.9% for stream water. This could solve several problems, which commonly occur in ultrasound-assisted emulsification micro-extraction (USAEME), dispersive liquid-liquid micro-extraction (DLLME) and other assisted emulsification methods. These problems include analyte degradation, increased solubility of the extraction solvent and analyte, and high toxicity and large volume of the organic solvent used.

  8. Rapid ionic liquid-based ultrasound assisted dual magnetic microextraction to preconcentrate and separate cadmium-4-(2-thiazolylazo)-resorcinol complex from environmental and biological samples.

    PubMed

    Khan, Sumaira; Kazi, Tasneem Gul; Soylak, Mustafa

    2014-04-05

    A rapid and innovative microextraction technique named as, ionic liquid-based ultrasound-assisted dual magnetic microextraction (IL-UA-DMME) was developed for the preconcentration and extraction of trace cadmium from environmental and biological samples, prior to analyzed by flame atomic absorption spectrometry (FAAS). The proposed method has many obvious advantages, including evading the use of organic solvents and achieved high extraction yields by the combination of dispersive liquid-liquid microextraction (DLLME) and magnetic mediated-solid phase extraction (MM-SPE). In this approach ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C4mim][PF6] play an important role to extract the cadmium-4-(2-thiazolylazo)-resorcinol (Cd-TAR) complex from acid digested sample solutions and ultrasonic irradiation was applied to assist emulsification. After then, dispersed small amount of Fe3O4 magnetic nanoparticles (MNPs) in sample solutions to salvaged the IL and complete phase separation was attained. Some analytical parameters that influencing the efficiency of proposed (IL-UA-DMME) method, such as pH, volume of IL, ligand concentration, ultra-sonication time, amount of Fe3O4 MNPs, sample volume and matrix effect were optimized. Limit of detection (LOD) and enrichment factor (EF) of the method under optimal experimental conditions were found to be 0.40μgL(-1) and 100, respectively. The relative standard deviation (RSD) of 50μgL(-1) Cd was 4.29%. The validity and accuracy of proposed method, was assessed to analyzed certified reference materials of fortified lake water TMDA-54.4, SPS-WW2 waste water, spinach leaves 1570a and also checked by standard addition method. The obtained values showed good agreement with the certified values and sufficiently high recovery were found in the range of 98.1-101% for Cd. The proposed method was facile, rapid and successfully applied for the determination of Cd in environmental and different biological samples.

  9. Impact of the emulsification-diffusion method on the development of pharmaceutical nanoparticles.

    PubMed

    Quintanar-Guerrero, David; Zambrano-Zaragoza, María de la Luz; Gutierrez-Cortez, Elsa; Mendoza-Munoz, Nestor

    2012-12-01

    Nanotechnology is having a profound impact in many scientific fields and it has become one of the most important and exciting discipline. Like all technological advances, nanotechnology has its own scientific basis with a broad interdisciplinary effect. Perhaps, we are witnessing an exponential growth of nanotechnology, reflection of this is the important increase in the number of patents, scientific papers and specialized "nano" meetings and journals. The impact in the pharmaceutical area is related to the use of colloidal drug delivery systems as carriers for bioactive agents, in particular, the nanoparticle technology. The term nanoparticles designates solid submicronic particles formed of acceptable materials (e.g. polymers, lipids, etc.) containing an active substance. It includes both nanospheres (matricial systems) and nanocapsules (membrane systems). The knowledge of the nanoparticle preparation methods is a key issue for the formulator involved with drug-delivery research and development. In general, the methods based on preformed polymers, in particular biodegradable polymers, are preferred due to their easy implementation and lower potential toxicity. One of the most widely used methods to prepare polymeric nanoparticles is emulsification-diffusion. This method has been discussed in some reviews that compile research works but has a small number of patents. In this review, the emulsification-diffusion method is discussed from a technological point of view in order to show the operating conditions and formulation variables from data extracted of recent patents and experimental works. The main idea is to provide the reader with a general guide for formulators to make decisions about the usefulness of this method to develop specific nanoparticulate systems. The first part of this review provides an overview of the emulsification-diffusion method to prepare polymeric nanoparticles, while the second part evaluates the influence of preparative variables on the

  10. Optimization of solid lipid nanoparticles prepared by a single emulsification-solvent evaporation method.

    PubMed

    Pooja, Deep; Tunki, Lakshmi; Kulhari, Hitesh; Reddy, Bharathi B; Sistla, Ramakrishna

    2016-03-01

    This data article contains the data related to the research article "Characterization, biorecognitive activity and stability of WGA grafted lipid nanostructures for the controlled delivery of rifampicin" (Pooja et al. 2015) [1]. In the present study, SLN were prepared by a single emulsification-solvent evaporation method and the various steps of SLN preparation are shown in a flow chart. The preparation of SLN was optimized for various formulation variables including type and quantity of lipid, surfactant, amount of co-surfactant and volume of organic phase. Similarly, effect of variables related to homogezation, sonication and stirring processes, on the size and surface potential of SLN was determined and optimized.

  11. Ultrasound emulsification: effect of ultrasonic and physicochemical properties on dispersed phase volume and droplet size.

    PubMed

    Gaikwad, Shashank G; Pandit, Aniruddha B

    2008-04-01

    Ultrasonic emulsification of oil and water was carried out and the effect of irradiation time, irradiation power and physicochemical properties of oil on the dispersed phase volume and dispersed phase droplet size has been studied. The increase in the irradiation time increases the dispersed phase volume while decreases the dispersed phase droplets size. With an increase in the ultrasonic irradiation power, there is an increase in the fraction of volume of the dispersed phase while the droplet size of the dispersed phase decreases. The fractional volume of the dispersed phase increases for the case of groundnut oil-water system while it is low for paraffin (heavy) oil-water system. The droplet size of soyabean oil dispersed in water is found to be small while that of paraffin (heavy) oil is found to be large. These variations could be explained on the basis of varying physicochemical properties of the system, i.e., viscosity of oil and the interfacial tension. During the ultrasonic emulsification, coalescence phenomenon which is only marginal, has been observed, which can be attributed to the collision of small droplets when the droplet concentration increases beyond a certain number and the acoustic streaming strength increases.

  12. Development of solid lipid nanoparticles (SLNs) of lopinavir using hot self nano-emulsification (SNE) technique.

    PubMed

    Negi, Jeetendra Singh; Chattopadhyay, Pronobesh; Sharma, Ashok Kumar; Ram, Veerma

    2013-01-23

    Solid lipid nanoparticles (SLNs) of poor orally bioavailable drug lopinavir were prepared using hot self nano-emulsification (SNE) technique. Hot isotropic mixture of stearic acid, poloxamer and polyethylene glycol was spontaneously self nano-emulsify in hot water and SLNs were formed with subsequent rapid cooling. Self nano-emulsification ability of stearic acid, poloxamer and polyethylene glycol mixture was assessed by ternary phase diagram study. Optimized SLNs were having particle size of 180.6 ± 2.32 nm (PDI=0.133 ± 0.001), 91.5 ± 1.3% entrapment efficiency and zeta potential of -13.4 ± 0.56 mV. SLNs were evaluated by transmission electron microscopy (TEM) and atomic force microscopy (AFM) for morphological study. Further, Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) of SLNs were also performed for checking solid state characterization. Higher oral bioavailability was found for lopinavir loaded SLNs in comparison to bulk lopinavir due to higher lymphatic drug transport (p<0.05). Results indicate that SLNs of higher fatty acids can be successfully prepared by hot SNE technique.

  13. Controlled tissue emulsification produced by high intensity focused ultrasound shock waves and millisecond boiling.

    PubMed

    Khokhlova, Tatiana D; Canney, Michael S; Khokhlova, Vera A; Sapozhnikov, Oleg A; Crum, Lawrence A; Bailey, Michael R

    2011-11-01

    In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound.

  14. Microencapsulation by Membrane Emulsification of Biophenols Recovered from Olive Mill Wastewaters

    PubMed Central

    Piacentini, Emma; Poerio, Teresa; Bazzarelli, Fabio; Giorno, Lidietta

    2016-01-01

    Biophenols are highly prized for their free radical scavenging and antioxidant activities. Olive mill wastewaters (OMWWs) are rich in biophenols. For this reason, there is a growing interest in the recovery and valorization of these compounds. Applications for the encapsulation have increased in the food industry as well as the pharmaceutical and cosmetic fields, among others. Advancements in micro-fabrication methods are needed to design new functional particles with target properties in terms of size, size distribution, and functional activity. This paper describes the use of the membrane emulsification method for the fine-tuning of microparticle production with biofunctional activity. In particular, in this pioneering work, membrane emulsification has been used as an advanced method for biophenols encapsulation. Catechol has been used as a biophenol model, while a biophenols mixture recovered from OMWWs were used as a real matrix. Water-in-oil emulsions with droplet sizes approximately 2.3 times the membrane pore diameter, a distribution span of 0.33, and high encapsulation efficiency (98% ± 1% and 92% ± 3%, for catechol and biophenols, respectively) were produced. The release of biophenols was also investigated. PMID:27171115

  15. Effect of emulsification on the skin permeation and UV protection of catechin.

    PubMed

    Yoshino, Sachie; Mitoma, Tomoaki; Tsuruta, Keiko; Todo, Hiroaki; Sugibayashi, Kenji

    2014-06-01

    An anti-aging effect may be obtained by skin application of tea catechins (Camellia sinensis) since they have high ultraviolet (UV)-protection activity. In this study, the skin permeation of catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECg) and epigallocatechin gallate (EGCg) was determined and compared, and the effect of emulsification on the skin permeation of C was measured. The UV-protective effect of C was also determined. The in vitro skin permeability of each catechin derivative was determined using side-by-side diffusion of cells. The UV-protective effect of C was determined by applying different concentrations of C to the solution or emulsion on a three-dimensional cultured human skin model or normal human epidermal keratinocytes with UV-irradiation. ECg and EGCg with gallate groups showed lower skin permeability than C, EC and EGC without gallate groups, suggesting that the skin permeability of catechin derivatives may be dependent on the existence of a gallate group. Interestingly, the skin permeation of C was increased by an o/w emulsification. In addition, the C emulsion showed a significantly higher UV-protective effect by C than that with its aqueous solution. These results suggest that the o/w emulsion of catechin derivatives is probably useful as a cosmetic formulation with anti-aging efficacy.

  16. Influence of emulsification process on the properties of Pickering emulsions stabilized by layered double hydroxide particles.

    PubMed

    Zhang, Nana; Zhang, Li; Sun, Dejun

    2015-04-28

    This paper reports the influence of emulsification process on the packing of layered double hydroxide (LDH) particles at the aqueous/oil phase interface and the properties of the resulting Pickering emulsions. Emulsions prepared by ultrasonication display superior long-term stability and gel-like characteristics at the dispersed phase volume fraction well below the random close packing limit, whereas emulsions with same compositions prepared by vortex mixing show some extent of sedimentation and liquid-like behaviors. Rheological measurements demonstrate that the zero-shear elastic modulus and yield stress of gel-like emulsions exhibit power-law dependences on particle concentration and independence on aqueous/oil phase ratio. The microstructural origin of this behavior is investigated by optical microscopy, revealing the droplets become strongly adhesive and a heterogeneous percolating network is formed among neighboring droplets. Fluorescent confocal microscopy measurements further confirm that the droplet adhesion is due to particle layers bridging opposite interfaces. In contrast, homogeneous, isolated, and densely packed droplets are present in emulsions prepared by vortex mixing, which results in these systems being dominantly viscous like the suspending fluid. This study shows that the emulsification process can be used as a trigger to modify long-term stability and rheology of solid-stabilized multiphase mixtures, which greatly expands their potential technological applications.

  17. Emulsification and antioxidation of biosurfactant extracts from Chinese medicinal herbs fermentation in vitro.

    PubMed

    Chen, Chunyeh; Lin, Tachen; Shieh, Youmin

    2015-10-01

    Much attention has been paid to biosurfactants produced using microorganisms, but little direct evidence for the development of natural biosurfactants combined with Chinese medicinal herbs are available. We investigated the emulsification and antioxidation of biosurfactant extracts from Chinese medicinal herb fermentation (BECMHF) in vitro and their application in water retention capacity and the skin prick and allergy test (SPAT) index for skin cells. The results showed that the water retention capacity of BECMHF was positively associated with the emulsification index. The SPAT index of 8 Chinese medicinal herbs was 0 at a 1% or 2% concentration, suggesting no sensitivity or adverse effects on the skin cells. Eight BECMHFs produced using Alcaligenes piechaudii CC-ESB2 exhibited antioxidant capabilities, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide scavenging activity, and superoxide dismutase (SOD)-like activity at a concentration of 10 mg/ml. The mechanism involved inhibitory effects on nitrite, inducible nitric oxide synthase (iNOS) expression, and reactive oxygen species (ROSs) generation. BECMHFs exhibit favorable antioxidative properties in health food and satisfactory emulsifying and moisturizing characteristics in cosmetic formulations, which have potential applications in the health food and cosmetic industries, respectively.

  18. Optimization of folic acid nano-emulsification and encapsulation by maltodextrin-whey protein double emulsions.

    PubMed

    Assadpour, Elham; Maghsoudlou, Yahya; Jafari, Seid-Mahdi; Ghorbani, Mohammad; Aalami, Mehran

    2016-05-01

    Due to susceptibility of folic acid like many other vitamins to environmental and processing conditions, it is necessary to protect it by highly efficient methods such as micro/nano-encapsulation. Our aim was to prepare and optimize real water in oil nano-emulsions containing folic acid by a low energy (spontaneous) emulsification technique so that the final product could be encapsulated within maltodextrin-whey protein double emulsions. A non ionic surfactant (Span 80) was used for making nano-emulsions at three dispersed phase/surfactant ratios of 0.2, 0.6, and 1.0. Folic acid content was 1.0, 2.0, and 3.0mg/mL of dispersed phase by a volume fraction of 5.0, 8.5, and 12%. The final optimum nano-emulsion formulation with 12% dispersed phase, a water to surfactant ratio of 0.9 and folic acid content of 3mg/mL in dispersed phase was encapsulated within maltodextrin-whey protein double emulsions. It was found that the emulsification time for preparing nano-emulsions was between 4 to 16 h based on formulation variables. Droplet size decreased at higher surfactant contents and final nano-emulsions had a droplet size<100 nm. Shear viscosity was higher for those formulations containing more surfactant. Our results revealed that spontaneous method could be used successfully for preparing stable W/O nano-emulsions containing folic acid.

  19. Ultrasound-assisted emulsification of cosmetic samples prior to elemental analysis by different atomic spectrometric techniques.

    PubMed

    Lavilla, I; Cabaleiro, N; Costas, M; de la Calle, I; Bendicho, C

    2009-11-15

    In this work, ultrasound-assisted emulsification with a probe system is proposed as a rapid and simple sample treatment for atomic spectrometric determinations (Electrothermal Atomic Absorption Spectrometry, Inductively Coupled Plasma Optical Emission Spectrometry, Flame Atomic Absorption Spectrometry and Cold Vapour Atomic Absorption Spectrometry) of trace elements (As, Cd, Cr, Cu, Hg, Mg, Mn, Ni, Sr and Zn) in cosmetic samples such as shampoos, gel (hair gel), crèmes (body milk, hair conditioner) and oil (body oil). The type of dispersion medium, the sample mass-to-dispersion medium volume ratio, as well as the parameters related to the ultrasound-assisted emulsification (sonication amplitude and treatment time) were exhaustively studied. Only 1 min of ultrasonic shaking and a dispersion medium containing 0.5% (w/v) of SDS+3% (v/v) of HNO(3) or HCl allows obtaining a stable emulsion at least for 3 months. Thermal programs, nebulization of emulsions, speed of pumps and concentration of reagents used in cold vapour generation were optimized. Calibration using aqueous standards was feasible in all cases. Calibration by the standard addition method and recovery studies was also applied for validation. Microwave-assisted digestion and Inductively Coupled Plasma Mass Spectrometry were used for comparison purposes. Relative standard deviations from analysis of five independent emulsions were less than 9% in all cases.

  20. Investigation into the Cause of Spontaneous Emulsification of a Free Steel Droplet; Validation of the Chemical Exchange Pathway

    NASA Astrophysics Data System (ADS)

    Spooner, Stephen; Assis, Andre N.; Warnett, Jason; Fruehan, Richard; Williams, Mark A.; Sridhar, Seetharaman

    2016-08-01

    Small Fe-based droplets have been heated to a molten phase suspended within a slag medium to replicate a partial environment within the basic oxygen furnace (BOF). The confocal scanning laser microscope (CSLM) has been used as a heating platform to interrogate the effect of impurities and their transfer across the metal/slag interface, on the emulsification of the droplet into the slag medium. The samples were then examined through X-ray computer tomography (XCT) giving the mapping of emulsion dispersion in 3D space, calculating the changing of interfacial area between the two materials, and changes of material volume due to material transfer between metal and slag. Null experiments to rule out thermal gradients being the cause of emulsification have been conducted as well as replication of the previously reported study by Assis et al.[1] which has given insights into the mechanism of emulsification. Finally chemical analysis was conducted to discover the transfer of oxygen to be the cause of emulsification, leading to a new study of a system with undergoing oxygen equilibration.

  1. Self-emulsification of alkaline-dissolved clove bud oil by whey protein, gum arabic, lecithin, and their combinations.

    PubMed

    Luo, Yangchao; Zhang, Yue; Pan, Kang; Critzer, Faith; Davidson, P Michael; Zhong, Qixin

    2014-05-14

    Low-cost emulsification technologies using food ingredients are critical to various applications. In the present study, a novel self-emulsification technique was studied to prepare clove bud oil (CBO) emulsions, without specialized equipment or organic solvents. CBO was first dissolved in hot alkaline solutions, added at 1% v/v into neutral solutions with 1% w/v emulsifier composed of whey protein concentrate (WPC), gum arabic, lecithin, or their equal mass mixtures, and adjusted to pH 7.0. The self-emulsification process did not affect UV-vis absorption spectrum, reversed-phase HPLC chromatogram, or antimicrobial activity of CBO against Escherichia coli O157:H7, Listeria monocytogenes Scott A, and Salmonella Enteritidis. The entrapment efficiency after extraction by petroleum ether was determined to be about 80%. Most emulsions were stable during 7 days of storage. Emulsions prepared with WPC had smaller particles, whereas emulsions prepared with emulsifier mixtures had more stable particle dimensions. The studied self-emulsification technique may find numerous applications in the preparation of low-cost food emulsions.

  2. Simultaneous derivatization and extraction of chlorophenols in water samples with up-and-down shaker-assisted dispersive liquid-liquid microextraction coupled with gas chromatography/mass spectrometric detection.

    PubMed

    Wang, Ke-Deng; Chen, Pai-Shan; Huang, Shang-Da

    2014-03-01

    A new up-and-down shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) for extraction and derivatization of five chlorophenols (4-chlorophenol, 4-chloro-2-methylphenol, 2,4-dichlorophenol, 2,4,6-trichloro-phenol, and pentachlorophenol) has been developed. The method requires minimal solvent usage. The relatively polar, water-soluble, and low-toxicity solvent 1-heptanol (12 μL) was selected as the extraction solvent and acetic anhydride (50 μL) as the derivatization reagent. With the use of an up-and-down shaker, the emulsification of aqueous samples was formed homogeneously and quickly. The derivatization and extraction of chlorophenols were completed simultaneously in 1 min. The common requirement of disperser solvent in DLLME could be avoided. After optimization, the linear range covered over two orders of magnitude, and the coefficient of determination (r (2)) was greater than 0.9981. The detection limit was from 0.05 to 0.2 μg L(-1), and the relative standard deviation was from 4.6 to 10.8 %. Real samples of river water and lake water had relative recoveries from 90.3 to 117.3 %. Other emulsification methods such as vortex-assisted, ultrasound-assisted, and manual shaking-enhanced ultrasound-assisted methods were also compared with the proposed UDSA-DLLME. The results revealed that UDSA-DLLME performed with higher extraction efficiency and precision compared with the other methods.

  3. An engineering approach to design of dextran microgels size fabricated by water/oil emulsification.

    PubMed

    Salimi-Kenari, Hamed; Imani, Mohammad; Nodehi, Azizollah; Abedini, Hossein

    2016-09-01

    A correlation, based on fluid mechanics, has been investigated for the mean particle diameter of crosslinked dextran microgels (CDMs) prepared via a water/oil emulsification methodology conducted in a single-stirred vessel. To this end, non-dimensional correlations were developed to predict the mean particle size of CDMs as a function of Weber number, Reynolds number and viscosity number similar to ones introduced for liquid-liquid dispersions. Moreover, a Rosin-Rammler distribution function has been successfully applied to the microgel particle size distributions. The correlations were validated using experimentally obtained mean particle sizes for CDMs prepared at different stirring conditions. The validated correlation is especially applicable to medical and pharmaceutical applications where strict control on the mean particle size and size distribution of CDMs are extremely essential. [Formula: see text].

  4. Preparation of uniform particle-stabilized emulsions using SPG membrane emulsification.

    PubMed

    Sun, Guanqing; Qi, Feng; Wu, Jie; Ma, Guanghui; Ngai, To

    2014-06-24

    Various aspects of particle-stabilized emulsions (or so-called Pickering emulsions) have been extensively investigated during the last two decades, but the preparation of uniform Pickering emulsion droplets via a simple and scalable method has been sparingly realized. We report the preparation of uniform Pickering emulsions by Shirasu porous glass (SPG) membrane emulsification. The size of the emulsion droplets ranging from 10-50 μm can be precisely controlled by the size of the membrane pore. The emulsion droplets have a high monodispersity with coefficients of variation (CV) lower than 15% in all of the investigated systems. We further demonstrate the feasibility of locking the assembled particles at the interface, and emulsion droplets have been shown to be excellent templates for the preparation of monodisperse colloidosomes that are necessary in drug-delivery systems.

  5. Phase behavior, self-assembly, and emulsification of Tween 80/water mixtures with limonene and perfluoromethyldecalin.

    PubMed

    Sharma, Suraj Chandra; Warr, Gregory G

    2012-08-14

    The phase behavior, microstructure, and emulsification of polyoxyethylene (20) sorbitan monooleate (Tween 80), water, and d-limonene (LM) or perfluoromethyldecalin (PFMD) has been studied by small-angle X-ray scattering and polarizing optical microscopy. In the Tween 80/water binary system, a micellar solution (L(1)), a hexagonal (H(1)) phase, and a water-swellable isotropic surfactant liquid (L(2)) phase are successively formed at 25 °C. LM can be solubilized into all of the phases formed by Tween 80/water mixtures, whereas no solubilization of PFMD occurs. The L(2) phase was found by small-angle neutron scattering to be bicontinuous with low interfacial curvature. Added water swells and amplifies the pre-existing amphiphilic structure. The stability of oil-in-H(1) complex emulsions is found to be sensitive to changes in structure that accompany solubilization.

  6. Emulsification/internal gelation as a method for preparation of diclofenac sodium-sodium alginate microparticles.

    PubMed

    Ahmed, Mahmoud M; El-Rasoul, Saleh Abd; Auda, Sayed H; Ibrahim, Mohamed A

    2013-01-01

    Emulsification/internal gelation has been suggested as an alternative to extrusion/external gelation in the encapsulation of several compounds including non-steroidal anti-inflammatory drugs such as diclofenac sodium. The objective of the present study was a trial to formulate diclofenac sodium as controlled release microparticles that might be administered once or twice daily. This could be achieved via emulsification/internal gelation technique applying Box-Behnken design to choose these formulae. Box-Behnken design determined fifteen formulae containing specified amounts of the independent variables, which included stirring speed in rpm (X1), drug:polymer ratio (X2) and the surfactant span 80% (X3). The dependent variables studied were cumulative percent release after two hours (Y1), four hours (Y2) and eight hours (Y3). The prepared microparticles were characterized for their production yield, sizes, shapes and morphology, entrapment efficiency and Diclofenac sodium in vitro release as well. The results showed that the production yield of the prepared diclofenac sodium microparticles was found to be between 79.55% and 97.41%. The formulated microparticles exhibited acceptable drug content values that lie in the range 66.20-96.36%. Also, the data obtained revealed that increasing the mixing speed (X1) generally resulted in decreased microparticle size. In addition, scanning electron microscope images of the microparticles illustrated that the formula contains lower span concentration (1%) in combination with lower stirring speed (200 rpm) which showed wrinkled, but smooth surfaces. However, by increasing surfactant concentration, microspheres' surfaces become smoother and slightly porous. Kinetic treatment of the in vitro release from drug-loaded microparticles indicated that the zero order is the drug release mechanism for the most formulae.

  7. Membrane emulsification and solvent pervaporation processes for the continuous synthesis of functional magnetic and Janus nanobeads.

    PubMed

    Chang, Emily P; Hatton, T Alan

    2012-06-26

    We discuss the integration of membrane emulsification and pervaporation processes for the continuous production of functional materials, such as silica-encapsulated magnetite nanoparticle clusters and asymmetric Janus nanoparticles, by the emulsion droplet solvent evaporation method, which has traditionally been performed in small-scale batch systems. An organic solvent containing primary magnetite nanoparticles (∼10 nm) coated with oleic acid was dispersed in a continuous aqueous phase by membrane emulsification, which enabled the consistent production of nanoparticle-laden solvent droplets of well-controlled size with narrow size distributions. The solvent was removed from the emulsion by pervaporation. Prior to complete solvent removal, the nanoparticle packing density within the clusters was a function of the residence time in the pervaporation unit. The final clusters formed, ∼100-300 nm in size, exhibited the same superparamagnetic behavior as the primary nanoparticles, and were stable in aqueous media with a zeta potential of -70 mV at neutral pH. A facile method was used to coat the nanoclusters with a silica shell, providing sites for surface functionalization with a range of organic ligands. The nanoparticles and clusters were analyzed by a variety of techniques, including TGA, DLS, TEM, EDS, and SQUID. The effects of various parameters, such as the membrane dimensions and flow rate through the unit, on the mass transport rates were elucidated through a parametric modeling study. The applicability of the methods to the production of polymeric beads and more complex particles was demonstrated; to create Janus structures, organic polymer solutions were dispersed as droplets in continuous aqueous phases, and the solvent was subsequently evaporated. The Janus particles consisted either of polymeric cores with magnetite nanoparticles clustered as islands on their surfaces, or of two phase-separated polymers, each constituting half of any given polymeric

  8. Membrane-based microextraction techniques in analytical chemistry: A review.

    PubMed

    Carasek, Eduardo; Merib, Josias

    2015-06-23

    The use of membrane-based sample preparation techniques in analytical chemistry has gained growing attention from the scientific community since the development of miniaturized sample preparation procedures in the 1990s. The use of membranes makes the microextraction procedures more stable, allowing the determination of analytes in complex and "dirty" samples. This review describes some characteristics of classical membrane-based microextraction techniques (membrane-protected solid-phase microextraction, hollow-fiber liquid-phase microextraction and hollow-fiber renewal liquid membrane) as well as some alternative configurations (thin film and electromembrane extraction) used successfully for the determination of different analytes in a large variety of matrices, some critical points regarding each technique are highlighted.

  9. 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.

    PubMed

    Gao, Shiqian; Yang, Xiao; Yu, Wei; Liu, Zhongling; Zhang, Hanqi

    2012-09-15

    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 [C(6)MIM][PF(6)] dispersed entirely into sample solution with help of [C(4)MIM][BF(4)]. The purification of sample and concentration of target analytes were performed simultaneously. The introduction of ion-pairing agent (NH(4)PF(6)) was beneficial to the improvement of recoveries for IL phase and analytes. The experimental parameters of the UA-IL/IL-DLLME, including concentration of [C(6)MIM][PF(6)] and [C(4)MIM][BF(4)] in sample solution, ultrasound extraction time, pH value of sample solution and amount of ion-pairing agent (NH(4)PF(6)), 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 6.66 μg kg(-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.

  10. Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility

    DTIC Science & Technology

    2008-06-01

    LABORATORY STUDY REPORT Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant...Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility 5a. CONTRACT NUMBER 5b...PDMS poly dimethylsiloxane SPME Solid phase microextraction TOC Total organic carbon     1 1. LABORATORY DEMONSTRATION GOALS The

  11. Fast screening of perfluorooctane sulfonate in water using vortex-assisted liquid-liquid microextraction coupled to liquid chromatography-mass spectrometry.

    PubMed

    Papadopoulou, Aikaterini; Román, Iván P; Canals, Antonio; Tyrovola, Konstantina; Psillakis, Elefteria

    2011-04-08

    Fast screening of trace amounts of the perfluorooctane sulfonate anion (PFOS) in water samples was performed following a simple, fast and efficient sample preparation procedure based on vortex-assisted liquid-liquid microextraction (VALLME) prior to liquid chromatography-mass spectrometry. VALLME initially uses vortex agitation, a mild emulsification procedure to disperse microvolumes of octanol, a low density extractant solvent, in the aqueous sample. Microextraction under equilibrium conditions is thus achieved within few minutes. Subsequently, centrifugation separates the two phases and restores the initial microdrop shape of the octanol acceptor phase, which can be collected and used for liquid chromatography-single quadrupole mass spectrometry analysis. Several experimental parameters were controlled and the optimum conditions found were: 50 μL of octanol as the extractant phase; 20 mL aqueous donor samples (pH=2); a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; no ionic strength adjustment. Centrifugation for 2 min at 3500 rpm yielded separation of the two phases throughout this study. Enhanced extraction efficiencies were observed at low pH which was likely due to enhanced electrostatic interaction between the negatively PFOS molecules and the positively charged octanol/water interface. The effect of pH was reduced in the presence of sodium chloride, likely due to electrical double layer compression. The linear response range for PFOS was from 5 to 500 ng L(-1) (coefficient of determination, r(2), 0.997) and the relative standard deviation for aqueous solutions containing 10 and 500 ng L(-1) PFOS were 7.4% and 6.5%, respectively. The limit of detection was 1.6 ng L(-1) with an enrichment factor of approximately 250. Analysis of spiked tap, river and well water samples revealed that matrix did not affect extraction.

  12. Offline solid phase microextraction sampling system

    DOEpatents

    Harvey, Chris A.

    2008-12-16

    An offline solid phase microextraction (SPME) sampling apparatus for enabling SPME samples to be taken a number of times from a previously collected fluid sample (e.g. sample atmosphere) stored in a fused silica lined bottle which keeps volatile organics in the fluid sample stable for weeks at a time. The offline SPME sampling apparatus has a hollow body surrounding a sampling chamber, with multiple ports through which a portion of a previously collected fluid sample may be (a) released into the sampling chamber, (b) SPME sampled to collect analytes for subsequent GC analysis, and (c) flushed/purged using a fluidically connected vacuum source and purging fluid source to prepare the sampling chamber for additional SPME samplings of the same original fluid sample, such as may have been collected in situ from a headspace.

  13. Microextraction of total lipid from mesopelagic animals

    NASA Astrophysics Data System (ADS)

    Reisenbichler, Kim R.; Bailey, Thomas G.

    1991-10-01

    A modification of the Bligh and Dyer lipid extraction method ( Canadian Journal of Biochemistry and Physiology, 37, 911-917, 1959) is described. The technique utilizes commercially available Teflon membrane microfiltration units that permit filtration and solvent separation to occur simultaneously. Thus, rapid and efficient microextraction of total lipid (20-200 μg) can be accomplished from tissue homogenates at reduced solvent volumes. The primary advantages of this modification include increased accuracy for small samples, increased productivity and reduced exposure to solvent fumes. Extraction efficiencies ranged from 95 to 100% for standards and naturally occurring lipid extracts of two midwater fish species. Precision of the method, measured as per cent standard deviation between replicate extracts of whole fish homogenates, range from 0.7 to 2.7%.

  14. Solid phase microextraction device using aerogel

    DOEpatents

    Miller, Fred S.; Andresen, Brian D.

    2005-06-14

    A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

  15. Ferrofluid-based liquid-phase microextraction.

    PubMed

    Shi, Zhi-Guo; Zhang, Yufeng; Lee, Hian Kee

    2010-11-19

    A new mode of liquid-phase microextraction based on a ferrofluid has been developed. The ferrofluid was composed of silica-coated magnetic particles and 1-octanol as the extractant solvent. The 1-octanol was firmly confined within the silica-coated particles, preventing it from being lost during extraction. Sixteen polycyclic aromatic hydrocarbons (PAHs) were used as model compounds in the development and evaluation of the extraction procedure in combination with gas chromatography-mass spectrometry. Parameters affecting the extraction efficiency were investigated in detail. The optimal conditions were as follows: 20mL sample volume, 10mg of the silica-coated magnetic particles (28mg of ferrofluid), agitation at 20Hz, 20min extraction time, and 2min by sonication with 100μL acetonitrile as the final extraction solvent. Under optimal extraction conditions, enrichment factors ranging from 102- to 173-fold were obtained for the analytes. The limits of detection and the limits of quantification were in the range of 16.8 and 56.7pgmL(-1) and 0.06 and 0.19ngmL(-1), respectively. The linearities were between 0.5-100 and 1-100ngmL(-1) for different PAHs. As the ferrofluid can respond to and be attracted by a magnet, the extraction can be easily achieved by reciprocating movement of an external magnet that served to agitate the sample. No other devices were needed in this new approach of extraction. This new technique is affordable, efficient and convenient for microextraction, and offers portability for potential onsite extraction.

  16. Surfactant-enhanced bicarbonate flooding. Final report

    SciTech Connect

    Peru, D.A.

    1986-10-01

    Coalescence rate constants were calculated for systems containing alcohol ethoxysulfate both with and without TRONACRAB (sodium bicarbonate). All systems containing TRONACRAB above 3.8% total salinity had higher coalescence rate constants than systems not containing TRONACARB. The results indicate that TRONACARB promotes faster coalescence of crude oil-surfactant brine emulsions. Additions of TRONACARB to preflush brine was found to be more economical than chloride brine in reducing divalent ion concentration. Silicon (Si) concentrations did not exceed 24 ppm after TRONACARB was in contact with Berea sandstone for 1 week at 42/sup 0/C. The occurrence of silica scales is expected to be minimal when using TRONACARB in chemical flooding or in a preflush. A chemical slug containing TRONACARB, petroleum sulfate, and polymer recovered from 6 to 20% more residual oil than did systems containing either: TRONACARB plus polymer or surfactant plus polymer. The results from the oil-displacement tests indicate that a synergistic relationship exists between TRONACARB and low concentrations of surfactant and polymer whereby the oil-recovery efficiency was improved, and the chemical cost per barrel of oil recovered was decreased when the three chemicals were used together. 8 refs., 9 figs., 5 tabs.

  17. Surfactant-enhanced cellulose nanocrystal Pickering emulsions.

    PubMed

    Hu, Zhen; Ballinger, Sarah; Pelton, Robert; Cranston, Emily D

    2015-02-01

    The effect of surfactants on the properties of Pickering emulsions stabilized by cellulose nanocrystals (CNCs) was investigated. Electrophoretic mobility, interfacial tension, confocal microscopy and three-phase contact angle measurements were used to elucidate the interactions between anionic CNCs and cationic alkyl ammonium surfactants didecyldimethylammonium bromide (DMAB) and cetyltrimethylammonium bromide (CTAB). Both surfactants were found to adsorb onto CNCs with concentration-dependent morphology. At low concentrations, individual surfactant molecules adsorbed with alkyl tails pointing outward leading to hydrophobic CNCs. At higher concentrations, above the surfactant's apparent critical micelle concentration, surfactant aggregate morphologies on CNCs were inferred and the hydrophobicity of CNCs decreased. DMAB, which has two alkyl tails, rendered the CNCs more hydrophobic than CTAB which has only a single alkyl tail, at all surfactant concentrations. The change in CNC wettability from surfactant adsorption was directly linked to emulsion properties; adding surfactant increased the emulsion stability, decreased the droplet size, and controlled the internal phase of CNC Pickering emulsions. More specifically, a double transitional phase inversion, from oil-in-water to water-in-oil and back to oil-in-water, was observed for emulsions with CNCs and increasing amounts of DMAB (the more hydrophobic surfactant). With CNCs and CTAB, no phase inversion was induced. This work represents the first report of CNC Pickering emulsions with surfactants as well as the first CNC Pickering emulsions that can be phase inverted. The ability to surface modify CNCs in situ and tailor emulsions by adding surfactants may extend the potential of CNCs to new liquid formulations and extruded/spray-dried materials.

  18. Surfactant-Enhanced In Situ Soils Washing

    DTIC Science & Technology

    1987-09-01

    technology . Several shortfa-- were observed and have been documented in this report. The report also contains. information on the operation of a groundwater...is 5.5 to 6.0. Atomic absorbtion analysis indicated dissolved iron levels as high as 24 mg/L in areas of high organic contamination. This iron...percent surfactant, consisting of a 50/50 mix of an ethoxylated alkyl phenol and ethoxylated fatty acid were passed through each column. Leachates from

  19. Role of medium-chain fatty acids in the emulsification mechanistics of self-micro-emulsifying lipid formulations

    PubMed Central

    Hasan, Naser M.Y.

    2014-01-01

    Purpose The objective of the present study was to design and develop stable o/w microemulsions comprising Miglyol 812, Imwitor 988 and Tagat TO as a non ionic surfactant. This was based on particle size measurements and phase behavior studies. The empirical role of incorporating medium-chain mono/di-glycerides in the lipid matrix in the mechanistic processes of emulsification was also established in various simulating physiological conditions. Methods The efficiency of self-emulsification was evaluated under conditions of varying key compositions in the lipid mixtures; oil, cosurfactant and surfactant. Droplet diameter was measured using laser diffraction and light scattering techniques. Equilibrium phase studies were performed and phase boundaries were determined for the lipid–water systems. Results Microemulsion systems were produced from blends of Miglyol 812, Imwitor 988 and Tagat TO. An optimized formulation consisted of {Miglyol 812/Imwitor 988} and Tagat TO spontaneously self-emulsified in water producing dispersions with droplet diameters of ∼50 nm. Phase equilibrium diagrams have revealed significant enhancement in the water-solubilized region (L2) without any presence of liquid crystalline materials. Conclusions Potential SMEDDS formulations for the bioavailability enhancement of poorly water-soluble compounds were developed by mixing blends of {Miglyol 812/Imwitor 988} and Tagat TO as a non-ionic surfactant. ‘Diffusion and stranding’ appears to be the dominant mechanism of emulsification. PMID:25561872

  20. Emulsification of algal oil with soy lecithin improved DHA bioaccessibility but did not change overall in vitro digestibility.

    PubMed

    Lin, Xinjie; Wang, Qi; Li, Weili; Wright, Amanda J

    2014-11-01

    Oil emulsification facilitates digestive lipolysis and subsequent lipid bioaccessibility. This study aimed to understand the effects of emulsification on DHA-rich algal oil digestion and bioaccessibility. An oil/water emulsion (50 : 44 : 6 oil-water-soy lecithin) was subjected to an in vitro digestion model with gastric pH 1.6 or 4.0 and particle size distributions, duodenal stage lipolysis and DHA bioaccessibility were determined. The emulsion was destabilized at gastric pH 1.6, with subsequent slow duodenal lipolysis. With gastric pH 4.0, the emulsion structure remained intact, initial lipolysis proceeded rapidly and DHA bioaccessibility was higher than for bulk oil, a mixture of oil, water and soy lecithin, and the gastric pH 1.6 destabilized emulsion (p < 0.05). However, the extent of lipolysis was not affected by emulsification or gastric pH. Therefore, the presence of an intact emulsion at the start of duodenal digestion, while not impacting the extent of lipolysis, did impact the initial lipolysis and DHA bioaccessibility.

  1. Effect of emulsification and spray-drying microencapsulation on the antilisterial activity of transcinnamaldehyde.

    PubMed

    Trinh, Nga-Thi-Thanh; Lejmi, Raja; Gharsallaoui, Adem; Dumas, Emilie; Degraeve, Pascal; Thanh, Mai Le; Oulahal, Nadia

    2015-01-01

    Spray-dried redispersible transcinnamaldehyde (TC)-in-water emulsions were prepared in order to preserve its antibacterial activity; 5% (w/w) TC emulsions were first obtained with a rotor-stator homogeniser in the presence of either soybean lecithin or sodium caseinate as emulsifiers. These emulsions were mixed with a 30% (w/w) maltodextrin solution before feeding a spray-dryer. The antibacterial activity of TC alone, TC emulsions with and without maltodextrin before and after spray-drying were assayed by monitoring the growth at 30 °C of Listeria innocua in their presence and in their absence (control). Whatever the emulsifier used, antilisterial activity of TC was increased following its emulsification. However, reconstituted spray-dried emulsions stabilised by sodium caseinate had a higher antibacterial activity suggesting that they better resisted to spray-drying. This was consistent with observation that microencapsulation efficiencies were 27.6% and 78.7% for emulsions stabilised by lecithin and sodium caseinate, respectively.

  2. CO2-Controllable Foaming and Emulsification Properties of the Stearic Acid Soap Systems.

    PubMed

    Xu, Wenlong; Gu, Hongyao; Zhu, Xionglu; Zhong, Yingping; Jiang, Liwen; Xu, Mengxin; Song, Aixin; Hao, Jingcheng

    2015-06-02

    Fatty acids, as a typical example of stearic acid, are a kind of cheap surfactant and have important applications. The challenging problem of industrial applications is their solubility. Herein, three organic amines-ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA)-were used as counterions to increase the solubility of stearic acid, and the phase behaviors were investigated systematically. The phase diagrams were delineated at 25 and 50 °C, respectively. The phase-transition temperature was measured by differential scanning calorimetry (DSC) measurements, and the microstructures were vesicles and planar sheets observed by cryogenic transmission electron microscopy (cryo-TEM) observations. The apparent viscosity of the samples was determined by rheological characterizations. The values, rcmc, for the three systems were less than 30 mN·m(-1). Typical samples of bilayers used as foaming agents and emulsifiers were investigated for the foaming and emulsification assays. CO2 was introduced to change the solubility of stearic acid, inducing the transition of their surface activity and further achieving the goal of defoaming and demulsification.

  3. Preparation of doublet, triangular, and tetrahedral colloidal clusters by controlled emulsification.

    PubMed

    Zerrouki, Djamal; Rotenberg, Benjamin; Abramson, Sébastien; Baudry, Jean; Goubault, Cécile; Leal-Calderon, Fernando; Pine, Dave J; Bibette, Jérome

    2006-01-03

    We describe a six-step method for making colloidal clusters of 2, 3, or 4 silica particles with a radius of 1.2 microm. This method, originally described by Manoharan et al. (Manoharan, V. N.; Elsesser, M. T.; Pine, D. J. Science 2003, 301, 483), is based on the encapsulation of silica spheres in emulsion droplets. The originality of our work lies in the preparation of monodisperse emulsions, which allows us to obtain some high yields of small aggregates over a wide range of conditions. Using optical microscopy and disk centrifugation, we show that the relative fractions of 2, 3, and 4 particle aggregates are controlled by the emulsification conditions, particularly the concentration of silica in the dispersed phase. Our best yields are obtained using low to moderate shear rates, a highly viscous continuous phase, and intermediate amounts of silica. The sedimentation of the colloidal solution into a gradient of concentration leads to aqueous suspensions of identical clusters. Since the overall process can easily be scaled up, large quantities of identical clusters may be prepared, which should allow the thermodynamic properties of these new colloidal objects to be measured for the first time. These nonspherical particles could serve as building blocks for more complex assemblies, such as colloidal crystals which could find applications as photonic materials.

  4. Acceleration of disproportionation of aromatic alcohols through self-emulsification of reactants in water.

    PubMed

    Zhang, Binbin; Song, Jinliang; Liu, Huizhen; Han, Buxing; Jiang, Tao; Fan, Honglei; Zhang, Zhaofu; Wu, Tianbin

    2012-12-01

    Exploration of new and effective routes to conduct organic reactions in water using the special properties of water/organics is of great importance. In this work, we performed the disproportionation of various aromatic alcohols in water and in different organic solvents. It was demonstrated that the disproportionation reactions of the alcohols were accelerated more effectively in water than organic-solvent-based or solvent-free reactions. A series of control experiments were conducted to study the mechanism of the accelerated reaction rate in water. It was shown that the reactants could emulsify the reactant/water systems at the reaction conditions owing to their amphiphilic nature. The regularly orientated reactant molecules at the water/reactant droplet interface improved the contact probability of the reactive groups and the Pd nanocatalysts, which is one of the main reasons for the enhanced reaction rate in water. Controlling the self-emulsification of amphiphilic reactant/water systems has great application potential for optimizing the rate and/or selectivity of many organic reactions.

  5. Preparation of monodisperse aqueous microspheres containing high concentration of l-ascorbic acid by microchannel emulsification.

    PubMed

    Khalid, Nauman; Kobayashi, Isao; Neves, Marcos A; Uemura, Kunihiko; Nakajima, Mitsutoshi; Nabetani, Hiroshi

    2015-01-01

    Monodisperse aqueous microspheres containing high concentrations of l-ascorbic acid with different concentrations of sodium alginate (Na-ALG) and magnesium sulfate (MgSO4) were prepared by using microchannel emulsification (MCE). The continuous phase was water-saturated decane containing a 5% (w/w) hydrophobic emulsifier. The flow rate of the continuous phase was maintained at 10 mL h(-1), whereas the pressure applied to the disperse phase was varied between 3 and 25 kPa. The disperse phase optimized for successfully generating aqueous microspheres included 2% (w/w) Na-ALG and 1% (w/w) MgSO4. At a higher MgSO4 concentration, the generated microspheres resulted in coalescence and subsequent bursting. At a lower MgSO4 concentration, unstable and polydisperse microspheres were obtained. The aqueous microspheres generated from the MCs under optimized conditions had a mean particle diameter (dav) of 14-16 µm and a coefficient of variation (CV) of less than 8% at the disperse phase pressures of 5-15 kPa.

  6. Open-channel, water-in-oil emulsification in paper-based microfluidic devices.

    PubMed

    Li, C; Boban, M; Tuteja, A

    2017-04-11

    Open-channel microfluidic devices have shown great potential in achieving a high degree of fluid control, at relatively low-cost, while enabling the opportunity for rapid fabrication. However, thus far, work in open channel microfluidics has largely focused on controlling the flow of water or other aqueous solutions. In this work we present new open channel microfluidic devices based on surfaces with patterned wettabilty that are capable of controlling the flow of virtually all high and low surface tension liquids. The fabricated open channel devices are capable of constraining a variety of low surface tension oils at high enough flow rates to enable, for the first time, water-in-oil microfluidic emulsification in an open channel device. By changing the flow rates for both the aqueous (dispersed) and organic (continuous) phases, we show that it is possible to vary the size of the emulsified droplets produced in the open channel device. Finally, we utilized the fabricated devices to synthesize relatively monodisperse, hydrogel microparticles that could incorporate a drug molecule. We also investigated the drug release characteristics of the fabricated particles.

  7. Thermal reversibility of vitamin E-enriched emulsion-based delivery systems produced using spontaneous emulsification.

    PubMed

    Saberi, Amir Hossein; Fang, Yuan; McClements, David Julian

    2015-10-15

    The influence of temperature scanning and isothermal storage conditions on turbidity, particle size, and thermal reversibility of vitamin E-enriched emulsions produced by spontaneous emulsification was examined. Initially, the mini-emulsions formed were optically transparent and contained small droplets (d ≈ 44 nm). When heated (20-90 °C), emulsions exhibited a complex turbidity-temperature profile with a phase inversion temperature (PIT) at ≈ 75-80 °C. Temperature scanning rate had a major influence on emulsion thermal reversibility. Slow heating (0.5 °C/min) above the PIT followed by quench cooling (≈ 67 °C min(-1)) to 30 °C did not appreciably increase turbidity or droplet diameter (d ≈ 50 nm), suggesting these systems were thermo-reversible. However, slow heating to temperatures below the PIT followed by rapid cooling appreciably increased droplet size and turbidity (thermo-irreversible). Cooling rate also affected emulsion thermo-reversibility: the turbidity and droplet size after heating above the PIT decreased with increasing cooling rate.

  8. Green aspects, developments and perspectives of liquid phase microextraction techniques.

    PubMed

    Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

    2014-02-01

    Determination of analytes at trace levels in complex samples (e.g. biological or contaminated water or soils) are often required for the environmental assessment and monitoring as well as for scientific research in the field of environmental pollution. A limited number of analytical techniques are sensitive enough for the direct determination of trace components in samples and, because of that, a preliminary step of the analyte isolation/enrichment prior to analysis is required in many cases. In this work the newest trends and innovations in liquid phase microextraction, like: single-drop microextraction (SDME), hollow fiber liquid-phase microextraction (HF-LPME), and dispersive liquid-liquid microextraction (DLLME) have been discussed, including their critical evaluation and possible application in analytical practice. The described modifications of extraction techniques deal with system miniaturization and/or automation, the use of ultrasound and physical agitation, and electrochemical methods. Particular attention was given to pro-ecological aspects therefore the possible use of novel, non-toxic extracting agents, inter alia, ionic liquids, coacervates, surfactant solutions and reverse micelles in the liquid phase microextraction techniques has been evaluated in depth. Also, new methodological solutions and the related instruments and devices for the efficient liquid phase micoextraction of analytes, which have found application at the stage of procedure prior to chromatographic determination, are presented.

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

    PubMed

    Zacharis, Constantinos K; Christophoridis, Christophoros; Fytianos, Konstantinos

    2012-09-01

    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.

  10. Conductive polymer-based microextraction methods: a review.

    PubMed

    Bagheri, Habib; Ayazi, Zahra; Naderi, Mehrnoush

    2013-03-12

    Conductive polymers (CPs) are classified as materials which exhibit highly reversible redox behavior and the unusual combined properties of metal and plastics. CPs, due to their multifunctionality, ease of synthesis and their stability, have attracted more attentions in different fields of research, including sample preparation. CPs along with several commercial hydrophilic sorbents, are alternative to the commercially available hydrophobic sorbents which despite their high specific surface areas, have poor interactions and retentions in the extraction of polar compounds. This review covers a general overview regarding the recent progress and new applications of CPs toward their synthesis and use in novel extraction and microextraction techniques including solid phase microextraction (SPME), electrochemically controlled solid-phase microextraction (EC-SPME) and other relevant techniques. Furthermore the contribution of nano-structured CPs in these methodologies is also reviewed.

  11. Preparation and characterization of solid lipid nanoparticles containing cyclosporine by the emulsification-diffusion method

    PubMed Central

    Urbán-Morlán, Zaida; Ganem-Rondero, Adriana; Melgoza-Contreras, Luz María; Escobar-Chávez, José Juan; Nava-Arzaluz, María Guadalupe; Quintanar-Guerrero, David

    2010-01-01

    Solid lipid nanoparticles (SLNs) have been used for carrying different therapeutic agents because they improve absorption and bioavailability. The aim of the study was to prepare lipidic nanoparticles containing cyclosporine (CyA) by the emulsification-diffusion method and to study their physicochemical stability. Glyceryl behenate (Compritol® ATO 888) and lauroyl macrogolglycerides (Gelucire® 44/14) were used as carrier materials. Nanoparticles with good stability were obtained with Gelucire®, while it was difficult to obtain stable systems with Compritol®. Systems with Gelucire® were characterized by particle size, Z-potential, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), entrapment efficiency and in vitro release. Particle size and Z-potential were evaluated for at least three months. With a high CyA content (≥60 mg) in Gelucire® SLNs, variations in size were greater and particle size also increased over time in all batches; this effect may have been caused by a probable expulsion of the drug due to the lipid’s partial rearrangement. While the Z-potential decreased 10 mV after three months, this effect may be explained by the superficial properties of the drug that make the molecules to be preferably oriented at the solid-liquid interface, causing a change in the net charge of the particle. SEM confirmed size and shape of the nanoparticles. DSC studies evidenced that CyA affects the lipid structure by a mechanism still unknown. The entrapment efficiency was higher than 92%, and CyA release from SLNs was relatively fast (99.60% in 45 min). PMID:20856836

  12. Patients' preferences for positioning during phaco-emulsification under topical-intracameral anaesthesia.

    PubMed

    Tsatsos, Michael; Chong, Loy; Eke, Tom

    2009-09-01

    In many eye departments it is routine to ask patients to lie completely flat for cataract surgery. However, many patients prefer not to lie completely flat, if given the choice. It is our practice to ensure patients are in a comfortable position before commencing surgery. We conducted a prospective observational study of our routine practice comprising 125 consecutive cataract operations conducted by a single surgeon with local anaesthesia (occasional phaco under general anaesthetic was not included). All patients were initially positioned lying flat on the reclining chair and were given the option of staying in that position throughout the operation or having the chair-back raised until they were comfortable. Only 27% (34 patients of 125 total) were happy to lie flat (angle between 0 degrees and 5 degrees ). The majority of our patients (62%--78 patients) preferred to sit up slightly, with the chair-back 10 degrees to 25 degrees above the horizontal; 8% (10 patients) of the patients were sited at an angle of 30 degrees to 35 degrees and 2% (three patients) needed to be sited at 35 degrees or more. Patients who sat up above 30 degrees generally had a medical reason such as orthopnoea (3%--four patients), back pain (5%--six patients), anxiety (2%--two patients), Meniere's disease (1%--one patient). Patients who sat up below 25 degrees chose this position for comfort or preference. Our results show that patient preferences for positioning during cataract phaco-emulsification under topical-intracameral anaesthesia should increase overall patient satisfaction without the need to compromise safety.

  13. Analysis of biosurfactants from industrially viable Pseudomonas strain isolated from crude oil suggests how rhamnolipids congeners affect emulsification property and antimicrobial activity

    PubMed Central

    Das, Palashpriya; Yang, Xin-Ping; Ma, Luyan Z.

    2014-01-01

    Rhamnolipid biosurfactants produced mainly by Pseudomonas sp. had been reported to possess a wide range of potential industrial application. These biosurfactants are produced as monorhamnolipid (MRL) and di-rhamnolipid (DRL) congeners. The present study deals with rhamnolipid biosurfactants produced by three bacterial isolates from crude oil. Biosurfactants produced by one of the strains (named as IMP67) was found to be very efficacious based on its critical micelle concentration value and hydrocarbon emulsification property. Strikingly, antimicrobial, and anti-biofilm potential of this biosurfactant were higher than biosurfactants produced by other two strains. Thin layer chromatography analysis and rhamnose quantification showed that the rhamnolipids of IMP67 had more MRL congeners than biosurfactants of the other two strains. Emulsification and antimicrobial actions were affected by manual change of MRL and DRL congener proportions. Increase of MRL proportion enhanced emulsification index and antimicrobial property to Gram negative bacteria. This result indicated that the ratio of MRL and DRL affected the emulsification potentials of rhamnolipids, and suggested that high emulsification potentials might enhance rhamnolipids to penetrate the cell wall of Gram negative bacteria. In line with this finding, rhamnolipids of IMP67 also reduced the MIC of some antibiotics against bacteria, suggesting their synergistic role with the antibiotics. PMID:25566212

  14. Effect of ultrasound radiation duration on emulsification and demulsification of paraffin oil and surfactant solution/brine using Hele-shaw models.

    PubMed

    Hamidi, Hossein; Mohammadian, Erfan; Asadullah, Mohammad; Azdarpour, Amin; Rafati, Roozbeh

    2015-09-01

    Ultrasound technique is one of the unconventional enhanced oil recovery methods which has been of interest for more than six decades. However, the majority of the oil recovery mechanisms under ultrasound reported in the previous studies are theoretical. Emulsification is one of the mechanisms happening at the interface of oil and water in porous media under ultrasound. Oppositely, ultrasound is one of the techniques using in oil industry for demulsification of oil/water emulsion. Therefore, the conditions in which emulsification becomes dominant over demulsification under ultrasound should be more investigated. Duration of ultrasound radiation could be one of the factors affecting emulsification and demulsification processes. In this study a technique was developed to investigate the effect of long and short period of ultrasound radiation on emulsification and demulsification of paraffin oil and surfactant solution in porous media. For this purpose, the 2D glass Hele-shaw models were placed inside the ultrasonic bath under long and short period of radiation of ultrasound. A microscope was used above the model for microscopic studies on the interface of oil and water. Diffusion of phases and formation of emulsion were observed in both long and short period of application of ultrasound at the beginning of ultrasound radiation. However, by passing time, demulsification and coalescence of brine droplets inside emulsion was initiated in long period of ultrasound application. Therefore, it was concluded that emulsification could be one of the significant oil recovery mechanisms happening in porous media under short period of application of ultrasound.

  15. Analysis of biosurfactants from industrially viable Pseudomonas strain isolated from crude oil suggests how rhamnolipids congeners affect emulsification property and antimicrobial activity.

    PubMed

    Das, Palashpriya; Yang, Xin-Ping; Ma, Luyan Z

    2014-01-01

    Rhamnolipid biosurfactants produced mainly by Pseudomonas sp. had been reported to possess a wide range of potential industrial application. These biosurfactants are produced as monorhamnolipid (MRL) and di-rhamnolipid (DRL) congeners. The present study deals with rhamnolipid biosurfactants produced by three bacterial isolates from crude oil. Biosurfactants produced by one of the strains (named as IMP67) was found to be very efficacious based on its critical micelle concentration value and hydrocarbon emulsification property. Strikingly, antimicrobial, and anti-biofilm potential of this biosurfactant were higher than biosurfactants produced by other two strains. Thin layer chromatography analysis and rhamnose quantification showed that the rhamnolipids of IMP67 had more MRL congeners than biosurfactants of the other two strains. Emulsification and antimicrobial actions were affected by manual change of MRL and DRL congener proportions. Increase of MRL proportion enhanced emulsification index and antimicrobial property to Gram negative bacteria. This result indicated that the ratio of MRL and DRL affected the emulsification potentials of rhamnolipids, and suggested that high emulsification potentials might enhance rhamnolipids to penetrate the cell wall of Gram negative bacteria. In line with this finding, rhamnolipids of IMP67 also reduced the MIC of some antibiotics against bacteria, suggesting their synergistic role with the antibiotics.

  16. Solid-phase microextraction versus single-drop microextraction for the analysis of nitroaromatic explosives in water samples.

    PubMed

    Psillakis, E; Kalogerakis, N

    2001-12-14

    This paper compares solid-phase microextraction (SPME) with a recently developed extraction method called single-drop microextraction (SDME) for the analysis of nitroaromatic explosives in water samples. The two techniques are examined in terms of procedure, chromatographic analysis and method performance. All practical considerations for both techniques are also reviewed. SPME requires dedicated apparatus and is relatively expensive, as the fiber's lifetime is limited. However, it has the advantages over SDME that it can be easily used for headspace analysis and has lower detection limits for all the target analytes. SDME requires more elaborate manual operations, thus affecting linearity and precision.

  17. Preparation of monodisperse SiO2 nanoparticles by membrane emulsification using ideally ordered anodic porous alumina.

    PubMed

    Yanagishita, Takashi; Tomabechi, Yasuyuki; Nishio, Kazuyuki; Masuda, Hideki

    2004-02-03

    Monodisperse SiO2 particles of nanometer dimensions were fabricated by membrane emulsification using ideally ordered anodic porous alumina. For the preparation of monodisperse emulsion droplets, the dispersed phase was pressed through a porous alumina membrane into the continuous phase. After solidification treatment of the emulsion droplets, prepared spherical SiO2 nanoparticles with uniform sizes were obtained. From scanning electron microscope observation of the obtained particles, it was confirmed that the size distribution of SiO2 nanoparticles is relatively narrow.

  18. Using Single Drop Microextraction for Headspace Analysis with Gas Chromatography

    ERIC Educational Resources Information Center

    Riccio, Daniel; Wood, Derrick C.; Miller, James M.

    2008-01-01

    Headspace (HS) gas chromatography (GC) is commonly used to analyze samples that contain non-volatiles. In 1996, a new sampling technique called single drop microextraction, SDME, was introduced, and in 2001 it was applied to HS analysis. It is a simple technique that uses equipment normally found in the undergraduate laboratory, making it ideal…

  19. Microchannel arrays with improved accessibility and use for cell studies and emulsification

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yuji; Kikuchi, Hiroko E.; Kuboki, Yoshinori; Nakajima, Mitsutoshi

    2000-03-01

    Arrays of microgrooves (groove width; 2, 3, 4, 5, 6, 7, 8, 10, 12, and 14 micrometer, groove interval; width x3, x10, and x20, one size and interval per chip) each connecting a center well and a side edge of a silicon substrate were created by photolithography and anisotropic wet etching. A penetrating hole was made by sand blast at the substrate center for the access to the center well. By tightly covering the substrate surface with a glass plate, the microgroove arrays were converted to microchannel arrays having one ends open at the side edges of the substrate. These microchannel arrays were used for cell trapping for microinjection and also used for emulsification. Poplar (Populus alba) protoplasts were used for the test of cell trapping. Cells showed a very large variation in size and irregularity in shape, and, furthermore, the protoplast preparation contained a number of cell membrane fragments and chloroplasts. Despite the cell size and shape variations and obstruction by the admixtures, many cells could be trapped by aspiration at the channel ends because of their openness to the outside free space and also their large multiplicity in parallel. The free space outside the side of the substrate allowed a free manipulation of a glass micropipette under microscopic observation using transmitted illumination. The microscopic observation direction nearly perpendicular to the movement directions of the micropipette further allowed the movement of the pipette tip nearly always in focus. These led to an easy pointing and puncturing. In addition, the cell trapping points in a line made successive approach to adjacent cells easier. Soybean oil containing 1.5 wt% polyoxyethylene(20)sorbitan monoolete as a surfactant was forced to flow into physiological saline filling the outside of the substrate through the microchannels. Regularly sized oil particles were created by this process with a variation coefficient (S.D./mean) 16% of their diameter. This variation, which is

  20. Solid-phase microextraction in biomedical analysis.

    PubMed

    Ulrich, S

    2000-12-01

    Chromatographic methods are preferred in the analysis of organic molecules with lower molecular mass (<500 g/mol) in body fluids, i.e., the assay of drugs, metabolites, endogenous substances and poisons as well as of environmental exposure by gas chromatography (GC) and liquid chromatography (LC), for example. Sample preparation in biomedical analysis is mainly performed by liquid-liquid extraction and solid-phase extraction. However, new methods are investigated with the aim to increase the sample throughput and to improve the quality of analytical methods. Solid-phase microextraction (SPME) was introduced about a decade ago and it was mainly applied to environmental and food analysis. All steps of sample preparation, i.e., extraction, concentration, derivatization and transfer to the chromatograph, are integrated in one step and in one device. This is accomplished by the intelligent combination of an immobilized extraction solvent (a polymer) with a special geometry (a fiber within a syringe). It was a challenge to test this novel principle in biomedical analysis. Thus, an introduction is provided to the theory of SPME in the present paper. A critical review of the first applications to biomedical analyses is presented in the main paragraph. The optimization of SPME as well as advantages and disadvantages are discussed. It is concluded that, because of some unique characteristics, SPME can be introduced with benefit into several areas of biomedical analysis. In particular, the application of headspace SPME-GC-MS in forensic toxicology and environmental medicine appears to be promising. However, it seems that SPME will not become a universal method. Thus, on-line SPE-LC coupling with column-switching technique may be a good alternative if an analytical problem cannot be sufficiently dealt with by SPME.

  1. Extensible automated dispersive liquid-liquid microextraction.

    PubMed

    Li, Songqing; Hu, Lu; Chen, Ketao; Gao, Haixiang

    2015-05-04

    In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid-liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C8MIM]NTf2) is formed through the reaction between [C8MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf2) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16-0.45 ng mL(-1). The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r>0.9986) was obtained over the calibration range from 2 to 500 ng mL(-1). The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples.

  2. Preparation and characterization of paclitaxel nanosuspension using novel emulsification method by combining high speed homogenizer and high pressure homogenization.

    PubMed

    Li, Yong; Zhao, Xiuhua; Zu, Yuangang; Zhang, Yin

    2015-07-25

    The aim of this study was to develop an alternative, more bio-available, better tolerated paclitaxel nanosuspension (PTXNS) for intravenous injection in comparison with commercially available Taxol(®) formulation. In this study, PTXNS was prepared by emulsification method through combination of high speed homogenizer and high pressure homogenization, followed by lyophilization process for intravenous administration. The main production parameters including volume ratio of organic phase in water and organic phase (Vo:Vw+o), concentration of PTX, content of PTX and emulsification time (Et), homogenization pressure (HP) and passes (Ps) for high pressure homogenization were optimized and their effects on mean particle size (MPS) and particle size distribution (PSD) of PTXNS were investigated. The characteristics of PTXNS, such as, surface morphology, physical status of paclitaxel (PTX) in PTXNS, redispersibility of PTXNS in purified water, in vitro dissolution study and bioavailability in vivo were all investigated. The PTXNS obtained under optimum conditions had an MPS of 186.8 nm and a zeta potential (ZP) of -6.87 mV. The PTX content in PTXNS was approximately 3.42%. Moreover, the residual amount of chloroform was lower than the International Conference on Harmonization limit (60 ppm) for solvents. The dissolution study indicated PTXNS had merits including effect to fast at the side of raw PTX and sustained-dissolution character compared with Taxol(®) formulation. Moreover, the bioavailability of PTXNS increased 14.38 and 3.51 times respectively compared with raw PTX and Taxol(®) formulation.

  3. Preparation and characterization of alginate-gelatin microencapsulated Bacillus subtilis SL-13 by emulsification/internal gelation.

    PubMed

    Tu, Liang; He, Yanhui; Yang, Hongbing; Wu, Zhansheng; Yi, Lijuan

    2015-01-01

    Gelatin was blended with sodium alginate (NaALG) to obtain a novel microbial fungicide, and dispersed micron Bacillus subtilis SL-13 microspheres prepared by emulsification/internal gelation method. Microscopic examination revealed that microcapsules were nearly spherical in shape. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction confirmed that the electrostatic interaction was occurred when gelatin added into NaALG. The maximum encapsulation efficiency was 93.44% at a gelatin concentration of 1.5%. Particle size, swelling, and biodegradation of beads increased with gelatin content increase. Furthermore, the viability of encapsulated SL-13 could be preserved at more than 10(8) CFU/mL after 120 d storage at 25 °C. The number of viable cells released from microcapsules presented an initial rapid increase followed by a gradual increase, and reached the maximum as 10(10) CFU/mL on day 35. Thus, it is feasible to prepare uniform, rounded shape, and well-dispersed micron microcapsules of SL-13 via emulsification/internal gelation using NaALG and gelatin composites. This encapsulation strategy could be considered as a potential alternative to future applications in the agricultural industry.

  4. Producing monodisperse drug-loaded polymer microspheres via cross-flow membrane emulsification: the effects of polymers and surfactants.

    PubMed

    Meyer, Robert F; Rogers, W Benjamin; McClendon, Mark T; Crocker, John C

    2010-09-21

    Cross-flow membrane emulsification (XME) is a method for producing highly uniform droplets by forcing a fluid through a small orifice into a transverse flow of a second, immiscible fluid. We investigate the feasibility of using XME to produce monodisperse solid microspheres made of a hydrolyzable polymer and a hydrophobic drug, a model system for depot drug delivery applications. This entails the emulsification of a drug and polymer-loaded volatile solvent into water followed by evaporation of the solvent. We use a unique side-view visualization technique to observe the details of emulsion droplet production, providing direct information regarding droplet size, dripping frequency, wetting of the membrane surface by the two phases, neck thinning during droplet break off, and droplet deformation before and after break off. To probe the effects that dissolved polymers, surfactants, and dynamic interfacial tension may have on droplet production, we compare our results to a polymer and surfactant-free fluid system with closely matched physical properties. Comparing the two systems, we find little difference in the variation of particle size as a function of continuous phase flow rate. In contrast, at low dripping frequencies, dynamic interfacial tension causes the particle size to vary significantly with drip frequency, which is not seen in simple fluids. No effects due to shear thinning or fluid elasticity are detected. Overall, we find no significant impediments to the application of XME to forming highly uniform drug-loaded microspheres.

  5. Microchannel emulsification study on formulation and stability characterization of monodisperse oil-in-water emulsions encapsulating quercetin.

    PubMed

    Khalid, Nauman; Kobayashi, Isao; Neves, Marcos A; Uemura, Kunihiko; Nakajima, Mitsutoshi; Nabetani, Hiroshi

    2016-12-01

    The study used microchannel emulsification (MCE) to encapsulate quercetin in food grade oil-in-water (O/W) emulsions. A silicon microchannel plate (Model WMS 1-2) comprised of 10,300 discrete 10×104μm microslots was connected to a circular microhole with an inner diameter of 10μm. 1% (w/w) Tween 20 was used as optimized emulsifier in Milli-Q water, while 0.4mgml(-1) quercetin in different oils served as a dispersed phase. The MCE was carried by injecting the dispersed phase at 2mlh(-1). Successful emulsification was conducted below the critical dispersed phase flux, with a Sauter mean diameter of 29μm and relative span factor below 0.25. The O/W emulsions remained stable in terms of droplet coalescence at 4 and 25°C for 30days. The encapsulation efficiency of quercetin in the O/W emulsions was 80% at 4°C and 70% at 25°C during the evaluated storage period.

  6. Air sampling with solid phase microextraction

    NASA Astrophysics Data System (ADS)

    Martos, Perry Anthony

    There is an increasing need for simple yet accurate air sampling methods. The acceptance of new air sampling methods requires compatibility with conventional chromatographic equipment, and the new methods have to be environmentally friendly, simple to use, yet with equal, or better, detection limits, accuracy and precision than standard methods. Solid phase microextraction (SPME) satisfies the conditions for new air sampling methods. Analyte detection limits, accuracy and precision of analysis with SPME are typically better than with any conventional air sampling methods. Yet, air sampling with SPME requires no pumps, solvents, is re-usable, extremely simple to use, is completely compatible with current chromatographic equipment, and requires a small capital investment. The first SPME fiber coating used in this study was poly(dimethylsiloxane) (PDMS), a hydrophobic liquid film, to sample a large range of airborne hydrocarbons such as benzene and octane. Quantification without an external calibration procedure is possible with this coating. Well understood are the physical and chemical properties of this coating, which are quite similar to those of the siloxane stationary phase used in capillary columns. The log of analyte distribution coefficients for PDMS are linearly related to chromatographic retention indices and to the inverse of temperature. Therefore, the actual chromatogram from the analysis of the PDMS air sampler will yield the calibration parameters which are used to quantify unknown airborne analyte concentrations (ppb v to ppm v range). The second fiber coating used in this study was PDMS/divinyl benzene (PDMS/DVB) onto which o-(2,3,4,5,6- pentafluorobenzyl) hydroxylamine (PFBHA) was adsorbed for the on-fiber derivatization of gaseous formaldehyde (ppb v range), with and without external calibration. The oxime formed from the reaction can be detected with conventional gas chromatographic detectors. Typical grab sampling times were as small as 5 seconds

  7. Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility. ESTCP Cost and Performance Report

    DTIC Science & Technology

    2012-08-01

    Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility August 2012 Report Documentation Page Form...DATES COVERED - 4. TITLE AND SUBTITLE Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and...polyoxymethylene PRC performance reference compounds SERDP Strategic Environmental Research and Development Program SPME solid phase microextraction

  8. Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility (User’s Manual)

    DTIC Science & Technology

    2012-05-01

    GUIDANCE DOCUMENT Demonstration and Evaluation of Solid Phase Microextraction For the Assessment of Bioavailability and Contaminant Mobility...Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility ER-200624Danny R. Reible...in-situ measurement of sediment pore water concentrations with solid phase microextraction using polydimethyl siloxane as the extractant. The method

  9. Headspace single drop microextraction versus dispersive liquid-liquid microextraction using magnetic ionic liquid extraction solvents.

    PubMed

    An, Jiwoo; Rahn, Kira L; Anderson, Jared L

    2017-05-15

    A headspace single drop microextraction (HS-SDME) method and a dispersive liquid-liquid microextraction (DLLME) method were developed using two tetrachloromanganate ([MnCl4(2-)])-based magnetic ionic liquids (MIL) as extraction solvents for the determination of twelve aromatic compounds, including four polyaromatic hydrocarbons, by reversed phase high-performance liquid chromatography (HPLC). The analytical performance of the developed HS-SDME method was compared to the DLLME approach employing the same MILs. In the HS-SDME approach, the magnetic field generated by the magnet was exploited to suspend the MIL solvent from the tip of a rod magnet. The utilization of MILs in HS-SDME resulted in a highly stable microdroplet under elevated temperatures and long extraction times, overcoming a common challenge encountered in traditional SDME approaches of droplet instability. The low UV absorbance of the [MnCl4(2-)]-based MILs permitted direct analysis of the analyte enriched extraction solvent by HPLC. In HS-SDME, the effects of ionic strength of the sample solution, temperature of the extraction system, extraction time, stir rate, and headspace volume on extraction efficiencies were examined. Coefficients of determination (R(2)) ranged from 0.994 to 0.999 and limits of detection (LODs) varied from 0.04 to 1.0μgL(-1) with relative recoveries from lake water ranging from 70.2% to 109.6%. For the DLLME method, parameters including disperser solvent type and volume, ionic strength of the sample solution, mass of extraction solvent, and extraction time were studied and optimized. Coefficients of determination for the DLLME method varied from 0.997 to 0.999 with LODs ranging from 0.05 to 1.0μgL(-1). Relative recoveries from lake water samples ranged from 68.7% to 104.5%. Overall, the DLLME approach permitted faster extraction times and higher enrichment factors for analytes with low vapor pressure whereas the HS-SDME approach exhibited better extraction efficiencies for

  10. Flame and graphite furnace atomic absorption spectrometry for trace element determination in vegetable oils, margarine and butter after sample emulsification.

    PubMed

    Ieggli, C V S; Bohrer, D; Do Nascimento, P C; De Carvalho, L M

    2011-05-01

    Trace element analysis plays an important role in oil characterisation and in the detection of oil adulteration because the quality of edible oils and fats is affected by their trace metal content. In this study, the quantification of selected metals in various oils and fats (rice oil, canola oil, sunflower oil, corn oil, soy oil, olive oil, light margarine, regular margarine and butter) was carried out using flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after sample emulsification. FAAS was used to determine the Na, K, Ca, Mg, Zn and Fe levels in the samples, while GFAAS was used for quantifying Cr, Ni, As, Pb, Cd, Cu and Mn, as these elements appeared in the samples at much lower concentrations. Tween-80 and Triton X-100 were employed as surfactants, and emulsions were prepared by a conventional method that involved heating and mixing of the constituents. Complete stabilisation was achieved through magnetic stirring for 15 min at room temperature. The evaluated figures of merit were linearity, accuracy and sensitivity, which were determined by the characteristic concentration and mass. Analysis of spiked samples demonstrated accuracy, which ranged from 90% (Na) to 112% (Fe) for FAAS and from 83% (Cd) to 121% (Pb) for GFAAS measurements. Atomic absorption spectrometry proved to be a promising approach for the analysis of metals in emulsified edible oils and fats. Additionally, under appropriate emulsification conditions (formulation, stirring time and temperature), the emulsions were homogeneous, had excellent stability, and had appropriate viscosity. The proposed method has proved to be simple, sensitive, reproducible, and economical.

  11. Solid Phase Microextraction for the Analysis of Nuclear Weapons

    SciTech Connect

    Chambers, D M

    2001-06-01

    This document is a compendium of answers to commonly asked questions about solid phase microextraction as it relates to the analysis of nuclear weapons. We have also included a glossary of terms associated with this analytical method as well as pertinent weapons engineering terminology. Microextraction is a new collection technique being developed to nonintrusively sample chemicals from weapon headspace gases for subsequent analysis. The chemicals that are being targeted outgas from the high explosives and other organic materials used in the weapon assembly. This technique is therefore a valuable tool to: (1) remotely detect and assess the aging of Lawrence Livermore National Laboratory (LLNL) and, in some cases, Sandia National Laboratory (SNL) organic materials; and (2) identify potential compatibility issues (i.e., materials interactions) that should be more carefully monitored during surveillance tear-downs. Microextraction is particularly attractive because of the practical constraints inherent to the weapon surveillance procedure. To remain transparent to other core surveillance activities and fall within nuclear safety guidelines, headspace analysis of the weapons requires a procedure that: (1) maintains ambient temperature conditions; (2) allows practical collection times of less than 20 min; (3) maintains the integrity of the weapon gas volume; (4) provides reproducible and quantitative results; and (5) can identify all possible targets.

  12. Dynamic headspace time-extended helix liquid-phase microextraction.

    PubMed

    Huang, Shih-Pin; Chen, Pai-Shan; Huang, Shang-Da

    2009-05-15

    Liquid-phase microextraction (LPME) has been proved to be a fast, inexpensive and effective sample pre-treatment technique for the analyses of pesticides and many other compounds. In this investigation, a new headspace microextraction technique, dynamic headspace time-extended helix liquid-phase microextraction (DHS-TEH-LPME), is presented. In this work, use of a solvent cooling system, permits the temperature of the extraction solvent to be lowered. Lowering the temperature of the extraction solvent not only reduces solvent loss but also extends the feasible extraction time, thereby improving extraction efficiency. Use of a larger volume of the solvent not only extends the feasible extraction time but also, after extraction, leaves a larger volume to be directly injected into the gas chromatography (GC) to increase extraction efficiency and instrument signal. The DHS-TEH-LPME technique was used to extract six organochlorine pesticides (OCPs) from 110ml water samples that had been spiked with the analytes at ng/l levels, and stirred for 60min. The proposed method attained enrichments up to 2121 fold. The effects of extraction solvent identity, sample agitation, extraction time, extraction temperature, and salt concentration on extraction performance were also investigated. The method detection limits (MDLs) varied from 0.2 to 25ng/l. The calibration curves were linear for at least 2 orders of magnitude with R(2)>==0.996. Relative recoveries in river water were more than 86%.

  13. Multi-residue method for determination of 58 pesticides, pharmaceuticals and personal care products in water using solvent demulsification dispersive liquid-liquid microextraction combined with liquid chromatography-tandem mass spectrometry.

    PubMed

    Caldas, Sergiane Souza; Rombaldi, Caroline; Arias, Jean Lucas de Oliveira; Marube, Liziane Cardoso; Primel, Ednei Gilberto

    2016-01-01

    A rapid and efficient sample pretreatment using solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was studied for the extraction of 58 pharmaceuticals and personal care products (PPCPs) and pesticides from water samples. Type and volume of extraction and disperser solvents, pH, salt addition, amount of salt and type of demulsification solvent were evaluated. Limits of quantification (LOQ) in the range from 0.0125 to 1.25 µg L(-1) were reached, and linearity was in the range from the LOQ of each compound to 25 μg L(-1). Recoveries ranged from 60% to 120% for 84% of the compounds, with relative standard deviations lower than 29%. The proposed method demonstrated, for the first time, that sample preparation by SD-DLLME with determination by LC-MS/MS can be successfully used for the simultaneous extraction of 32 pesticides and 26 PPCPs from water samples. The entire procedure, including the extraction of 58 organic compounds from the aqueous sample solution and the breaking up of the emulsion after extraction with water, rather than with an organic solvent, was environmentally friendly. In addition, this technique was less expensive and faster than traditional techniques. Finally, the analytical method under study was successfully applied to the analysis of all 58 pesticides and PPCPs in surface water samples.

  14. Microextraction techniques for the determination of volatile and semivolatile organic compounds from plants: a review.

    PubMed

    Yang, Cui; Wang, Juan; Li, Donghao

    2013-10-17

    Vegetables and fruits are necessary for human health, and traditional Chinese medicine that uses plant materials can cure diseases. Thus, understanding the composition of plant matrix has gained increased attention in recent years. Since plant matrix is very complex, the extraction, separation and quantitation of these chemicals are challenging. In this review we focus on the microextraction techniques used in the determination of volatile and semivolatile organic compounds (such as esters, alcohols, aldehydes, hydrocarbons, ketones, terpenes, sesquiterpene, phenols, acids, plant secondary metabolites and pesticides) from plants (e.g., fruits, vegetables, medicinal plants, tree leaves, etc.). These microextraction techniques include: solid phase microextraction (SPME), stir-bar sorptive extraction (SBSE), single drop microextraction (SDME), hollow fiber liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME), and gas purge microsyringe extraction (GP-MSE). We have taken into consideration papers published from 2008 to the end of January 2013, and provided critical and interpretative review on these techniques, and formulated future trends in microextraction for the determination of volatile and semivolatile compounds from plants.

  15. COHORT SAFETY AND EFFICACY STUDY OF SILURON2000 EMULSIFICATION-RESISTANT SILICONE OIL AND F4H5 IN THE TREATMENT OF FULL-THICKNESS MACULAR HOLE

    PubMed Central

    Pinxten, Anne-Marie; Wong, David S.

    2015-01-01

    Purpose: To evaluate safety and efficacy of using Siluron2000 silicone oil in the treatment of full-thickness macular hole by comparing its propensity to emulsify with emulsification of the “gold standard” Siluron5000, and to assess safety and efficacy of F4H5 (perfluorobutylpentane) in removing emulsified oil droplets from the eye. Methods: A single-center, randomized controlled parallel group trial in 72 patients undergoing vitrectomy for treatment of full-thickness macular hole. The study comprises four treatment groups. First, the total patient group was divided into 2 study arms of 36 patients each, receiving either Siluron2000 or Siluron5000 after vitrectomy with a 3-month follow-up after vitrectomy. Second, F4H5 was used during oil removal in half of the patients in each study arm (18 patients within each study arm) with follow-up at 6 weeks after oil removal. Oil droplets were counted within the removed oil; residual emulsification bubbles were quantified using ultrasound imaging. Results: Safety and efficacy of the oils were comparable. Injection and removal time of Siluron2000 oil was significantly less than that of Siluron5000 oil. Patients treated with F4H5 had borderline significantly less emulsification droplets than those not treated with F4H5. Conclusion: Siluron2000 silicone oil seems to be equally safe and effective as Siluron5000 oil but allows for better handling with the potential of reducing procedure time. The application of F4H5 seems to be safe and effective in reducing residual emulsification. PMID:26066703

  16. Preparation and evaluation of water-in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using cellulose acetate membrane.

    PubMed

    Muhamad, Ida Idayu; Quin, Chang Hui; Selvakumaran, Suguna

    2016-04-01

    The purpose of this study was to investigate the preparation of formulated water- in-soybean oil-in-water emulsions by repeated premix membrane emulsification method using a cellulose acetate membrane. The effect of selective membrane emulsification process parameters (concentration of the emulsifiers, number of passes of the emulsions through the membrane and storage temperature) on the properties and stability of the developed emulsions were also investigated. 1, 3, 6, 8-pyrenetetrasulfonic acid tetrasodium salt (PTSA) was used as a hydrophilic model ingredient for the encapsulation of bioactive substances. W/O emulsions with 7 wt% (weight percentage) PGPR displays homogeneous and very fine dispersions, with the median diameter at 0.640 μm. Meanwhile, emulsions prepared by membrane emulsification (fine W/O/W) showed the highest stability at Tween 80 concentrations of 0.5 wt.% (weight percentage). It concluded that at 7 wt.% (weight percentage) PGPR concentration and 0.5 wt.% (weight percentage) Tween 80 concentrations, the most uniform particles with minimum mean size of oil drops (9.926 μm) were obtained after four passes through the membrane. Thus, cellulose acetate membrane can be used for preparing a stable W/O/W emulsions by repeated premix ME due to low cost and relatively easy to handle.

  17. Progress of solid-phase microextraction coatings and coating techniques.

    PubMed

    Jiang, Guibin; Huang, Minjia; Cai, Yaqi; Lv, Jianxia; Zhao, Zongshan

    2006-07-01

    Solid-phase microextraction (SPME) has been popular as an environmentally friendly sample pretreatment technique to extract a very wide range of analytes. This is partly owing to the development of SPME coatings. One of the key factors affecting the extraction performances, such as the sensitivity, selectivity, and reproducibility, is the properties of the coatings on SPME fibers. This paper classifies the materials used as SPME coatings and introduces some common preparation techniques of SPME coating in detail, such as sol-gel technique, electrochemical polymerization technique, particle direct pasting technique, restricted access matrix SPME technique, and molecularly imprinted SPME technique.

  18. Combination of dispersive liquid-liquid microextraction and solid-phase microextraction: An efficient hyphenated sample preparation method.

    PubMed

    Jafari, Mohammad T; Saraji, Mohammad; Mossaddegh, Mehdi

    2016-09-30

    Two well-known microextraction methods, dispersive liquid-liquid microextraction (DLLME) and solid-phase microextraction (SPME), were combined, resulting in as an encouraging method. The method, named DLLME-SPME, was performed based on total vaporization technique. For the DLLME step, 1,1,2,2-tetrachloroethane and acetonitrile were used as extraction and disperser solvents, respectively. Halloysite nanotubes-titanium dioxide was used as the fiber coating in the SPME step. The method was applied for the extraction of diazinon and parathion (as the test compounds) in environmental water samples and fruit juices, and gas chromatography-corona discharge ion mobility spectrometry was used as the determination apparatus. Desorption temperature and time, extraction temperature and time, and the volume of the extracting solvent in the DLLME step were optimized as the effective parameters on the extraction efficiency. The relative standard deviations (RSDs) of intra-day were found to be 4-7% and 6-8% for diazinon and parathion, respectively. Also, the RSDs of inter-day were 7-9% and 8-10% for diazinon and parathion, respectively. The limits of quantification and detection were obtained to be 0.015 and 0.005μgL(-1) for diazinon, and 0.020 and 0.007μgL(-1) for parathion. A good linearity range (r(2)˃0.993) was obtained in the range of 0.015-3.000 and 0.020-3.000μgL(-1) for diazinon and parathion, respectively. The high enrichment factors were obtained as 3150 and 2965 for diazinon and parathion, respectively. This method showed high sensitivity with good recovery values (between 87 and 99%) for the extraction of target analytes in the real samples. Overall, the results revealed that the developed DLLME-SPME method had better extraction efficiency than DLLME and SPME alone.

  19. Formulation and characterization of esterified xylo-oligosaccharides-stabilized oil-in-water emulsions using microchannel emulsification.

    PubMed

    Udomrati, Sunsanee; Khalid, Nauman; Gohtani, Shoichi; Nakajima, Mitsutoshi; Uemura, Kunihiko; Kobayashi, Isao

    2016-12-01

    A series of amphiphilically esterified xylo-oligosaccharides (xylo esters) with different fatty acids residues - decanoic acid (C-10), lauric acid (C-12) and palmitic acid (C-16) - were enzymatically modified at 60°C for 4h. These xylo esters were used as emulsifiers to formulate oil-in-water (O/W) emulsions by microchannel emulsification (MCE). Grooved and straight-through MCE was used to investigate the droplet generation and/or emulsion stability. Xylo ester-stabilized oil droplets were generated smoothly from microchannels arranged linearly or two dimensionally, while xylo ester-stabilized emulsions were less monodispersed owing to low surface activity of the xylo esters. The combined use of xylo esters (2.5% (w/w)) and Tween series (0.1% (w/w)) in the continuous phase can improve the monodispersity of the resultant oil. Successful droplet generation was achieved with the straight-through MCE using 2.5% (w/w) xylo laurate and 0.1% (w/w) Tween 20. The optimized combination of xylo laurate and Tween 20 inhibited coalescence and oiling off more efficiently than the droplets solely stabilized by Tween 20 during 30days of storage.

  20. Continuous synthesis of drug-loaded nanoparticles using microchannel emulsification and numerical modeling: effect of passive mixing.

    PubMed

    Ortiz de Solorzano, Isabel; Uson, Laura; Larrea, Ane; Miana, Mario; Sebastian, Victor; Arruebo, Manuel

    2016-01-01

    By using interdigital microfluidic reactors, monodisperse poly(d,l lactic-co-glycolic acid) nanoparticles (NPs) can be produced in a continuous manner and at a large scale (~10 g/h). An optimized synthesis protocol was obtained by selecting the appropriated passive mixer and fluid flow conditions to produce monodisperse NPs. A reduced NP polydispersity was obtained when using the microfluidic platform compared with the one obtained with NPs produced in a conventional discontinuous batch reactor. Cyclosporin, an immunosuppressant drug, was used as a model to validate the efficiency of the microfluidic platform to produce drug-loaded monodisperse poly(d,l lactic-co-glycolic acid) NPs. The influence of the mixer geometries and temperatures were analyzed, and the experimental results were corroborated by using computational fluid dynamic three-dimensional simulations. Flow patterns, mixing times, and mixing efficiencies were calculated, and the model supported with experimental results. The progress of mixing in the interdigital mixer was quantified by using the volume fractions of the organic and aqueous phases used during the emulsification-evaporation process. The developed model and methods were applied to determine the required time for achieving a complete mixing in each microreactor at different fluid flow conditions, temperatures, and mixing rates.

  1. Nano-liter droplet libraries from a pipette: step emulsificator that stabilizes droplet volume against variation in flow rate.

    PubMed

    Dutka, Filip; Opalski, Adam S; Garstecki, Piotr

    2016-05-24

    Many modern analytical assays, for example, droplet digital PCR, or screening of the properties of single cells or single mutated genes require splitting a liquid sample into a number of small (typically ca. nano-liter in volume) independent compartments or droplets. This calls for a method that would allow splitting small (microliter) samples of liquid into libraries of nano-liter droplets without any dead volume or waste. Step emulsification allows for facile protocols that require delivery of only the sample liquid, yet they typically exhibit dependence of the droplet size on the rate at which the sample is injected. Here, we report a novel microfluidic junction that reduces the dependence of the volume of droplets on the rate of injection. We also demonstrate generation of tightly monodisperse nanoliter droplets by introduction of solely the dispersed phase into the system from an automatic pipette. The method presented here can readily be used and can replace the sophisticated devices typically used to generate libraries of nano-liter droplets from liquid samples.

  2. Emulsification and size control of insulating and/or viscous liquids in liquid-liquid systems by electrostatic dispersion

    SciTech Connect

    Sato, M.; Saito, M.; Hatori, T. )

    1993-03-15

    Electrostatic atomization has been utilized in applications such as electrostatic printing, paint spraying, thin-film coating, production of ultrafine powders, and control of fuel spraying. Electrostatic emulsification of insulating and/or viscous liquids which have been impossible to disperse by ordinary methods was studied using a liquid/distilled-water system. A dc potential was applied to a capillary nozzle to produce droplets. The size of the droplets decreased with increasing potential. The mean droplet diameter (corresponding to the applied potential) could be varied over a wide range (from several mm to [mu]m). A very fine cloudy emulsion (mean diameter of c.a. 5 [mu]m) having a narrow size distribution was obtained by applying approximately -3500 V to the nozzle. In the case of liquids with low viscosity, i.e., kerosene and carbon tetrachloride, droplets were produced regularly from the cusp of the meniscus formed at the nozzle tip. On the other hand, for castor oil, a highly viscous liquid, a liquid thread was drawn out from the meniscus and then disintegrated into small droplets. The mean diameter of the caster oil droplets was larger (one order of magnitude) than that of the low viscosity kerosene at the same applied potential.

  3. Surface nanodroplets for highly efficient liquid-liquid microextraction

    NASA Astrophysics Data System (ADS)

    Li, Miaosi; Lu, Ziyang; Yu, Haitao; Zhang, Xuehua

    2016-11-01

    Nanoscale droplets on a substrate are an essential element for a wide range of applications, such as laboratory-on-chip devices, simple and highly efficient miniaturized reactors for concentrating products, high-throughput single-bacteria or single-biomolecular analysis, encapsulation, and high-resolution imaging techniques. The solvent exchange process is a simple bottom-up approach for producing droplets at solid-liquid interfaces that are only several tens to hundreds of nanometers in height, or a few femtoliters in volume Oil nanodroplets can be produced on a substrate by solvent exchange in which a good solvent of oil is displaced by a poor solvent. Our previous work has significantly advanced understanding of the principle of solvent exchange, and the droplet size can be well-controlled by several parameters, including flow rates, flow geometry, gravitational effect and composition of solutions. In this work, we studied the microextraction effect of surface nanodroplets. Oil nanodroplets have been demonstrated to provide highly-efficient liquid-liquid microextraction of hydrophobic solute in a highly diluted solution. This effect proved the feasibility of nanodroplets as a platform for preconcentrating compounds for in situ highly sensitive microanalysis without further separation. Also the long lifetime and temporal stability of surface nanodroplets allow for some long-term extraction process and extraction without addition of stabilisers.

  4. Applications of liquid-phase microextraction techniques in natural product analysis: a review.

    PubMed

    Yan, Yunyan; Chen, Xuan; Hu, Shuang; Bai, Xiaohong

    2014-11-14

    Over the last years, liquid-phase microextraction (LPME) as a simple, rapid, practical and effective sample-preparation technique, coupled with various instrumental analytical methods, has been increasingly and widely used to research and determine trace or ultra-micro-levels of both inorganic and organic analytes from different matrix-complex samples. In this review, different kinds of LPMEs such as single drop liquid-phase microextraction, dispersive liquid-liquid microextraction, and hollow fibre liquid-phase microextraction are summarized and recent applications of LPMEs in trace compounds in vivo and in vitro from different natural product matrice analysis such as tea, vegetables, seeds, herbs, and galenical are also discussed. Finally, future developments and applications of LPMEs in complex sample analysis are prospected.

  5. EVALUATION OF SOLID PHASE MICROEXTRACTION FOR THE ANALYSIS OF HYDROPHILIC COMPOUNDS

    EPA Science Inventory

    Two commercially available solid phase microextractions (SPME) fibers, polyacrylate and carboxem/polydimethylsiloxane (PDMS), were evaluated for their ability to extract hydrophilic compounds from drinking water. Conditions, such as desorption time, desorption temperature, sample...

  6. Emerging Environmental Contaminants and Soled Phase Microextraction: Janusz Pawliszyn's Legacy in the Environmental Arena

    EPA Science Inventory

    Solid phase microextraction (SPME) has revolutionized the way samples are extracted, enabling rapid, automated, and solventless extraction of many different sample types, including air, water, soil, and biological samples. As such, SPME is widely used for environmental, food, fo...

  7. Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection

    DTIC Science & Technology

    2007-06-04

    Title of Thesis: Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection Name of...TITLE AND SUBTITLE Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection 5a. CONTRACT...SUPPLEMENTARY NOTES 14. ABSTRACT The High Surface Area Solid Phase Microextraction (HSA-SPME) device is an internally heated sampling device designed for

  8. Solid phase microextraction analysis of B83 SLTS and Core B compatibility test units

    SciTech Connect

    Chambers, D M; Ithaca, J; King, H A; Malcolm, S

    1999-03-26

    Solid phase microextraction has permitted the efficient collection and analysis of a broad range of volatile and semivolatile compounds outgassed from materials. In 1998, we implemented a microextraction protocol at Mason and Hanger, Pantex Plant, for the analysis of weapons and compatibility test units. The chemical information that was obtained from this work is interpreted by determining the source and outgas mechanism for each compound in the weapon signature, which is a task only accomplished by analysis of material standards.

  9. Microextraction by Packed Sorbent (MEPS) and Solid-Phase Microextraction (SPME) as Sample Preparation Procedures for the Metabolomic Profiling of Urine

    PubMed Central

    Silva, Catarina; Cavaco, Carina; Perestrelo, Rosa; Pereira, Jorge; Câmara, José S.

    2014-01-01

    For a long time, sample preparation was unrecognized as a critical issue in the analytical methodology, thus limiting the performance that could be achieved. However, the improvement of microextraction techniques, particularly microextraction by packed sorbent (MEPS) and solid-phase microextraction (SPME), completely modified this scenario by introducing unprecedented control over this process. Urine is a biological fluid that is very interesting for metabolomics studies, allowing human health and disease characterization in a minimally invasive form. In this manuscript, we will critically review the most relevant and promising works in this field, highlighting how the metabolomic profiling of urine can be an extremely valuable tool for the early diagnosis of highly prevalent diseases, such as cardiovascular, oncologic and neurodegenerative ones. PMID:24958388

  10. Ultrasonic emulsification of parenteral valproic acid-loaded nanoemulsion with response surface methodology and evaluation of its stability.

    PubMed

    Tan, Suk Fei; Masoumi, Hamid Reza Fard; Karjiban, Roghayeh Abedi; Stanslas, Johnson; Kirby, Brian P; Basri, Mahiran; Basri, Hamidon Bin

    2016-03-01

    Response surface methodology (RSM) was used to optimize the formulation of a nanoemulsion for central delivery following parenteral administration. A mixture of medium-chain triglyceride (MCT) and safflower seed oil (SSO) was determined as a sole phase from the emulsification properties. Similarly, a natural surfactant (lecithin) and non-ionic surfactant (Tween 80) (ratio 1:2) were used in the formulation. A central composite design (CCD) with three-factor at five-levels was used to optimize the processing method of high energy ultrasonicator. Effects of pre-sonication ultrasonic intensity (A), sonication time (B), and temperature (C) were studied on the preparation of nanoemulsion loaded with valproic acid. Influence of the aforementioned specifically the effects of the ultrasonic processing parameters on droplet size and polydispersity index were investigated. From the analysis, it was found that the interaction between ultrasonic intensity and sonication time was the most influential factor on the droplet size of nanoemulsion formulated. Ultrasonic intensity (A) significantly affects the polydispersity index value. With this optimization method, a favorable droplet size of a nanoemulsion with reasonable polydispersity index was able to be formulated within a short sonication time. A valproic acid loaded nanoemulsion can be obtained with 60% power intensity for 15 min at 60 °C. Droplet size of 43.21±0.11 nm with polydispersity index of 0.211 were produced. The drug content was then increased to 1.5%. Stability study of nanoemulsion containing 1.5% of valproic acid had a good stability as there are no significant changes in physicochemical aspects such as droplet size and polydispersity index. With the characteristisation study of pH, viscosity, transmission electron microscope (TEM) and stability assessment study the formulated nanoemulsion has the potential to penetrate blood-brain barrier in the treatment of epilepsy.

  11. Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical Warfare Agent Sulfur Mustard

    DTIC Science & Technology

    2002-05-16

    Title of Thesis: “Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid...TITLE AND SUBTITLE Application of Headspace Solid Phase Microextraction and Gas Chromatography/Mass Spectrometry for Rapid Detection of the Chemical...phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). Five commercially available SPME fibers were investigated to determine the

  12. Identification and Quantification of Pesticides in Environmental Waters With Solid Phase Microextraction and Analysis Using Field-Portable Gas Chromatography-Mass Spectrometry

    DTIC Science & Technology

    2004-06-10

    Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry Name of Candidate: CPT Michael J. Nack...in the thesis manuscript entitled: Identification and Quantification of Pesticides in Environmental Waters with Solid Phase Microextraction ...Pesticides in Environmental Waters with Solid Phase Microextraction and Analysis using Field-Portable Gas Chromatography-Mass Spectrometry

  13. Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas Chromatography-Mass Spectrometry (GC-MS)

    DTIC Science & Technology

    2007-11-02

    1 Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas...DATES COVERED - 4. TITLE AND SUBTITLE Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles...3 Characterization of Human Skin Emanations by Solid Phase Microextraction (SPME) Extraction of Volatiles and Subsequent Analysis by Gas

  14. Method for preparing a solid phase microextraction device using aerogel

    DOEpatents

    Miller, Fred S.; Andresen, Brian D.

    2006-10-24

    A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

  15. Recent developments in dispersive liquid-liquid microextraction.

    PubMed

    Saraji, Mohammad; Boroujeni, Malihe Khalili

    2014-03-01

    During the past 7 years and since the introduction of dispersive liquid-liquid microextraction (DLLME), the method has gained widespread acceptance as a simple, fast, and miniaturized sample preparation technique. Owing to its simplicity of operation, rapidity, low cost, high recovery, and low consumption of organic solvents and reagents, it has been applied for determination of a vast variety of organic and inorganic compounds in different matrices. This review summarizes the DLLME principles, historical developments, and various modes of the technique, recent trends, and selected applications. The main focus is on recent technological advances and important applications of DLLME. In this review, six important aspects in the development of DLLME are discussed: (1) the type of extraction solvent, (2) the type of disperser solvent, (3) combination of DLLME with other extraction methods, (4) automation of DLLME, (5) derivatization reactions in DLLME, and (6) the application of DLLME for metal analysis. Literature published from 2010 to April 2013 is covered.

  16. Studies on the formation of polymeric nano-emulsions obtained via low-energy emulsification and their use as templates for drug delivery nanoparticle dispersions.

    PubMed

    Calderó, G; Montes, R; Llinàs, M; García-Celma, M J; Porras, M; Solans, C

    2016-09-01

    Ethylcellulose nanoparticles have been obtained from O/W nano-emulsions of the water/polyoxyethylene 10 oleyl ether/[ethyl acetate+4wt% ethylcellulose] system by low energy-energy emulsification at 25°C. Nano-emulsions with droplet sizes below 200nm and high kinetic stability were chosen for solubilising dexamethasone (DXM). Phase behaviour, conductivity and optical analysis studies of the system have evidenced for the first time that both, the polymer and the drug play a role on the structure of the aggregates formed along the emulsification path. Nano-emulsion formation may take place by both, phase inversion and self-emulsification. Spherical polymeric nanoparticles containing surfactant, showing sizes below 160nm have been obtained from the nano-emulsions by organic solvent evaporation. DXM loading in the nanoparticles was high (>90%). The release kinetics of nanoparticle dispersions with similar particle size and encapsulated DXM but different polymer to surfactant ratio were studied and compared to an aqueous DXM solution. Drug release from the nanoparticle dispersions was slower than from the aqueous solution. While the DXM solution showed a Fickian release pattern, the release behaviour from the nanoparticle dispersions was faster than that expected from a pure Fickian release. A coupled diffusion/relaxation model fitted the results very well, suggesting that polymer chains undergo conformational changes enhancing drug release. The contribution of diffusion and relaxation to drug transport in the nanoparticle dispersions depended on their composition and release time. Surfactant micelles present in the nanoparticle dispersion may exert a mild reservoir effect. The small particle size and the prolonged DXM release provided by the ethylcellulose nanoparticle dispersions make them suitable vehicles for controlled drug delivery applications.

  17. Determination of fluoroquinolone antibiotics via ionic-liquid-based, salt-induced, dual microextraction in swine feed.

    PubMed

    Wang, Huili; Gao, Ming; Gao, Jiajia; Yu, Nana; Huang, Hong; Yu, Qing; Wang, Xuedong

    2016-09-01

    In conventional microextraction procedures, the disperser (organic solvent or ionic liquid) is left in the aqueous phase and discarded after finishing the microextraction process. Because the disperser is water-soluble, it results in low extraction recovery for polar compounds. In this investigation, an ionic-liquid-based microextraction (ILBME) was integrated with salting-out assisted liquid-liquid microextraction (SALLME) to build an ionic-liquid-based, salt-induced, dual microextraction (ILSDME) for isolation of five fluoroquinolone antibiotics (FQs) with high polarity (log P, -1.0 to 1.0). The proposed ILSDME method incorporates a dual microextraction by converting the disperser in the ILBME to the extractor in the SALLME. Optimization of key factors was conducted by integrating single-factor experiments and central composite design. The optimized experimental parameters were 80 μL [C8MIM][PF6] as extractor, 505 μL acetone as disperser, pH = 2.0, 4.1 min extraction time, and 4.2 g of Na2SO4. Under optimized conditions, high ERs (90.6-103.2 %) and low LODs (0.07-0.61 μg kg(-1)) were determined for five FQs in swine feed. Experimental precision based on RSDs was 1.4-5.2 % for intra-day and 2.4-6.9 % for inter-day analyses. The combination of ILBME with SALLME increased FQ recoveries by 15-20 % as compared with SALLME, demonstrating that the ILSDME method can enhance extraction efficiency for polar compounds compared to single-step microextraction. Therefore, the ILSDME method developed in this study has wide application for pretreatment of moderately to highly polar pollutants in complex matrices. Graphical Abstract A dual microextraction was developed by integrating ionic-liquid-based microextraction with salting-out assisted liquid-liquid microextraction for isolation of five fluoroquinolone antibiotics (FQs) with high polarity (log P = -1.0 to 1.0). The principle of dual microextraction is based on converting the remaining disperser from

  18. Effect of glycerol on formation, stability, and properties of vitamin-E enriched nanoemulsions produced using spontaneous emulsification.

    PubMed

    Saberi, Amir Hossein; Fang, Yuan; McClements, David Julian

    2013-12-01

    Oil-in-water nanoemulsions are finding increasing use as delivery systems to encapsulate lipophilic bioactive components in functional food, personal care, and pharmaceutical products. We investigated the influence of a water-soluble cosolvent (glycerol) on the formation, stability, and properties of vitamin E acetate-loaded nanoemulsions (VE-NEs) prepared by spontaneous emulsification. VE-NEs were formed by titration of a mixture of vitamin E acetate, carrier oil (MCT) and non-ionic surfactant (Tween 80) into an aqueous glycerol solution with continuous mixing. Cosolvent concentration had an appreciable effect on the particle size produced, with the smallest mean droplet diameters (d<50 nm) being formed at 40 and 50 wt% glycerol. Nanoemulsions (d<100 nm) containing 10% vitamin E acetate could be produced at relatively low surfactant concentrations (5%) using these high glycerol levels. The turbidity of the NEs decreased at high glycerol concentrations due to the reduction in droplet size and refractive index contrast. The long-term stability of the VE-NEs was strongly influenced by glycerol concentration and storage temperature. VE-NEs containing 40% glycerol were relatively stable to droplet growth when stored at 5 and 20°C, but a rapid increase in droplet size and turbidity occurred during storage at 37°C. Temperature scanning experiments (20-80-20°C) indicated that a steep and irreversible increase in turbidity occurred during heating, which was around 70°C in the absence of glycerol and 60°C in the presence of 40% glycerol. Droplet instability was attributed to an increase in the rate of Ostwald ripening and/or coalescence as the temperature was increased, associated with dehydration of the non-ionic surfactant head-group leading to a reduction in phase inversion temperature. Dilution (100×) of VE-NEs containing glycerol with water considerably improved their stability to droplet growth, especially at high storage temperatures. This study provides

  19. Solvent-impregnated agarose gel liquid phase microextraction of polycyclic aromatic hydrocarbons in water.

    PubMed

    Loh, Saw Hong; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2013-08-09

    A new microextraction procedure termed agarose gel liquid phase microextraction (AG-LPME) combined with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of selected polycyclic aromatic hydrocarbons (PAHs) in water. The technique utilized an agarose gel disc impregnated with the acceptor phase (1-octanol). The extraction procedure was performed by allowing the solvent-impregnated agarose gel disc to tumble freely in the stirred sample solution. After extraction, the agarose gel disc was removed and subjected to centrifugation to disrupt its framework and to release the impregnated solvent, which was subsequently withdrawn and injected into the GC-MS for analysis. Under optimized extraction conditions, the new method offered high enrichment factors (89-177), trace level LODs (9-14ngL(-1)) and efficient extraction with good relative recoveries in the range of 93.3-108.2% for spiked drinking water samples. AG-LPME did not exhibit any problems related to solvent dissolution, and it provided high extraction efficiencies that were comparable to those of hollow fiber liquid phase microextraction (HF-LPME) and significantly higher than those of agarose film liquid phase microextraction (AF-LPME). This technique employed a microextraction format and utilized an environmentally compatible solvent holder that supported the green chemistry concept.

  20. Novel mode of liquid-phase microextraction: A magnetic stirrer as the extractant phase holder.

    PubMed

    Luo, Zhi-Yuan; Liu, Hai-Yan; Shi, Zhi-Guo

    2016-01-01

    In the present study, a novel configuration of liquid-phase microextraction was proposed, in which a magnetic stirrer with a groove was used as the extractant phase holder. It was termed as magnetic stirrer liquid-phase microextraction. In this way, the stability of the organic solvent was much improved under high stirring speed; the extraction efficiency was enhanced due to the enormously enlarged contact area between the organic solvent and aqueous phase. The extraction performance of the magnetic stirrer liquid-phase microextraction was studied using chlorobenzenes as the probe analytes. A wide linearity range (20 pg/mL to 200 ng/mL) with a satisfactory linearity coefficient (r(2) > 0.998) was obtained. Limits of detection ranged from 9.0 to 12.0 pg/mL. Good reproducibility was achieved with intra- and inter-day relative standard deviations <4.8%. The proposed magnetic stirrer liquid-phase microextraction was simple, environmentally friendly and efficient; compared to single-drop microextraction, it had obvious advantages in terms of reproducibility and extraction efficiency. It is a promising miniaturized liquid-phase technology for real applications.

  1. Liquid phase microextraction for the analysis of trace elements and their speciation

    NASA Astrophysics Data System (ADS)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-08-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated.

  2. Preferential extraction of hydrocarbons from fire debris samples by solid phase microextraction.

    PubMed

    Lloyd, Julie A; Edmiston, Paul L

    2003-01-01

    Headspace analysis by extraction/GC-MS is a common method of detecting volatile hydrocarbon accelerants in fire debris samples. Solid-phase microextraction was tested to determine if there is selective extraction of chemically distinct compounds. It was found that both the polydimethylsiloxane (PDMS) and Carboxen/PDMS solid phase microextraction fibers show preferential extraction of aliphatic or aromatic compounds from the headspace depending on fiber type and temperature. The Carboxen/PDMS fiber type showed particular (although not exclusive) selectivity for extraction of aromatic hydrocarbons. Other experimental considerations of SPME are noted.

  3. Headspace single drop microextraction coupled with microwave extraction of essential oil from plant materials.

    PubMed

    Zhai, Yujuan; Sun, Shuo; Wang, Ziming; Zhang, Yupu; Liu, He; Sun, Ye; Zhang, Hanqi; Yu, Aimin

    2011-05-01

    Headspace single drop microextraction (HS-SDME) coupled with microwave extraction (ME) was developed and applied to the extraction of the essential oil from dried Syzygium aromaticum (L.) Merr. et Perry and Cuminum cyminum L. The operational parameters, such as microdrop volume, microwave absorption medium (MAM), extraction time, and microwave power were optimized. Ten microliters of decane was used as the microextraction solvent. Ionic liquid and carbonyl iron powder were used as MAM. The extraction time was less than 7 min at the microwave power of 440 W. The proposed method was compared with hydrodistillation (HD). There were no obvious differences in the constituents of essential oils obtained by the two methods.

  4. Dispersive liquid-liquid microextraction in food analysis. A critical review.

    PubMed

    Viñas, Pilar; Campillo, Natalia; López-García, Ignacio; Hernández-Córdoba, Manuel

    2014-03-01

    An extensive critical evaluation of the application of dispersive liquid-liquid microextraction (DLLME) combined with chromatographic and atomic-spectroscopic methods for the determination of organic and inorganic compounds is presented. The review emphasizes the procedures used for the prior treatment of food samples, which are very different from the DLLME procedures generally proposed for water samples. The main contribution of this work in the field of DLLME reviews is its critical review of the abundant literature showing the increasing interest and practical advantages of using DLLME and closely related microextraction techniques for food analysis.

  5. Surfactants Enhance Primisulfuron Activity in Common Lambsquarters (Chenopodium album L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common lambsquarters (Chenopodium album L.) is one of the most widely distributed weed species in the world and is competitive with 40 crops. Greenhouse and laboratory studies were conducted to determine the effect of non-ionic (Induce®) and organosilicone (Silwet L-77®) surfactants on primisulfuron...

  6. Nonionic surfactants enhancing bactericidal activity at their critical micelle concentrations.

    PubMed

    Tobe, Seiichi; Majima, Toshiaki; Tadenuma, Hirohiko; Suekuni, Tomonari; Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko

    2015-01-01

    Bactericidal activities of benzalkonium chloride [also known as alkyldimethylbenzylammonium chloride (ADBAC)] containing nonionic surfactants such as methyl ester ethoxylates (MEE) with the alkyl group C8-C14 and oxyethylene (EO) group of average adduct number 3-15 were measured against Escherichia coli and Staphylococcus aureus. Sample solutions containing MEE in the vicinity of the critical micelle concentration exhibited a dramatic decrease in viable bacterial counts. MEE with an alkyl group of C12 and an oxyethylene group of lower adduct number exhibited little viable bacterial counts than those having higher EO adduct numbers. MEE with reduced EO adduct numbers increased fluorescence intensity in E. coli using the viability stain SYTO 9. Our results show that MEE molecules with low EO adduct numbers exhibited bactericidal activity by increasing the permeability of the E. coli cell membrane. Sample solution containing ADBAC and MEE molecules with lower EO adduct numbers also displayed higher zeta potentials. Moreover, ADBAC molecules incorporated into micelles of MEE with lower EO adduct numbers were adsorbed onto the surface of E. coli, which augmented bactericidal activity.

  7. Microbial surfactant-enhanced mineral oil recovery under laboratory conditions.

    PubMed

    Bordoloi, N K; Konwar, B K

    2008-05-01

    Microbial enhanced oil recovery (MEOR) is potentially useful to recover incremental oil from a reservoir being beyond primary and secondary recovery operations. Effort has been made to isolate and characterize natural biosurfactant produced by bacterial isolates collected from various oil fields of ONGC in Assam. Production of biosurfactant has been considered to be an effective major index for the purpose of enhanced oil recovery. On the basis of the index, four promising bacterial isolates: Pseudomonas aeruginosa (MTCC7815), P. aeruginosa (MTCC7814), P. aeruginosa (MTCC7812) and P. aeruginosa (MTCC8165) were selected for subsequent testing. Biosurfactant produced by the promising bacterial isolates have been found to be effective in the recovery of crude oil from saturated column under laboratory conditions. Two bacterial strains: P. aeruginosa (MTCC7815) and P. aeruginosa (MTCC7812) have been found to be the highest producer of biosurfactant. Tensiometer studies revealed that biosurfactants produced by these bacterial strains could reduce the surface tension (sigma) of the growth medium from 68 to 30 mN m(-1) after 96 h of growth. The bacterial biosurfactants were found to be functionally stable at varying pH (2.5-11) conditions and temperature of 100 degrees C. The treatment of biosurfactant containing, cell free culture broth in crude oil saturated sand pack column could release about 15% more crude oil at 90 degrees C than at room temperature and 10% more than at 70 degrees C under laboratory condition.

  8. Surfactant Enhanced Microbial Degradation of JP-8 Contaminated Soil

    DTIC Science & Technology

    1996-12-01

    temperature on the respiration of soil microorganisms. Graph of the oxygen consumption rate of uncontaminated Kittyhawk silt soil. Small fluctuations in...Temperature result in increases or decreases in the respiration rate of the indigenous organisms present in the soil. Each observation (interval) represents...problem due to different respiration rates of replicate microcosms. Also, the experiment revealed that Novell II appeared to be inhibitory, since the

  9. SURFACTANT ENHANCED REMEDIATION OF SOIL COLUMNS CONTAMINATED BY RESIDUAL TETRACHLOROETHYLENE

    EPA Science Inventory

    The ability of aqueous surfactant solutions to recover tetrachloroethylene (PCE) entrapped in Ottawa sand was evaluated in four column experiments. Residual PCE was emplaced by injecting 14C-labeled PCE into water-saturated soil columns and displacing the free product ...

  10. Surfactant mixing rules applied to surfactant enhanced alkaline flooding

    SciTech Connect

    Taylor, K.C. )

    1992-01-01

    This paper discusses surfactant mixing rules which have been used to describe crude oil/alkali/surfactant phase behavior, using David Lloydminster crude oil and the surfactant Neodol 25-3S. It was found that at a fixed salinity and alkali concentration, a specific mole fraction of synthetic surfactant to petroleum soap was required to produce optimal phase behavior as the water-to-oil ratio varied. This methodology is useful in understanding the relationship between the variables of water-to-oil ratio and synthetic surfactant concentration in phase behavior systems that produce a petroleum soap.

  11. Competitive substrate biodegradation during surfactant-enhanced remediation

    SciTech Connect

    Goudar, C.; Strevett, K.; Grego, J.

    1999-12-01

    The impact of synthetic surfactants on the aqueous phase biodegradation of benzene, toluene, and p-xylene (BTpX) was studied using two anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS), and two nonionic surfactants, POE(20) sorbitan monooleate (T-maz-80) and octyl-phenolpoly(ethyleneoxy) ethanol (CA-620). Batch biodegradation experiments were performed to evaluate surfactant biodegradability using two different microbial cultures. Of the four surfactants used in this study, SDS and T-maz-80 were readily degraded by a microbial consortium obtained from an activated sludge treatment system, whereas only SDS was degraded by a microbial culture that was acclimated to BTpX. Biodegradation kinetic parameters associated with SDS and T-maz-80 degradation by the activated sludge consortium were estimated using respirometric data in conjunction with a nonlinear parameter estimation technique as {mu}{sub max} = 0.93 h{sup {minus}1}, K{sub s}= 96.18 mg/L and {mu}{sub max} = 0.41 h{sup {minus}1}, K{sub s} = 31.92 mg/L, respectively. When both BTpX and surfactant were present in the reactor along with BTpX-acclimated microorganisms, two distinct biodegradation patterns were seen. SDS was preferentially utilized inhibiting hydrocarbon biodegradation, whereas, the other three surfactants had no impact on BTpX biodegradation. None of the four surfactants were toxic to the microbial cultures used in this study. Readily biodegradable surfactants are not very effective for subsurface remediation applications as they are rapidly consumed, and also because of their potential inhibitory effects on intrinsic hydrocarbon biodegradation. This greatly increases treatment costs as surfactant recovery and reuse are adversely affected.

  12. Surfactant-Enhanced Aquifer Remediation (SEAR) Implementation Manual

    DTIC Science & Technology

    2003-04-01

    conventional processes such as air-stripping and steam-stripping, or innovative processes such as liquid-liquid extraction and pervaporation ...Hitchens, L., Alvarez, F.R., and E.L. Giroux. 2001. “Field demonstration of pervaporation for the separation of volatile organic compounds from a

  13. Dynamic headspace liquid-phase microextraction of alcohols.

    PubMed

    Saraji, Mohammad

    2005-01-07

    A method was developed using dynamic headspace liquid-phase microextraction and gas chromatography-mass spectrometry for extraction and determination of 9 alcohols from water samples. Four different solvents, hexyl acetate, n-octanol, o-xylene and n-decane were studied as extractants. The analytes were extracted using 0.8 microl of n-octanol from the headspace of a 2 ml sample solution. The effect of sampling volume, solvent volume, sample temperature, syringe plunger withdrawal rate and ionic strength of the solution on the extraction performance were studied. A semiautomated system including a variable speed stirring motor was used to ensure a uniform movement of syringe plunger through the barrel. The method provided a fairly good precision for all compounds (5.5-9.3%), except methanol (16.4%). Detection limits were found to be between 1 and 97 microg/l within an extraction time of approximately 9.5 min under GC-MS in full scan mode.

  14. Monolithic graphene fibers for solid-phase microextraction.

    PubMed

    Fan, Jing; Dong, Zelin; Qi, Meiling; Fu, Ruonong; Qu, Liangti

    2013-12-13

    Monolithic graphene fibers for solid-phase microextraction (SPME) were fabricated through a dimensionally confined hydrothermal strategy and their extraction performance was evaluated. For the fiber fabrication, a glass pipeline was innovatively used as a hydrothermal reactor instead of a Teflon-lined autoclave. Compared with conventional methods for SPME fibers, the proposed strategy can fabricate a uniform graphene fiber as long as several meters or more at a time. Coupled to capillary gas chromatography (GC), the monolithic graphene fibers in a direct-immersion (DI) mode achieved higher extraction efficiencies for aromatics than those for n-alkanes, especially for polycyclic aromatic hydrocarbons (PAHs), thanks to π-π stacking interaction and hydrophobic effect. Additionally, the fibers exhibited excellent durability and can be repetitively used more than 160 times without significant loss of extraction performance. As a result, an optimum extraction condition of 40°C for 50min with 20% NaCl (w/w) was finally used for SPME of PAHs in aqueous samples. For the determination of PAHs in water samples, the proposed DI-SPME-GC method exhibited linear range of 0.05-200μg/L, limits of detection (LOD) of 4.0-50ng/L, relative standard deviation (RSD) less than 9.4% and 12.1% for one fiber and different fibers, respectively, and recoveries of 78.9-115.9%. The proposed method can be used for analysis of PAHs in environmental water samples.

  15. Recent development and applications of dispersive liquid-liquid microextraction.

    PubMed

    Yan, Hongyuan; Wang, Hui

    2013-06-21

    Dispersive liquid-liquid microextraction (DLLME) is a modern sample pretreatment technique that is regarded as consilient with the current trends of modern analytical chemistry. DLLME is simple, inexpensive, environmentally friendly, and could offer high enrichment factors from a wide gap between acceptor and donor phases. As a consequence, DLLME has attracted considerable attention from researchers and, based on the numerous publications concerning DLLME, has been generally accepted in separation science since the technique's invention in 2006. However, several innate weaknesses of DLLME, which restrict the technique's use in certain fields, have led to various attempts or suggestions to improve this technique. The present review focuses on the recent advances made in DLLME; the selected papers that are discussed in this work represent modifications that fall into three main categories (exploration of new extraction solvents, disperser solvents and combination with other techniques). The recent applications of DLLME in environmental, food and biological samples are also summarised, covering almost all of the publications related to the technology from the beginning. In addition, the feasibility of future trends of DLLME is discussed.

  16. Evolution of dispersive liquid-liquid microextraction method.

    PubMed

    Rezaee, Mohammad; Yamini, Yadollah; Faraji, Mohammad

    2010-04-16

    Dispersive liquid-liquid microextraction (DLLME) has become a very popular environmentally benign sample-preparation technique, because it is fast, inexpensive, easy to operate with a high enrichment factor and consumes low volume of organic solvent. DLLME is a modified solvent extraction method in which acceptor-to-donor phase ratio is greatly reduced compared with other methods. In this review, in order to encourage further development of DLLME, its combination with different analytical techniques such as gas chromatography (GC), high-performance liquid chromatography (HPLC), inductively coupled plasma-optical emission spectrometry (ICP-OES) and electrothermal atomic absorption spectrometry (ET AAS) will be discussed. Also, its applications in conjunction with different extraction techniques such as solid-phase extraction (SPE), solidification of floating organic drop (SFO) and supercritical fluid extraction (SFE) are summarized. This review focuses on the extra steps in sample preparation for application of DLLME in different matrixes such as food, biological fluids and solid samples. Further, the recent developments in DLLME are presented. DLLME does have some limitations, which will also be discussed in detail. Finally, an outlook on the future of the technique will be given.

  17. Chemically modified cellulose paper as a thin film microextraction phase.

    PubMed

    Saraji, Mohammad; Farajmand, Bahman

    2013-11-01

    In this paper, chemically modified cellulose paper was introduced as a novel extracting phase for thin film microextraction (TFME). Different reagents (Octadecyltrichlorosilane, diphenyldichlorosilane, cyclohexyl isocyanate and phenyl isocyanate) were used to modify the cellulose papers. The modified papers were evaluated as a sorbent for the extraction of some synthetic and natural estrogenic hormones (17α-ethynylestradiol, estriol and estradiol) from aqueous samples. Liquid chromatography-fluorescence detection was used for the quantification of the extracted compounds. The cellulose paper modified with phenyl isocyanate showed the best affinity to the target compounds. TEME parameters such as desorption condition, shaking rate, sample ionic strength and extraction time were investigated and optimized. Limit of detections were between 0.05 and 0.23μgL(-1) and relative standard deviations were less than 11.1% under the optimized condition. The calibration curves were obtained in the range of 0.2-100μgL(-1) with a good linearity (r(2)>0.9935). Wastewater, human urine, pool and river water samples were studied as real samples for the evaluation of the method. Relative recoveries were found to be between 75% and 101%.

  18. Ionic liquids in solid-phase microextraction: a review.

    PubMed

    Ho, Tien D; Canestraro, Anthony J; Anderson, Jared L

    2011-06-10

    Solid-phase microextraction (SPME) has undergone a surge in popularity within the field of analytical chemistry in the past two decades since its introduction. Owing to its nature of extraction, SPME has become widely known as a quick and cost-effective sample preparation technique. Although SPME has demonstrated extraordinary versatility in sampling capabilities, the technique continues to experience a tremendous growth in innovation. Presently, increasing efforts have been directed towards the engineering of novel sorbent material in order to expand the applicability of SPME for a wider range of analytes and matrices. This review highlights the application of ionic liquids (ILs) and polymeric ionic liquids (PILs) as innovative sorbent materials for SPME. Characterized by their unique physico-chemical properties, these compounds can be structurally-designed to selectively extract target analytes based on unique molecular interactions. To examine the advantages of IL and PIL-based sorbent coatings in SPME, the field is reviewed by gathering available experimental data and exploring the sensitivity, linear calibration range, as well as detection limits for a variety of target analytes in the methods that have been developed.

  19. Comparison of headspace and direct single-drop microextraction and headspace solid-phase microextraction for the measurement of volatile sulfur compounds in beer and beverage by gas chromatography with flame photometric detection.

    PubMed

    Xiao, Qin; Yu, Chunhe; Xing, Jun; Hu, Bin

    2006-08-25

    Three approaches based on headspace single-drop microextraction (HS-SDME), direct single-drop microextraction (Direct-SDME), and headspace solid-phase microextraction (HS-SPME), have been compared for analyzing volatile sulphur compounds (VSCs) in beer and beverage. Procedures and performance of the three methods have been contrasted through the determination of extraction efficiencies, precision, linearity and limits of detection. The overall process of HS-SDME and HS-SPME was applied to GC-FPD determination of five VSCs in beer and beverage.

  20. Methods of Soft Tissue Emulsification Using a Mechanism of Ultrasonic Atomization Inside Gas or Vapor Cavities and Associated Systems and Devices

    NASA Technical Reports Server (NTRS)

    Sapozhnikov, Oleg A. (Inventor); Bailey, Michael R. (Inventor); Crum, Lawrence A. (Inventor); Khokhlova, Tatiana D. (Inventor); Khokhlova, Vera A. (Inventor); Simon, Julianna C. (Inventor); Wang, Yak-Nam (Inventor)

    2016-01-01

    The present technology is directed to methods of soft tissue emulsification using a mechanism of ultrasonic atomization inside gas or vapor cavities, and associated systems and devices. In several embodiments, for example, a method of non-invasively treating tissue includes pulsing ultrasound energy from the ultrasound source toward the target site in tissue. The ultrasound source is configured to emit high intensity focused ultrasound (HIFU) waves. The target site comprises a pressure-release interface of a gas or vapor cavity located within the tissue. The method continues by generating shock waves in the tissue to induce a lesion in the tissue at the target site. The method additionally includes characterizing the lesion based on a degree of at least one of a mechanical or thermal ablation of the tissue.

  1. O/W nano-emulsion formation using an isothermal low-energy emulsification method in a mixture of polyglycerol polyricinoleate and hexaglycerol monolaurate with glycerol system.

    PubMed

    Wakisaka, Satoshi; Nishimura, Takahisa; Gohtani, Shoichi

    2015-01-01

    We investigated how phase behavior changes by replacing water with glycerol in water/mixture of polyglycerol polyricinoleate (PGPR) and hexaglycerol monolaurate (HGML) /vegetable oil system, and studied the effect of glycerol on o/w nano-emulsion formation using an isothermal low-energy method. In the phase behavior study, the liquid crystalline phase (Lc) + the sponge phase (L3) expanded toward lower surfactant concentration when water was replaced with glycerol in a system containing surfactant HLP (a mixture of PGPR and HGML). O/W nano-emulsions were formed by emulsification of samples in a region of Lc + L3. In the glycerol/surfactant HLP/vegetable oil system, replacing water with glycerol was responsible for the expansion of a region containing Lc + L3 toward lower surfactant concentration, and as a result, in the glycerol/surfactant HLP/vegetable oil system, the region where o/w nano-emulsions or o/w emulsions could be prepared using an isothermal low-energy emulsification method was wide, and the droplet diameter of the prepared o/w emulsions was also smaller than that in the water/surfactant HLP/vegetable oil system. Therefore, glycerol was confirmed to facilitate the preparation of nano-emulsions from a system of surfactant HLP. Moreover, in this study, we could prepare o/w nano-emulsions with a simple one-step addition of water at room temperature without using a stirrer. Thus, the present technique is highly valuable for applications in several industries.

  2. Soluble non-starch polysaccharides derived from complex food matrices do not increase average lipid droplet size during gastric lipid emulsification in rats.

    PubMed

    Fillery-Travis, A J; Gee, J M; Waldron, K W; Robins, M M; Johnson, I T

    1997-11-01

    The creation of a finely dispersed lipid emulsion is essential for efficient hydrolysis of dietary triglycerides. The effectiveness of emulsification within the stomach depends upon the shear force generated by gastric motility and the concentration of emulsifiers present in the gastric contents. Other dietary constituents can modify these factors, and previous studies have suggested that the presence of soluble non-starch polysaccharides (NSP) during digestion might increase the average size of intraluminal emulsion droplets. In the present study, we developed a new technique for the isolation and analysis of intraluminal lipid emulsions by optical diffraction analysis. The method was applied to rats fed powdered semipurified diets that were free of all NSP or supplemented with insoluble cellulose, guar gum, or NSP derived from apple, carrot or rolled oats. Cellulose had no significant effect on emulsion size, and there was no evidence that the average sizes of lipid droplets in the gastric fundus or antrum were higher than control values in rats fed diets supplemented with any source of soluble NSP. In the groups fed oats and cooked carrot NSP, the mean droplet diameters approached half the values for diets free of NSP or containing insoluble cellulose. The difference between rats fed NSP from cooked carrot and those fed cellulose was significant in the proximal stomach (P < 0.05), and that between rats fed raw oats and rats fed cellulose was significant in the distal stomach (P < 0.05). Soluble dietary fiber does not inhibit lipid or cholesterol absorption via any inhibition of lipid emulsification.

  3. Solid Phase Microextraction and Related Techniques for Drugs in Biological Samples

    PubMed Central

    Moein, Mohammad Mahdi; Said, Rana; Bassyouni, Fatma

    2014-01-01

    In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from one side, toward automatization and online coupling of sample preparation units. The primary objective of this review is to present the recent developments in microextraction sample preparation methods for analysis of drugs in biological fluids. Microextraction techniques allow for less consumption of solvent, reagents, and packing materials, and small sample volumes can be used. In this review the use of solid phase microextraction (SPME), microextraction in packed sorbent (MEPS), and stir-bar sorbtive extraction (SBSE) in drug analysis will be discussed. In addition, the use of new sorbents such as monoliths and molecularly imprinted polymers will be presented. PMID:24688797

  4. Sol-gel microextraction phases for sample preconcentration in chromatographic analysis.

    PubMed

    Segro, Scott S; Tran, Minh Phuong; Kesani, Sheshanka; Alhendal, Abdullah; Turner, Erica B

    2010-10-01

    Sol-gel technology provides a simple and reliable method for solid-phase microextraction (SPME) fiber preparation through in situ creation of surface-bonded organic-inorganic hybrid coatings characterized by enhanced thermal stability and solvent-resistance properties that are important for the coupling of SPME with GC and HPLC, respectively. The sol-gel coating technology has led to the development of an extensive array of sol-gel sorbent coatings for SPME. In this article, sol-gel microextraction coatings are reviewed, with particular attention on their synthesis, characterization, and applications in conjunction with GC and HPLC analyses. In addition, the development of sol-gel-coated stir bars, their inherent advantages, and applications are discussed. Next, the development and applications of sol-gel capillary microextraction (CME) in hyphenation with GC and HPLC is extensively reviewed. The newly emerging germania- and titania-based sol-gel microextraction phases look promising, especially in terms of pH and hot solvent stability. Finally, sol-gel monolithic beds for CME are reviewed. Such monolithic beds are in a position to greatly improve the extracting capabilities and enhanced sensitivity in CME.

  5. Determination of Plant Volatiles Using Solid Phase Microextraction GC-MS

    ERIC Educational Resources Information Center

    Van Bramer, Scott; Goodrich, Katherine R.

    2015-01-01

    This experiment combines analytical techniques of solid phase microextraction and gas chromatography-mass spectrometry with easily relatable and accessible plant volatile chemistry (floral and vegetative scents of local/available plants). The biosynthesis and structure of these chemicals are of interest in the areas of organic chemistry,…

  6. Headspace analysis of polar organic compounds in biological matrixes using solid phase microextraction (SPME)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analysis of biological fluids and waste material is difficult and tedious given the sample matrix. A rapid automated method for the determination of volatile fatty acids and phenolic and indole compounds was developed using a multipurpose sampler (MPS) with solid phase microextraction (SPME) and GC-...

  7. SOLID PHASE MICROEXTRACTION FOR TRACE LEVEL ANALYSIS OF DISINFECTION BY-PRODUCTS

    EPA Science Inventory

    This presentation focuses on the development of a solid-phase microextraction (SPME)-gas chromatography (GC)/ion trap mass spectrometry (MS) method for the analysis of semivolatile disinfection by-products (DBPs) in drinking water in the low ug/L range. These DBPs were selected ...

  8. Solid-phase microextraction of hydrocarbons from water in a centrifuge

    NASA Astrophysics Data System (ADS)

    Ryabov, A. Yu.; Chuikin, A. V.; Velikov, A. A.

    2016-06-01

    The results of our study of solid-phase microextraction of substances using a centrifuge for determining the microquantities of hydrocarbon impurities in water are presented. The cartridge diameter, sorbent mass, and solvent volume were shown to affect the percent extraction of substances and the analytical signal intensity. The relationship between the cartridge geometry, the sorbent mass, and the solvent volume was considered.

  9. Comparison of two ultrasound-enhanced microextractions combined with HPLC for determining acaricides in water.

    PubMed

    Peng, Bing; Yang, Xiaoling; Zhang, Jiaheng; Du, Fengpei; Zhou, Wenfeng; Gao, Haixiang; Lu, Runhua

    2013-07-01

    An ultrasound-enhanced in situ solvent formation microextraction has been developed first time and compared with ultrasound-enhanced ionic-liquid-assisted dispersive liquid-liquid microextraction for the HPLC analysis of acaricides in environmental water samples. A ionic liquid ([C8MIM][PF6]) was used as the green extraction solvent through two pathways. The experimental parameters, such as the type and volume of both of the extraction solvent disperser solvent, ultrasonication time, and salt addition, were investigated and optimized. The analytical performance using the optimized conditions proved the feasibility of the developed methods for the quantitation of trace levels of acaricides by obtaining limits of detection that range from 0.54 to 3.68 μg/L. The in situ solvent formation microextraction method possesses more positive characteristics than the ionic-liquid-assisted dispersive liquid-liquid microextraction method (except for spirodiclofen determination) when comparing the validation parameters. Both methods were successfully applied to determining acaricides in real water samples.

  10. Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid - liquid microextraction cleanup

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A rapid luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile-2.5% trifluoroacetic acid-NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally de...

  11. Vortex-assisted liquid-liquid-liquid microextraction (VALLLME) technique: A new microextraction approach for direct liquid chromatography and capillary electrophoresis analysis.

    PubMed

    Makahleh, Ahmad; Yap, Hui Fang; Saad, Bahruddin

    2015-10-01

    A new, rapid and sensitive microextraction technique named vortex-assisted liquid-liquid-liquid microextraction (VALLLME) is proposed. The complete extraction process involves two steps. First, a vortex-assisted liquid-liquid microextraction (VALLME) procedure was used to extract the analytes from a relatively large volume of sample (donor phase) to a small volume of organic solvent (intermediate phase). Next, a micro-vortex-assisted liquid-liquid extraction (µ-VALLE) was used to extract the target analytes from the intermediate phase to a smaller volume of aqueous solution (acceptor phase). The final extract (acceptor phase) can be directly injected into the high performance liquid chromatography or capillary electrophoresis units without any further treatments. The selection of the intermediate phase and the manipulation of pH are key parameters that ensure good extraction efficiency of the technique. The proposed technique has been successfully applied for the determination of carvedilol (used as model analyte) in biological fluid samples. The optimum extraction conditions were: toluene as intermediate phase (150 μL); pH of the donor phase, 9.5; vortex time of the VALLME, 45 s (maximum speed, 2500 rpm); 0.1M HCl (15 μL) as acceptor phase; vortexing time of the µ-VALLME, 75 s (maximum stirring speed, 2500 rpm) and salt concentration in the donor phase, 5% (w/v). Under these conditions, enrichment factors of 51- and 418-fold for VALLME step and VALLLME procedure, respectively, were achieved.

  12. Comparison of continuous-flow microextraction and static liquid-phase microextraction for the determination of p-toluidine in Chlamydomonas reinhardtii.

    PubMed

    Liu, Xiujuan; Chen, Xiaowen; Yang, Shao; Wang, Xuedong

    2007-10-01

    In this study, two microextraction methods, viz. continuous-flow microextraction (CFME) and static liquid-phase microextraction (s-LPME), were optimized and compared for the determination of p-toluidine in water and Chlamydomonas reinhardtii samples. The calibration curve for p-toluidine was linear in the concentration range of 0.01-5 microg/mL, and the squared regression coefficients (r(2)) for the lines were up to 0.999 for both CFME and s-LPME treatments. Detection limits in CFME and s-LPME were 8.2 ng/mL and 4.9 ng/mL, based on a signal-to-noise (S/N) ratio of 3, respectively. The precision was tested, in five replicates, by analysis of a 100-ng/mL standard solution of p-toluidine and the relative standard deviations were 5.43 and 3.08% for CFME and s-LPME, respectively. The concentration factors were 5.5 and 14.4 for CFME and s-LPME, respectively. s-LPME has a higher extraction efficiency, lower detection limit, and higher concentration factor than that of CFME. Additionally, the s-LPME method is precise and reproducible, and requires only a 3.0-microL microdrop of extraction solvent. Therefore, this procedure is more convenient in use, and viable for qualitative and quantitative analysis of p-toluidine in water and biota samples.

  13. Simultaneous sampling and analysis of indoor air infested with Cimex lectularius L. (Hemiptera: Cimicidae) by solid phase microextraction, thin film microextraction and needle trap device.

    PubMed

    Eom, In-Yong; Risticevic, Sanja; Pawliszyn, Janusz

    2012-02-24

    Air in a room infested by Cimex lectularius L. (Hemiptera: Cimicidae) was sampled simultaneously by three different sampling devices including solid phase microextraction (SPME) fiber coatings, thin film microextraction (TFME) devices, and needle trap devices (NTDs) and then analyzed by gas chromatography-mass spectrometry (GC-MS). The main focus of this study was to fully characterize indoor air by identifying compounds extracted by three different microextraction formats and, therefore, perform both the device comparison and more complete characterization of C. lectularius pheromone. The NTD technique was capable of extracting both (E)-2-hexenal and (E)-2-octenal, which were previously identified as alarm pheromones of bedbugs, and superior NTD recoveries for these two components allowed reliable identification based on mass spectral library searching and linear temperature programmed retention index (LTPRI) technique. While the use of DVB/CAR/PDMS SPME fiber coatings provided complementary sample fingerprinting and profiling results, TFME sampling devices provided discriminative extraction coverage toward highly volatile analytes. In addition to two alarm pheromones, relative abundances of all other analytes were recorded for all three devices and aligned across all examined samples, namely, highly infested area, less infested area, and control samples which were characterized by different bedbug populations. The results presented in the current study illustrate comprehensive characterization of infested indoor air samples through the use of three different non-invasive SPME formats and identification of novel components comprising C. lectularius pheromone, therefore, promising future alternatives for use of potential synthetic pheromones for detection of infestations.

  14. Preparation of a graphene-based magnetic nanocomposite for the extraction of carbamate pesticides from environmental water samples.

    PubMed

    Wu, Qiuhua; Zhao, Guangying; Feng, Cheng; Wang, Chun; Wang, Zhi

    2011-11-04

    A graphene-based magnetic nanocomposite was synthesized and used for the first time as an effective adsorbent for the preconcentration of the five carbamate pesticides (metolcarb, carbofuran, pirimicarb, isoprocarb and diethofencarb) in environmental water samples prior to high performance liquid chromatography-diode array detection. The properties of the magnetic nanocomposite were characterized by scanning electron microscopy and X-ray diffraction. This novel graphene-based magnetic nanocomposite showed great adsorptive ability towards the analytes. The method, which takes the advantages of both nanoparticle adsorption and magnetic phase separation from the sample solution, could avoid some of the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies have been investigated. Under the optimum conditions, the enrichment factors of the method for the analytes were in the range from 474 to 868. A linear response was achieved in the concentration range of 0.1-50 ng mL(-1). The limits of detection of the method at a signal to noise ratio of 3 for the pesticides were 0.02-0.04 ng mL(-1). Compared with the dispersive liquid-liquid microextraction and the ultrasound-assisted surfactant-enhanced emulsification microextraction, much higher enrichment factors and sensitivities were achieved with the developed method. The method has been successfully applied for the determination of the carbamate pesticides in environmental water samples.

  15. Capillary microextraction: A new method for sampling methamphetamine vapour.

    PubMed

    Nair, M V; Miskelly, G M

    2016-11-01

    Clandestine laboratories pose a serious health risk to first responders, investigators, decontamination companies, and the public who may be inadvertently exposed to methamphetamine and other chemicals used in its manufacture. Therefore there is an urgent need for reliable methods to detect and measure methamphetamine at such sites. The most common method for determining methamphetamine contamination at former clandestine laboratory sites is selected surface wipe sampling, followed by analysis with gas chromatography-mass spectrometry (GC-MS). We are investigating the use of sampling for methamphetamine vapour to complement such wipe sampling. In this study, we report the use of capillary microextraction (CME) devices for sampling airborne methamphetamine, and compare their sampling efficiency with a previously reported dynamic SPME method. The CME devices consisted of PDMS-coated glass filter strips inside a glass tube. The devices were used to dynamically sample methamphetamine vapour in the range of 0.42-4.2μgm(-3), generated by a custom-built vapour dosing system, for 1-15min, and methamphetamine was analysed using a GC-MS fitted with a ChromatoProbe thermal desorption unit. The devices showed good reproducibility (RSD<15%), and a curvilinear pre-equilibrium relationship between sampling times and peak area, which can be utilised for calibration. Under identical sampling conditions, the CME devices were approximately 30 times more sensitive than the dynamic SPME method. The CME devices could be stored for up to 3days after sampling prior to analysis. Consecutive sampling of methamphetamine and its isotopic substitute, d-9 methamphetamine showed no competitive displacement. This suggests that CME devices, pre-loaded with an internal standard, could be a feasible method for sampling airborne methamphetamine at former clandestine laboratories.

  16. Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

    PubMed

    Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

    2016-02-02

    We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested

  17. Application of polyurethane-based devices as sorption-desorption phases for microextraction analysis - The all-in-one microextraction concept.

    PubMed

    Mourão, M P B; Silva, I; Almeida, C; Neng, N R; Nogueira, J M F

    2017-02-17

    In this work, polyurethane-based (PU) devices having cylindrical geometry soaked with suitable organic solvents are proposed for microextraction analysis. This novel analytical approach (PU microextraction; PUμE) operates under the floating sampling technology for extraction, followed by mechanical compression using a manual syringe for back-extraction. To test the performance of the PUμE method, two series of priority contaminants were used as model compounds (group #1: metalaxyl-M, penconazole and tebuconazole; group #2: atrazine, terbuthylazine, alachlor and benzo[a]pyrene) and extracted from aqueous samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. The preparation of the PUμE devices and the device handling procedures are described. Also, the optimization experiments as well as the application of the new method to real matrices are discussed. Assays performed on 25mL water samples spiked at trace levels yielded average recoveries ranging from (50.1±6.7) % to (93.3±1.6) %, under optimized experimental conditions. The analytical performance showed good detection limits (0.01-0.50μg/L) and linear dynamic ranges (0.1-50.0μg/L) with acceptable determination coefficients (r(2)>0.9937). Excellent repeatability was also achieved in both intraday (RSD<3.5%) and inter-day (RSD<7.0%) experiments. With standard addition quantification, the proposed analytical approach revealed good sensitivity and selectivity at trace levels with absence of matrix effects for environmental water and wine samples. The PUμE technique is simple, cost-effective and very easy to apply, using an all-in-one microextraction concept.

  18. Determination of aromatic amines from textiles using dispersive liquid-liquid microextraction.

    PubMed

    Yang, Lu; Yiwei, Wang; Caiying, Lou; Yan, Zhu

    2013-03-01

    A dispersive liquid-liquid microextraction procedure coupled with GC-MS is described for preconcentration and determination of banned aromatic amines from textile samples. Experimental conditions affecting the microextraction procedure were optimized. A mixture of 30 μL chlorobenzene (extraction solvent) and 800 μL ACN (disperser solvent), 5 min extraction time, and 5 mL aqueous sample volume were chosen for the best extraction efficiency by the proposed procedure. Satisfactory linearity (with correlation coefficients >0.9962) and repeatability (<9.78%) were obtained for all 20 aromatic amines; detection limits attained were much lower than the standardized liquid-liquid method. The proposed method has advantages of being quicker and easier to operate, and lower consumption of organic solvent.

  19. Application of solvent microextraction to the analysis of nitroaromatic explosives in water samples.

    PubMed

    Psillakis, E; Kalogerakis, N

    2001-01-12

    The application of solvent microextraction to the analysis of nitroaromatic explosives is presented. Extraction of 11 nitroaromatics was achieved by suspending 1 microl of organic solvent to the tip of a microsyringe in a stirred aqueous solution. Parameters such as extraction solvent, stirring rate, salt concentration and sampling time were studied and optimized. The limits of detection using bench-top quadrupole mass spectrometry and short extraction times (15 min) were found to be between 0.08 and 1.3 microg/l and the relative standard deviations ranged between 4.3 and 9.8%. Although precision and accuracy of quantification of the method are still needed, solvent microextraction proved to be a fast, simple and inexpensive tool for preconcentration and matrix isolation of nitroaromatics on a microscale.

  20. Solventless determination of caffeine in beverages using solid-phase microextraction with fused-silica fibers.

    PubMed

    Hawthorne, S B; Miller, D J; Pawliszyn, J; Arthur, C L

    1992-06-19

    Caffeine concentrations in beverages were determined using a simple and rapid method based on microextraction of caffeine onto the surface of a fused-silica fiber. The uncoated fiber was dipped into the beverage sample for 5 min after the addition of isotopically labeled (trimethyl 13C)caffeine. The adsorbed caffeine was then thermally desorbed in a conventional split/splitless injection port, and the concentration of caffeine was determined using gas chromatography with mass spectrometric detection. Quantitative reproducibilities were ca. 5% (relative standard deviation) and the entire scheme including sample preparation and gas chromatographic analysis was completed in ca. 15 min per sample. The potential of the microextraction technique for the analysis of flavor and fragrance compounds in non-caffeinated beverages is also demonstrated. Since no solvents or class-fractionation steps are required, the method has good potential for automation.

  1. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review.

    PubMed

    de la Calle, Inmaculada; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2016-09-14

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included.

  2. On-line extraction and determination of two herbicides: comparison between two modes of three-phase hollow fiber microextraction.

    PubMed

    Tajik, Mohammad; Yamini, Yadollah; Esrafili, Ali; Ebrahimpour, Behnam

    2015-02-01

    Two different modes of three-phase hollow fiber liquid-phase microextraction were studied for the extraction of two herbicides, bensulfuron-methyl and linuron. In these two modes, the acceptor phases in the lumen of the hollow fiber were aqueous and organic solvents. The extraction and determination were performed using an automated hollow fiber microextraction instrument followed by high-performance liquid chromatography. For both three-phase hollow fiber liquid-phase microextraction modes, the effect of the main parameters on the extraction efficiency were investigated and optimized by central composite design. Under optimal conditions, both modes showed good linearity and repeatability, but the three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents has a better extraction efficiency and figures of merit. The calibration curves for three-phase hollow fiber liquid-phase microextraction with an organic acceptor phase were linear in the range of 0.3-200 and 0.1-150 μg/L and the limits of detection were 0.1 and 0.06 μg/L for bensulfuron-methyl and linuron, respectively. For the conventional three-phase hollow fiber liquid-phase microextraction, the calibration curves were linear in the range of 3.0-250 and 15-400 μg/L and LODs were 1.0 and 5.0 μg/L for bensulfuron-methyl and linuron, respectively. The real sample analysis was carried out by three-phase hollow fiber liquid phase microextraction based on two immiscible organic solvents because of its more favorable characteristics.

  3. Microextraction versus exhaustive extraction approaches for simultaneous analysis of compounds in wide range of polarity.

    PubMed

    Mirnaghi, Fatemeh S; Goryński, Krzysztof; Rodriguez-Lafuente, Angel; Boyacı, Ezel; Bojko, Barbara; Pawliszyn, Janusz

    2013-11-05

    This article discusses comparison of microextraction versus exhaustive extraction approaches for simultaneous extraction of compounds in wide range of polarity at low and high volumes of sample by comparing solid phase extraction (SPE) and solid phase microextraction (SPME). Here, both systems are discussed theoretically and evaluated based on experimental data. Experimental comparisons were conducted in terms of extraction recovery, sensitivity, and selectivity for the extraction of doping agent compounds (logP: 0.14-4.98), using C18 as the extraction phase. The extraction recovery of both systems was studied at different volumes of phosphate buffered saline (PBS). The distribution constant of SPME in thin-film geometry (i.e., thin-film microextraction/TFME) as well as the retention factor and breakthrough volume for the SPE system were evaluated for the simultaneous extraction of polar and non-polar compounds. Using 1 mL of sample, the extraction recovery and sensitivity of the SPE system (100 mg sorbent) was comparable with that of TFME format of SPME (15 mg sorbent) for all analytes, with the exception of most polar compounds, due to the smaller amount of the extraction phase in SPME. Breakthrough in the SPE system was observed for more polar compounds in a 25 mL sample; however, this situation did not affect the quantitation of TFME, as this technique operates in equilibrium mode. Experimental values for breakthrough volume were in good match with the calculated theoretical values. Results indicate that the microextraction approach is more suitable for untargeted determinations, where the breakthrough volume cannot be determined prior to the experiment. In addition, when both methods are at optimum conditions, findings suggest that, despite the smaller volume of the extraction phase in TFME, the sensitivity of TFME can exceed that of SPE for samples where the target analytes vary substantially in polarity.

  4. Application of solid-phase microextraction to the analysis of volatile compounds in virgin olive oils.

    PubMed

    Jiménez, A; Beltrán, G; Aguilera, M P

    2004-03-05

    Solid-phase microextraction was used as a technique for headspace sampling of extra virgin olive oil and virgin olive oil samples with different off-flavours. A 100 microm coated polydimethylsiloxane fiber was used to extract volatile aldehydes, the sampling temperature was 45 degrees C and the fiber has been exposed to the headspace for 15 min. Nonanal and 2-decenal were present in all the olive oils with extraction off-flavours but were not in extra virgin olive oil sample.

  5. Sorbent coated glass wool fabric as a thin film microextraction device.

    PubMed

    Riazi Kermani, Farhad; Pawliszyn, Janusz

    2012-11-06

    A new approach for thin film microextraction (TFME) with mixed-phase sorptive coating is presented. Carboxen/polydimethylsiloxane (CAR/PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) TFME samplers were prepared using spin coating and glass wool fabric mesh as substrate. The samplers were easily tailored in size and shape by cutting tools. Good durability and flat-shape stability were observed during extraction, stirring in water, and thermal desorption. The latter characteristic obviates the need for an extra framed holder for rapid TFME and makes the samplers more robust and easier to deploy. The samplers combine the advantages of adsorptive solid-phase microextraction (SPME) and TFME, including one-step solvent-free extraction and preconcentration, direct thermal desorption, and enhanced sensitivity without sacrificing analysis time due to thin film geometry. The analytical performance of these new devices was demonstrated using water samples spiked with N-nitrosamines (NAs) as model compounds. Over an order of magnitude enhancement of extraction efficiencies was obtained for the model compounds compared with the SPME fibers of similar coatings and PDMS thin film membrane. The results of this study indicate that these novel thin film devices are promising for rapid and efficient microextraction of polar analytes in water.

  6. Spectroscopic analysis of bosentan in biological samples after a liquid-liquid microextraction

    PubMed Central

    Sajedi-Amin, Sanaz; Assadpour-Zeynali, Karim; Panahi-Azar, Vahid; Kebriaeezadeh, Abbas; Khoubnasabjafari, Maryam; Ansarin, Khalil; Jouyban-Gharamaleki, Vahid; Jouyban, Abolghasem

    2015-01-01

    Introduction:Microextraction processes with UV-Vis measurement have been developed and validated for analysis of bosentan in biological samples. Methods:In this work, liquid–liquid microextraction procedures (DLLME & USAEME) were employed for cleanup, pre-concentration, and determination of bosentan in biological samples by UV-Vis spectroscopy at 270 nm. The method was validated and applied to the determination of bosentan in spiked serum, exhaled breath condensate and urine samples. Results:Various experimental factors including type of extraction and dispersive solvents and their volumes, pH, sonication time and centrifuging time were investigated. Under the optimum conditions, the method was linear in the range of 1.0–5.0 μg.mL-1, with coefficient of determination (R2) of > 0.998. The limit of detection (LOD) was 0.07 mg.L-1. Recovery of the target analyte in biological samples was 106.2%. The method could be easily applied for higher concentration of bosentan and needs more improvement for application in the pharmacokinetic investigations where more sensitive methods are required. Conclusion:A simple, low cost, precise and accurate spectrophotometric analysis of bosentan in biological samples after liquid-liquid microextraction were developed and validated for routine analyses. PMID:26929923

  7. Hollow-fiber-supported liquid membrane microextraction of amlodipine and atorvastatin.

    PubMed

    Panahi, Homayon Ahmad; Chabouk, Monireh; Ejlali, Maryam

    2014-08-01

    A simple, environmentally friendly, and efficient method, based on hollow-fiber-supported liquid membrane microextraction, followed by high-performance liquid chromatography has been developed for the extraction and determination of amlodipine (AML) and atorvastatin (ATO) in water and urine samples. The AML in two-phase hollow-fiber liquid microextraction is extracted from 24.0 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the ATO in three-phase hollow-fiber liquid microextraction is extracted from aqueous donor phase to organic phase and then back-extracted to the aqueous acceptor phase, which can be directly injected into the high-performance liquid chromatograph for analysis. The preconcentration factors in a range of 34-135 were obtained under the optimum conditions. The calibration curves were linear (R(2) ≥ 0.990) in the concentration range of 2.0-200 μg/L for AML and 5.0-200 μg/L for ATO. The limits of detection for AML and ATO were 0.5 and 2.0 μg/L, respectively. Tap water and human urine samples were successfully analyzed for the existence of AML and ATO using the proposed methods.

  8. Application of vesicular coacervate phase for microextraction based on solidification of floating drop.

    PubMed

    Moradi, Morteza; Yamini, Yadollah

    2012-03-16

    A new, efficient and environmentally friendly method for the analysis of parabens as model compounds was developed using solidified floating vesicular coacervative drop microextraction (SFVCDME). A supramolecular solvent consisting of vesicles of decanoic acid in the nano- and microscale regimes was firstly used as the solvent in solidification of floating drop microextraction. The solvent was produced from the coacervation of decanoic acid aqueous vesicles in the presence of tetrabutylammonium (Bu(4)N(+)). Methylparaben (MP), ethylparaben (EP), and propylparaben (PP) were extracted on the basis of hydrophobic and π-cation interactions and the formation of hydrogen bonds. Microliter volume of vesicular coacervative droplet was delivered to the surface of the aqueous sample, and the sample was stirred for a desired time. The sample vial was cooled by immersing it into an ice bath for 3 min. The solidified solvent was transferred into a suitable vial and melted immediately. Twenty microliter of the vesicular coacervative solvent was directly injected to high-performance liquid chromatography-ultraviolet detection, with no need to dilution or solvent evaporation. Several parameters affecting the microextraction efficiency including sample temperature, stirring rate, pH, salt effect, volume of the solvent and extraction time were investigated and optimized. Under optimum conditions, preconcentration factors and relative recoveries of the studied compounds were obtained in the range of 81-174 and 91-108%, respectively; and the performance of the method was comparable with that of solid-phase extraction as the reference method.

  9. Dynamic three-phase microextraction as a sample preparation technique prior to capillary electrophoresis.

    PubMed

    Hou, Li; Lee, Hian Kee

    2003-06-01

    Dynamic three-phase (liquid-liquid-liquid) microextraction was developed for capillary electrophoresis. Four aromatic amines as model compounds were extracted from 4-mL aqueous samples adjusted to basic condition (donor solution) through a small volume of organic solvent impregnated in a hollow fiber, which was held by the needle of a conventional syringe, and retracted into a 5-microL acidic acceptor solution inside the syringe. A renewable organic film and aqueous sample plug were formed inside the hollow fiber with the repeated movement of the syringe plunger enabled by a programmable syringe pump. This is believed to be the first reported instance of a semiautomated dynamic liquid-liquid-liquid microextraction (LLLME) procedure. Following this microextraction, the 5-microL acceptor solution was analyzed by capillary zone electrophoresis (CE). This new technique provided approximately 140-fold enrichment in 20 min. Utilizing 4-chloroaniline as internal standard, dynamic LLLME could provide good reproducibility (<4.0%). In addition, this method allowed the direct transfer of extracted analytes to a CE system for analysis.

  10. Analysis of Whiskey by Dispersive Liquid-Liquid Microextraction Coupled with Gas Chromatography/Mass Spectrometry: An Upper Division Analytical Chemistry Experiment Guided by Green Chemistry

    ERIC Educational Resources Information Center

    Owens, Janel E.; Zimmerman, Laura B.; Gardner, Michael A.; Lowe, Luis E.

    2016-01-01

    Analysis of whiskey samples prepared by a green microextraction technique, dispersive liquid-liquid microextraction (DLLME), before analysis by a qualitative gas chromatography-mass spectrometry (GC/MS) method, is described as a laboratory experiment for an upper division instrumental methods of analysis laboratory course. Here, aroma compounds in…

  11. A modified spontaneous emulsification solvent diffusion method for the preparation of curcumin-loaded PLGA nanoparticles with enhanced in vitro anti-tumor activity

    NASA Astrophysics Data System (ADS)

    Chen, Cen; Yang, Wei; Wang, Dan-Tong; Chen, Chao-Long; Zhuang, Qing-Ye; Kong, Xiang-Dong

    2014-12-01

    To improve the anti-tumor activity of hydrophobic drug curcumin, we prepared curcumin-loaded PLGA nanoparticles (PLGA-Cur NPs) through a modified spontaneous emulsification solvent diffusion (modified-SESD) method. The influence of main preparation parameters was investigated, such as the volume ratio of binary organic solvents and the concentration of surfactant. Results indicated that the synthesized regular spherical PLGA NPs with the average diameter of 189.7 nm exhibited relatively higher yield (58.9%), drug loading (11.0% (w/w)) and encapsulation efficiency (33.5%), and also a controllable drug release profile. In order to evaluate the in vitro cytotoxicity of the prepared NPs, MTT assay was conducted, and results showed that the NPs could effectively inhibit HL60 and HepG2 cells with lower IC50 values compared with free curcumin. Furthermore, confocal microscopy together with flow cytometry analysis proved the enhanced apoptosis-inducing ability of PLGA-Cur NPs. Polymeric NP formulations are potential to be used for hydrophobic drug delivery systems in cancer therapy.

  12. Graphene-Enveloped Poly(N-vinylcarbazole)/Sulfur Composites with Improved Performances for Lithium-Sulfur Batteries by A Simple Vibrating-Emulsification Method.

    PubMed

    Qu, Guoxing; Cheng, Jianli; Li, Xiaodong; Huang, Ling; Ni, Wei; Wang, Zhiyu; Wang, Bin

    2015-08-05

    We prepared the Poly(N-vinylcarbazole)/sulfur@reduced graphene oxide (PVK/S@RGO) composites via a facile vibrating-emulsification synthesis method, which consist of the composites cores of large sulfur particles integrated into PVK conductive network and the conducting shell of reduced graphene oxide sheets. The PVK in the composites plays multiple roles in different processes. In preparation processes, PVK functions as dispersants to prevent sulfur particles from aggregating into excessively large size. And in the cycling test, PVK could play as additional electroactive binders and barriers to reinforce the electrode stability, accommodate volume change and reduce polysulfides shuttling. The resulting PVK/S@RGO composites containing 71 wt % sulfur exhibit excellent cycling performance and rate properties with a high discharge capacity of 843.5 mA h g(-1) and a charge capacity retention of 77% (only 0.07% capacity degradation per cycle) from 20th to 400th at 1 C, corresponding to an average Coulombic efficiency of over 94%.

  13. Vortex-assisted emulsification semimicroextraction for the analytical control of restricted ingredients in cosmetic products: determination of bronopol by liquid chromatography.

    PubMed

    Miralles, Pablo; Bellver, Raquel; Chisvert, Alberto; Salvador, Amparo

    2016-03-01

    Vortex-assisted emulsification semimicroextraction is proposed as a one-step solution-extraction procedure for sample preparation in cosmetic products. The procedure allows rapid preparation based on dispersion of the sample in a mixture of 1 mL of n-hexane and 0.5 mL of ethanol, followed by the addition of 0.5 mL of water and centrifugation to obtain two separated phases. This procedure provides good sample clean-up with minimum dilution and is very useful for the determination of ingredients with restricted concentrations, such as bronopol. The procedure was applied to the determination of bronopol by liquid chromatography with UV detection. The best chromatographic separation was obtained by using a C18 column set at 40 °C and performing a stepwise elution with a mixture of ethanol/aqueous 1 % acetic acid solution as mobile phase pumped at 0.5 mL min(-1). The detection wavelength was set at 250 nm and the total run time required was 12 min. The method was successfully applied to 18 commercial cosmetic samples including creams, shampoos, and bath gels. Good recoveries and repeatability were obtained, with a limit of detection of 0.9 μg mL(-1), which makes the method suitable for the analytical control of cosmetic products. Moreover, it could be considered environmentally friendly, because water, ethanol, and only a low volume of n-hexane are used as solvents.

  14. In vitro biomineralization and bulk characterization of chitosan/hydroxyapatite composite microparticles prepared by emulsification cross-linking method: orthopedic use.

    PubMed

    Maachou, Hamida; Bal, Kheireddine; Bal, Youcef; Chagnes, Alexandre; Cote, Gerard; Aliouche, Djamel

    2012-11-01

    Chitosan/hydroxyapatite composite microparticles were prepared by a solid-in-water-in-oil emulsification cross-linking method. The characteristics and activity in presence of simulated body fluid for 14 and 21 days were investigated. The size distribution, surface morphology, and microstructure of these biomaterials were evaluated. The scanning electron microscopy revealed an aggregate of microparticles with a particle size, ranged from 4 to 10 μm. The deposited calcium phosphate was studied using X-ray diffraction analysis, Fourier transform infrared spectroscopy, and inductively coupled plasma/atomic emission spectroscopy analysis of phosphorus. These results show that the mineral, formed on microparticles, was a mixture of carbonated hydroxyapatite and calcite. Scanning electron microscopy revealed that calcium phosphate crystals growth was in form of rods organized as concentric triangular packets interconnected to each other by junctions. Interaction between chitosan and growing carbonated hydroxyapatite and calcite crystals are responsible for a composite growth into triangular and spherical shapes. The results demonstrated that these microparticles were potential materials for bone repair.

  15. Using procedure of emulsification-lyophilization to form lipid A-incorporating cochleates as an effective oral mucosal vaccine adjuvant-delivery system (VADS).

    PubMed

    Wang, Ning; Wang, Ting; Zhang, Meiling; Chen, Ruonan; Deng, Yihui

    2014-07-01

    Using a procedure of emulsification-lyophilization (PEL), adjuvant lipid A-cochleates (LACs) were prepared as a carrier for model antigen bovine serum albumin (BSA). With phosphatidylserine and lipid A as emulsifiers dissolved in oil phase (O), sucrose and CaCl2 in the inner water phase (W1), and BSA, sucrose and PEG2000 in the outer water phase (W2), the W1/O/W2 emulsions were prepared and subsequently lyophilized to form a dry product which was stable enough to be stored at room temperature. Upon rehydration of the dry products, cochleates formed with a size of 800 nm and antigen association rates of 38%. After vaccination of mice through oral mucosal (o.m.) administration, LACs showed no side effects but induced potent immune responses as evidenced by high levels of IgG in the sera and IgA in the salivary, intestinal and vaginal secretions of mice. In addition, high levels of IgG2a and IFN-γ in the sera or culture supernatants of splenocytes of the immunized mice were also detected. These results revealed that LACs induced a mixed Th1/Th2 response against the loaded antigens. Thus, the LACs prepared by PEL were able to induce both systemic and mucosal immune responses and may act as a potent cold-chain-free oral mucosal vaccine adjuvant delivery system (VADS).

  16. Kinetic stability and cellular uptake of lutein in WPI-stabilised nanoemulsions and emulsions prepared by emulsification and solvent evaporation method.

    PubMed

    Teo, Anges; Lee, Sung Je; Goh, Kelvin K T; Wolber, Frances M

    2017-04-15

    The particle size and lutein encapsulation efficiency of nanoemulsions prepared by emulsification and solvent evaporation method were 68.8±0.3nm and 80.7±0.8%, respectively, whereas they were 147.3±0.6nm and 86.3±0.3% for conventional emulsions. All the emulsions had no change in their particle size during storage (28days at 5, 20 and 40°C) but their lutein content and emulsion colour decreased, especially at 40°C. The lutein emulsions were analysed using MTT assay on the gut enterocyte cell line Caco-2 and they showed no toxicity as the cell viability was more than 80% at 10times or higher dilution after 24h of incubation. However, there was a higher cellular uptake of lutein by Caco-2 cells in nanoemulsions (872.9±88.3pmol/mgprotein) than conventional emulsions (329.5±214.6pmol/mgprotein). The results of this study indicated that nanoemulsions can be used as a delivery system to improve the cellular uptake of lutein.

  17. Comparison between solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HFLPME) for determination of extractables from post-consumer recycled PET into food simulants.

    PubMed

    Oliveira, Éder Costa; Echegoyen, Yolanda; Cruz, Sandra Andrea; Nerin, Cristina

    2014-09-01

    Hollow fiber liquid phase microextraction (HFLPME) and solid phase microextraction (SPME) methods for pre-concentration of contaminants (toluene, benzophenone, tetracosane and chloroform) in food simulants were investigated. For HFLPME 1-heptanol, 2-octanone and dibutyl-ether were studied as extracting solvents. Analysis by gas chromatography coupled to mass spectrometry (GC-MS), flame ionization (GC-FID) and electron capture detectors (GC-ECD) were carried out. In addition, the methods were employed to evaluate the safety in use of a PET material after the recycling process (comprising washing, extrusion and solid state polymerization (SSP)) through extractability studies of the contaminants using 10% (v/v) ethanol in deionized water and 3% (w/v) acetic acid in deionized water as food simulants in different conditions: 10 days at 40°C and 2h at 70°C. The HFLPME preconcentration method provided increased sensitivity when compared to the SPME method and allowed to analyze concentration levels below 10 µg surrogate per kg food simulant. The results of the extractability studies showed considerable reductions after the extrusion and SSP processes and indicated the compliance with regulations for using recycled PET in contact with food.

  18. Development of dispersive liquid-liquid microextraction based on solidification of floating organic drop for the determination of trace nickel.

    PubMed

    Wang, Yukun; Zhang, Jingwen; Zhao, Bin; Du, Xin; Ma, Jingjun; Li, Jingci

    2011-12-01

    A liquid-phase microextraction technique was developed using dispersive liquid-liquid microextraction based on solidification of floating organic drop combined with flame atomic absorption spectrometry, for the extraction and determination of trace amounts of nickel in water samples. Microextraction efficiency factors, such as the type and volume of extraction and dispersive solvents, pH, extraction time, the chelating agent amount, and ionic strength, were investigated and optimized. Under optimum conditions, the calibration graph was linear in the range of 4.23-250 μg L(-1) with a detection limit of 1.27 μg L(-1). The relative standard deviation for ten replicate measurements of 10 and 100 μg L(-1) of nickel were 3.21% and 2.55%, respectively. The proposed method was assessed through the analysis of certified reference water or recovery experiments.

  19. Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

    PubMed

    Yang, Yanqin; Chu, Guohai; Zhou, Guojun; Jiang, Jian; Yuan, Kailong; Pan, Yuanjiang; Song, Zhiyu; Li, Zuguang; Xia, Qian; Lu, Xinbo; Xiao, Weiqiang

    2016-03-01

    An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco.

  20. Single-drop coacervative microextraction of organic compounds prior to liquid chromatography. Theoretical and practical considerations.

    PubMed

    López-Jiménez, Francisco José; Rubio, Soledad; Pérez-Bendito, Dolores

    2008-06-27

    Coacervates made of surfactant aggregates, namely aqueous and reverse micelles and vesicles, were firstly used as solvents in single-drop microextraction (SDME) and proposed for the extraction and concentration of chlorophenols prior to liquid chromatography. The formation of coacervate drops in the needle tip of conventional microsyringes depended on the type of intermolecular forces established between the surfactant headgroups making up the supramolecular aggregates; hydrogen bond interactions were strong enough to permit the formation of spherical drops. Stability of 1-50 microL coacervate drops was achieved by introducing the microsyringe needle tip in a PTFE rod, the end of which had been machined out with a heated flanging-tool to get circular flanges (diameters in the range 3.5-6 mm). The parameters affecting the efficiency of single-drop coacervative microextraction (SDCME) were investigated using vesicular coacervates as a solvent and 2-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) as model analytes. Coacervative microextraction dynamics fit to the general rate equation of liquid-liquid extraction. The effect of variables such as extraction time, drop volume, stirring rate, pH and temperature, on the extraction of chlorophenols was similar to that described for organic solvent drops. Electrolyte concentrations above 0.1 M caused drop instability. Under the optimum conditions, detection limits were in the range 0.1-0.3 microg L(-1). The relative standard deviation was between 4.3 and 5.6 at 20 microg L(-1) spiked level. The method was applied to the determination of the four chlorophenols in wastewater, superficial water from a reservoir and groundwater and the recoveries were in the range 79 and 106% at 5-20 microg L(-1) spiked level.

  1. Novel and simple headspace in-tube microextraction coupled with capillary electrophoresis.

    PubMed

    Lee, Hye Ryeo; Cho, Sung Min; Kim, Jihye; Chung, Doo Soo

    2014-06-13

    In liquid phase microextraction, high enrichment factors can be obtained using an acceptor phase of small volume. By hanging an acceptor drop at the separation capillary tip, single drop microextraction (SDME) can be in-line coupled with capillary electrophoresis (CE). The small surface-to-volume ratio of the drop enables high enrichment factors to be obtained in a short time. One practical issue in SDME is how to keep the drop attached to the capillary stable. Here, we present novel but extremely simple in-tube microextraction (ITME) using the liquid inside the capillary as an acceptor phase, without forming a drop at the capillary tip. As a first example, ITME has been combined with headspace (HS) extraction. Simply by placing a capillary filled with a basic run buffer in the HS above an acidic donor solution, volatile acidic analytes were extracted into the acceptor phase in the capillary. After extraction, electrophoresis of the extracts in the capillary was carried out. Owing to the robust nature of the acceptor phase, the extraction temperature and time ranges of HS-ITME can be extended significantly, compared to HS-SDME. The enrichment factors for chlorophenols in a standard solution were up to 1100 under an optimal HS-ITME condition of 80°C for 15min and the limits of detections (LODs) obtained by monitoring the absorbance at 214nm were about 4nM. The whole procedures of HS-ITME-CE were carried out automatically using built-in programs of a commercial CE instrument.

  2. Direct Mass Spectrometry Analysis of Biofluid Samples Using Slug Flow Microextraction NanoESI**

    PubMed Central

    Ren, Yue; McLuckey, Morgan N.; Liu, Jiangjiang; Ouyang, Zheng

    2015-01-01

    Direct mass spectrometry (MS) analysis of biofluids with simple procedures represents a key step in translation of MS technologies to the clinical and point-of-care applications. The current study reports the development of a single-step method using slug flow microextraction and nanoESI (electrospray ionization) for MS analysis of organic compounds in blood and urine. High sensitivity and quantitation precision have been achieved for analysis of therapeutic and illicit drugs in 5 μL samples. Real-time chemical derivatization has been incorporated for analyzing anabolic steroids. The monitoring of enzymatic functions has also been demonstrated with the cholinesterase in wet blood. PMID:25284028

  3. Selective Stationary Phase for Solid-Phase Microextraction Analysis of Sarin (GB)

    SciTech Connect

    Harvey, Scott; Nelson, D. A.; Wright, Bob W.; Gates, J. W.

    2002-03-02

    A number of critical field applications require monitoring air samples for trace levels of chemical warfare agents. Solid-phase microextraction (SPME) is a convenient format to conduct these analyses. Measurements could be significantly improved if a SPME phase selective for nerve agents were substituted for nonselective polymers typically used (e.g., polydimethylsiloxane). This paper evaluates a novel stationary phase, previously developed for methylphosphonate sensor applications, for use with SPME sampling. The phenol-based polymer, BSP3, was found to offer far higher selectivity toward sarin (GB) than polydimethylsiloxane due to a pronounced affinity toward the target analyte and a lower affinity toward hydrocarbons.

  4. Selective Stationary Phase for Solid-Phase Microextraction Analysis of Sarin (GB)

    SciTech Connect

    Harvey, Scott D.; Nelson, David A.; Wright, Bob W.; Grate, Jay W.

    2002-04-19

    A number of critical field applications require monitoring air samples for trace levels of chemical warfare agents. Solid-phase microextraction (SPME) is a convenient format to conduct these analyses. Measurements could be significantly improved if a SPME phase selective for nerve agents were substituted for nonselective polymers typically used (e.g.,polydimethylsiloxane). This paper evaluates a novel stationary phase, previously developed for methylphosphonate sensor applications, for use with SPME sampling. The phenol-based polymer, BSP3, was found to offer far higher selectivity toward sarin (GB) than polydimethylsiloxane due to a pronounced affinity toward the target analyte and a lower affinity toward hydrocarbons.

  5. Liquid-phase micro-extraction techniques in pesticide residue analysis.

    PubMed

    Lambropoulou, Dimitra A; Albanis, Triantafyllos A

    2007-03-10

    Modern trends in analytical chemistry are towards the simplification and miniaturization of sample preparation, as well as the minimization of organic solvent used. In view of this aspect, several novel micro-extraction techniques are being developed in order to reduce the analysis step, increase the sample throughput and to improve the quality and the sensitivity of analytical methods. One of the emerging techniques in this area is liquid-phase micro-extraction (LPME). It is a miniaturized implementation of conventional liquid/liquid extraction (LLE) in which only microliters of solvents are used instead of several hundred milliliters in LLE. It is quick, inexpensive and can be automated. In the last few years, LPME has been combined with liquid chromatography (LC) and capillary electrophoresis (CE), besides the generally used coupling to gas chromatography (GC), and has been applied to various matrices, including biological, environmental, and food samples. This work is aimed at providing an overview of the major developments of LPME, coupled with chromatography and CE, as reported in the literature. The paper will focus on the application of the technique to different matrices and the aim is to reveal the panorama of opportunities and to try to indicate the potential of LPME in pesticide analysis. A critical review of the first applications to pesticide analyses is presented in the main part of the manuscript. The optimization of LPME as well as advantages and disadvantages are discussed. It is concluded that, because of its high pre-concentration factor, LPME can be introduced with benefit into water analysis for several pesticide groups. In particular, the application of LPME to non-polar pesticides in environmental analysis appears to be promising. However, similar to other micro-extraction techniques, such as solid phase micro-extraction (SPME), serious limitations still remain when analyzing semi-solid and solid environmental, food or biological matrices

  6. Importance of extracting solvent vapor pressure in headspace liquid-phase microextraction.

    PubMed

    Yan, Xue; Yang, Cui; Ren, Chunyan; Li, Donghao

    2008-09-26

    Of the many parameters that affect the enrichment factors in headspace liquid-phase microextraction, in this study, we systematically investigated the influence of the vapor pressure of the extracting solvent. Seven extracting solvents with different vapor pressures were selected and tested. It was found that the vapor pressure of the extracting solvent dramatically affects the enrichment factor and the factor was increasing by decreasing the extracting solvent vapor pressure under given experimental conditions. The result was validated for volatile organic compounds such as polynuclear aromatic hydrocarbons, organochlorine pesticides and polychlorinated biphenyls.

  7. Screening of Brazilian fruit aromas using solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Augusto, F; Valente, A L; dos Santos Tada, E; Rivellino, S R

    2000-03-17

    Manual headspace solid-phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS) was used for the qualitative analysis of the aromas of four native Brazilian fruits: cupuassu (Theobroma grandiflorum, Spreng.), cajá (Spondias lutea. L.), siriguela (Spondias purpurea, L.) and graviola (Anona reticulata, L). Industrialized pulps of these fruits were used as samples, and extractions with SPME fibers coated with polydimethylsiloxane, polyacrylate, Carbowax and Carboxen were carried out. The analytes identified included several alcohols, esters, carbonyl compounds and terpernoids. The highest amounts extracted, evaluated from the sum of peak areas, were achieved using the Carboxen fiber.

  8. Ultrasound-assisted magnetic dispersive solid-phase microextraction: A novel approach for the rapid and efficient microextraction of naproxen and ibuprofen employing experimental design with high-performance liquid chromatography.

    PubMed

    Ghorbani, Mahdi; Chamsaz, Mahmoud; Rounaghi, Gholam Hossein

    2016-03-01

    A simple, rapid, and sensitive method for the determination of naproxen and ibuprofen in complex biological and water matrices (cow milk, human urine, river, and well water samples) has been developed using ultrasound-assisted magnetic dispersive solid-phase microextraction. Magnetic ethylendiamine-functionalized graphene oxide nanocomposite was synthesized and used as a novel adsorbent for the microextraction process and showed great adsorptive ability toward these analytes. Different parameters affecting the microextraction were optimized with the aid of the experimental design approach. A Plackett-Burman screening design was used to study the main variables affecting the microextraction process, and the Box-Behnken optimization design was used to optimize the previously selected variables for extraction of naproxen and ibuprofen. The optimized technique provides good repeatability (relative standard deviations of the intraday precision 3.1 and 3.3, interday precision of 5.6 and 6.1%), linearity (0.1-500 and 0.3-650 ng/mL), low limits of detection (0.03 and 0.1 ng/mL), and a high enrichment factor (168 and 146) for naproxen and ibuprofen, respectively. The proposed method can be successfully applied in routine analysis for determination of naproxen and ibuprofen in cow milk, human urine, and real water samples.

  9. Application of graphene nanoplatelets silica composite, prepared by sol-gel technology, as a novel sorbent in two microextraction techniques.

    PubMed

    Heidari, Mahmoud; Bahrami, Abdolrahman; Ghiasvand, Ali Reza; Shahna, Farshid Ghorbani; Soltanian, Ali Reza; Rafieiemam, Maryam

    2015-12-01

    In this study, the application of a novel nanomaterial composite was investigated in two microextraction techniques of solid-phase microextraction and a needle trap device in a variety of sampling conditions. The optimum sampling temperature and relative humidity were 10°C and 20%, respectively, for both techniques with two sorbents of graphene/silica composite and polydimethyl siloxane. The two microextraction techniques with the proposed sorbent showed recoveries of 95.2 and 94.6% after 7 days. For the needle trap device the optimums desorption time and temperature were 3 min at 290°C and for SPME these measures were 1 and 1.5 min at 240-250°C for the graphene/silica composite and polydimethyl siloxane, respectively. The relative standard division obtained in inter- and intra-day comparative studies were 3.3-14.3 and 5.1-25.4, respectively. For four sample the limit of detection was 0.021-0.25 ng/mL, and the limit of quantitation was 0.08-0.75 ng/mL. The results show that the graphene/silica composite is an appropriate extraction media for both techniques. Combining an appropriate sorbent with microextraction techniques, and using these in conjunction with a sensitive analytical instrument can introduce a strong method for sampling and analysis of occupational and environmental pollutants in air.

  10. Dynamic microwave-assisted extraction combined with continuous-flow microextraction for determination of pesticides in vegetables.

    PubMed

    Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Yu, Cui; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2016-02-01

    A simple, rapid, solventless and cost-effective dynamic microwave-assisted extraction (DMAE) combined with continuous-flow microextraction (CFME) system was firstly assembled and validated for extraction of eight organophosphorus pesticides in vegetables. The method combines the advantages of DMAE and CFME, and extends the application of the single drop microextraction to complex solid samples. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, analytes were first extracted from the vegetables using 3% NaCl solution as extraction solvent, then concentrated into microextraction solvent. After extraction, the microextraction solvent containing the enriched analyte was directly analyzed by GC-MS without any filtration or clean-up process. Several parameters affecting the extraction efficiency were investigated and optimized. Real vegetable samples were analyzed, satisfactory recoveries were obtained in the range of 80.7-106.7%, and relative standard deviations were lower than 8.7%.

  11. Hollow-fiber solvent bar microextraction with gas chromatography and electron capture detection determination of disinfection byproducts in water samples.

    PubMed

    Correa, Liliana; Fiscal, Jhon Alex; Ceballos, Sandra; de la Ossa, Alberto; Taborda, Gonzalo; Nerin, Cristina; Rosero-Moreano, Milton

    2015-09-10

    A liquid-phase microextraction method that uses a hollow-fiber solvent bar microextraction technique was developed by combining gas chromatography with electron capture detection for the analysis of four trihalomethanes (chloroform, dichlorobromomethane, chlorodibromomethane, and bromoform) in drinking water. In the microextraction process, 1-octanol was used as the solvent. The technique operates in a two-phase mode with a 5 min extraction time, a 700 rpm stirring speed, a 30°C extraction temperature, and NaCl concentration of 20%. After microextraction, one edge of the membrane was cut, and 1 μL of solvent was collected from the membrane using a 10 μL syringe. The solvent sample was directly injected into the gas chromatograph. The analytical characteristics of the developed method were as follows: detection limits, 0.017-0.037 ng mL(-1) ; linear working range, 10-900 ng mL(-1) ; recovery, 74 ± 9-91 ± 2; relative standard deviation, 5.7-10.3; and enrichment factor, 330-455. A simple, fast, economic, selective, and efficient method with big possibilities for automation was developed with a potential use to apply with other matrices and analytes.

  12. SCREENING METHOD FOR NITROAROMATIC COMPOUNDS IN WATER BASED ON SOLID-PHASE MICROEXTRACTION AND INFRARED SPECTROSCOPY. (R825343)

    EPA Science Inventory

    A new method is described for determining nitroaromatic compounds in water
    that combines solid-phase microextraction (SPME) and infrared (IR) spectroscopy. In this method, the compounds are extracted from a 250-mL volume of water into a small square (3.2 cm ? 3.2 cm ? 61.2...

  13. PARTITION INFRARED METHOD FOR TOTAL GASOLINE RANGE ORGANICS IN WATER BASED ON SOLID PHASE MICROEXTRACTION. (R825343)

    EPA Science Inventory

    A new method is described for determining total gasoline-range organics
    (TGRO) in water that combines solid-phase microextraction (SPME) and infrared
    (IR) spectroscopy. In this method, the organic compounds are extracted from
    250-mL of water into a small square (3....

  14. Sensitive determination of terazosin in pharmaceutical formulations and biological samples by ionic-liquid microextraction prior to spectrofluorimetry.

    PubMed

    Zeeb, Mohsen; Sadeghi, Mahdi

    2012-01-01

    An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF(6)] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L(-1) and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future.

  15. Sensitive Determination of Terazosin in Pharmaceutical Formulations and Biological Samples by Ionic-Liquid Microextraction Prior to Spectrofluorimetry

    PubMed Central

    Zeeb, Mohsen; Sadeghi, Mahdi

    2012-01-01

    An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF6] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L−1 and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future. PMID:22505920

  16. Rapid screening of oxytetracycline residue in catfish muscle by dispersive liquid-liquid microextraction and europium-sensitized luminescence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxytetracycline (OTC) residue in catfish muscle was screened by dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). After extraction in EDTA, HCl, and acetonitrile, cleanup was carried out by DLLME, and ESL was measured at microgram = 385 nm and wavelength = ...

  17. Liquid phase microextraction and ultratrace determination of cadmium by modified graphite furnace atomic absorption spectrometry.

    PubMed

    Nazari, Saeid

    2009-06-15

    A powerful microextraction technique was used for determination of cadmium in water samples using liquid phase microextraction (LPME) followed by graphite furnace atomic absorption spectrometry (GF-AAS). In a preconcentration step, cadmium was extracted from a 2 ml of its aqueous sample in the pH 7 as 5,7-dibromoquinoline-8-ol (DBQ) complex into a 4 microl drop of benzyl alcohol. After extraction, the micro drop was retracted and directly transferred into a graphite tube modified by [W.Rh.Pd](c). Some effective parameters on extraction and complex formation, such as type and volume of organic solvent, pH, concentration of chelating agent, extraction time and stirring rate were optimized. Under the optimum conditions, the enrichment factor and recovery were 450% and 90%, respectively. The calibration graph was linear in the range of 0.008-1 microg L(-1) with correlation coefficient of 0.9961 under the optimum conditions of the recommended procedure. The detection limit based on the 3Sb criterion was 0.0035 microg L(-1) and relative standard deviation (RSD) for eight replicate measurement of 0.1 microg L(-1) and 0.4 microg L(-1) cadmium was 5.2% and 4.5%, respectively. The characteristic concentration was 0.0032 microg L(-1) equivalent to a characteristic mass of 12.8 fg. In order to evaluate the accuracy and recovery of the presented method the procedure was applied to the analysis of reference materials and seawater.

  18. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil.

    PubMed

    Zygmunt, B; Namiesnik, J

    2001-08-01

    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  19. Carbon nanocones/disks as new coating for solid-phase microextraction.

    PubMed

    Jiménez-Soto, Juan Manuel; Cárdenas, Soledad; Valcárcel, Miguel

    2010-05-14

    In this article, the potential of carbon nanocones/disks as coating for solid-phase microextraction has been evaluated for the first time. The nanostructures were immobilized on a stainless steel needle by means of an organic binder. The fiber coating obtained was ca. 50 microm of thickness and 35 mm in length. The evaluation of the sorbent capacity was carried out through the determination of toluene, ethylbenzene, xylene isomers and styrene in water samples following the headspace sampling modality (15 min, 30 degrees C). The fiber was then transferred to a 10 mL vial which was sealed and heated at 110 degrees C for 15 min in the headspace module of the instrument to achieve the thermal desorption of the analytes. Then 2.5 mL of the headspace generated were injected in the gas chromatograph-mass spectrometer for analytes separation and quantitation. The detection and quantitation limits obtained for 10 mL of sample were 0.15 and 0.5 ng mL(-1) (0.6 and 2 ng mL(-1) for toluene). The optimized procedure was applied to the determination of the selected volatile compounds in waters collected from different locations. The recovery values obtained (average recovery ca. 92%) demonstrated the usefulness of the carbon nanocones/disks as sorbent material in solid-phase microextraction.

  20. Recent developments and future trends in solid phase microextraction techniques towards green analytical chemistry.

    PubMed

    Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

    2013-12-20

    Solid phase microextraction find increasing applications in the sample preparation step before chromatographic determination of analytes in samples with a complex composition. These techniques allow for integrating several operations, such as sample collection, extraction, analyte enrichment above the detection limit of a given measuring instrument and the isolation of analytes from sample matrix. In this work the information about novel methodological and instrumental solutions in relation to different variants of solid phase extraction techniques, solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) and magnetic solid phase extraction (MSPE) is presented, including practical applications of these techniques and a critical discussion about their advantages and disadvantages. The proposed solutions fulfill the requirements resulting from the concept of sustainable development, and specifically from the implementation of green chemistry principles in analytical laboratories. Therefore, particular attention was paid to the description of possible uses of novel, selective stationary phases in extraction techniques, inter alia, polymeric ionic liquids, carbon nanotubes, and silica- and carbon-based sorbents. The methodological solutions, together with properly matched sampling devices for collecting analytes from samples with varying matrix composition, enable us to reduce the number of errors during the sample preparation prior to chromatographic analysis as well as to limit the negative impact of this analytical step on the natural environment and the health of laboratory employees.

  1. Extraction of pesticides in water samples using vortex-assisted liquid-liquid microextraction.

    PubMed

    Jia, Chunhong; Zhu, Xiaodan; Wang, Jihua; Zhao, Ercheng; He, Min; Chen, Li; Yu, Pingzhong

    2010-09-10

    A simple solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VALLME) coupled with gas chromatography micro electron-capture detector (GC-microECD) has been developed and used for the pesticide residue analysis in water samples. In the VALLME method, aliquots of 30 microL toluene used as extraction solvent were directly injected into a 25 mL volumetric flask containing the water sample. The extraction solvent was dispersed into the water phase under vigorously shaking with the vortex. The parameters affecting the extraction efficiency of the proposed VALLME such as extraction solvent, vortex time, volumes of extraction solvent and salt addition were investigated. Under the optimum condition, enrichment factors (EFs) in a range of 835-1115 and limits of detection below 0.010 microg L(-1) were obtained for the determination of target pesticides in water. The calculated calibration curves provide high levels of linearity yielding correlation coefficients (r(2)) greater than 0.9958 with the concentration level ranged from 0.05 to 2.5 microg L(-1). Finally, the proposed method has been successfully applied to the determination of pesticides from real water samples and acceptable recoveries over the range of 72-106.3% were obtained.

  2. Determination of pesticides in soil by liquid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Hou, Li; Lee, Hian Kee

    2004-06-04

    Trace amounts of pesticides in soil were determined by liquid-phase microextraction (LPME) coupled to gas chromatography-mass spectrometry (GC-MS). The technique involved the use of a small amount (3 microl) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The organic solvent was repeatedly discharged into and withdrawn from the porous polypropylene hollow fiber by a syringe pump, with the pesticides being extracted from a 4 ml aqueous soil sample into the organic solvent within the hollow fiber. Aspects of the developed procedure such as organic solvent selection, extraction time, movement pattern of plunger, concentrations of humic acid and salt, and the proportion of organic solvent in the soil sample, were optimized. Limits of detection (LOD) were between 0.05 and 0.1 microg/g with GC-MS analysis under selected-ion monitoring (SIM). Also, this method provided good precision ranging from 6 to 13%; the relative standard deviations were lower than 10% for most target pesticides (at spiked levels of 0.5 microg/g in aqueous soil sample). Finally, the results were compared to those achieved using solid-phase microextraction (SPME). The results demonstrated that LPME was a fast (within 4 min) and accurate method to determine trace amounts of pesticides in soil.

  3. Evaluation of polyethersulfone performance for the microextraction of polar chlorinated herbicides from environmental water samples.

    PubMed

    Prieto, Ailette; Rodil, Rosario; Quintana, José Benito; Cela, Rafael; Möder, Monika; Rodríguez, Isaac

    2014-05-01

    In this work, the suitability of bulk polyethersulfone (PES) for sorptive microextraction of eight polar, chlorinated phenoxy acids and dicamba from environmental water samples is assessed and the analytical features of the optimized method are compared to those reported for other microextraction techniques. Under optimized conditions, extractions were performed with samples (18 mL) adjusted at pH 2 and containing a 30% (w/v) of sodium chloride, using a tubular PES sorbent (1 cm length × 0.7 mm o.d., sorbent volume 8 µL). Equilibrium conditions were achieved after 3h of direct sampling, with absolute extraction efficiencies ranging from 39 to 66%, depending on the compound. Analytes were recovered soaking the polymer with 0.1 mL of ethyl acetate, derivatized and determined by gas chromatography-mass spectrometry (GC-MS). Achieved quantification limits (LOQs) varied between 0.005 and 0.073 ng mL(-1). After normalization with the internal surrogate (IS), the efficiency of the extraction was only moderately affected by the particular characteristics of different water samples (surface and sewage water); thus, pseudo-external calibration, using spiked ultrapure water solutions, can be used as quantification technique. The reduced cost of the PES polymer allowed considering it as a disposable sorbent, avoiding variations in the performance of the extraction due to cross-contamination problems and/or surface modification with usage.

  4. Determination of four heterocyclic insecticides by ionic liquid dispersive liquid-liquid microextraction in water samples.

    PubMed

    Liu, Yu; Zhao, Ercheng; Zhu, Wentao; Gao, Haixiang; Zhou, Zhiqiang

    2009-02-06

    A novel microextraction method termed ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) combining high-performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of insecticides in water samples. Four heterocyclic insecticides (fipronil, chlorfenapyr, buprofezin, and hexythiazox) were selected as the model compounds for validating this new method. This technique combines extraction and concentration of the analytes into one step, and the ionic liquid was used instead of a volatile organic solvent as the extraction solvent. Several important parameters influencing the IL-DLLME extraction efficiency such as the volume of extraction solvent, the type and volume of disperser solvent, extraction time, centrifugation time, salt effect as well as acid addition were investigated. Under the optimized conditions, good enrichment factors (209-276) and accepted recoveries (79-110%) were obtained for the extraction of the target analytes in water samples. The calibration curves were linear with correlation coefficient ranged from 0.9947 to 0.9973 in the concentration level of 2-100 microg/L, and the relative standard deviations (RSDs, n=5) were 4.5-10.7%. The limits of detection for the four insecticides were 0.53-1.28 microg/L at a signal-to-noise ratio (S/N) of 3.

  5. Matrix compatible solid phase microextraction coating, a greener approach to sample preparation in vegetable matrices.

    PubMed

    Naccarato, Attilio; Pawliszyn, Janusz

    2016-09-01

    This work proposes the novel PDMS/DVB/PDMS fiber as a greener strategy for analysis by direct immersion solid phase microextraction (SPME) in vegetables. SPME is an established sample preparation approach that has not yet been adequately explored for food analysis in direct immersion mode due to the limitations of the available commercial coatings. The robustness and endurance of this new coating were investigated by direct immersion extractions in raw blended vegetables without any further sample preparation steps. The PDMS/DVB/PDMS coating exhibited superior features related to the capability of the external PDMS layer to protect the commercial coating, and showed improvements in terms of extraction capability and in the cleanability of the coating surface. In addition to having contributed to the recognition of the superior features of this new fiber concept before commercialization, the outcomes of this work serve to confirm advancements in the matrix compatibility of the PDMS-modified fiber, and open new prospects for the development of greener high-throughput analytical methods in food analysis using solid phase microextraction in the near future.

  6. Determination of amphetamines in human urine by headspace solid-phase microextraction and gas chromatography.

    PubMed

    Raikos, Nikolaos; Christopoulou, Klio; Theodoridis, Georgios; Tsoukali, Heleni; Psaroulis, Dimitrios

    2003-06-05

    Solid-phase microextraction (SPME) is under investigation for its usefulness in the determination of a widening variety of volatile and semivolatile analytes in biological fluids and materials. Semivolatiles are increasingly under study as analytical targets, and difficulties with small partition coefficients and long equilibration times have been identified. Amphetamines were selected as semivolatiles exhibiting these limitations and methods to optimize their determination were investigated. A 100- micro m polydimethylsiloxane (PDMS)-coated SPME fiber was used for the extraction of the amphetamines from human urine. Amphetamine determination was made using gas chromatography (GC) with flame-ionization detection (FID). Temperature, time and salt saturation were optimized to obtain consistent extraction. A simple procedure for the analysis of amphetamine (AMP) and methamphetamine (MA) in urine was developed and another for 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-methamphetamine (MDMA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) using headspace solid-phase microextraction (HS-SPME) and GC-FID. Higher recoveries were obtained for amphetamine (19.5-47%) and methamphetamine (20-38.1%) than MDA (5.1-6.6%), MDMA (7-9.6%) and MDEA (5.4-9.6%).

  7. Headspace in-tube microextraction coupled with micellar electrokinetic chromatography of neutral aromatic compounds.

    PubMed

    Cho, Sung Min; Park, Bum Su; Jung, Woo Sung; Lee, Sang Won; Jung, Yunhwan; Chung, Doo Soo

    2016-02-01

    Headspace (HS) extraction can be carried out easily and aptly via single drop microextraction coupled with capillary electrophoresis (CE). However, one drawback is the difficulty of keeping the single drop stably at the capillary tip. To solve this problem, we have recently demonstrated HS in-tube microextraction (ITME) of acidic compounds such as chlrophenols in an acidic sample using a basic run buffer plug in the separation capillary for CE as an acceptor phase. In this report, an organic acceptor plug in a capillary was used to extract neutral organic volatile pollutants such as BTEX (benzene, toluene, ethylbenzene, and m-xylene). After extraction, the analytes enriched in the organic acceptor plug were analyzed with micellar electrokinetic chromatography (MEKC). The enrichment factors for BTEX in a standard solution were up to 350 under an optimal condition of 25°C for 20 min. As an application, BTEX spiked into bottled water were analyzed with HS-ITME-MEKC, and the enrichment factors for BTEX were up to 320. The limits of detections were 1-4 ppb, which are at least 200 times lower than the US Environmental Protection Agency guidelines for drinking water, except benzene. The entire procedure of HS-ITME-MEKC was carried out automatically using a commercial CE instrument.

  8. Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME).

    PubMed

    Benhabib, Karim; Town, Raewyn M; van Leeuwen, Herman P

    2009-04-09

    Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the coupled diffusion of free and particle-bound atrazine toward the solid/sample solution interface. In the eventual equilibrium the total atrazine concentration in the solid phase is dictated by the solid phase/water partition coefficient (K(sw)) and the concentration of the free atrazine in the sample solution. These observations demonstrate that the nanoparticles do not enter the solid phase. The experimental data show that the rate of release of sorbed atrazine from the latex particles is fast on the effective time scale of the microextraction process. A lability criterion is derived to quantitatively describe the relative rates of these two processes. All together, the results indicate that SPME has a strong potential for dynamic speciation analysis of organic compounds in media containing sorbing nanoparticles.

  9. Microextraction techniques coupled to liquid chromatography with mass spectrometry for the determination of organic micropollutants in environmental water samples.

    PubMed

    Padrón, Ma Esther Torres; Afonso-Olivares, Cristina; Sosa-Ferrera, Zoraida; Santana-Rodríguez, José Juan

    2014-07-16

    Until recently, sample preparation was carried out using traditional techniques, such as liquid-liquid extraction (LLE), that use large volumes of organic solvents. Solid-phase extraction (SPE) uses much less solvent than LLE, although the volume can still be significant. These preparation methods are expensive, time-consuming and environmentally unfriendly. Recently, a great effort has been made to develop new analytical methodologies able to perform direct analyses using miniaturised equipment, thereby achieving high enrichment factors, minimising solvent consumption and reducing waste. These microextraction techniques improve the performance during sample preparation, particularly in complex water environmental samples, such as wastewaters, surface and ground waters, tap waters, sea and river waters. Liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) and time-of-flight mass spectrometric (TOF/MS) techniques can be used when analysing a broad range of organic micropollutants. Before separating and detecting these compounds in environmental samples, the target analytes must be extracted and pre-concentrated to make them detectable. In this work, we review the most recent applications of microextraction preparation techniques in different water environmental matrices to determine organic micropollutants: solid-phase microextraction SPME, in-tube solid-phase microextraction (IT-SPME), stir bar sorptive extraction (SBSE) and liquid-phase microextraction (LPME). Several groups of compounds are considered organic micropollutants because these are being released continuously into the environment. Many of these compounds are considered emerging contaminants. These analytes are generally compounds that are not covered by the existing regulations and are now detected more frequently in different environmental compartments. Pharmaceuticals, surfactants, personal care products and other chemicals are considered micropollutants. These compounds must be

  10. RETRACTED: Size-controlled spherical polymer nanoparticles: synthesis with tandem acoustic emulsification followed by soap-free emulsion polymerization and one-step fabrication of colloidal crystal films of various colors.

    PubMed

    Hirai, Yuki; Nakabayashi, Koji; Kojima, Maya; Atobe, Mahito

    2014-11-01

    We have developed a novel synthesis method for size-controlled polymer nanoparticles using soap-free emulsion polymerization. This new synthetic method involves sequential ultrasonic irradiation (20kHz→500kHz→1.6MHz→2.4MHz) for acoustic emulsification of a water-insoluble monomer such as methylmethacrylate (MMA) in an aqueous medium, followed by emulsion polymerization in the obtained solution without using any surfactants. The sequential ultrasonication (tandem acoustic emulsification) could provide a clear and stable emulsified solution containing monomer droplets with relatively narrow size distribution in the nanometer range. The subsequent polymerization in this solution yielded size-controlled polymethylmethacrylate (PMMA) nanoparticles and monodisperse PMMA nanoparticles of different sizes. Furthermore, colloidal crystal films could be easily prepared from the as-polymerized nanoparticle solution using the fluidic-cell method. Moreover, we succeeded to modify the structural color of colloidal crystal films by the addition of a small amount of organic solvent to the as-polymerized nanoparticle solution for the fluidic-cell method.

  11. Application of Solid Phase Microextraction Coupled with Gas Chromatography/Mass Spectrometry as a Rapid Method for Field Sampling and Analysis of Chemical Warfare Agents and Toxic Industrial Chemicals

    DTIC Science & Technology

    2003-01-01

    PHASE MICROEXTRACTION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD SAMPLING AND ANALYSIS OF CHEMICAL WARFARE AGENTS...4. TITLE AND SUBTITLE APPLICATION OF SOLID PHASE MICROEXTRACTION COUPLED WITH GAS CHROMATOGRAPHY/MASS SPECTROMETRY AS A RAPID METHOD FOR FIELD...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 iii ABSTRACT APPLICATION OF SOLID PHASE MICROEXTRACTION COUPLED WITH

  12. Determination of 3,5,6-trichloro-2-pyridinol, phoxim and chlorpyrifos-methyl in water samples using a new pretreatment method coupled with high-performance liquid chromatography.

    PubMed

    Peng, Guilong; Lu, Ying; He, Qiang; Mmereki, Daniel; Zhou, Guangming; Chen, Junhua; Tang, Xiaohui

    2015-12-01

    A novel low-density solvent-based vortex-assisted surfactant-enhanced-emulsification liquid-liquid microextraction with the solidification of floating organic droplet method coupled with high-performance liquid chromatography was developed for the determination of 3,5,6-trichloro-2-pyridinol, phoxim and chlorpyrifos-methyl in water samples. In this method, the addition of a surfactant could enhance the speed of the mass transfer from the sample solution into the extraction solvent. The extraction solvent could be dispersed into the aqueous by the vortex process. The main parameters affecting the extraction efficiency were investigated and the optimum conditions were established as follows: 80 μL 1-undecanol as extraction solvent, 0.2 mmol/L of Triton X-114 selected as the surfactant, the vortex time was fixed at 60 s with the vortex agitator set at 3000 rpm, the concentration of acetic acid in sample solution was 0.4% v/v and 1.0 g addition of NaCl. Under the optimum conditions, the enrichment factors were from 172 to 186 for the three analytes. The linear ranges were from 0.5 to 500 μg/L with a coefficient of determination (r(2) ) of between 0.9991 and 0.9995. Limits of detections were varied between 0.05 and 0.12 μg/L. The relative standard deviations (n = 6) ranged from 0.26 to 2.62%.

  13. Preparation and selective recognition of a novel solid-phase microextraction fiber combined with molecularly imprinted polymers for the extraction of parabens in soy sample.

    PubMed

    He, Juan; Chen, Si; Jiang, Yili; Shen, Yanzheng; Zhu, Jing; Wei, Hongliang; Zhang, Hongxia; Lu, Kui

    2012-01-01

    A prepared molecularly imprinted polymer with ethyl p-hydroxybenzoate as template molecule was applied for the first time to a homemade solid-phase microextraction fiber. The molecularly imprinted polymer-coated solid-phase microextraction fiber was characterized by scanning electron microscopy and thermogravimetric analysis. Various parameters were investigated, including extraction temperature, extraction time, and desorption time. Under the optimum extraction conditions, the molecularly imprinted polymer-coated solid-phase microextraction fiber exhibited higher selectivity with greater extraction capacity toward parabens compared with the nonimprinted polymer-coated solid-phase microextraction fiber and commercial fibers. The molecularly imprinted polymer-coated solid-phase microextraction fiber was tested using gas chromatography to determine parabens, including methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, and propyl p-hydroxybenzoate. The linear ranges were 0.01-10 μg/mL with a correlation coefficient above 0.9943. The detection limits (under signal-to-noise ratio of 3) were below 0.30 μg/L. The fiber was successfully applied to the simultaneous analysis of three parabens in spiked soy samples with satisfactory recoveries of 95.48, 97.86, and 92.17%, respectively. The relative standard deviations (n=6) were within 2.83-3.91%. The proposed molecularly imprinted polymer-coated solid-phase microextraction method is suitable for selective extraction and determination of trace parabens in food samples.

  14. Comparison of dual solvent-stir bars microextraction and U-shaped hollow fiber-liquid phase microextraction for the analysis of Sudan dyes in food samples by high-performance liquid chromatography-ultraviolet/mass spectrometry.

    PubMed

    Yu, Chunhe; Liu, Qing; Lan, Lidan; Hu, Bin

    2008-04-25

    Two sample preparation methods, dual solvent-stir bars microextraction (DSSBME) and U-shaped hollow fiber-liquid phase microextraction (U-shaped HF-LPME), are proposed and critically compared for high-performance liquid chromatography (HPLC)-ultraviolet (UV)/mass spectrometry (MS) analysis of Sudan dyes in this paper. In DSSBME, the organic solvent was confined to a pair of hollow fiber membrane fixed on a stir bar, which can stir by itself, while the hollow fiber in U-shaped HF-LPME was fixed by two microsyringes. The significant factors affecting the microextraction of Sudan dyes in both microextraction techniques have been examined and no obvious difference in the effect of extraction solvent, pH and salt concentration on the extraction efficiency of Sudan dyes was observed except extraction time and stirring speed. Both microextraction techniques were similar in terms of analytical performance from aqueous solutions (LODs ranged from 0.09 to 0.95 microgL(-1) by HPLC-UV and 2.5-6.2 microgL(-1) by HPLC-MS; the absolute LODs ranged from 0.9 to 11.25 pg by HPLC-UV and 5-21.2 pg by HPLC-MS), however, DSSBME was more stable (lower stirring speed required), less sample consuming and much shorter time required to reach extraction equilibrium; while U-shaped HF-LPME was easier to operate and no more special device required. The two microextraction techniques combined with HPLC-UV/MS were successfully applied to the analysis of real samples including strawberry sauce, capsicum oil, salted egg, and two kinds of chilli sauce. Although the LODs of HPLC-UV are lower than that of HPLC-MS by a factor of 10 in this work, the absolute LODs for both HPLC-UV and HPLC-MS are comparable. HPLC-UV cannot identify the suspicious peaks at the same retention time as that of Sudan II and III in salted egg, while HPLC-MS can give exact information of Sudan I-IV in real sample analysis and is more reliable. The sensitivity of HPLC-MS is enough for real sample analysis.

  15. Bar adsorptive microextraction technique - application for the determination of pharmaceuticals in real matrices.

    PubMed

    Almeida, Carlos; Ahmad, Samir M; Nogueira, José Manuel F

    2017-03-01

    In the present work, bar adsorptive microextraction using miniaturized devices (7.5 × 3.0 mm) coated with suitable sorbent phases, combined with microliquid desorption (100 μL) followed by high-performance liquid chromatography with diode array detection (BAμE-μLD/HPLC-DAD), is proposed for the determination of trace level of six pharmaceuticals (furosemide, mebeverine, ketoprofen, naproxen, diclofenac and mefenamic acid) in environmental water and urine matrices. By comparing ten distinct sorbent materials (five polymeric and five activated carbons), the polymer P5 proved to be the most suitable to achieve the best selectivity and efficiency. The solvent volume minimization in the liquid desorption stage demonstrated remarkable effectiveness, being more environmentally friendly, and simultaneously increased the microextraction enrichment factor two-fold. Assays performed through BAμE(P5, 0.9 mg)-μLD(100 μL)/HPLC-DAD on 25 mL of ultrapure water samples spiked at the 4.0 μg/L level yielded average recoveries ranging from 91.4% (furosemide) to 101.0% (ketoprofen) with good precision (RSD < 10.6%), under optimized experimental conditions. The analytical performance showed convenient detection limits (25.0 - 120.0 ng/L), good linear dynamic ranges (0.1 to 24.0 μg/L), appropriate determination coefficients (r (2) > 0.9983), and excellent repeatability through intraday (RSD < 10.4%)) and interday (RSD < 10.0%) assays. By using the standard addition methodology, the application of the present analytical approach on environmental waters and urine samples revealed the occurrence of trace levels of some pharmaceuticals. The solvent minimization during the back-extraction step associated with the miniaturization of BAμE devices proved to be a very promising analytical technology for static microextraction analysis. Graphical abstract BAμE operating under the floating sampling technology for the determination of pharmaceuticals in aqueous media.

  16. A novel silver-coated solid-phase microextraction metal fiber based on electroless plating technique.

    PubMed

    Feng, Juanjuan; Sun, Min; Li, Jubai; Liu, Xia; Jiang, Shengxiang

    2011-09-09

    A novel silver-coated solid-phase microextraction fiber was prepared based on electroless plating technique. Good extraction performance of the fiber for model compounds including phthalate esters (dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate and diallyl phthalate) and polycyclic aromatic hydrocarbons (naphthalene, fluorene, phenanthrene, fluoranthene) in aqueous solution was obtained. Under the optimized conditions (extraction temperature, extraction time, ionic strength and desorption temperature), the proposed SPME-GC method showed wide linear ranges with correlation coefficients (R(2)) ranging from 0.9745 to 0.9984. The limits of detection were at the range of 0.02 to 0.1 μg L(-1). Single fiber repeatability and fiber-to-fiber reproducibility as well as stability to acid, alkali and high temperature were studied and the results were all satisfactory. The method was applied successfully to the aqueous extracts of disposable paper cup and instant noodle barrel. Several kinds of analytes were detected and quantified.

  17. Improvements in the vapor-time profile analysis of explosive odorants using solid-phase microextraction.

    PubMed

    Young, Mimy; Schantz, Michele; MacCrehan, William

    2016-07-15

    A modified approach for characterization of the vapor-time profile of the headspace odors of explosives was developed using solid-phase microextraction (SPME) incorporating introduction of an externally-sampled internal standard (ESIS) followed by gas chromatography/mass spectrometry (GC/MS) analysis. With this new method, reproducibility of the measurements of 2-ethyl-1-hexanol and cyclohexanone were improved compared to previous work (Hoffman et al., 2009; Arthur and Pawliszyn, 1990) through the use of stable-isotope-labeled internal standards. Exposing the SPME fiber to the ESIS after sampling the target analyte proved to be advantageous, while still correcting for fiber variability and detector drift. For the analysis of high volatility compounds, incorporation of the ESIS using the SPME fiber in the retracted position minimized the subsequent competitive loss of the target analyte, allowing for much longer sampling times.

  18. Headspace solid-phase microextraction analysis of volatile components in Phalaenopsis Nobby's Pacific Sunset.

    PubMed

    Yeh, Chih-Hsin; Tsai, Wan-Yu; Chiang, Hsiu-Mei; Wu, Chin-Sheng; Lee, Yung-I; Lin, Li-Yun; Chen, Hsin-Chun

    2014-09-09

    Phalaenopsis is the most important economic crop in the Orchidaceae family. There are currently numerous beautiful and colorful Phalaenopsis flowers, but only a few species of Phalaenopsis have an aroma. This study reports the analysis volatile components present in P. Nobby's Pacific Sunset by solid-phase microextraction (SPME) coupled with gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The results show that the optimal extraction conditions were obtained by using a DVB/CAR/PDMS fiber. A total of 31 compounds were identified, with the major compounds being geraniol, linalool and α-farnesene. P. Nobby's Pacific Sunset had the highest odor concentration from 09:00 to 13:00 on the eighth day of storage. It was also found that in P. Nobby's Pacific Sunset orchids the dorsal sepals and petals had the highest odor concentrations, whereas the column had the lowest.

  19. Solid-phase microextraction technology for in vitro and in vivo metabolite analysis

    PubMed Central

    Zhang, Qihui; Zhou, Liandi; Chen, Hua; Wang, Chong-Zhi; Xia, Zhining; Yuan, Chun-Su

    2016-01-01

    Analysis of endogenous metabolites in biological samples may lead to the identification of biomarkers in metabolomics studies. To achieve accurate sample analysis, a combined method of continuous quick sampling and extraction is required for online compound detection. Solid-phase microextraction (SPME) integrates sampling, extraction and concentration into a single solvent-free step for chemical analysis. SPME has a number of advantages, including simplicity, high sensitivity and a relatively non-invasive nature. In this article, we reviewed SPME technology in in vitro and in vivo analyses of metabolites after the ingestion of herbal medicines, foods and pharmaceutical agents. The metabolites of microorganisms in dietary supplements and in the gastrointestinal tract will also be examined. As a promising technology in biomedical and pharmaceutical research, SPME and its future applications will depend on advances in analytical technologies and material science. PMID:27695152

  20. Determination of trace lead in biological and water samples with dispersive liquid-liquid microextraction preconcentration.

    PubMed

    Liang, Pei; Sang, Hongbo

    2008-09-01

    A new method for the determination of trace lead was developed by dispersive liquid-liquid microextraction preconcentration and graphite furnace atomic absorption spectrometry. In the proposed approach, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) was used as a chelating agent, and carbon tetrachloride and ethanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of lead and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent, and extraction time, were studied and optimized. Under the optimum conditions, the enrichment factor of this method for lead was reached at 78. The detection limit for lead was 39 ng L(-1) (3 sigma), and the relative standard deviation (RSD) was 3.2% (n=7, c=10 ng mL(-1)). The method was successfully applied to the determination of trace amounts of lead in human urine and water samples.

  1. Thermal desorption solid-phase microextraction inlet for differential mobility spectrometry.

    PubMed

    Rainsberg, Matthew R; de Harrington, Peter B

    2005-06-01

    A splitless thermal desorber unit that interfaces a differential mobility spectrometry (DMS) sensor has been devised. This device was characterized by the detection of benzene, toluene, and xylene (BTX) in water. The detection of BTX in water is important for environmental monitoring, and ion mobility measurements are traditionally difficult for hydrocarbons in water because water competes for charge and quenches the hydrocarbon signals. This paper reports the use of a DMS with a photoionization source that is directly coupled to a solid-phase microextraction (SPME) desorber. The separation and detection capabilities of the DMS were demonstrated using BTX components. Detection limits for benzene, toluene, and m-xylene were 75, 50, and 5 microg mL(-1), respectively.

  2. Molecularly imprinted calixarene fiber for solid-phase microextraction of four organophosphorous pesticides in fruits.

    PubMed

    Li, Jing-Wen; Wang, Yu-Long; Yan, Shan; Li, Xiu-Juan; Pan, Si-Yi

    2016-02-01

    Calixarene was used as a functional monomer to fabricate a molecularly imprinted polymer (MIP) by sol-gel technique for solid-phase microextraction (SPME) of parathion-methyl and its structural analogs. The MIP-coated fiber possessed excellent thermal and chemical stability as well as high extraction capacity. Its selectivity and possible recognition mechanism were investigated. The similarities in molecular shape and functional group play a key role in the selective recognition of the imprinted material. Any changes to the structure of the template would decrease the imprinting factor. A comparison of MIP-SPME was made with liquid-liquid extraction coupled with gas chromatography for the determination of organophosphorus pesticides (OPPs) in fruits. Much lower limits of detection and better recoveries were achieved by SPME in spiked apple and pineapple samples. The experiment demonstrates that the proposed method using the calixarene MIP fiber was more suitable for selective determination of trace OPPs in those fruit samples.

  3. Rapid screening of water soluble arsenic species in edible oils using dispersive liquid-liquid microextraction.

    PubMed

    López-García, Ignacio; Briceño, Marisol; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2015-01-15

    A methodology for the non-chromatographic screening of the main arsenic species present in edible oils is discussed. Reverse dispersive liquid-liquid microextraction was used to extract water soluble arsenic compounds (inorganic arsenic, methylarsonate, dimethylarsinate and arsenobetaine) from the edible oils into a slightly acidic aqueous medium. The total arsenic content was measured in the extracts by electrothermal atomic absorption spectrometry using palladium as the chemical modifier. By repeating the measurement using cerium instead of palladium, the sum of inorganic arsenic and methylarsonate was obtained. The detection limit was 0.03 ng As per gram of oil. Data for the total and water-soluble arsenic levels of 29 samples of different origin are presented. Inorganic arsenic was not found in any of the samples marketed as edible oils.

  4. A novel hybrid metal-organic framework-polymeric monolith for solid-phase microextraction.

    PubMed

    Lin, Chen-Lan; Lirio, Stephen; Chen, Ya-Ting; Lin, Chia-Her; Huang, Hsi-Ya

    2014-03-17

    This study describes the fabrication of a novel hybrid metal-organic framework- organic polymer (MOF-polymer) for use as a stationary phase in fritless solid-phase microextraction (SPME) for validating analytical methods. The MOF-polymer was prepared by using ethylene dimethacrylate (EDMA), butyl methacrylate (BMA), and an imidazolium-based ionic liquid as porogenic solvent followed by microwave-assisted polymerization with the addition of 25 % MOF. This novel hybrid MOF-polymer was used to extract penicillin (penicillin G, penicillin V, oxacillin, cloxacillin, nafcillin, dicloxacillin) under different conditions. Quantitative analysis of the extracted penicillin samples using the MOF-organic polymer for SPME was conducted by using capillary electrochromatography (CEC) coupled with UV analysis. The penicillin recovery was 63-96.2 % with high reproducibility, sensitivity, and reusability. The extraction time with the proposed fabricated SPME was only 34 min.

  5. Microextraction method of medium and long chain fatty acids from milk.

    PubMed

    Añorve-Morga, Javier; Castañeda-Ovando, Araceli; Cepeda-Saez, Alberto; Archibold, Armando Durant; Jaimez-Ordaz, Judith; Contreras-López, Elizabeth; González-Olivares, Luis Guillermo; Rodríguez-Rodríguez, José Luis

    2015-04-01

    The aim of this research was to develop a method for microextraction and quantification of long and medium chain fatty acids from milk. The proposed method was carried out on three steps: (1) lipids extraction from 10 μL of whole or skimmed milk containing omega-3 fatty acids (FAs) during 12, 24, 48, 72 and 96 h, in 2 mL chloroform: methanol mixture (2:1); (2) acid methylation of FAs; and (3) quantification of FAs methyl esters by gas chromatography. Using this method, the percentage recovery of FAs was higher (67% for whole and 85% for skimmed milk) compared with AOAC method 905.02 recovery (49% and 83%, respectively). Good reproducibility and repeatability (<3%) were obtained. The method developed can be useful for researching and in routine quality control. Additionally, it is simpler, faster and cheaper than the reference procedure since it requires minimum sample and solvents volume as well as fewer steps.

  6. Headspace liquid phase microextraction for quantitation of hexanal in potato crisps by gas chromatography.

    PubMed

    Kaykhaii, Massoud; Rahmani, Mashaallah

    2007-03-01

    A simple and rapid method using headspace liquid-phase microextraction (HS-LPME) was developed for the determination of hexanal at low levels in potato crisp samples. Parameters such as extraction solvent, agitation of the sample, salt addition, organic drop volume, exposure time, and extraction time were controlled and optimised. The developed protocol was found to yield a linear calibration curve in the concentration range from 0.001 to 2 mg/L and a limit of detection of 0.1 microg/L with a good enrichment factor of > 107 for the analyte. The repeatability of the method was satisfactory (4%). The results demonstrate that HS-LPME is a rapid, accurate, and effective preparation method and could be successfully used for the determination of hexanal in potato crisp samples.

  7. Profiling flavor compounds of potato crisps during storage using solid-phase microextraction.

    PubMed

    Sanches-Silva, A; Lopez-Hernández, J; Paseiro-Losada, P

    2005-02-04

    Headspace solid-phase microextraction (HS-SPME) was studied as a solvent free alternative method for the extraction and characterisation of volatile compounds in stored potato crisps by capillary gas chromatography coupled with mass detection. Better results were obtained when extraction was carried out at 70 degrees C using a divinylbenzene (DVB)-carboxen (CAR)-polydimethylsiloxane fiber. The fiber was exposed for 20 min (extraction time) to the sample headspace, immediately after an equilibrium time of 5 min (time needed to reach the equilibrium between sample and above headspace). A total of 31 compounds were identified in oxidised potato crisps and resulted mainly from the degradation/rearrangement of lipids and carbohydrates.

  8. Solid-phase microextraction of hop volatiles. Potential use for determination and verification of hop varieties.

    PubMed

    Kovacevic, M; Kac, M

    2001-05-18

    The composition of hop essential oil is an important tool for evaluation of hop quality. As each hop variety has a typical essential oil pattern (fingerprint), hop oil analyses can be used to distinguish between hop varieties. The headspace solid-phase microextraction (SPME) method as described in this contribution is a simple sample preparation technique and represents an alternative procedure for essential oil fingerprint determination. Different SPME parameters (extraction temperature, extraction time and sample mass) were studied and the results were compared with those obtained by the routine distillation method. It is shown that SPME results can be used for determination and verification of varieties grown in Slovenia by means of principal components analysis.

  9. Solid-phase microextraction (SPME) of drugs and poisons from biological samples.

    PubMed

    Junting, L; Peng, C; Suzuki, O

    1998-11-09

    Solid-phase microextraction (SPME), a new solvent-free sample preparation technique, was invented by C. Arthur and J. Pawliszyn in 1990. This method mainly was applied for the extraction of volatile and semi-volatile organic pollutants in water samples. However, since 1995, SPME has been developed to various biological samples, such as whole blood, plasma, urine, hair and breath, in order to extract drugs and poisons in forensic field. The main advantages of SPME are: high sensitivity, solventless, small sample volume, simplicity and rapidity. We have reviewed the papers published in recent years about SPME in biological samples, and sorted out main experimental conditions, such as fibers, matrixes, the extraction approaches and time, as well as the acceleration method. We would expect SPME technique to have a promising future for toxicological analysis in forensic practice.

  10. A highly efficient three-phase single drop microextraction technique for sample preconcentration.

    PubMed

    Jahan, Sharmin; Xie, Haiyang; Zhong, Ran; Yan, Jian; Xiao, Hua; Fan, Liuyin; Cao, Chengxi

    2015-05-07

    A highly efficient three-phase single drop microextraction (SDME) method is presented by using an organic-aqueous compound droplet. A coupling microdevice is designed to produce compound droplets in different sizes conveniently. In this way, the volume ratio of organic phase to aqueous phase in a compound droplet can be significantly reduced. Good operability and droplet stability were observed during extraction under vigorous stirring conditions. Five statins were used as model compounds and spiked in river water and human serum samples to evaluate the analytical performance of the proposed method. By using a 1.2 μL toluene-aqueous compound droplet (volume ratio 0.2 : 1), a 350 to 1712 fold enrichment of statins was obtained within 4 minutes. The results indicate that the proposed method is a very rapid and efficient sample pretreatment method, and is promising for automated and high-throughput applications.

  11. [Determination of organophosphorous pesticide residues in red wine by solid phase microextraction-gas chromatography].

    PubMed

    Hu, Yuan; Liu, Wenmin; Zhou, Yanming; Guan, Yafeng

    2006-05-01

    A method for the determination of 12 organophosphorus pesticide residues (OPs) in red wine by fiber solid phase microextraction (SPME) coupled with gas chromatography (GC) was developed and validated. The SPME phase was prepared by sol-gel technology of physical incorporation. The extraction conditions were optimized with the results of stirring rate of 1,250 r/min, NaCl mass concentration of 150 g/L, and extraction time of 30 min. With the sample volume of 25 mL, the relative standard deviations (RSD) of peak areas for most of OPs were below 5%, and the detection limits of OPs were in the range of 5 ng/L-0.38 microg/L. It can be seen from the results that this method has the potential to analyze OPs in other beverages and soft drinking materials.

  12. Single-drop liquid phase microextraction accelerated by surface acoustic wave.

    PubMed

    Zhang, Anliang; Zha, Yan

    2013-03-01

    A single-drop liquid phase microextraction method is presented, in which surface acoustic wave (SAW) is used for accelerating extraction speed. A pair of interdigital transducers with 27.5 MHz center frequency is fabricated on a 128° yx-LiNbO3 substrate. A radio frequency signal is applied to one of interdigital transducers to excite SAW. Plastic straw is filled with PDMS, leaving 1 mL for holding sample solution. Plastic straw with sample solution droplet is then dipping into extractant, into which SAW is radiated. Mass transportation from sample solution to extractant drop is accelerated due to acoustic streaming, and extraction time is decreased. An ionic liquid and an acid green-25 solution are used for extraction experiments. Results show that the extraction process is almost finished within 2 min, and extraction speed is increased with radio frequency signal power.

  13. Ballpoint pen inks: the quantitative analysis of ink solvents on paper by solid-phase microextraction.

    PubMed

    Brazeau, Luc; Gaudreau, Marc

    2007-01-01

    We wish to describe further developments to a method previously reported on the detection of 2-phenoxyethanol in ink. The solid-phase microextraction (SPME) sampling technique, together with gas chromatography-mass spectrometry (GC-MS), has been used to quantify solvents in writing ink. In conventional approaches, the analysis of ink on documents requires some degree of destructive sampling. The methods commonly used remove ink samples from paper using a scalpel or a paper punch. To avoid document destruction, a sampling cell was constructed that allows solvents to be adsorbed directly onto the SPME fiber from the headspace above the document surface. Analytes (ink volatiles) are then desorbed from the SPME fiber on a gas chromatograph equipped with a mass selective detector (GC-MSD). With this method, it was possible to detect the presence of ink solvents on documents for a period lasting up to c. 2 years.

  14. Application of solid-phase microextraction combined with derivatization to the enantiomeric determination of amphetamines.

    PubMed

    Cháfer-Pericás, C; Campíns-Falcó, P; Herráez-Hernández, R

    2006-03-18

    The utility of combining chiral derivatization and solid-phase microextraction (SPME) for the enantiomeric analysis of primary amphetamines by liquid chromatography has been investigated. Different derivatization/extraction strategies have been evaluated and compared using the chiral reagent o-phthaldialdehyde (OPA)-N-acetyl-l-cysteine (NAC) and fibres with a Carbowax-templated resin coating. Amphetamine, norephedrine and 3,4-methylenedioxyamphetamine (MDA) were used as model compounds. On the basis of the results obtained, a new method is presented based on the derivatization of the analytes in solution followed by SPME of the OPA-NAC derivatives formed. The proposed conditions have been applied to determine the compounds of interest at low ppm levels (

  15. A digital microfluidic interface between solid-phase microextraction and liquid chromatography-mass spectrometry.

    PubMed

    Choi, Kihwan; Boyacı, Ezel; Kim, Jihye; Seale, Brendon; Barrera-Arbelaez, Luis; Pawliszyn, Janusz; Wheeler, Aaron R

    2016-04-29

    We introduce a method to couple solid-phase microextraction (SPME) with HPLC-MS using digital microfluidics (DMF). In the new system, SPME fibers are used to extract analytes from complex sample solutions, after which the analytes are desorbed into solvent droplets in a DMF device. The open geometry of DMF allows straightforward insertion of SPME fibers without requiring a complicated interface, and automated droplet manipulation enables multiplexed processing of the fibers. In contrast to other multiplexed SPME elution interfaces, the low volumes inherent to DMF allow for pre-concentration of analytes prior to analysis. The new SPME-DMF-HPLC-MS method was applied to the quantification of pg/mL-level free steroid hormones in urine. We propose that this new method will be useful for a wide range of applications requiring cleanup and pre-concentration with convenient coupling to high-performance analytical techniques.

  16. Analysis of volatiles of malt whisky by solid-phase microextraction and stir bar sorptive extraction.

    PubMed

    Demyttenaere, Jan C R; Martínez, Jorge I Sánchez; Verhé, Roland; Sandra, Pat; De Kimpe, Norbert

    2003-01-24

    Blended Scotch whisky was analysed by solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE) to study the composition of the volatiles. For SPME analysis, three different fibres were compared, poly(dimethylsiloxane) (PDMS) (100 microm). poly(acrylate) (PA) (85 microm) and divinylbenzene-Carboxen on poly(dimethylsiloxane) (DVB-CAR-(PDMS) (50/30 microm). It was found that the PDMS and DVB-CAR-PDMS fibres showed a higher enrichment capacity than PA as well as a better reproducibility. The influence of sampling time, temperature and salt addition on the enrichment of volatiles as well as the difference between liquid and headspace SPME were studied. An optimum SPME method was developed. Finally a more recent sample preparation technique, namely SBSE was evaluated to extract whisky volatiles.

  17. A metal organic framework-polyaniline nanocomposite as a fiber coating for solid phase microextraction.

    PubMed

    Bagheri, Habib; Javanmardi, Hasan; Abbasi, Alireza; Banihashemi, Solmaz

    2016-01-29

    A metal organic framework-polyaniline (MOF/PANI) nanocomposite was electrodeposited on a stainless steel wire and used as a solid phase microextraction (SPME) fiber coating. The electropolymerization process was carried out under a constant deposition potential and applied to the corresponding aqueous electrolyte containing aniline and MOF particles. The employment of MOFs with their large and small cages and 3-D structures in synthesizing a nanocomposite was assumed to be efficient constitutes to induce more non-smooth and porous structures, approved by scanning electron microscopy (SEM) images. Three different MOFs were incorporated to synthesize the desired nanocomposites and the preliminary experiments showed that all of them, particularly the one containing MOF2, have higher extraction performances in compared with PANI. The applicability of the new fiber coating was examined by headspace-solid phase microextraction (HS-SPME) of some chlorobenzenes (CBs) from aqueous samples. Influencing parameters on the synthesize and extraction processes including the electrodeposition voltage and its duration time, the weight ratio of PANI and MOF, the ionic strength, desorption temperature and time, and extraction time and temperature were optimized. The developed method was validated by analyzing the spiked distilled water and gas chromatography-mass spectrometry (GC-MS). Under optimum condition, the relative standard deviation (RSD%) values for a double distilled water spiked with the selected CBs at 20ngL(-1) were 5-8% (n=3) and the detection limits were below 0.2ngL(-1). The linear dynamic range (LDR) of the method was in the concentration range of 0.5-1000ngL(-1) (R(2)>0.9994). The fiber-to-fiber reproducibility was found to be in the range of 4-7%. Eventually, various real-water samples were analyzed by the MOF/PANI-based HS-SPME and GC-MS and the relative recovery values were found to be in the range of 92-98%.

  18. Cold fiber solid-phase microextraction device based on thermoelectric cooling of metal fiber.

    PubMed

    Haddadi, Shokouh Hosseinzadeh; Pawliszyn, Janusz

    2009-04-03

    A new cold fiber solid-phase microextraction device was designed and constructed based on thermoelectric cooling. A three-stage thermoelectric cooler (TEC) was used for cooling a copper rod coated with a poly(dimethylsiloxane) (PDMS) hollow fiber, which served as the solid-phase microextraction (SPME) fiber. The copper rod was mounted on a commercial SPME plunger and exposed to the cold surface of the TEC, which was enclosed in a small aluminum box. A heat sink and a fan were used to dissipate the generated heat at the hot side of the TEC. By applying an appropriate dc voltage to the TEC, the upper part of the copper rod, which was in contact to the cold side of the TEC, was cooled and the hollow fiber reached a lower temperature through heat transfer. A thermocouple was embedded in the cold side of the TEC for indirect measurement of the fiber temperature. The device was applied in quantitative analysis of off-flavors in a rice sample. Hexanal, nonanal, and undecanal were chosen as three off-flavors in rice. They were identified according to their retention times and analyzed by GC-flame ionization detection instrument. Headspace extraction conditions (i.e., temperature and time) were optimized. Standard addition calibration graphs were obtained at the optimized conditions and the concentrations of the three analytes were calculated. The concentration of hexanal was also measured using a conventional solvent extraction method (697+/-143ng/g) which was comparable to that obtained from the cold fiber SPME method (644+/-8). Moreover, the cold fiber SPME resulted in better reproducibility and shorter analysis time. Cold fiber SPME with TEC device can also be used as a portable device for field sampling.

  19. Sample preparation with solid phase microextraction and exhaustive extraction approaches: Comparison for challenging cases.

    PubMed

    Boyacı, Ezel; Rodríguez-Lafuente, Ángel; Gorynski, Krzysztof; Mirnaghi, Fatemeh; Souza-Silva, Érica A; Hein, Dietmar; Pawliszyn, Janusz

    2015-05-11

    In chemical analysis, sample preparation is frequently considered the bottleneck of the entire analytical method. The success of the final method strongly depends on understanding the entire process of analysis of a particular type of analyte in a sample, namely: the physicochemical properties of the analytes (solubility, volatility, polarity etc.), the environmental conditions, and the matrix components of the sample. Various sample preparation strategies have been developed based on exhaustive or non-exhaustive extraction of analytes from matrices. Undoubtedly, amongst all sample preparation approaches, liquid extraction, including liquid-liquid (LLE) and solid phase extraction (SPE), are the most well-known, widely used, and commonly accepted methods by many international organizations and accredited laboratories. Both methods are well documented and there are many well defined procedures, which make them, at first sight, the methods of choice. However, many challenging tasks, such as complex matrix applications, on-site and in vivo applications, and determination of matrix-bound and free concentrations of analytes, are not easily attainable with these classical approaches for sample preparation. In the last two decades, the introduction of solid phase microextraction (SPME) has brought significant progress in the sample preparation area by facilitating on-site and in vivo applications, time weighted average (TWA) and instantaneous concentration determinations. Recently introduced matrix compatible coatings for SPME facilitate direct extraction from complex matrices and fill the gap in direct sampling from challenging matrices. Following introduction of SPME, numerous other microextraction approaches evolved to address limitations of the above mentioned techniques. There is not a single method that can be considered as a universal solution for sample preparation. This review aims to show the main advantages and limitations of the above mentioned sample

  20. Determination of volatile organic compounds in water using headspace knotted hollow fiber microextraction.

    PubMed

    Chen, Pai-Shan; Tseng, Yu-Hsiang; Chuang, Yuh-Lin; Chen, Jung-Hsuan

    2015-05-22

    An efficient and effective headspace microextraction technique named static headspace knotted hollow fiber microextraction (HS-K-HFME) has been developed for the determination of volatile organic compounds (VOCs) in water samples. The knot-shaped hollow fiber is filled with 25μL of the extraction solvent. The excess solvent forms a large droplet (13μL) and is held in the center of the knot. Even after 20min of extraction time at high temperature (95°C) without cooling, there was still enough volume of extraction solvent for gas chromatography-mass spectrometry (GC-MS) analysis, which extends the choice of solvents for headspace LPME. Moreover, the knot-shaped fiber has a larger extraction contact interface, which increases the rate of mass transfer between the headspace and extraction solvent film attached to the fiber, thus improving the extraction efficiency. The effects of extraction solvent, temperature, stirring rate, salt concentration and extraction time on extraction performance were optimized. The calibration curves exhibited coefficients of determination (R(2)) ranging from 0.9957 to 0.9999 and the limit of detection (LOD) ranged from 0.2 to 10μgL(-1). Relative standard deviations (RSDs) ranged from 4.5% to 11.6% for intraday measurements (n=5). Interday (n=15) values were between 2.2% and 12.9%. The relative recoveries (RRs) ranged from 90.3% to 106.0% for river water and 95.9% to 103.6% for wastewater.

  1. Determination of organic compounds in water using dispersive liquid-liquid microextraction.

    PubMed

    Rezaee, Mohammad; Assadi, Yaghoub; Milani Hosseini, Mohammad-Reza; Aghaee, Elham; Ahmadi, Fardin; Berijani, Sana

    2006-05-26

    A new microextraction technique termed dispersive liquid-liquid microextraction (DLLME) was developed. DLLME is a very simple and rapid method for extraction and preconcentration of organic compounds from water samples. In this method, the appropriate mixture of extraction solvent (8.0 microL C2Cl4) and disperser solvent (1.00 mL acetone) are injected into the aqueous sample (5.00 mL) by syringe, rapidly. Therefore, cloudy solution is formed. In fact, it is consisted of fine particles of extraction solvent which is dispersed entirely into aqueous phase. After centrifuging, the fine particles of extraction solvent are sedimented in the bottom of the conical test tube (5.0 +/- 0.2 microL). The performance of DLLME is illustrated with the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by using gas chromatography-flame ionization detection (GC-FID). Some important parameters, such as kind of extraction and disperser solvent and volume of them, and extraction time were investigated. Under the optimum conditions the enrichment factor ranged from 603 to 1113 and the recovery ranged from 60.3 to 111.3%. The linear range was 0.02-200 microg/L (four orders of magnitude) and limit of detection was 0.007-0.030 microg/L for most of analytes. The relative standard deviations (RSDs) for 2 microg/L of PAHs in water by using internal standard were in the range 1.4-10.2% (n = 5). The recoveries of PAHs from surface water at spiking level of 5.0 microg/L were 82.0-111.0%. The ability of DLLME technique in the extraction of other organic compounds such as organochlorine pesticides, organophosphorus pesticides and substituted benzene compounds (benzene, toluene, ethyl benzene, and xylenes) from water samples were studied. The advantages of DLLME method are simplicity of operation, rapidity, low cost, high recovery, and enrichment factor.

  2. Solvent-bar microextraction--using a silica monolith as the extractant phase holder.

    PubMed

    Xu, Li; Lee, Hian Kee

    2009-07-17

    In this paper, a novel liquid-phase microextraction (LPME) approach, based on solvent-bar microextraction (SBME), was developed in which a silica monolith was used as the extractant solvent holder. Owing to the porous nature of the monolith, the extractant solvent could be easily held in the material; when the monolith containing the extractant solvent was exposed to the sample solution, analytes could directly diffuse from the sample solution into the extractant solvent. Polycyclic aromatic hydrocarbons (PAHs) were used as model analytes to evaluate the procedure. Through the investigation of the effect of agitation speed, extraction time, length of the monolith (that determined the volume of organic extractant solvent) and salt concentration on extraction efficiency, the following optimal extraction conditions were obtained: stirring at 1000 rpm for 30 min without salt addition using a 4-mm silica monolith. The limits of detection ranged from 3.9 pg/mL to 28.8 pg/mL, with relative standard deviations of between 8.16% and 10.5% on the same silica monolith. The linearity was 0.05-200 ng/mL for fluoranthene and pyrene, and 0.5-200 ng/mL for chrysene and benzo[b]fluoranthene, with acceptable correlation coefficient. When this method was applied for the spiked real river sample, the relative recoveries ranged from 87.1% to 100.7% for the tested PAHs. This method was also compared to polymeric hollow fiber-based SBME and hollow fiber-protected LPME and found to provide better results. Additionally, compared with the polymeric hollow fiber, the silica monolith possesses good resistance to extreme conditions, such as high temperature and pH, and is more compatible with various organic solvents. This is the first report of an application of a monolithic material for LPME, and as a solvent holder for SBME. It extends the scope of applications of such materials, to analytical chemistry, specifically to sample preparation.

  3. Characterization and semiquantitative analysis of volatiles in seedless watermelon varieties using solid-phase microextraction.

    PubMed

    Beaulieu, John C; Lea, Jeanne M

    2006-10-04

    Seedless triploid watermelons have increased in popularity since the early 1990s, and the demand for seedless fruit is on the rise. Sweetness and sugars are crucial breeding focuses for fruit quality. Volatiles also play an important role; yet, we found no literature for seedless varieties and no reports using solid-phase microextraction (SPME) in watermelon. The objective of this experiment was to identify volatile and semivolatile compounds in five seedless watermelon varieties using carboxen divinylbenzene polydimethylsiloxane solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS). Fully ripe watermelon was squeezed through miracloth to produce rapid juice extracts for immediate headspace SPME GC-MS. Aldehydes, alcohols, ketones, and one furan (2-pentyl furan, a lipid oxidation product) were recovered. On the basis of total ion count peak area, the most abundant compounds in five varieties were 3-nonen-1-ol/(E,Z)-2,6-nonadienal (16.5-28.2%), (E)-2-nonenal (10.6-22.5%), and (Z)-6-nonenal (2.0-11.3%). Hexanal was most abundant (37.7%) in one variety (Petite Perfection) [corrected] The most abundant ketone was 6-methyl-5-hepten-2-one (2.7-7.7%). Some sensory attributes reported for these compounds are melon, citrus, cucumber, orange, rose, floral, guava, violet, vegetable, green, grassy, herbaceous, pungent, fatty, sweet, and waxy. Identifying and relating these compounds to sensory attributes will allow for future monitoring of the critical flavor compounds in seedless watermelon after processing and throughout fresh-cut storage.

  4. In-Vial Temperature Gradient Headspace Single Drop Microextraction Designed by Multiphysics Simulation.

    PubMed

    Jahan, Sharmin; Zhang, Qiang; Pratush, Amit; Xie, Haiyang; Xiao, Hua; Fan, Liuyin; Cao, Chengxi

    2016-11-01

    Presented herein is a novel headspace single drop microextraction (HS-SDME) based on temperature gradient (TG) for an on-site preconcentration technique of volatile and semivolatile samples. First, an inner vial cap was designed as a cooling device for acceptor droplet in HS-SDME unit to achieve fast and efficient microextraction. Second, for the first time, an in-vial TG was generated between the donor phase in a sample vial at 80 °C and the acceptor droplet under the inner vial cap containing cooling liquid at -20 °C for a TG-HS-SDME. Third, a simple mathematic model and numerical simulations were developed by using heat transfer in fluids, Navier-Stokes and mass balance equations for conditional optimization, and dynamic illumination of the proposed extraction based on COMSOL Multiphysics. Five chlorophenols (CPs) were selected as model analytes to authenticate the proposed method. The comparisons revealed that the simulative results were in good agreement with the quantitative experiments, verifying the design of TG-HS-SDME via the numerical simulation. Under the optimum conditions, the extraction enrichments were improved from 302- to 388-fold within 2 min only, providing 3.5 to 4 times higher enrichment factors as compared to a typical HS-SDME. The simulation indicated that these improvements in the extraction kinetics could be attributed due to the applied temperature gap between the sample matrix and acceptor droplet within the small volume of headspace. Additionally, the experiments demonstrated a good linearity (0.03-100 μg/L, R(2) > 0.9986), low limit of detection (7-10 ng/L), and fair repeatability (<5.9% RSD, n = 6). All of the simulative and experimental results indicated the robustness, precision, and usefulness of TG-HS-SDME for trace analyses of analytes in a wide variety of environmental, pharmaceutical, food safety, and forensic samples.

  5. Application of single-drop microextraction and comparison with solid-phase microextraction and solid-phase extraction for the determination of alpha- and beta-endosulfan in water samples by gas chromatography-electron-capture detection.

    PubMed

    López-Blanco, M C; Blanco-Cid, S; Cancho-Grande, B; Simal-Gándara, J

    2003-01-17

    Water contamination due to the wide variety of pesticides used in agriculture practices is a global environmental pollution problem. The 98/83 European Directive requires the measurement of pesticides residues at a target concentration of 1.0 microg/l in surface water and 0.1 microg/l in drinking water. In order to reach the level of detection required, efficient extraction techniques are necessary. The application of a new extraction technique: single-drop microextraction (SDME), followed by gas chromatography with electron-capture detection, was assessed for determining alpha-endosulfan and beta-endosulfan in water samples. Experimental parameters which control the performance of SDME, such as selection of microextraction solvent and internal standard, optimization of organic drop volume, effects of sample stirring, temperature and salt addition, and sorption time profiles were studied. Once SDME was optimized, analytical parameters such as linearity, precision, detection and quantitation limits, plus matrix effects were evaluated. The SDME method was compared with solid-phase microextraction and solid-phase extraction with the aim of selecting the most appropriate method for a certain application.

  6. Identification of dimethoate-containing water using partitioned dispersive liquid-liquid microextraction coupled with near-infrared spectroscopy.

    PubMed

    Zhang, Ming; Geng, Ying; Xiang, Bingren

    2011-01-01

    A simple, rapid and efficient extraction procedure, partitioned dispersive liquid-liquid microextraction, has been developed in combination with near-infrared spectroscopy for the extraction and discrimination of dimethoate from aqueous samples. For this technique, the appropriate mixture of extraction solvent (CCl(4)) and disperser solvent (THF) was utilized. Partial least squares discriminant analysis was applied to build the model with several pre-process methods over the wavenumber regions between 7100 cm(-1) to 7300 cm(-1). The best model gave satisfactory classification accuracy, 98.6% for calibration set (n=74) and 97.6% for prediction set (n=42), using preprocessing of standard normal variate followed by Savitzky-Golay first derivative. The method was successfully applied to bottled water, tap water, lake water and farm water samples. The results demonstrated the possibility of near-infrared spectroscopy after partitioned dispersive liquid-liquid microextraction for the identification of water contaminated by dimethoate.

  7. Fuel spill identification using solid-phase extraction and solid-phase microextraction. 1. Aviation turbine fuels.

    PubMed

    Lavine, B K; Brzozowski, D M; Ritter, J; Moores, A J; Mayfield, H T

    2001-12-01

    The water-soluble fraction of aviation jet fuels is examined using solid-phase extraction and solid-phase microextraction. Gas chromatographic profiles of solid-phase extracts and solid-phase microextracts of the water-soluble fraction of kerosene- and nonkerosene-based jet fuels reveal that each jet fuel possesses a unique profile. Pattern recognition analysis reveals fingerprint patterns within the data characteristic of fuel type. By using a novel genetic algorithm (GA) that emulates human pattern recognition through machine learning, it is possible to identify features characteristic of the chromatographic profile of each fuel class. The pattern recognition GA identifies a set of features that optimize the separation of the fuel classes in a plot of the two largest principal components of the data. Because principal components maximize variance, the bulk of the information encoded by the selected features is primarily about the differences between the fuel classes.

  8. Hollow-fiber liquid-phase microextraction combined with capillary electrophoresis for trace analysis of sulfonamide compounds.

    PubMed

    Tong, Fanghong; Zhang, Yang; Chen, Fang; Li, Ying; Ma, Guanhua; Chen, Yanping; Liu, Kun; Dong, Jiaming; Ye, Jiannong; Chu, Qingcui

    2013-12-30

    A hollow-fiber liquid-phase microextraction (HF-LPME) method has been developed for the preconcentration of trace sulfonamides in water samples. Six commonly used sulfonamides including sulfamethazine (SMZ), sulfamerazine (SMR), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and sulfathiazole (STZ) were determined by CE with electrochemical detection (CE-ED) after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, above sulfonamide compounds could achieve baseline separation within 35min, exhibiting a linear calibration over three orders of magnitude (r(2)≥0.998); the obtained enrichment factors were between 121 (for SDZ) and 996 (for SDM), and the LODs were in the range of 0.033-0.44ng/mL. The proposed HF-LPME/CE-ED method has been applied for the sensitive analyses of the real-world water samples with recoveries in the range of 75.1-109%.

  9. Determination of organochlorine pesticides in snow water samples by low density solvent based dispersive liquid-liquid microextraction.

    PubMed

    Zhao, Wenting; Li, Jindong; Wu, Tong; Wang, Peng; Zhou, Zhiqiang

    2014-09-01

    A simple, rapid, efficient, and environmentally friendly pretreatment based on a low-density solvent based dispersive liquid-liquid microextraction was developed for determining trace levels of 17 organochlorine pesticides in snow. The parameters affecting the extraction efficiency, such as the type and volume of the extraction and dispersive solvents, extraction time, and salt content, were optimized. The optimized conditions yielded a good performance, with enrichment factors ranging from 271 to 474 and recoveries ranging from 71.4 to 114.5% and relative standard deviations between 1.6 and 14.8%. The detection limits, calculated as three times the signal-to-noise ratio, ranged from 0.02 to 0.11 μg/L. The validated method was used to successfully analyze 17 analytes in snow water samples, overcoming the drawbacks of some existing low-density solvent liquid microextraction methods, which require special devices, large volumes of organic solvents, or complicated operation procedures.

  10. Automated hollow-fiber liquid-phase microextraction followed by liquid chromatography with mass spectrometry for the determination of benzodiazepine drugs in biological samples.

    PubMed

    Nazaripour, Ali; Yamini, Yadollah; Ebrahimpour, Behnam; Fasihi, Javad

    2016-07-01

    In this study, two-phase hollow-fiber liquid-phase microextraction and three-phase hollow-fiber liquid-phase microextraction based on two immiscible organic solvents were compared for extraction of oxazepam and Lorazepam. Separations were performed on a liquid chromatography with mass spectrometry instrument. Under optimal conditions, three-phase hollow-fiber liquid-phase microextraction based on two immiscible organic solvents has a better extraction efficiency. In a urine sample, for three-phase hollow fiber liquid-phase microextraction based on two immiscible organic solvents, the calibration curves were found to be linear in the range of 0.6-200 and 0.9-200 μg L(-1) and the limits of detection were 0.2 and 0.3 μg L(-1) for oxazepam and lorazepam, respectively. For two-phase hollow fiber liquid-phase microextraction, the calibration curves were found to be linear in the range of 1-200 and 1.5-200 μg L(-1) and the limits of detection were 0.3 and 0.5 μg L(-1) for oxazepam and lorazepam, respectively. In a urine sample, for three-phase hollow-fiber-based liquid-phase microextraction based on two immiscible organic solvents, relative standard deviations in the range of 4.2-4.5% and preconcentration factors in the range of 70-180 were obtained for oxazepam and lorazepam, respectively. Also for the two-phase hollow-fiber liquid-phase microextraction, preconcentration factors in the range of 101-257 were obtained for oxazepam and lorazepam, respectively.

  11. Tandem air-agitated liquid-liquid microextraction as an efficient method for determination of acidic drugs in complicated matrices.

    PubMed

    Bazregar, Mohammad; Rajabi, Maryam; Yamini, Yadollah; Asghari, Alireza; Hemmati, Maryam

    2016-04-21

    A rapid and simple microextraction method with a high sample clean-up, termed as tandem air-agitated liquid-liquid microextraction (TAALLME), is described. This method is based upon the tandem implementation of the air-agitated liquid-liquid microextraction (AALLME), and this approach improves the applicability of the dispersive liquid-liquid microextraction (DLLME) methods in complicated matrices. With very simple tools, the three non-steroidal anti-inflammatory drugs diclofenac, ibuprofen, and mefenamic acid were efficiently extracted, with an overall extraction time of 7 min. By performing the first AALLME, these acidic analytes, contained in an aqueous sample solution (donor phase, 8.0 mL), were extracted into the organic solvent (1,2-dichloroethane, 37 μL), and their simple back-extraction into the aqueous acceptor solution (pH, 10.01, 51 μL) was obtained in 2 min by a second implementation of AALLME. Response surface methodology (RSM) was used for optimization of the experimental parameters. The pH values 2.94 and 10.01 were obtained for the donor and acceptor phases, respectively, and the volumes 99.5 and 51 μL were obtained for the organic solvent and the acceptor phase, respectively, as the optimal extraction conditions. Under the optimized conditions, tandem AALLME-HPLC-UV provided a good linearity in the range of 0.5-4000 ng mL(-1), limits of detection (0.1-0.3 ng mL(-1)), extraction repeatabilities (relative standard deviations (RSDs) below 7.7%, n = 5), and the enrichment factors (EFs) of 80-104. Finally, the applicability of the proposed method was evaluated by the extraction and determination of the drugs under study in the wastewater and human plasma samples.

  12. Dynamic microwave-assisted extraction online coupled with single drop microextraction of organophosphorus pesticides in tea samples.

    PubMed

    Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

    2015-08-14

    A new method for the determination of seven organophosphorus pesticides was developed using dynamic microwave-assisted extraction online coupled with single drop microextraction prior to gas chromatographic mass spectrometry (GC-MS). The method combines the advantages of dynamic microwave-assisted extraction and single-drop microextraction, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, tea samples were extracted with 25% ethanol aqueous solution and purified with acidic alumina at the same time, and then the analytes were concentrated into microextraction solvent. When the extraction was completed, the solvent microdrop containing the enriched analytes was retracted into the microsyringe and directly analyzed by GC-MS without any filtration or cleanup step. The method makes extraction, cleanup, separation, and enrichment to be carried out in one step. Several experimental parameters, including type of extraction solvent, type and amount of dispersant, type and volume of microextraction solvent, microwave power, extraction time, and flow rate of extraction solvent were investigated and optimized. Under optimal experimental conditions, good linearity was observed in the range of 2.00-500.00 μg kg(-1). The limits of detection and quantification were in the range of 0.4-1.7 μg kg(-1) and 1.1-5.6 μg kg(-1), respectively. The present method was applied to the analysis of tea samples, and the recoveries of analytes were in the range of 84.9-106.4% with the relative standard deviations ranging from 1.0 to 6.1%. The results showed that the present method was a rapid and feasible method for the determination of organophosphorus pesticides in tea samples.

  13. Solid phase microextraction, sand flies, oviposition pheromones, plaster of Paris and siloxanes-What is in common?

    PubMed

    Goulart, Thais Marchi; Tosta, Christiann Davis; Machado, Vicente Estevam; da Rocha Silva, Flávia Benini; de Castro, Camila Feitosa; Ortiz, Dennys Ghenry Samillan; Oliveira, Wanderson Henrique Cruz; Pinto, Mara Cristina

    2017-04-01

    Sand flies are natural hosts of various microorganisms. Due to their epidemiological importance, sand fly colonies are kept in laboratories to be studied in terms of their biology and vector/host/parasite interactions. In order to investigate the presence of oviposition pheromones in Nyssomyia neivai, experiments using Solid Phase Microextraction (SPME) were performed. However, siloxanes which is an external class of contamination, present in breeding containers made by plaster used to maintain sand flies in colonies, may be hindered the experiments.

  14. A passive microfluidic system based on step emulsification allows the generation of libraries of nanoliter-sized droplets from microliter droplets of varying and known concentrations of a sample.

    PubMed

    Postek, W; Kaminski, T S; Garstecki, P

    2017-03-29

    We present a novel geometry of microfluidic channels that allows us to passively generate monodisperse emulsions of hundreds of droplets smaller than 1 nL from collections of larger (ca. 0.4 μL) mother droplets. We introduce a new microfluidic module for the generation of droplets via passive break-up at a step. The module alleviates a common problem in step emulsification with efficient removal of the droplets from the vicinity of the step. In our solution, the droplets are pushed away from the step by a continuous liquid that bypasses the mother droplets via specially engineered bypasses that lead to the step around the main channel. We show that the bypasses tighten the distribution of volume of daughter droplets and eliminate subpopulations of daughter droplets. Clearing away the just produced droplets from the vicinity of the step provides for similar conditions of break-up for every subsequent droplet and, consequently, leads to superior monodispersity of the generated emulsions. Importantly, this function is realized autonomously (passively) in a protocol in which only a sequence of large mother droplets is forced through the module. Our system features the advantage of step emulsification systems in that the volumes of the generated droplets depend very weakly on the rate of flow through the module - an increase in the flow rate by 300% causes only a slight increase of the average diameter of generated droplets by less than 5%. We combined our geometry with a simple T-junction and a simple trap-based microdroplet dilutor to produce a collection of libraries of droplets of gradually changing and known concentrations of a sample. The microfluidic system can be operated with only two syringe pumps set at constant rates of flow during the experiment.

  15. Vortex-assisted liquid-liquid microextraction for the rapid screening of short-chain chlorinated paraffins in water.

    PubMed

    Chang, Chia-Yu; Chung, Wu-Hsun; Ding, Wang-Hsien

    2016-01-01

    The rapid screening of trace levels of short-chain chlorinated paraffins in various aqueous samples was performed by a simple and reliable procedure based on vortex-assisted liquid-liquid microextraction combined with gas chromatography and electron capture negative ionization mass spectrometry. The optimal vortex-assisted liquid-liquid microextraction conditions for 20 mL water sample were as follows: extractant 400 μL of dichloromethane; vortex extraction time of 1 min at 2500 × g; centrifugation of 3 min at 5000 × g; and no ionic strength adjustment. Under the optimum conditions, the limit of quantitation was 0.05 μg/L. Precision, as indicated by relative standard deviations, was less than 9% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was above 91%. The vortex-assisted liquid-liquid microextraction with gas chromatography and electron capture negative ionization mass spectrometry method was successfully applied to quantitatively extract short-chain chlorinated paraffins from samples of river water and the effluent of a wastewater treatment plant, and the concentrations ranged from 0.8 to 1.6 μg/L.

  16. Highly porous nanostructured copper foam fiber impregnated with an organic solvent for headspace liquid-phase microextraction.

    PubMed

    Saraji, Mohammad; Ghani, Milad; Rezaei, Behzad; Mokhtarianpour, Maryam

    2016-10-21

    A new headspace liquid-phase microextraction technique based on using a copper foam nanostructure substrate followed by gas chromatography-flame ionization detection was developed for the determination of volatile organic compounds in water and wastewater samples. The copper foam with highly porous nanostructured walls was fabricated on the surface of a copper wire by a rapid and facile electrochemical process and used as the extractant solvent holder. Propyl benzoate was immobilized in the pores of the copper foam coating and used for the microextraction of benzene, toluene, ethylbenzene and xylenes. The experimental parameters such as the type of organic solvent, desorption temperature, desorption time, salt concentration, sample temperature, equilibrium time and extraction time, were investigated and optimized. Under the optimum conditions, the method detection limit was between 0.06 and 0.25μgL(-1). The relative standard deviation of the method for the analytes at 4-8μgL(-1) concentration level ranged from 7.9 to 11%. The fiber-to-fiber reproducibility for three fibers prepared under the same condition was 9.3-12%. The enrichment factor was in the range of 615-744. Different water samples were analyzed for the evaluation of the method in real sample analysis. Relative recoveries for spiked tap, river and wastewater samples were in the range of 85-94%. Finally, the extraction efficiency of the method was compared with those of headspace single drop microextraction and headspace SPME with the commercial fibers.

  17. Determination of salmeterol in dried blood spot using an ionic liquid based dispersive liquid-liquid microextraction coupled with HPLC.

    PubMed

    Hatami, Mehdi; Karimnia, Elham; Farhadi, Khalil

    2013-11-01

    A novel analytical method based on the use of a modified dispersive liquid-liquid microextraction (DLLME) technique by ionic liquids has been developed for the first time. This method was applied for the determination of salmeterol in dried blood spot samples from asthmatic patients followed by HPLC system equipped with fluorescence detector. The main novelty of the present work deals with the analysis of salmeterol in dried blood spot with significant advantages with regard to invasive sampling, volume of blood used (<20 μL), storage and transport of biological materials and requirements for special biohazard arrangements. The effects of significant factors in microextraction procedure including extracting and disperser solvents volume, sample pH and salt contents were investigated. Under optimized conditions, the mean recoveries were higher than 90.0% with linear responses about 1.00-500 ng mL(-1) concentration range. The limit of detection (LOD) was 0.30 ng mL(-1) in S/N of 3. Intra-day (n=6) and inter-day (n=3) assay precision showed relative standard deviation lower than 6.0 and 8.5% for studied drug, respectively. The developed microextraction procedure was simpler and faster than conventional extraction techniques and was omitted hazard organic solvents. Finally, the proposed method is suitable for the analysis of salmeterol in dried blood spots from asthmatic patients for therapeutic drug monitoring purpose.

  18. Study of enrichment factors for six β-blockers in aliphatic alcohols by hollow-fiber liquid-phase microextraction.

    PubMed

    Li, Qing-Lian; Jing, Shao-Jun; Zhang, Jin-Feng; Zhang, Lin; Ran, Cong-Cong; Du, Chao-Hui; Jiang, Ye

    2015-10-01

    The selectivity of a suitable organic solvent is key for extraction in liquid-phase microextraction experiments. Nevertheless, the screening process remains a daunting task. Our research aimed to study the relationship between extraction efficiency and extraction solvents, analytes, and finally select the appropriate extraction solvent. In the present article, β-blockers and six extraction solvents were chosen as the models and hollow-fiber liquid-phase microextraction was conducted. The relationship was built by statistical analysis on the data. Factors affecting extraction efficiency including the logarithms of the octanol/water partition coefficient (logPo/w ) of analytes, acid dissociation constants, the logarithms of the octanol/water partition coefficient of solvents and pH of the sample solution were investigated. The results showed that a low water solubility of extraction solvent is the foundation to ensure higher extraction efficiency. Moreover, when ΔlogPo/w > 0, a higher extraction efficiency is observed at lower ΔlogPo/w , on the contrary, when ΔlogPo/w < 0, extraction efficiency is higher as the absolute value of ΔlogPo/w becomes greater. Finally, the relationship between enrichment factor and extraction solvents, analytes was established and a helpful guidance was provided for the selection of an optimal solvent to obtain the best extraction efficiency by liquid-phase microextraction.

  19. Introduction of a coiled solid-phase microextraction fiber based on a coating of animal bone waste for chromatographic analysis.

    PubMed

    Razmi, Habib; Farrokhzadeh, Samaneh

    2017-03-07

    We attempt to introduce animal bone waste as a coating material with an organic-inorganic structure for the fabrication of a coiled solid-phase microextraction fiber for the first time. The coiled fiber was simply prepared with the use of copper wire and coated with bone waste suspension through the dip-coating method. The bone waste coating was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. It was applied as new type of solid-phase microextraction fiber for preconcentration of polycyclic aromatic hydrocarbons before determination by high-performance liquid chromatography with UV detection. A wide linear range 0.01-99.0 μg/L and limits of detection in the range 3.0-11.1 ng/L were obtained at optimized conditions. The bone waste coated coiled solid-phase microextraction fiber has promise in sample preparation techniques because it is cost effective, available, stable in aqueous and organic solutions, environmentally friendly, and easy to fabricate and operate.

  20. Graphene-sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii.

    PubMed

    Xing, Rongrong; Hu, Shuang; Chen, Xuan; Bai, Xiaohong

    2014-09-01

    A novel graphene-sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high-performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99-104%) and precision (1.1-10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii.

  1. Microextraction techniques for the non-chromatographic speciation of ultratraces of elements in waters: some significant cases

    NASA Astrophysics Data System (ADS)

    Lopez-Garcia, Ignacio; Vicente-Martinez, Yesica; Hernandez-Cordoba, Manuel; Martínez-Sanchez, Maria Jose; Perez-Sirvent, Carmen

    2015-04-01

    The speciation of very low concentrations of some elements in waters is of interest due to the different behaviour and toxicity the species can have. This task can be carried out by using liquid chromatographic techniques (LC) for separation together with inductively coupled plasma mass spectrometry (ICP-MS) for detection. However, this combination is not easily available in all laboratories mainly due to the relative high cost of acquisition and maintenance of the ICP-MS spectrometer, and so other alternatives are of practical interest. Present knowledge of microextraction techniques involving minimal (or none) amounts of organic solvents allows, in some cases, speciation to be carried out without the need of such an expensive instrument, and even avoiding the use of a chromatographic stage. The selectivity of the separation (fractionation or speciation) can be achieved by modifying the experimental conditions used for microextraction, and a sensitive final measurement be obtained by means of electrothermal atomic absorption spectrometry (ETAAS). In this way, since an ETAAS instrument is common (and sometimes underused) in all laboratories, the speciation procedures are made available to most laboratories worldwide. The high preconcentration factor achieved by means of the microextraction stage together with the high sensitivity inherent in ETAAS measurements result in extremely sensitive methods that permit the speciation at ultratrace levels. The advantages of this methodology are presented by discussing speciation of chromium and arsenic as representative examples.

  2. Determination of arsenic and selenium by hydride generation and headspace solid phase microextraction coupled with optical emission spectrometry

    NASA Astrophysics Data System (ADS)

    Tyburska, Anna; Jankowski, Krzysztof; Rodzik, Agnieszka

    2011-07-01

    A hydride generation headspace solid phase microextraction technique has been developed in combination with optical emission spectrometry for determination of total arsenic and selenium. Hydrides were generated in a 10 mL volume septum-sealed vial and subsequently collected onto a polydimethylsiloxane/Carboxen solid phase microextraction fiber from the headspace of sample solution. After completion of the sorption, the fiber was transferred into a thermal desorption unit and the analytes were vaporized and directly introduced into argon inductively coupled plasma or helium microwave induced plasma radiation source. Experimental conditions of hydride formation reaction as well as sorption and desorption of analytes have been optimized showing the significant effect of the type of the solid phase microextraction fiber coating, the sorption time and hydrochloric acid concentration of the sample solution on analytical characteristics of the method developed. The limits of detection of arsenic and selenium were 0.1 and 0.8 ng mL - 1 , respectively. The limit of detection of selenium could be improved further using biosorption with baker's yeast Saccharomyces cerevisiae for analyte preconcentration. The technique was applied for the determination of total As and Se in real samples.

  3. Enzymatic single-drop microextraction for the assay of ethanol in alcohol-free cosmetics using microvolume fluorospectrometry detection.

    PubMed

    Cabaleiro, Noelia; de la Calle, Inmaculada; Bendicho, Carlos; Lavilla, Isela

    2012-07-06

    A green assay based on the development of an enzymatic reaction in drop format under headspace single-drop microextraction conditions is described for the first time. An aqueous drop containing the enzyme alcohol dehydrogenase and the cofactor β-Nicotinamide adenine dinucleotide has been used as fluorescence probe for determining ethanol in alcohol-free cosmetics by microvolume fluorospectrometry. Experimental parameters affecting the microextraction performance were carefully optimized. Under the conditions employed, the contribution of other alcohols was found to be negligible. After 10 min of microextraction, a detection limit of 0.04 μg g(-1) ethanol, a repeatability, expressed as relative standard deviation, of 5.3% for a 0.05 mM ethanol standard and a preconcentration factor of 391, were reached. Accuracy of the proposed methodology was evaluated by comparison of calibration slopes corresponding to external calibration with aqueous standards and standard addition calibration. The method was successfully applied to different alcohol-free cosmetics (external calibration was carried out in all cases). Additional advantages such as simplicity and high sample throughput can be highlighted. The greenness profile of proposed methodology was established using NEMI criteria (US National Environmental Methods Index).

  4. Comparison of three different solid-phase microextraction fibres for analysis of essential oils in yacon (Smallanthus sonchifolius) leaves.

    PubMed

    Adam, M; Juklová, M; Bajer, T; Eisner, A; Ventura, K

    2005-08-19

    A headspace solid-phase microextraction (HS-SPME) procedure based on three commercialised fibers (100 microm polydimethylsiloxane, 65 microm polydimethylsiloxane-divinylbenzene and 50/30 microm divinylbenzene-Carboxen-polydimethylsiloxane) is presented for the determination of a selected essential oils in dried leaves of yacon (Smallanthus sonchifolius). The extraction performances of these compounds were compared using fibers with one, two and three coatings. The optimal experimental procedures for the adsorption and desorption of target compounds were determined. Significant parameters affecting sorption process such as sample weight, sorption and desorption time and temperature were optimised and discussed. Finally, the optimised procedures were applied successfully for the determination of these compounds in various yacon species. The relative concentration factors of three characteristic components of yacon were measured for relative evaluation of the fiber efficiency. Main essential oils were isolated from dried yacon leaves by appropriate solid-phase microextraction fiber and semi-quantitative analysis of the target volatiles was conducted by gas chromatography-flame ionisation detection (GC-FID) using a capillary column. Three compounds--beta-pinene, caryophylene and y-cadinene were found as the predominant essential oils. Its relative content was important for specification of yacon varieties. Solid-phase microextraction in combination with gas chromatography enabled a rapid and simple determination of relative content of essential oils in yacon.

  5. Multi-walled carbon nanotube-impregnated agarose film microextraction of polycyclic aromatic hydrocarbons in green tea beverage.

    PubMed

    Loh, Saw Hong; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Hasan, Mohamed Noor

    2013-03-15

    A new microextraction procedure termed multi-walled carbon nanotube-impregnated agarose film microextraction (MWCNT-AFME) has been developed. The method utilized multi-walled carbon nanotubes (MWCNTs) immobilized in agarose film to serve as adsorbent in solid phase microextraction (SPME). The film was prepared by mixing the MWCNTs in agarose solution and drying the mixture in oven. Extraction of selected polycyclic aromatic hydrocarbons was performed by inserting a needle through circular MWCNT-impregnated agarose films (5 mm diameter) and the assembly was dipped into an agitated sample solution prior to micro high performance liquid chromatography-ultraviolet analysis. Back extraction was then performed using ultrasonication of the films in 100 μL of solvent. The film was discarded after single use, thus avoiding any analyte carry-over effect. Due to the mesoporous nature of the agarose film, the MWCNTs were immobilized easily within the film and thus allowing for close contact between adsorbent and analytes. Under the optimized extraction conditions, the technique achieved trace LODs in the range of 0.1 to 50 ng L(-1) for the targeted analytes, namely fluoranthene, phenanthrene and benzo[a]pyrene. The method was successfully applied to the analysis of spiked green tea beverage samples with good relative recoveries in the range of 91.1 to 107.2%. The results supported the feasibility of agarose to serve as adsorbent holder in SPME which then minimizes the consumption of chemicals and disposal cost of organic wastes.

  6. Ionic-liquid-based dispersive liquid-liquid microextraction for high-throughput multiple food contaminant screening.

    PubMed

    Ho, Yee-Man; Tsoi, Yeuk-Ki; Leung, Kelvin Sze-Yin

    2013-12-01

    This paper describes an innovation of dispersive liquid-liquid microextraction enabling multiple-component analysis of eight high-priority food contaminants in two chemically distinctive families: Sudan dyes and phthalate plasticizers. To provide convenient sample handling for solid and solid-containing matrices, a modified dispersive liquid-liquid microextraction procedure used an extractant precoated frit to perform simultaneous filtration, solvent mixing, and phase dispersion in one simple step. A binary ionic liquid extractant system was carefully tuned to deliver high quality analysis based only on affordable LC with diode array detector instrumentation. The method is comprehensively validated for robust quantification with good precision (6.9-9.8% RSD) in a linear 2-1000 μg/L range. Having accomplished enrichment factors up to 451, the treatment enables sensitive detection at 0.09-1.01 μg/L levels. Analysis of six high-risk solid condiments and sauces further verified its practical applicability within a 70-120% recovery range. Compared to other approaches, the current dispersive liquid-liquid microextraction treatment offers major advantages in terms of minimal solvent (1.5 mL) and sample (0.1 g) consumption, ultra-high analytical throughput (6 min), and the ability to handle complex solid matrices. The idea of performing simultaneous analysis for multiple contaminants presented here fosters a more effective mode of operation in food control routines.

  7. Combination of counter current salting-out homogenous liquid-liquid extraction and dispersive liquid-liquid microextraction as a novel microextraction of drugs in urine samples.

    PubMed

    Akramipour, Reza; Fattahi, Nazir; Pirsaheb, Meghdad; Gheini, Simin

    2016-02-15

    The counter current salting-out homogenous liquid-liquid extraction (CCSHLLE) joined with the dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) has been developed as a high preconcentration technique for the determination of different drugs in urine samples. Amphetamines were employed as model compounds to assess the extraction procedure and were determined by high performance liquid chromatography-ultraviolet detection (HPLC-UV). In this method, initially, NaCl as a separation reagent is filled into a small column and a mixture of urine and acetonitrile is passed through the column. By passing the mixture, NaCl is dissolved and the fine droplets of acetonitrile are formed due to salting-out effect. The produced droplets go up through the remained mixture and collect as a separated layer. Then, the collected acetonitrile is removed with a syringe and mixed with 30.0μL 1-undecanol (extraction solvent). In the second step, the 5.00mLK2CO3 solution (2% w/v) is rapidly injected into the above mixture placed in a test tube for further DLLME-SFO. Under the optimum conditions, calibration curves are linear in the range of 1-3000μgL(-1) and limit of detections (LODs) are in the range of 0.5-2μgL(-1). The extraction recoveries and enrichment factors ranged from 78 to 84% and 157 to 168, respectively. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100μgL(-1) of amphetamines were in the range of 3.5-4.5% and 4-5%, respectively. The method was successfully applied for the determination of amphetamines in the actual urine samples. The relative recoveries of urine samples spiked with amphetamine and methamphetamine are 90-108%.

  8. Ionic liquid-mediated sol-gel coatings for capillary microextraction.

    PubMed

    Shearrow, Anne M; Harris, Glenn A; Fang, Li; Sekhar, Praveen K; Nguyen, Ly T; Turner, Erica B; Bhansali, Shekhar; Malik, Abdul

    2009-07-17

    Ionic liquid (IL)-mediated sol-gel hybrid organic-inorganic materials present enormous potential for effective use in analytical microextraction. This opportunity, however, has not yet been explored. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol-gel reactions. In this work, we developed a method that overcomes this hurdle and provides IL-mediated advanced sol-gel materials for capillary microextraction (CME). We examined two different ILs: (a) a phosphonium-based IL, trihexyltetradecylphosphonium tetrafluoroborate, and (b) a pyridinium-based ionic liquid, N-butyl-4-methylpyridinium tetrafluoroborate. These ILs were evaluated in conjunction with two types of hydroxy-terminated polymers: (a) two Si-OH terminated polymers (PDMS and BMPO), and (b) two C-OH terminated polymers (PEG and polyTHF) that differ in their sol-gel reactivity. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol-gel reactions. The IL-mediated sol-gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions in off-line CME-GC compared to analogous sol-gel coatings prepared without any IL in the sol solution. Contrary to this, the IL-mediated sol-gel coatings prepared with C-OH terminated polymers provided lower extraction efficiencies compared to their IL-free counterparts. These observations were explained by (a) lower sol-gel reactivity of C-OH groups in PEG and polyTHF compared to Si-OH groups in PDMS and in hydrolyzed alkoxysilane precursors and (b) extremely high viscosity of ionic liquids. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol-gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol-gel material to be able to provide the desired sorbent characteristics

  9. Hollow fiber-liquid-phase microextraction of fungicides from orange juices.

    PubMed

    Barahona, Francisco; Gjelstad, Astrid; Pedersen-Bjergaard, Stig; Rasmussen, Knut Einar

    2010-03-26

    Liquid-phase microextraction (LPME) based on polypropylene hollow fibers was evaluated for the extraction of the post-harvest fungicides thiabendazole (TBZ), carbendazim (CBZ) and imazalil (IMZ) from orange juices. Direct LPME was performed without any sample pretreatment prior to the extraction, using a simple home-built equipment. A volume of 500 microL of 840 mM NaOH was added to 3 mL of orange juice in order to compensate the acidity of the samples and to adjust pH into the alkaline region. Analytes were extracted in their neutral state through a supported liquid membrane (SLM) of 2-octanone into 20 microL of a stagnant aqueous solution of 10 mM HCl inside the lumen of the hollow fiber. Subsequently, the acceptor solution was directly subjected to analysis. Capillary electrophoresis (CE) was used during the optimization of the extraction procedure. Working under the optimized extraction conditions, LPME effectively extracted the analytes from different orange juices, regardless of different pH or solid material (pulp) present in the sample, with recoveries that ranged between 17.0 and 33.7%. The analytical performance of the method was evaluated by liquid chromatography coupled with mass spectrometry (LC/MS). This technique provided better sensitivity than CE and permitted the detection below the microg L(-1) level. The relative standard deviations of the recoveries (RSDs) ranged between 3.4 and 10.6%, which are acceptable values for a manual microextraction technique without any previous sample treatment, using a home-built equipment and working under non-equilibrium conditions (30 min extraction). Linearity was obtained in the range 0.1-10.0 microg L(-1), with r=0.999 and 0.998 for TBZ and IMZ, respectively. Limits of detection were below 0.1 microg L(-1) and are consistent with the maximum residue levels permitted for pesticides in drinking water, which is the most restrictive regulation applicable for these kinds of samples. It has been demonstrated the

  10. Preparation of Al2O3/TiO2 composite sol-gel fiber for headspace solid-phase microextraction of chlorinated organic solvents from urine.

    PubMed

    Farhadi, Khalil; Maleki, Ramin; Tahmasebi, Raheleh

    2011-07-01

    A new solid-phase microextraction fiber based on alumina/titania sol-gel-coated on copper wire for headspace sampling of chlorinated organic solvents (chloroform, carbon tetrachloride, trichloroethene, and tetrachloroethene) from urine samples is introduced. The influences of fiber coating composition and microextraction conditions (extraction temperature, extraction time, and ionic strength of the sample matrix) on the fiber performance were investigated. Also, the influence of temperature and time on desorption of analytes from fiber was studied. The proposed fiber has high capacity and demonstrates fast sampling of chlorinated organic solvents from urine samples with high sensitivity. The relative standard deviation (RSD, n=5) for all analytes was below 6.5%.

  11. Applications of Experimental Design to the Optimization of Microextraction Sample Preparation Parameters for the Analysis of Pesticide Residues in Fruits and Vegetables.

    PubMed

    Abdulra'uf, Lukman Bola; Sirhan, Ala Yahya; Tan, Guan Huat

    2015-01-01

    Sample preparation has been identified as the most important step in analytical chemistry and has been tagged as the bottleneck of analytical methodology. The current trend is aimed at developing cost-effective, miniaturized, simplified, and environmentally friendly sample preparation techniques. The fundamentals and applications of multivariate statistical techniques for the optimization of microextraction sample preparation and chromatographic analysis of pesticide residues are described in this review. The use of Placket-Burman, Doehlert matrix, and Box-Behnken designs are discussed. As observed in this review, a number of analytical chemists have combined chemometrics and microextraction techniques, which has helped to streamline sample preparation and improve sample throughput.

  12. Solid-phase microextraction applied to the analysis of pesticide residues in honey using gas chromatography with electron-capture detection.

    PubMed

    Jiménez, J J; Bernal, J L; del Nozal, M J; Martín, M T; Mayorga, A L

    1998-12-31

    The possibilities of using solid-phase microextraction to determine residues of pesticides in honey have been examined. For this purpose, three types of fiber have been assayed: polyacrylate of 85 microns thickness, and polydimethylsiloxane of 7 and 100 microns thickness. They have been applied to the extraction of 21 pesticides of different chemical families. The effects of the temperature, extraction time and ionic strength on the microextraction have been studied, proposing the most adequate for each fiber. Under optimized conditions, precision, intervals of linearity and detection limits were evaluated.

  13. Low-density solvent-based dispersive liquid-liquid microextraction combined with single-drop microextraction for the fast determination of chlorophenols in environmental water samples by high performance liquid chromatography-ultraviolet detection.

    PubMed

    Li, Xiaoyi; Xue, Aifang; Chen, Hao; Li, Shengqing

    2013-03-08

    A new format of fast three-phase microextraction by combining low-density solvent-based dispersive liquid-liquid microextraction (DLLME) and single-drop microextraction (SDME) was for the first time developed for the determination of chlorophenols in environmental water samples. The extraction procedure includes a 2 min DLLME pre-extraction and a 10 min SDME back-extraction. A portion of low-density solvent (toluene) was used as organic phase and injected into the aqueous sample (donor phase) with methanol as disperser. The analytes were pre-extracted into the organic phase within 2 min. A thin layer of the organic phase formed on the top of the aqueous phase by a 2 min centrifugation. Then a drop of acceptor solution was introduced into the upper layer and SDME was carried out for the back-extraction. The stirring step typically involved in SDME and LLLME is avoided with the benefit of the high speed and efficiency of DLLME pre-extraction. After extraction, the acceptor drop was withdrawn and directly injected into a high performance liquid chromatography instrument with ultraviolet detection for analysis. Five chlorophenols, 4-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol, were selected as model compounds for developing and evaluating the method. Factors affecting extraction efficiency were studied, including the organic solvent, the disperser solvent, the composition of donor phase and acceptor phase, the volume of acceptor microdrop, and the extraction time. At optimal conditions, the method showed low detection limit (0.016-0.084 μg/L) for the five chlorophenols, good linearity (from 0.2-250 to 1.0-250 μg/L, depending on the analytes) and repeatability (RSD below 8.2, n=5). The simple, fast, and efficient feature of the proposed method was demonstrated by the analysis of chlorophenols in environmental water samples.

  14. Comparison of ultrasound-enhanced air-assisted liquid-liquid microextraction and low-density solvent-based dispersive liquid-liquid microextraction methods for determination of nonsteroidal anti-inflammatory drugs in human urine samples.

    PubMed

    Barfi, Behruz; Asghari, Alireza; Rajabi, Maryam; Goochani Moghadam, Ahmad; Mirkhani, Nasim; Ahmadi, Farhad

    2015-01-01

    Two dispersive-based liquid-liquid microextraction methods including ultrasound-enhanced air-assisted liquid-liquid microextraction (USE-AALLME) and low-density solvent-based dispersive liquid-liquid microextraction (LDS-DLLME) were compared for the extraction of salicylic acid (the hydrolysis product of acetylsalicylic acid), diclofenac and ibuprofen, as instances of the most commonly used nonsteroidal anti-inflammatory drugs (NSAIDs), in human urine prior to their determination by gas chromatography with flame ionization detection (GC-FID). The influence of different parameters affecting the USE-AALLME (including type and volume of the extraction solvent, sample pH, ionic strength, and simultaneous sonication and number of extraction cycles) and the LDS-DLLME (including type and volume of the extraction and disperser solvents, sample pH, and ionic strength) were investigated to optimize their extraction efficiencies. Both methods are fast, simple and convenient with organic solvent consumption at μL level. However, the best results were obtained using the USE-AALLME method, applying 30 μL of 1-octanol as extraction solvent, 5.0 mL of sample at pH 3.0, without salt addition, and 5 extraction cycles during 20s of sonication. This method was validated based on linearities (r(2) >0 .971), limits of detection (0.1-1.0 μg L(-1)), linear dynamic ranges (0.4-1000.0 μg L(-1)), enrichment factors (115 ± 3-135 ± 3), consumptive indices (0.043-0.037), inter- and intra-day precisions (4.3-4.8 and 5.6-6.1, respectively), and relative recoveries (94-103%). The USE-AALLME in combination with GC-FID, and with no need to derivatization step, was demonstrated to be a simple, inexpensive, sensitive and efficient method to determine NSAIDs in human urine samples.

  15. Comparison of hollow fiber liquid-phase microextraction and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of drugs of abuse in biological samples by gas chromatography-mass spectrometry.

    PubMed

    Meng, Liang; Zhang, Wenwen; Meng, Pinjia; Zhu, Binling; Zheng, Kefang

    2015-05-01

    Two microextraction techniques based on hollow fiber liquid-phase microextraction (HF-LPME) and ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) had been applied for the determination of drugs of abuse (methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, methcathinone, ketamine, meperidine, and methadone) in urine and blood samples by gas chromatography-mass spectrometry. Parameters affecting extraction efficiency have been investigated and optimized for both methods. Under the optimum conditions, linearities were observed for all analytes in the range 0.0030-10 μg/ml with the correlation coefficient (R) ranging from 0.9985 to 0.9995 for HF-LPME and in the range 0.0030-10 μg/ml with the R ranging from 0.9985 to 0.9994 for DLLME. The recovery of 79.3-98.6% with RSDs of 1.2-4.5% was obtained for HF-LPME, and the recovery of 79.3-103.4% with RSDs of 2.4-5.7% was obtained for DLLME. The LODs (S/N=3) were estimated to be in the range from 0.5 to 5 ng/ml and 0.5 to 4 ng/ml, respectively. Compared with HF-LPME, the UA-LDS-DLLME technique had the advantages of less extraction time, suitability for batches of sample pretreatment simultaneously, and higher extraction efficiency, while HF-LPME has excellent sample clean-up effect, and is a robust and suitable technique for various sample matrices with better repeatability. Both methods were successfully applied to the analysis of drugs of abuse in real human blood sample.

  16. Comparison of air-agitated liquid-liquid microextraction technique and conventional dispersive liquid-liquid micro-extraction for determination of triazole pesticides in aqueous samples by gas chromatography with flame ionization detection.

    PubMed

    Farajzadeh, Mir Ali; Mogaddam, Mohammad Reza Afshar; Aghdam, Abdollah Abdollahi

    2013-07-26

    Two micro-extraction methods, air-agitated liquid-liquid microextraction (AALLME) and dispersive liquid-liquid microextraction (DLLME), have been compared with each other by applying them for the analysis of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole and triticonazole) in aqueous samples by gas chromatography with flame ionization detection (GC-FID). In the AALLME method, which excludes any disperser solvent, much less volume of organic solvent is used. In order to form fine and dispersed organic droplets in the aqueous phase, the mixture of aqueous sample solution and extraction solvent is repeatedly aspirated and dispensed with a syringe. In the DLLME method, an appropriate mixture of extraction solvent and disperser solvent is rapidly injected by a syringe into the aqueous sample. Effect of the pertinent experimental factors on DLLME (i.e. identity and volume of the extraction and disperser solvents and ionic strength) and on AALLME (identity and volume of the extraction solvent, number of agitations, and ionic strength) were investigated. Under optimal conditions, limits of detection for the five target pesticides obtained by AALLME-GC-FID and DLLME-GC-FID ranged from 0.20 to 1.1ngmL(-1) and 1.9 to 5.9ngmL(-1), respectively. The relative standard deviations (RSDs, n=5) were in the range of 1-4% and 3-5% with the enrichment factors of 449-504 and 79-143 for AALLME-GC-FID and DLLME-GC-FID, respectively. Both of the compared methods are simple, fast, efficient, inexpensive and can be applied to the analysis of the five pesticides in different aqueous samples in which penconazole and hexaconazole were found. For spiked samples, the recoveries were in the ranges of 92-105%, and 92-104% for AALLME and DLLME, respectively.

  17. Facile preparation and applications of graphitic carbon nitride coating in solid-phase microextraction.

    PubMed

    Xu, Na; Wang, Yiru; Rong, Mingcong; Ye, Zhifeng; Deng, Zhuo; Chen, Xi

    2014-10-17

    In this study, graphitic carbon nitride (g-C3N4) was used as a coating material for solid-phase microextraction (SPME) applications. Coupled to gas chromatography (GC), the extraction ability of the SPME fiber was investigated and compared with the commercial fibers of 100 μm PDMS and 85 μm CAR/PDMS using six target analytes including deltamethrin, nerolidol, amphetamine, dodecane, ametryn and acrylamide. The g-C3N4 coating revealed excellent extraction ability and durability comparing with those of the commercial fibers due to its loose structure and unique physicochemical properties. The repeatability for each single fiber was found to be 3.46% and reproducibility for fiber to fiber was 8.53%. The g-C3N4 SPME fiber was applied to the determination of acrylamide in potato chips, the linearity and detection limit was 0.5-250 μg g(-1) and 0.018 μg g(-1), respectively.

  18. Synthesis and characterization of titania hollow fiber and its application to the microextraction of trace metals.

    PubMed

    Huang, Chaozhang; Hu, Bin

    2011-04-07

    A titania hollow fiber membrane was successfully synthesized in a macro range via a template method coupled with a sol-gel process. Thermal gravimetric and differential thermal analysis (TG-DTA) was employed to study the effect of heat treatment on the synthesized hollow fiber, and the crystal forms of the titania hollow fiber membranes at different temperatures were studied by X-ray diffraction (XRD). The pore structure of the prepared titania hollow fiber was characterized by scanning electron micrograph (SEM) and nitrogen adsorption/desorption measurements. The prepared titania hollow fiber membrane was explored as a new adsorption material for trace metals for the first time and a new method of titania hollow fiber membrane solid phase microextraction (MSPME) online coupled to inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace amount of Cd, Co, V and Ni in human serum samples. In order to validate the developed method, two certified reference materials of NIES.No.10-b rice flour and BCR No.184 bovine muscle were analyzed and the determined values were in good agreement with the certified values.

  19. Solid-phase microextraction gas chromatography-mass spectrometry determination of fragrance allergens in baby bathwater.

    PubMed

    Lamas, J Pablo; Sanchez-Prado, Lucia; Garcia-Jares, Carmen; Llompart, Maria

    2009-07-01

    A method based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized for the determination of fragrance allergens in water samples. This is the first study devoted to this family of cosmetic ingredients performed by SPME. The influence of parameters such as fibre coating, extraction and desorption temperatures, salting-out effect and sampling mode on the extraction efficiency has been studied by means of a mixed-level factorial design, which allowed the study of the main effects as well as two-factor interactions. Excluding desorption temperature, the other parameters were, in general, very important for the achievement of high response. The final procedure was based on headspace sampling at 100 degrees C, using polydimethylsiloxane/divinylbenzene fibres. The method showed good linearity and precision for all compounds, with detection limits ranging from 0.001 to 0.3 ng mL(-1). Reliability was demonstrated through the evaluation of the recoveries in different real water samples, including baby bathwater and swimming pool water. The absence of matrix effects allowed the use of external standard calibration to quantify the target compounds in the samples. The proposed procedure was applied to the determination of allergens in several real samples. All the target compounds were found in the samples, and, in some cases, at quite high concentrations. The presence and the levels of these chemicals in baby bathwater should be a matter of concern.

  20. Carbonized polydopamine as coating for solid-phase microextraction of organochlorine pesticides.

    PubMed

    Huang, Zhenzhen; Chua, Pey Ee; Lee, Hian Kee

    2015-06-19

    A facile preparation route for coating a stainless steel fiber with carbonaceous material derived from polydopamine is reported in this work. The self-oxidation induced polymerization of dopamine in alkaline solution enables growth of polydopamine on the inert surface of the fiber. The robust adhesion of dopamine to metal oxides ensured sufficient stability of the polymer coating. After carbonization of the polymer coating, the obtained carbon coated fiber was utilized for solid-phase microextraction and exhibited effectiveness in the extraction of organochlorine pesticides (OCPs) from aqueous solution. Extraction time, agitation speed and salt addition were optimized. The possible interference of humic acid on the extraction of these analytes was also investigated. The results showed that most of the analytes could be detected efficiently in the presence of humic acid at a concentration of 20mg/L. Under the optimized conditions, enrichment factors of 102-757 were obtained for the selected OCPs in aqueous solution. The proposed method provided low limits of detection (1.4-15 ng/L), good linearity (correlation coefficients>0.9971) and acceptable precision (relative standard deviations<16.3%).

  1. Conductive polymeric ionic liquids for electroanalysis and solid-phase microextraction.

    PubMed

    Young, Joshua A; Zhang, Cheng; Devasurendra, Amila M; Tillekeratne, L M Viranga; Anderson, Jared L; Kirchhoff, Jon R

    2016-03-03

    Three novel electropolymerizable thiophene-based ionic liquids (ILs) were synthesized and characterized as potential candidates for developing selective extraction media for chemical analysis. Electropolymerization of the bis[(trifluoromethyl)sulfonyl]imide ([NTf2](-)) analogs successfully produced uniform polymeric thin-films on macro- and microelectrode substrates from both vinyl and methylimidazolium IL monomer derivatives. The resultant conducting polymer IL (CPIL) films were characterized by electrochemical methods and found to exhibit attractive behavior towards anionic species while simultaneously providing an exclusion barrier toward cationic species. Thermogravimetric analysis of the thiophene-based IL monomers established a high thermal stability, particularly for the methylimidazolium IL, which was stable until temperatures above 350 °C. Subsequently, the methylimidazolium IL was polymerized on 125 μm platinum wires and utilized for the first time as a sorbent coating for headspace solid-phase microextraction (HS-SPME). The sorbent coating was easily prepared in a reproducible manner, provided high thermal stability, and allowed for the gas chromatographic analysis of polar analytes. The normalized response of the poly[thioph-C6MIm][NTf2]-based sorbent coating exhibited higher extraction efficiency compared to an 85 μm polyacrylate fiber and excellent fiber-to-fiber reproducibility. Therefore, the electropolymerizable thiophene-based ILs were found to be viable new materials for the preparation of sorbent coatings for HS-SPME.

  2. Air sampling of aromatic hydrocarbons in the presence of ozone by solid-phase microextraction.

    PubMed

    Xiong, Gouhua; Koziel, Jacek A; Pawliszyn, Janusz

    2004-01-30

    Effects of ozone on air sampling of standard gas mixtures of aromatic hydrocarbons were tested using solid-phase microextraction (SPME). Standard concentrations of ozone ranging from 10 ppb (v/v) to 6400 ppm (v/v) were generated using an in-house built ozone generator based on corona discharge. Effects of temperature, discharge voltage, and oxygen flow on the ozone generation were tested. The working dc voltage had the greatest effect on generated ozone concentration and was proportional to the ozone concentration. Generation temperature and oxygen flow rate were inversely proportional to ozone concentrations. Produced ozone was mixed with standard benzene, toluene, ethylbenzene, and xylenes (BTEX) gas at less than 100 ppb (v/v). Air samples were collected with poly(dimethylsiloxane) (PDMS) 100 microm SPME fibers and analyzed by gas chromatography (GC)-flame ionization detection (FID) and GC-MS. Significant reductions of BTEX concentrations were observed. In addition, some products of BTEX-ozone-oxygen reactions were identified. SPME worked well as a rapid sampler for BTEX and BTEX-ozone-oxygen reaction products. No significant deterioration of the PDMS coating and no significant reduction of absorption capacity were observed after repeated exposure to ozone.

  3. Passive sampling of ambient ozone by solid phase microextraction with on-fiber derivatization.

    PubMed

    Lee, I-Su; Tsai, Shih-Wei

    2008-03-10

    The solid phase microextraction (SPME) device with the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used as a passive sampler for ambient ozone. Both O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) and 1,2-di-(4-pyridyl)ethylene (DPE) were loaded onto the fiber before sampling. The SPME fiber assembly was then inserted into a PTFE tubing as a passive sampler. Known concentrations of ozone around the ambient ground level were generated by a calibrated ozone generator. Laboratory validations of the SPME passive sampler with the direct-reading ozone monitor were performed side-by-side in an exposure chamber at 25 degrees C. After exposures, pyriden-4-aldehyde was formed due to the reaction between DPE and ozone. Further on-fiber derivatizations between pyriden-4-aldehyde and PFBHA were followed and the derivatives, oximes, were then determined by portable gas chromatography with electron capture detector. The experimental sampling rate of the SPME ozone passive sampler was found to be 1.10 x 10(-4) cm(3) s(-1) with detection limit of 58.8 microg m(-3) h(-1). Field validations with both SPME device and the direct-reading ozone monitor were also performed. The correlations between the results from both methods were found to be consistent with r=0.9837. Compared with other methods, the current designed sampler provides a convenient and sensitive tool for the exposure assessments of ozone.

  4. Tailored micro-extraction method for Raman/SERS detection of indigoids in ancient textiles.

    PubMed

    Platania, Elena; Lofrumento, Cristiana; Lottini, Elisabetta; Azzaro, Elena; Ricci, Marilena; Becucci, Maurizio

    2015-08-01

    Indigoid dyes are well known as vat dyes. In their oxidized dichetonic form they are stable and insoluble in water, whereas in their reduced form, commonly known as leuco, they are soluble in water and able to be attached to fabric for dyeing purposes. These blue dyes are usually easily detectable in art objects by means of Raman spectroscopy by adopting for analyses a laser line at a high wavelength, such as a 785 nm diode laser. Unfortunately, in ancient artworks, that are often highly degraded, it is not always possible to collect high quality Raman spectra, which makes the analysis and identification of these compounds particularly challenging. In this work, we present a tailor-made methodology for the extraction and the recognition of indigoid dyes in works of art, which exploits the solubility of these compounds in their reduced form. Excellent Raman and surface enhanced Raman spectroscopy (SERS) spectra of indigo were acquired after micro-extraction on ancient and reference textiles, confirming the reliability of the presented procedure. Moreover, the methodology has been applied also for the extraction of the indigoid dye Tyrian purple on a reference textile, showing excellent results. This analytical method has been found to be extremely safe both for the reference textiles and the investigated ancient textiles, thus being a promising procedure for the selective analysis and detection of indigoid compounds in objects of artistic relevance.

  5. Crosslinked polymeric ionic liquids as solid-phase microextraction sorbent coatings for high performance liquid chromatography.

    PubMed

    Yu, Honglian; Merib, Josias; Anderson, Jared L

    2016-03-18

    Neat crosslinked polymeric ionic liquid (PIL) sorbent coatings for solid-phase microextraction (SPME) compatible with high-performance liquid chromatography (HPLC) are reported for the first time. Six structurally different PILs were crosslinked to nitinol supports and applied for the determination of select pharmaceutical drugs, phenolics, and insecticides. Sampling conditions including sample solution pH, extraction time, desorption solvent, desorption time, and desorption solvent volume were optimized using design of experiment (DOE). The developed PIL sorbent coatings were stable when performing extractions under acidic pH and remained intact in various organic desorption solvents (i.e., methanol, acetonitrile, acetone). The PIL-based sorbent coating polymerized from the IL monomer 1-vinyl-3-(10-hydroxydecyl) imidazolium chloride [VC10OHIM][Cl] and IL crosslinker 1,12-di(3-vinylbenzylimidazolium) dodecane dichloride [(VBIM)2C12] 2[Cl] exhibited superior extraction performance compared to the other studied PILs. The extraction efficiency of pharmaceutical drugs and phenolics increased when the film thickness of the PIL-based sorbent coating was increased while many insecticides were largely unaffected. Satisfactory analytical performance was obtained with limits of detection (LODs) ranging from 0.2 to 2 μg L(-1) for the target analytes. The accuracy of the analytical method was examined by studying the relative recovery of analytes in real water samples, including tap water and lake water, with recoveries varying from 50.2% to 115.9% and from 48.8% to 116.6%, respectively.

  6. Solid-phase microextraction for the analysis of short-chain chlorinated paraffins in water samples.

    PubMed

    Castells, P; Santos, F J; Galceran, M T

    2003-01-10

    A novel solid-phase microextraction (SPME) method coupled to gas chromatography with electron capture detection (GC-ECD) was developed as an alternative to liquid-liquid and solid-phase extraction for the analysis of short-chain chlorinated paraffins (SCCPs) in water samples. The extraction efficiency of five different commercially available fibres was evaluated and the 100-microm polydimethylsiloxane coating was the most suitable for the absorption of the SCCPs. Optimisation of several SPME parameters, such as extraction time and temperature, ionic strength and desorption time, was performed. Quality parameters were established using Milli-Q, tap water and river water. Linearity ranged between 0.06 and 6 microg l(-1) for spiked Milli-Q water and between 0.6 and 6 microg l(-1) for natural waters. The precision of the SPME-GC-ECD method for the three aqueous matrices was similar and gave relative standard deviations (RSD) between 12 and 14%. The limit of detection (LOD) was 0.02 microg l(-1) for Milli-Q water and 0.3 microg l(-1) for both tap water and river water. The optimised SPME-GC-ECD method was successfully applied to the determination of SCCPs in river water samples.

  7. Robust aptamer sol-gel solid phase microextraction of very polar adenosine from human plasma.

    PubMed

    Mu, Li; Hu, Xiangang; Wen, Jianping; Zhou, Qixing

    2013-03-01

    Conventional solid phase microextraction (SPME) has a limited capacity to extract very polar analytes, such as adenosine. To solve this problem, aptamer conjugating sol-gel methodology was coupled with an SPME fiber. According to the authors' knowledge, this is the first reported use of aptamer SPME. The fiber of aptamer sol-gel SPME with a mesoporous structure has high porosity, large surface area, and small water contact angle. Rather than employing direct entrapment, covalent immobilization was the dominant method of aptamer loading in sol-gel. Aptamer sol-gel fiber captured a specified analyte from among the analog molecules, thereby, exhibiting an excellent selective property. Compared with commercial SPME fibers, this aptamer fiber was suitable for extracting adenosine, presenting an extraction efficiency higher than 20-fold. The values of repeatability and reproducibility expressed by relative standard deviation were low (9.4%). Interestingly, the sol-gel network enhanced the resistance of aptamer SPME to both nuclease and nonspecific proteins. Furthermore, the aptamer sol-gel fiber was applied in human plasma with LOQ 1.5 μg/L, which is an acceptable level. This fiber also demonstrates durability and regeneration over 20-cycles without significant loss of efficiency. Given the various targets (from metal ions to biomacromolecules and cells) of aptamers, this methodology will extend the multi-domain applications of SPME.

  8. Automation of solid-phase microextraction in high-throughput format and applications to drug analysis.

    PubMed

    Vuckovic, Dajana; Cudjoe, Erasmus; Hein, Dietmar; Pawliszyn, Janusz

    2008-09-15

    The automation of solid-phase microextraction (SPME) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) was accomplished using a 96 multiwell plate format, a SPME multifiber device, two orbital shakers, and a three-arm robotic system. Extensive optimization of the proposed setup was performed including coating selection, optimization of the fiber coating procedure, confirmation of uniform agitation in all wells, and the selection of the optimal calibration method. The system allows the use of pre-equilibrium extraction times with no deterioration in method precision due to reproducible timing of extraction and desorption steps and reproducible positioning of all fibers within the wells. The applicability of the system for the extraction of several common drugs is demonstrated. The optimized multifiber SPME-LC-MS/MS was subsequently fully validated for the high-throughput analysis of diazepam, lorazepam, nordiazepam, and oxazepam in human whole blood. The proposed method allowed the automated sample preparation of 96 samples in 100 min, which represents the highest throughput of any SPME technique to date, while achieving excellent accuracy (87-113%), precision (

  9. SOLID PHASE MICROEXTRACTION SAMPLING OF FIRE DEBRIS RESIDUES IN THE PRESENCE OF RADIONUCLIDE SURROGATE METALS

    SciTech Connect

    Duff, M; Keisha Martin, K; S Crump, S

    2007-03-23

    The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating highly radioactive fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of FD residue from radionuclide metals involves using solid phase microextraction (SPME) fibers to remove the residues of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most (radioactive) metals. The focus of this research was to develop an examination protocol that was applicable to safe work in facilities where high radiation doses are shielded from the workers (as in radioactive shielded cells or ''hot cells''). We also examined the affinity of stable radionuclide surrogate metals (Co, Ir, Re, Ni, Ba, Cs, Nb, Zr and Nd) for sorption by the SPME fibers. This was done under exposure conditions that favor the uptake of FD residues under conditions that will provide little contact between the SPME and the FD material (such as charred carpet or wood that contains commonly-used accelerants). Our results from mass spectrometric analyses indicate that SPME fibers show promise for use in the room temperature head space uptake of organic FD residue (namely, diesel fuel oil, kerosene, gasoline and paint thinner) with subsequent analysis by gas chromatography (GC) with mass spectrometric (MS) detection. No inorganic forms of ignitable fluids were included in this study.

  10. A solid-phase microextraction method for the detection of ignitable liquids in fire debris.

    PubMed

    Yoshida, Hiroaki; Kaneko, Tsuyoshi; Suzuki, Shinichi

    2008-05-01

    A solid-phase microextraction (SPME) procedure involving direct contact between the SPME fibers and the solid matrix and subsequent gas chromatography/mass spectrometric analysis for the detection of accelerants in fire debris is described. The extraction performances of six fibers (100 mum polydimethylsiloxane, 65 mum polydimethylsiloxane-divinylbenzene, 85 mum polyacrylate, 85 mum carboxen-polydimethylsiloxane, 70 mum Carbowax-divinylbenzene, and 50/30 mum divinylbenzene-Carboxen-polydimethylsiloxane) were investigated by directly immersing the fibers into gasoline, kerosene, and diesel fuel. For simulated fire debris, in the direct contact extraction method, the SPME fiber was kept in contact with the fire debris matrix during extraction by penetrating plastic bags wrapping the sample. This method gave comparable results to the headspace SPME method in the extraction of gasoline and kerosene, and gave an improved recovery of low-volatile components in the extraction of diesel fuel from fire debris. The results demonstrate that this procedure is suitable as a simple and rapid screening method for detecting ignitable liquids in fire debris packed in plastic bags.

  11. Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop.

    PubMed

    He, Yi; Vargas, Angelica; Kang, Youn-Jung

    2007-04-25

    This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H(3)PO(4) drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 microg L(-1), repeatability of the extraction (R.S.D.<5%, n=6), and low detection limits (0.3 microg L(-1) for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples.

  12. Single drop liquid-liquid-liquid microextraction of methamphetamine and amphetamine in urine.

    PubMed

    He, Yi; Kang, Youn-Jung

    2006-11-10

    Single drop liquid-liquid-liquid microextraction (LLLME) combined with high performance liquid chromatography (HPLC)-UV detection was investigated for the determination of a popular drug of abuse, methamphetamine (MAP), and its major metabolite, amphetamine (AP), in urine samples. The target compounds were extracted from NaOH modified sample solution to a thin layer of organic solvent membrane, and back-extracted to an acidic acceptor drop suspended on the tip of a 50-microL HPLC syringe in the aforementioned organic layer. This syringe was also used for direct injection after extraction. Factors affecting extraction efficiency were studied. At optimal conditions, the overall enrichment factor (EF) was 500-fold for AP and 730-fold for MAP, respectively. The method exhibited a wide linear range (1.0-1500 microg/L), low detection limit (0.5 microg/L), and good repeatability (RSD<5.0%) for both analytes. The feasibility of the method was demonstrated by the analysis of human urine samples.

  13. Solid-phase microextraction for cannabinoids analysis in hair and its possible application to other drugs.

    PubMed

    Strano-Rossi, S; Chiarotti, M

    1999-01-01

    This paper describes the application of solid-phase microextraction (SPME) to cannabis testing in hair. Fifty milligrams of hair was washed with petroleum ether, hydrolyzed with NaOH, neutralized, deuterated internal standard was added and directly submitted to SPME. The SPME was analyzed by GC-MS. The limit of detection was 0.1 ng/mg for cannabinol (CBN) and delta9-tetrahydrocannabinol (THC) and 0.2 ng/mg for cannabidiol (CBD). THC was detected in a range spanning from 0.1 to 0.7 ng/mg. CBD concentrations ranged from 0.7 to 14.1 ng/mg, and CBN concentrations ranged from 0.4 to 0.7 ng/mg. The effectiveness of different decontamination procedures was also studied on passively contaminated hair. The proposed method is also suitable for the analysis of methadone in hair; cocaine and cocaethylene can be detected in hair with SPME extraction after enzymatic hydrolysis.

  14. Magnetism-Enhanced Monolith-Based In-Tube Solid Phase Microextraction.

    PubMed

    Mei, Meng; Huang, Xiaojia; Luo, Qing; Yuan, Dongxin

    2016-02-02

    Monolith-based in-tube solid phase microextraction (MB/IT-SPME) has received wide attention because of miniaturization, automation, expected loading capacity, and environmental friendliness. However, the unsatisfactory extraction efficiency becomes the main disadvantage of MB/IT-SPME. To overcome this circumstance, magnetism-enhanced MB/IT-SPME (ME-MB/IT-SPME) was developed in the present work, taking advantage of magnetic microfluidic principles. First, modified Fe3O4 nanoparticles were mixed with polymerization solution and in situ polymerized in the capillary to obtain a magnetic monolith extraction phase. After that, the monolithic capillary column was placed inside a magnetic coil that allowed the exertion of a variable magnetic field. The effects of intensity of magnetic field, adsorption and desorption flow rate, volume of sample, and desorption solvent on the performance of ME-MB/IT-SPME were investigated in detail. The analysis of six steroid hormones in water samples by the combination of ME-MB/IT-SPME with high-performance liquid chromatography with diode array detection was selected as a paradigm for the practical evaluation of ME-MB/IT-SPME. The application of a controlled magnetic field resulted in an obvious increase of extraction efficiencies of the target analytes between 70% and 100%. The present work demonstrated that application of different magnetic forces in adsorption and desorption steps can effectively enhance extraction efficiency of MB/IT-SPME systems.

  15. Graphene-coated fiber for solid-phase microextraction of triazine herbicides in water samples.

    PubMed

    Wu, Qiuhua; Feng, Cheng; Zhao, Guangying; Wang, Chun; Wang, Zhi

    2012-01-01

    Graphene is a novel and interesting carbon material that could be used for the separation and purification of some chemical compounds. In this investigation, graphene was used as a novel fiber-coating material for the solid-phase microextraction (SPME) of four triazine herbicides (atrazine, prometon, ametryn and prometryn) in water samples. The main parameters that affect the extraction and desorption efficiencies, such as the extraction time, stirring rate, salt addition, desorption solvent and desorption time, were investigated and optimized. The optimized SPME by graphene-coated fiber coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) was successfully applied for the determination of the four triazine herbicides in water samples. The linearity of the method was in the range from 0.5 to 200 ng/mL, with the correlation coefficients (r) ranging from 0.9989 to 0.9998. The limits of detection of the method were 0.05-0.2 ng/mL. The relative standard deviations varied from 3.5 to 4.9% (n=5). The recoveries of the triazine herbicides from water samples at spiking levels of 20.0 and 50.0  ng/mL were in the range between 86.0 and 94.6%. Compared with two commercial fibers (CW/TPR, 50 μm; PDMS/DVB, 60 μm), the graphene-coated fiber showed higher extraction efficiency.

  16. Liquid-phase microextraction of organophosphorus pesticides using supramolecular solvent as a carrier for ferrofluid.

    PubMed

    Zohrabi, Parvin; Shamsipur, Mojtaba; Hashemi, Mahdi; Hashemi, Beshare

    2016-11-01

    A liquid-phase microextraction based on application of supramolecular solvent as a carrier for ferrofluid has been developed for the extraction and determination of three organophosphorus pesticides (OPPs). The ferrofluid was produced from combination of oleic acid coated magnetic particles and supramolecular solvent as the extractant solvent. Ferrofluid can be attracted by a magnet, and no centrifugation step was needed for phase separation. A response surface methodology (RSM) based on central composite design (CCD) was used for efficient optimization of the main variables in the extraction procedure. Under the optimum experimental conditions, the calibration curves found to be linear in the range of 0.5-400µgL(-1) with correlation coefficients ranging from 0.9967 to 0.9984. The intra-day and inter-day precision (RSD %) for 100 and 200µgL(-1) of each pesticides were in the range of 2.0-5.3% and 2.6-5.7%, respectively. The limit of detection (S/N=3), ranged from 0.1 to 0.35μgL(-1). The proposed method was successfully applied to the extraction and determination of organophosphorus pesticide residues in water and fruit juice samples.

  17. Characterisation of volatile organic compounds in stemwood using solid-phase microextraction.

    PubMed

    Wajs, A; Pranovich, A; Reunanen, M; Willför, S; Holmbom, B

    2006-01-01

    Solid-phase microextraction (SPME), hydrodistillation and dynamic headspace combined with GC and GC-MS were applied and compared for the analysis of volatile organic compounds (VOCs) from coniferous wood. The SPME conditions (type of fibre, size of wood sample, temperature and exposure time) were optimised, and more than 100 VOCs and semi-volatile compounds extracted and identified from the sapwood and heartwood of Norway spruce (Picea abies). The total number of mono- and sesquiterpenes eluted and identified was similar for the SPME and hydrodistillation methods, but more semi-volatile compounds were released by hydrodistillation. By applying dynamic headspace at room temperature, it was possible to analyse only the most volatile compounds. The qualitative composition of VOCs was similar in spruce sapwood and heartwood, although Z-beta-ocimene occurred only in sapwood while fenchol was present only in heartwood. SPME sampling coupled with GC, applied here to the analysis of VOCs released from stemwood of firs for the first time, is a convenient, sensitive, fast, solvent-free and simple method for the determination of wood volatiles. The technique requires much smaller sample amounts compared with hydrodistillation, and the total amount of VOCs extracted and identified is higher than that obtained by hydrodistillation or dynamic headspace. The relative ratios of the main mono- and sesquiterpenes and -terpenoids were similar using the SPME-GC and hydrodistillation methods.

  18. Knitting aromatic polymers for efficient solid-phase microextraction of trace organic pollutants.

    PubMed

    Liu, Shuqin; Hu, Qingkun; Zheng, Juan; Xie, Lijun; Wei, Songbo; Jiang, Ruifen; Zhu, Fang; Liu, Yuan; Ouyang, Gangfeng

    2016-06-10

    A series of knitting aromatic polymers (KAPs) were successfully synthesized using a simple one-step Friedel-Crafts alkylation of aromatic monomers and were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then, as-synthesized KAPs with large surface areas, unique pore structures and high thermal stability were prepared as solid-phase microextraction (SPME) coatings that exhibited good extraction abilities for a series of benzene compounds (i.e., benzene, toluene, ethylbenzene and m-xylene, which are referred to as BTEX) and polycyclic aromatic hydrocarbons (PAHs). Under the optimized conditions, the methodologies established for the determination of BTEX and PAHs using the KAPs-triPB and KAPs-B coatings, respectively, possessed wide linear ranges, low limits of detection (LODs, 0.10-1.13ngL(-1) for BTEX and 0.05-0.49ngL(-1) for PAHs) and good reproducibility. Finally, the proposed methods were successfully applied to the determination of BTEX and PAHs in environmental water samples, and satisfactory recoveries (93.6-124.2% for BTEX and 77.2-113.3% for PAHs) were achieved. This study provides a benchmark for exploiting novel microporous organic polymers (MOPs) for SPME applications.

  19. In-syringe dispersive solid phase extraction: a novel format for electrospun fiber based microextraction.

    PubMed

    Zhu, Gang-Tian; He, Xiao-Mei; Cai, Bao-Dong; Wang, Han; Ding, Jun; Yuan, Bi-Feng; Feng, Yu-Qi

    2014-12-07

    A novel in-syringe dispersive solid phase extraction (dSPE) system using electrospun silica fibers as adsorbents has been developed in the current work. A few milligrams of electrospun silica fibers were incubated in sample solution in the barrel of a syringe for microextraction assisted by vortex. Due to the benefit of dispersion and the high mass transfer rate of the sub-microscale electrospun silica fibers, the extraction equilibrium was achieved in a very short time (less than 1 min). Moreover, thanks to the long fibrous properties of electrospun fibers, the separation of the adsorbent from sample solution was easily achieved by pushing out the sample solution which therefore simplified the sample pretreatment procedure. Besides, the analytical throughput was largely increased by using a multi-syringe plate to perform the extraction experiment. The performance of the in-syringe dSPE device was evaluated by extraction of endogenous cytokinins from plant tissue samples based on the hydrophilic interaction. Six endogenous cytokinins in 20 mg of Oryza sativa L. (O. sativa) leaves were successfully determined under optimized conditions using in-syringe dSPE combined with liquid chromatography-mass spectrometry analysis. The results demonstrated that the in-syringe dSPE method was a rapid and high-throughput strategy for the extraction of target compounds, which has great potential in microscale sample pretreatment using electrospun fibers.

  20. Dispersive liquid-liquid microextraction of thiram followed by microvolume UV-vis spectrophotometric determination

    NASA Astrophysics Data System (ADS)

    Rastegarzadeh, Saadat; Pourreza, Nahid; Larki, Arash

    2013-10-01

    A novel and simple method for the sensitive determination of trace amounts of fungicide thiram is developed by combination of dispersive liquid-liquid microextraction (DLLME) and microvolume UV-vis spectrophotometry. The method is based on the conversion of thiram to a yellow product in the presence of ethanolic potassium hydroxide and copper sulfate, and its extraction into CCL4 using DLLME technique. In this method the ethanol existing in ethanolic KOH plays as disperser solvent and a cloudy solution is formed by injection of only CCl4 as extractant solvent into sample solution. Under the optimum conditions, the calibration graph was linear over the range of 25-1000 ng mL-1 of thiram with limit of detection of 11.5 ng mL-1. The relative standard deviation (RSD) for 100 and 500 ng mL-1 of thiram was 2.7 and 1.1% (n = 8), respectively. The proposed method was successfully applied to determination of thiram in water and plant seed samples.

  1. Hierarchical Graphene coating for highly sensitive solid phase microextraction of organochlorine pesticides.

    PubMed

    Wang, Fuxin; Liu, Shuqin; Yang, Hao; Zheng, Juan; Qiu, Junlang; Xu, Jianqiao; Tong, Yexiang; Zhu, Fang; Ouyang, Gangfeng

    2016-11-01

    Graphene, a novel class of carbon nanostructures, has received great attention as sorbents due to its fascinating structures, ultrahigh specific surface area, and good extraction ability. In this paper, a new type of hierarchical graphene was synthesized through employing a mild and environment-friendly method. Such 3D interconnected graphene own a high specific surface area up to 524m(2)g(-1), which is about 2.5 fold larger than the graphene, since the synthetic material has interlayer pores between nanosheets and in-plane pores. Then a superior solid-phase microextraction fiber was fabricated by sequentially coating the stainless steel fiber with silicone sealant film and hierarchical graphene powder. Since the novel hierarchical graphene possessed large surface area and good adsorption property, the as-prepared fiber exhibited good extraction properties of the organochlorine pesticides (OCPs). As for the analytical performance, the as-prepared fiber achieved low detection limits (0.08-0.80ngL(-1)) and wide linearity (10-30,000ngL(-1)) under the optimal conditions. The repeatability (n=5) for single fiber were between 5.1% and 11%, while the reproducibility (n=3) of fiber-to-fiber were range from 6.2% to14%. Moreover, the fiber was successfully applied to the analysis of OCPs in the Pearl River water.

  2. Estimation of the main dill seeds odorant carvone by solid-phase microextraction and gas chromatography.

    PubMed

    Zawirska-Wojtasiak, Renata; Wasowicz, Erwin

    2002-10-01

    Solid-phase microextraction (SPME) was examined for its suitability for isolation of volatiles from seeds of dill in comparison with the traditional steam distillation procedure. Two main dill seeds volatiles, carvone and limonene, were taken into consideration. Two Supelco SPME fibers were used for the extraction: polyacrylic (PAc) and polydimethylsiloxane (PDMS). The time required to saturate the fibers was 3 min, while distillation took 3 h. Gas chromatography (GC) separation was reduced to 5 min by use of microcapillary column HP-5 cross-linked 5% Ph Me Siloxane. The standards of limonene and carvone were used to prepare calibration curves. PAc fiber responses were described by quadratic curves while PDMS responded linearly. Six varieties of dill were examined by distillation and SPME with both fibers. The good results were achieved for carvone by SPME-PDMS with significant regression between distillation and SPME. This compound can be measured in dill seeds samples within 10 min. The SPME-PDMS were also tested for its application to chiral resolution of carvone and limonene enantiomers in dill seeds oil. The enantiomeric separation was done with two chiral columns. The enantiomeric ratios measured by SPME were just the same as with distillation.

  3. Dynamic solid phase microextraction sampling for reactive terpenes in the presence of ozone.

    PubMed

    Shu, Shi; Morrison, Glenn

    2010-10-15

    Dynamic gas sampling using solid phase microextraction (SPME) was evaluated for recovery of reactive terpenes and terpenoids in the presence of ozone. For limonene, α-terpineol and dihydromyrcenol in the 20-60 ppb range, this method achieves >80% recovery for ozone mixing ratios up to 100 ppb. Both the experimental results and a model analysis indicate that higher ozone concentrations and longer sampling times result in lower percent recovery. Typically greater than 90% recovery and ppb level method detection limits were achieved with a 5 min sample time. Increasing the flow rate from 100 to 400 sccm flow (5-20 cms(-1)) through the active sampler did not significantly affect sensitivity or recovery in most cases, probably due to negligible mass-transfer improvements. The recovery for each compound improves when sampling from a mixture of different species than that from a single compound sample. This may be due to competition for ozone amongst adsorbed species. Dynamic SPME sampling can improve detection and quantification of terpenes in reactive environments, especially for low vapor pressure (<5 mm Hg at 25°C) compounds that can be adsorbed to ozone scrubbers used in other methods.

  4. Analysis of quinolones by voltage-assisted liquid-phase microextraction combined with LC-MS.

    PubMed

    Wang, Mi-Hung; Wang, Shu-Ping

    2012-03-01

    The method of liquid-phase microextraction assisted with voltage was developed and applied on determination of quinolones in water sample in this study. Both of the reproducibility and extraction time were improved with the aid of applying voltage. Four analytes in neutral state such as cinoxacin, oxolinic acid, nalidixic acid, and flumequine were extracted from a sample solution at pH 2.0, through a polypropylene hollow fiber which was immobilized with 2-octanone, and then into a 25 μL of the acceptor phase of 40 mM borate buffer at pH 10.0 by applying voltage of 100 V. Subsequently, the acceptor solution was directly subjected to analysis by LC-MS. The performance of the method for four quinolones was also evaluated. Linearity was obtained in the range of 1.0-25.0 ng/mL with R(2) > 0.996. Limits of detection were below 0.6 ng/mL, and recoveries of water sample were ranged from 90.8 to 109.6%.

  5. Liquid chromatographic determination of quinolones in water and human urine samples after microextraction by packed sorbent.

    PubMed

    Rani, Susheela; Kumar, Ashwini; Malik, Ashok Kumar; Singh, Baldev

    2012-01-01

    A method for the simultaneous determination of quinolones in water and urine samples by microextraction in a sorbent-packed syringe (MEPS) with LC is described. MEPS is a new miniaturized SPE technique that can be used with chromatographic instruments without any modifications. In MEPS, approximately 1 mg of the solid packing material is inserted into a syringe (100-250 microL) as a plug. Sample preparation takes place on the packed bed. The new method is promising, easy to use, economical, and rapid. The determination of quinolones in groundwater and urine was performed using MEPS as a sample preparation method with LC-UV determination. Four quinolone antibiotics--enrofloxacin, enoxacin, danofloxacin, and nalidixic acid--in groundwater and urine samples were used as analytes. The extraction recovery was found to be between 64.9 and 98.9%. The results showed high correlation coefficients (R2 > 0.992) for all of the analytes within the calibration range. The LOQ was between 0.091 and 0.315 ng/mL.

  6. Determination of explosives in environmental water samples by solid-phase microextraction-liquid chromatography.

    PubMed

    Monteil-Rivera, Fanny; Beaulieu, Chantale; Deschamps, Stéphane; Paquet, Louise; Hawari, Jalal

    2004-09-10

    When explosives are present in natural aqueous media, their concentration is usually limited to trace levels. A preconcentration step able to remove matrix interferences and to enhance sensitivity is therefore necessary. In the present study, we evaluated solid-phase microextraction (SPME) technique for the recovery of nine explosives from aqueous samples using high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Several parameters, including adsorption and desorption time, coating type, rate of stirring, salt addition, and pH, were optimized to obtain reproducible data with good accuracy. Carbowax coating was the only adsorbent found capable of adsorbing all explosives including nitramines. Method detection limits (MDL) were found to range from 1 to 10 microg/L, depending on the analyte. SPME/HPLC-UV coupling was then applied to the analysis of natural ocean and groundwater samples and compared to conventional solid-phase extraction (SPE/HPLC-UV). Excellent agreement was observed between both techniques, but with an analysis time around five times shorter, SPME/HPLC-UV was considered to be applicable for quantitative analysis of explosives.

  7. Development of dispersive liquid-liquid microextraction method for the analysis of organophosphorus pesticides in tea.

    PubMed

    Moinfar, Soleyman; Hosseini, Mohammad-Reza Milani

    2009-09-30

    In this article, a new method for the determination of organophosphorus pesticides (OPPs) in tea was developed by using dispersive liquid-liquid microextraction (DLLME) and gas chromatography-flame photometric detection (GC-FPD). A mixture of acetonitrile and n-hexane was used as an extraction solvent for the extraction of OPPs from tea samples. When the extraction process was finished, the mixture of solvents was rapidly dispersed in water; target analyte was extracted to a small volume of n-hexane, using DLLME. Recovery tests were performed for concentration 5.0 microg/kg. The recovery for each target analyte was in the range between 83.3 and 117.4%. The repeatability of the proposed method, expressed as relative standard deviation, varied between 3 and 7.8% (n=3). The detection limit of the method for tea was found ranging from 0.030 to 1 microg/kg for all the target pesticides. Compared with the conventional sample preparation method, the proposed method has the advantage of being quick and easy to operate, and has high-enrichment factors and low consumption of organic solvent.

  8. Preparation and characterization of porous carbon material-coated solid-phase microextraction metal fibers.

    PubMed

    Zhu, Fang; Guo, Jiaming; Zeng, Feng; Fu, Ruowen; Wu, Dingcai; Luan, Tiangang; Tong, Yexiang; Lu, Tongbu; Ouyang, Gangfeng

    2010-12-10

    Two kinds of porous carbon materials, including carbon aerogels (CAs), wormhole-like mesoporous carbons (WMCs), were synthesized and used as the coatings of solid-phase microextraction (SPME) fibers. By using stainless steel wire as the supporting core, six types of fibers were prepared with sol-gel method, direct coating method and direct coating plus sol-gel method. Headspace SPME experiments indicated that the extraction efficiencies of the CA fibers are better than those of the WMC fibers, although the surface area of WMCs is much higher than that of CAs. The sol-gel-CA fiber (CA-A) exhibited excellent extraction properties for non-polar compounds (BTEX, benzene, toluene, ethylbenzene, o-xylene), while direct-coated CA fiber (CA-B) presented the best performance in extracting polar compounds (phenols). The two CA fibers showed wide linear ranges, low detection limits (0.008-0.047μgL(-1) for BTEX, 0.15-5.7μgL(-1) for phenols) and good repeatabilities (RSDs less than 4.6% for BTEX, and less than 9.5% for phenols) and satisfying reproducibilities between fibers (RSDs less than 5.2% for BTEX, and less than 9.9% for phenols). These fibers were successfully used for the analysis of water samples from the Pearl River, which demonstrated the applicability of the home-made CA fibers.

  9. Determination of polychlorinated biphenyls in milk samples by saponification-solid-phase microextraction.

    PubMed

    Llompart, M; Pazos, M; Landin, P; Cela, R

    2001-12-15

    A saponification-HSSPME procedure has been developed for the extraction of PCBs from milk samples. Saponification of the samples improves the PCB extraction efficiency and allows attaining lower background. A mixed-level fractional design has been used to optimize the sample preparation process. Five variables have been considered: extraction time, agitation, kind of microextraction fiber, concentration, and volume of NaOH aqueous solution. Also the kinetic of the process has been studied with the two fibers (100-microm PDMS and 65-microm PDMS-DVB) included in this study. Analyses were performed on a gas chromatograph equipped with an electron capture detector and a gas chromatograph coupled to a mass selective detector working in MS-MS mode. The proposed method is simple and rapid, and yields high sensitivity, with detection limits below 1 ng/mL, good linearity, and reproducibility. The method has been applied to liquid milk samples with different fat content covering the whole commercial range, and it has been validated with powdered milk certified reference material.

  10. Dispersive liquid-liquid microextraction of copper ions as neocuproine complex in environmental aqueous samples.

    PubMed

    Shariati, Shahab; Golshekan, Mostafa

    2011-06-01

    In the present study, a simple and efficient extraction method based on dispersive liquid-liquid microextraction prior to UV-Vis spectrophotometry was developed for the preconcentration and determination of copper ions in environmental samples. Briefly, cupric ions (Cu II) were reduced to cuprous (Cu I) with addition of hydroxyl amine hydrochloride and formed hydrophobic chelates with neocuproine. Then, a proper mixture of acetonitrile (as dispersive solvent) and choloroform (as extraction solvent) was rapidly injected into the solution and a cloudy solution was formed. After centrifuging, choloroform was sedimented at the bottom of a conical tube and diluted with 100 µL of methanol for further UV-Vis spectrophotometry measurement. An orthogonal array design (OAD) was employed to study the effects of different parameters on the extraction efficiency. Under the optimum experimental conditions, a preconcentration factor up to 63.6 was achieved for extraction from 5.0 mL of sample solution. The limit of detection (LOD) based on S/N = 3 was 0.33 µg L-1 and the calibration curve was linear in the range of 1-200 µg L-1 with reasonable linearity (r2 > 0.997). Finally, the accuracy of the proposed method was successfully evaluated by determination of trace amounts of copper ions in different water samples and satisfactory results were obtained.

  11. Solid-phase microextraction and chiral HPLC analysis of ibuprofen in urine.

    PubMed

    de Oliveira, Anderson Rodrigo Moraes; Cesarino, Evandro José; Bonato, Pierina Sueli

    2005-04-25

    A simple and rapid solid-phase microextraction method was developed for the enantioselective analysis of ibuprofen in urine. The sampling was made with a polydimethylsiloxane-divinylbenzene coated fiber immersed in the liquid sample. After desorptioning from the fiber, ibuprofen enantiomers were analyzed by HPLC using a Chiralpak AD-RH column and UV detection. The mobile phase was made of methanol-pH 3.0 phosphoric acid solution (75:25, v/v), at a flow rate of 0.45 mL/min. The mean recoveries of SPME were 19.8 and 19.1% for (-)-R-ibuprofen and (+)-(S)-ibuprofen, respectively. The method was linear at the range of 0.25-25 microg/mL. Within-day and between-day assay precision and accuracy were below 15% for both ibuprofen enantiomers at concentrations of 0.75, 7.5 and 20 microg/mL. The method was tested with urine quality control samples and human urine fractions after administration of 200 mg rac-ibuprofen.

  12. Determination of terpenes in tequila by solid phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Peña-Alvarez, Araceli; Capella, Santiago; Juárez, Rocío; Labastida, Carmen

    2006-11-17

    Solid phase microextraction and capillary gas chromatography-mass spectrometry were used for the determination of seven terpenes in tequila. The method was selected based on the following parameters: coating selection (PA, PDMS, CW/DVB, and PDMS/DVB), extraction temperature, addition of salt, and extraction time profile. The extraction conditions were: PDMS/DVB fiber, Headspace, 100% NaCl, 25 degrees C extraction temperature, 30 min extraction time and stirring at 1200 rpm. The calibration curves (50-1000 ng/ml) for the terpenes followed linear relationships with correlation coefficients (r) greater than 0.99, except for trans,trans-farnesol (r = 0.98). RSD values were smaller than 10% confirmed that the technique was precise. Samples from 18 different trade brands of "Aged" tequila analyzed with the developed method showed the same terpenes in different concentrations. The analytical procedure used is selective, robust (more than 100 analyses with the same fiber), fast and of low-cost.

  13. Potential sources of background contaminants in solid phase extraction and microextraction.

    PubMed

    Stiles, Robert; Yang, Ill; Lippincott, Robert Lee; Murphy, Eileen; Buckley, Brian

    2007-05-01

    A study to identify the sources of background contamination from SPE, using a C-18 sorbent, and solid-phase microextraction (SPME), using a 70 microm carbowax/divinylbenzene (CW/DVB) fiber, was carried out. To determine the source of contamination, each material used in the procedure was isolated and examined for their contribution. The solid-phase column components examined were: sorbent material and frits, column housings and each solvent used to elute analytes off the column. The components examined in the SPME procedure were: SPME fiber, SPME vials, water (HPLC grade), and salt (sodium chloride) used to increase the ionic strength. The majority of the background contaminants from SPE were found to be from the SPE sorbent material and frits. The class of contaminants extracted during a blank extraction were phthalates and other plasticizers used during the manufacturing process. All had blank levels corresponding to measured concentrations below 2 ng/ mL, except for undecane, which had a concentration of 5.4 ng/mL. The most prevalent contaminants in the SPME blank procedure are 1,9-nonanediol, a mixture of phthalates and highly bis-substituted phenols. All the concentrations were below 2 ng/mL, with the exception of bis (2-ethylhexyl) phthalate, which had concentrations ranging from 5 to 20 ng/mL.

  14. Time-weighted average water sampling in Lake Ontario with solid-phase microextraction passive samplers.

    PubMed

    Ouyang, Gangfeng; Zhao, Wennan; Bragg, Leslie; Qin, Zhipei; Alaee, Mehran; Pawliszyn, Janusz

    2007-06-01

    In this study, three types of solid-phase microextraction (SPME) passive samplers, including a fiber-retracted device, a polydimethylsiloxane (PDMS)-rod and a PDMS-membrane, were evaluated to determine the time weighted average (TWA) concentrations of polycyclic aromatic hydrocarbons (PAHs) in Hamilton Harbor (the western tip of Lake Ontario, ON, Canada). Field trials demonstrated that these types of SPME samplers are suitable for the long-term monitoring of organic pollutants in water. These samplers possess all of the advantages of SPME: they are solvent-free, sampling, extraction and concentration are combined into one step, and they can be directly injected into a gas chromatograph (GC) for analysis without further treatment. These samplers also address the additional needs of a passive sampling technique: they are economical, easy to deploy, and the TWA concentrations of target analytes can be obtained with one sampler. Moreover, the mass uptake of these samplers is independent of the face velocity, or the effect can be calibrated, which is desirable for long-term field sampling, especially when the convection conditions of the sampling environment are difficult to measure and calibrate. Among the three types of SPME samplers that were tested, the PDMS-membrane possesses the highest surface-to-volume ratio, which results in the highest sensitivity and mass uptake and the lowest detection level.

  15. Determination of amphetamines in biological samples using electro enhanced solid-phase microextraction-gas chromatography.

    PubMed

    Zeng, Jingbin; Chen, Jingjing; Li, Min; Subhan, Fazle; Chong, Fayun; Wen, Chongying; Yu, Jianfeng; Cui, Bingwen; Chen, Xi

    2015-09-01

    In this work, an ordered mesoporous carbon (OMC)/Nafion coated fiber for solid-phase microextraction (SPME) was prepared and used as the working electrode for electro-enhanced SPME (EE-SPME) of amphetamines. The EE-SPME strategy is primarily based on the electro-migration and complementary charge interaction between fiber coating and ionic compounds. Compared with traditional SPME, EE-SPME exhibited excellent extraction efficiency for amphetamine (AP) and methamphetamine (MA) with an enhancement factor of 7.8 and 12.1, respectively. The present strategy exhibited good linearity for the determination of AP and MA in urine samples in the range of 10-1000ngmL(-1) and 20-1000ngmL(-1), respectively. The detection limits were found to be 1.2ngmL(-1) for AP and 4.8ngmL(-1) for MA. The relative standard deviations were calculated to be 6.2% and 8.5% for AP and MA, respectively. Moreover, the practical application of the proposed method was demonstrated by analyzing the amphetamines in urine and serum samples with satisfactory results.

  16. [Application of solid-phase microextraction technique to the detection of amphetamines in urine by GC].

    PubMed

    Liu, W; Shen, M

    1999-05-01

    A simple and rapid detection of nine amphetamines co-existing in urine was described. In the test, the method of solid-phase micro-extraction (SPME) by GC technique was used. Urine (1.0 ml), NaCl (0.3 g) and 4-phenylbutylamine (internal standard) were added into a vial (1.5 ml), then the sample was adjusted to pH 12 with 10% NaOH and sealed with a teflon-coated septum. After immersion of the SPME fiber (100 PDME) in the sample for 15 min, the SPME needle was inserted into the injection port of the GC and extruded for 3 min. The result showed that each peak from nine amphetamines compounds and internal standard was clearly separated. The calibration curves were linear from 0.2 to 15 micrograms/ml for most of five amphetamines with r between 0.9928-0.9995. The CV were less 10%. It is concluded that the method is simple, quick, accurate and useful for the practical detection of urine concentration of amphetamines.

  17. Application of solvent microextraction to the analysis of amphetamines and phencyclidine in urine.

    PubMed

    Casari, C; Andrews, A R

    2001-09-01

    A fast and simple method to detect some commonly abused illicit drugs, amphetamine, methamphetamine, 3,4-methylendioxy-amphetamine (MDA), 3,4-methylendioxy-methamphetamine (MDMA), 3,4-methylendioxy-N-ethylamphetamine (MDEA) and phencyclidine (PCP) in urine using solvent microextraction (SME) combined with gas chromatography (GC) analysis has been developed. The extraction is conducted by suspending a 2 microl drop of chloroform in a 2 ml urine sample. Following 8 min of extraction, the organic solvent is withdrawn into the syringe and injected into a GC with a pulsed discharge helium ionization detector (PDHID). The effects of different extraction solvents and times, pH and sample preparation were studied. The optimized method was capable of detecting drugs in urine at concentrations below Substance Abuse and Mental Health Services Administration (SAMHSA) established cut-off values for preliminary testing. Good linearity and reproducibility of extraction were obtained. The limits of detection were 0.5 microg/ml for amphetamine, 0.1 microg/ml for methamphetamine and MDA, 0.05 microg/ml for MDMA, 0.025 microg/ml for MDEA and 0.015 microg/ml for PCP. Relative standard deviation (R.S.D.) values ranged between 5 and 20% for the studied drugs.

  18. A new interface for coupling solid phase microextraction with liquid chromatography.

    PubMed

    Chen, Yong; Sidisky, Leonard M

    2014-03-19

    A modified Rheodyne 7520 microsample injector was used as a new solid phase microextraction (SPME)-liquid chromatography (LC) interface. The modification was focused on the construction of a new sample rotor, which was built by gluing two sample rotors together. The new sample rotor was further reinforced with 3 pieces of stainless steel tubing. The enlarged central flow passage in the new sample rotor was used as a desorption chamber. SPME fiber desorption occurred in static mode. But all desorption solvent in the desorption chamber was injected into LC system with the interface. The analytical performance of the interface was evaluated by SPME-LC analysis of PAHs in water. At least 90% polycyclic aromatic hydrocarbons (PAHs) were desorbed from a polyacrylonitrile (PAN)/C18 bonded fuse silica fiber in 30s. And injection was completed in 20s. About 10-20% total carryovers were found on the fiber and in the interface. The carryover in the interface was eliminated by flushing the desorption chamber with acetonitrile at 1mL min(-1) for 2min. The repeatability of the method was from 2% to 8%. The limit of detection (LOD) was in the mid pg mL(-1) range. The linear ranges were from 0.1 to 100ng mL(-1). The new SPME-LC interface was reliable for coupling SPME with LC for both qualitative and quantitative analysis.

  19. Rapid detection of haloarchaeal carotenoids via liquid-liquid microextraction enabled direct TLC MALDI-MS.

    PubMed

    Manikandan, Muthu; Hasan, Nazim; Wu, Hui-Fen

    2013-03-30

    For the first time, we demonstrate the use of TiO2 nanoparticles (NPs) for enhancing the carotenoid production by the extremophilic haloarchea, Haloferax mediterranei. TiO2 NPs at optimal concentration of 375 mg/L results in a 95% increase in the production of carotenoid pigment compared to the control (no TiO2 NPs). The carotenoid pigments extracted from TiO2 NPs treated H. mediterranei cells, were separated using thin layer chromatography (TLC). The separated carotenoid spots were subjected directly for MALDI MS detection. To limit the sample diffusion during matrix addition on TLC plates, a simple bordering mode was exercised. Using this method we were able to detect the pigments successfully using MALDI-MS, directly from TLC plates after separation. In addition, we also applied the Pt NPs capped with ODT via Liquid-liquid microextraction (LLME) for extracting the pigment molecules from the halobacteria in MALDI-MS. These novel NP approaches possess numerous advantages such as; rapidity, ease in synthesis, high sensitivity and low cost.

  20. Graphenized pencil lead fiber: facile preparation and application in solid-phase microextraction.

    PubMed

    Liu, Qian; Cheng, Mengting; Long, Yanmin; Yu, Miao; Wang, Thanh; Jiang, Guibin

    2014-01-17

    Graphenized pencil lead fiber was facilely prepared by in situ chemical exfoliation of graphite in pencil lead fiber to few-layered graphene sheets via a one-pot, one-step pressurized oxidation reaction for the first time. This new fiber was characterized and demonstrated to be a highly efficient but low-cost solid-phase microextraction (SPME) fiber. The extraction performance of the fiber was evaluated with four bisphenol analogs [bisphenol A (BPA), bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA)] as model analytes in direct SPME mode. Unlike commercially available fibers, the graphenized pencil lead fiber showed an excellent chemical stability in highly saline, acidic, alkaline and organic conditions due to its coating-free configuration. The fiber also showed a very long lifespan. Furthermore, high extraction efficiency and good selectivity for the analytes with a wide polarity range could be obtained due to the exceptional properties of graphene. The detection limits (LODs) for the analytes were in the range of 1.1-25ng/L. The fiber was successfully applied in the analysis of tap water and effluent samples from a waste water treatment plant with spike recoveries ranging from 68.5 to 105.1%. Therefore, the graphenized pencil lead fiber provides a high performance, cheap, robust, and reliable tool for SPME.

  1. A simple supported liquid hollow fiber membrane microextraction for sample preparation of trihalomethanes in water samples.

    PubMed

    Vora-adisak, Narongchai; Varanusupakul, Pakorn

    2006-07-21

    A simple and efficient liquid-phase microextraction (LPME) technique using a supported liquid hollow fiber membrane, in conjunction with gas chromatography-electron capture detector has been developed for extraction and determination of trihalomethanes (THMs) in water samples. THMs were extracted from water samples through an organic extracting solvent impregnated in the pores and filled inside the porous hollow fiber membrane. Our simple conditions were conducted at 35 degrees C with no stirring and no salt addition in order to minimize sample preparation steps. Parameters such as types of hollow fiber membranes, extracting solvents and extraction time were studied and optimized. The method exhibited enrichment factors ranged from 28- to 62-fold within 30 min extraction time. The linearity of the method ranged from 0.2 to 100 microg l(-1). The limits of detection were in the low microg l(-1) level, ranging between 0.01 and 0.2 microg l(-1). The recoveries of spiked THMs at 5 microg l(-1) in water were between 98 and 105% with relative standard deviations (RSDs) less than 4%. Furthermore, the method was applied for determination of THMs in drinking water and tap water samples was reported.

  2. Determination of tramadol by dispersive liquid-liquid microextraction combined with GC-MS.

    PubMed

    Habibollahi, Saeed; Tavakkoli, Nahid; Nasirian, Vahid; Khani, Hossein

    2015-01-01

    Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed for preconcentration and determination of tramadol, ((±)-cis-2-[(dimethylamino)methyl]-1-(3-methoxyphenyl)cyclohexanol-HCl), in aqueous and biological samples (urine, blood). DLLME is a simple, rapid and efficient method for determination of drugs in aqueous samples. Efficient factors on the DLLME process has defined and optimized for extraction of tramadol including type of extraction and disperser solvents and their volumes, pH of donor phase, time of extraction and ionic strength of donor phase. Based on the results of this study, under optimal conditions and by using 2-nitro phenol as internal standard, tramadol was determined by GC-MS, and the figures of merit of this work were evaluated. The enrichment factor, relative recovery and limit of detection were obtained 420, 99.2% and 0.08 µg L(-1), respectively. The linear range was between 0.26 and 220.00 µg L(-1) (R(2) = 0.9970). The relative standard deviation for 50.00 µg L(-1) of tramadol in aqueous samples by using 2-nitro phenol as IS was 3.6% (n = 7). Finally, the performance of DLLME was evaluated for analysis of tramadol in urine and blood.

  3. Sequential dispersive liquid-liquid microextraction for the determination of aryloxyphenoxy-propionate herbicides in water.

    PubMed

    Li, Songqing; Gao, Peng; Zhang, Jiaheng; Li, Yubo; Peng, Bing; Gao, Haixiang; Zhou, Wenfeng

    2012-12-01

    A novel dispersive liquid-liquid microextraction (DLLME) method followed by HPLC analysis, termed sequential DLLME, was developed for the preconcentration and determination of aryloxyphenoxy-propionate herbicides (i.e. haloxyfop-R-methyl, cyhalofop-butyl, fenoxaprop-P-ethyl, and fluazifop-P-butyl) in aqueous samples. The method is based on the combination of ultrasound-assisted DLLME with in situ ionic liquid (IL) DLLME into one extraction procedure and achieved better performance than widely used DLLME procedures. Chlorobenzene was used as the extraction solvent during the first extraction. Hydrophilic IL 1-octyl-3-methylimidazolium chloride was used as a dispersive solvent during the first extraction and as an extraction solvent during the second extraction after an in situ chloride exchange by bis[(trifluoromethane)sulfonyl]imide. Several experimental parameters affecting the extraction efficiency were studied and optimized with the design of experiments using MINITAB® 16 software. Under the optimized conditions, the extractions resulted in analyte recoveries of 78-91%. The correlation coefficients of the calibration curves ranged from 0.9994 to 0.9997 at concentrations of 10-300, 15-300, and 20-300 μg L(-1). The relative SDs (n = 5) ranged from 2.9 to 5.4%. The LODs for the four herbicides were between 1.50 and 6.12 μg L(-1).

  4. Determination of phenolic compounds in honey using dispersive liquid-liquid microextraction.

    PubMed

    Campone, Luca; Piccinelli, Anna Lisa; Pagano, Imma; Carabetta, Sonia; Di Sanzo, Rosa; Russo, Mariateresa; Rastrelli, Luca

    2014-03-21

    Honey is a valuable functional food rich in phenolic compounds with a broad spectrum of biological activities. Analysis of the phenolic compounds in honey is a very promising tool for the quality control, the authentication and characterization of botanical origin, and the nutraceutical research. This work describes a novel approach for the rapid analysis of five phenolic acids and 10 flavonoids in honey. Phenolic compounds were rapidly extracted and concentrated from diluted honey by dispersive liquid-liquid microextraction (DLLME) and then analyzed using high performance liquid chromatography with UV absorbance detection (HPLC-UV). Some important parameters, such as the nature and volume of extraction and dispersive solvents, pH and salt effect were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, an exhaustive extraction for twelve of the investigated analytes (recoveries >70%), with a precision (RSD<10%) highly acceptable for complex matrices, and detection and quantification limits at ppb levels (1.4-12 and 4.7-40ngg(-1), respectively) were attained. The proposed method, compared with the most widely used method in the analysis of phenolic compounds in honey, provided similar or higher extraction efficiency, except in the case of the most hydrophilic phenolic acids. The capability of DLLME to the extraction of other honey phytochemicals, such as abscisic acid, was also demonstrated. The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost.

  5. Gas-diffusion microextraction coupled with spectrophotometry for the determination of formaldehyde in cork agglomerates.

    PubMed

    Brandão, Pedro F; Ramos, Rui M; Valente, Inês M; Almeida, Paulo J; Carro, Antonia M; Lorenzo, Rosa A; Rodrigues, José A

    2017-04-01

    In this work, a simple methodology was developed for the extraction and determination of free formaldehyde content in cork agglomerate samples. For the first time, gas-diffusion microextraction was used for the extraction of volatile formaldehyde directly from samples, with simultaneous derivatization with acetylacetone (Hantzsch reaction). The absorbance of the coloured solution was read in a spectrophotometer at 412 nm. Different extraction parameters were studied and optimized (extraction temperature, sample mass, volume of acceptor solution, extraction time and concentration of derivatization reagent) by means of an asymmetric screening. The developed methodology proved to be a reliable tool for the determination of formaldehyde in cork agglomerates with the following suitable method features: low LOD (0.14 mg kg(-1)) and LOQ (0.47 mg kg(-1)), r (2) = 0.9994, and intraday and interday precision of 3.5 and 4.9%, respectively. The developed methodology was applied to the determination of formaldehyde in different cork agglomerate samples, and contents between 1.9 and 9.4 mg kg(-1) were found. Furthermore, formaldehyde was also determined by the standard method EN 717-3 for comparison purposes; no significant differences between the results of both methods were observed. Graphical abstract Representation of the GDME system and its main components.

  6. Extraction optimization of Loratadine by supramolecular solvent-based microextraction and its determination using HPLC.

    PubMed

    Peyrovi, Moazameh; Hadjmohammadi, Mohammadreza

    2015-02-01

    Optimization of supramolecular solvent-based microextraction (SSME) of Loratadine and its determination with high-performance liquid chromatography (HPLC) with ultra violet (UV) detection were investigated. A factorial design (FD) and a central composite face-centered (CCF) were applied to evaluate the SSME procedure. The effect of four parameters on extraction efficiency was investigated. The factors studied were decanoic acid amount, percentage of tetrahydrofuran (THF) (v/v), pH and extraction time. According to half factorial design results, the effective parameters were decanoic acid amount, THF percentage (v/v) and pH. Then, a CCF was applied to obtain optimal condition. The optimized conditions were obtained at 110mg of decanoic acid, 10% of THF and pH=3. The limits of detection were in the range of 0.3-0.4ng/ml. Linearity of the method was determined to be in the range of 1.0-400.0ng/ml for distilled water and 1.3-400.0ng/ml for plasma. The extraction recovery was >92%. RSD for intra and inter day (n=5) of extraction of Loratadine were 3.1% and 6.2%, respectively. The developed method was successfully applied for the determination of Loratadine in distilled water and plasma samples.

  7. Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.

    PubMed

    Zeng, Jingbin; Zhao, Cuiying; Chen, Jingjing; Subhan, Fazle; Luo, Liwen; Yu, Jianfeng; Cui, Bingwen; Xing, Wei; Chen, Xi; Yan, Zifeng

    2014-10-24

    In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes.

  8. Predicting bioavailability of PAHs and PCBs with porewater concentrations measured by solid-phase microextraction fibers.

    PubMed

    Lu, Xiaoxia; Skwarski, Alison; Drake, Brian; Reible, Danny D

    2011-05-01

    Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) was measured in the deposit-feeding oligochaete Ilyodrilus templetoni exposed for 28 d to Anacostia River sediment (Washington, DC, USA) and to an initially uncontaminated sediment from Brown Lake (Vicksburg, MS, USA) sequentially diluted with 3 to 25% contaminated New Bedford Harbor sediment (New Bedford, MA, USA). The Anacostia River sediment studies represented exposure to a historically contaminated sediment with limited availability, whereas exposure to the other sediment included both the historically contaminated New Bedford Harbor sediment and fresh redistribution of contaminants into the Brown Lake sediments. Organism tissue concentrations did not correlate with bulk sediment concentrations in the Anacostia River sediment but did correlate with the sequentially diluted sediment. Porewater concentrations measured via disposable solid-phase microextraction fiber (SPME) with polydimethylsiloxane (PDMS), however, correlated well with organism uptake in all sediments. Bioaccumulation was predicted well by a linear relationship with the product of porewater concentration and compound octanol-water partition coefficient (Anacostia, slope = 1.08, r² = 0.76; sequentially diluted sediments, slope = 1.24, r² = 0.76). The data demonstrate that the octanol-water partition coefficient is a good indicator of the lipid-water partition coefficient and that porewater concentrations provide a more reliable indicator of bioaccumulation in the organism than sediment concentrations, even when the route of uptake is expected to be via sediment ingestion.

  9. Carbon nanotube-coated solid-phase microextraction metal fiber based on sol-gel technique.

    PubMed

    Jiang, Ruifen; Zhu, Fang; Luan, Tiangang; Tong, Yexiang; Liu, Hong; Ouyang, Gangfeng; Pawliszyn, Janusz

    2009-05-29

    A novel carbon nanotube (CNT)-coated solid-phase microextraction fiber was prepared based on sol-gel technique. Commonly used fragile fused silica fiber was replaced with stainless steel wire, which made the fiber unbreakable. An approach was also proposed for batch producing, and good reproducibilities for fiber to fiber and between fibers were achieved. Experiments showed that the sol-gel-CNT fiber exhibited high thermal stability to resist 350 degrees C and excellent solvent durability in methanol and acetonitrile. Compared to commercial polydimethylsiloxane (PDMS) fiber, the sol-gel-CNT fiber represented significantly improved extraction efficiencies for both polar (phenols) and non-polar (benzene, toluene, ethylbenzene, and o-xylene) compounds. Meanwhile, no replacement effect, low carry-over and wide linear range demonstrated that the newly prepared sol-gel-CNT coating has liquid properties, which allow a relatively easy quantification procedure. Moreover, the characterization of the sol-gel-CNT coating was also evaluated with McReynold probe solutes. The results showed that the coating has better affinity for all the five types of solutes compared to commercial 7microm PDMS fiber, which suggested that the coating has the potential to be developed as GC stationary phase.

  10. Collection and separation of extract in dispersive liquid-liquid microextraction with hollow fiber.

    PubMed

    Wang, Kun; Li, Na; Lei, Lei; Yang, Xiao; Wang, Zhibing; Li, Dan; Zang, Shuang; Zhang, Hanqi; Yu, Aimin; Zhang, Ziwei

    2016-05-01

    Dispersive liquid-liquid microextraction combined with collection of the extraction phase with the hollow fiber was applied to the extraction of estrogens from environmental water samples. 1-Undecanol with relatively lower toxicity was used as the extraction solvent. The hollow fiber was used to collect the extraction phase containing the analytes from the aqueous phase. Hollow fibers collecting the extraction phase were eluted with acetonitrile and the resulting eluate was analyzed by high performance liquid chromatography. Several parameters, including pH of sample, the type and volume of the extraction and dispersive solvent, salt concentration, extraction time, and collection time were optimized. Under the optimal experimental conditions, the limits of detection for estriol, 17α-estradiol, and ethynylestradiol were 4.58, 1.41, and 1.41 μg L(-1), respectively. When the present method was applied to the analysis of real water samples, the recoveries of estrogens at two spiked levels were in the range of 55.8-107.4%. In this method, the separation of the extraction phase and aqueous phase becomes easy with no need for centrifugation, refrigeration-thaw, or any special device. The hollow fiber was commercially available and the collection procedure was easy to perform, which make the present method have potential for automation and wide promotion. Small sizes of pores on the walls of the hollow fibers can block large molecules, which makes the present method have the potential for the treatment of complex matrices.

  11. NanoLC-MS coupling of liquid microjunction microextraction for on-tissue proteomic analysis.

    PubMed

    Quanico, Jusal; Franck, Julien; Cardon, Tristan; Leblanc, Eric; Wisztorski, Maxence; Salzet, Michel; Fournier, Isabelle

    2016-11-09

    Mass spectrometry (MS)-based microproteomics on localized regions of tissue sections was achieved by direct coupling of liquid microjunction microextraction with a nanoscale liquid chromatography-tandem MS, resulting in the identification of >500 protein groups from a region as small as 250μm in diameter representing only a few hundred of cells. The method was applied on the examination of benign and tumor regions initially defined by imaging mass spectrometry (IMS) analysis of a consecutive high grade serous ovarian tumor tissue section. Results identified the higher abundance of eukaryotic translation initiation factors eIF4A, its isoform eIF4A2, and eIF5A and its isoform eIF5A2, and lower abundance of actin-binding proteins OBSCN, TAGLN and CNN3 on tumor regions, concomitant with previous findings. This demonstrates the use of the method for downstream characterization of distinct regions identified by IMS. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.

  12. Ionic liquid coated copper wires and tubes for fiber-in-tube solid-phase microextraction.

    PubMed

    Sun, Min; Feng, Juanjuan; Bu, Yanan; Luo, Chuannan

    2016-08-05

    A fiber-in-tube solid-phase microextraction (SPME) device was developed by filling eleven copper wires into a copper tube, and all of those were functionalized with ionic liquids. Its morphology and surface properties were characterized by scanning electron microscopy. It was connected into high performance liquid chromatography (HPLC) equipment by replacing the sample loop of six-port injection valve, building the online SPME-HPLC system. In the optimization of extraction conditions, sampling rate, sample volume, pH of sample and desorption time were investigated with five estrogens as model analytes. Under the optimum conditions, an online SPME-HPLC analysis method was achieved, showing enrichment efficiency from 611 to 1661 and a good linearity of 0.06-60μgL(-1) with low detection limits of 0.02-0.05μgL(-1). It was applied to detect estrogens analytes in two water samples, with recoveries in the range of 85-114%. Relative standard deviation (n=3) of extraction repeatability is in the range of 1.9-3.0%. Relative standard deviation of extraction tubes (n=3) is in the range of 12-19%. The extraction mechanism is probably related to hydrophobic, π-π and dipole-dipole interactions between ionic liquids coating and estrogens analytes.

  13. One-step in-syringe ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Cruz-Vera, Marta; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

    2009-09-11

    Dispersive liquid-liquid microextraction (DLLME) has been proved to be a powerful tool for the rapid sample treatment of liquid samples providing at the same time high enrichment factors and extraction recoveries. A new, simple and easy to handle one step in-syringe set-up for DLLME is presented and critically discussed in this paper. The novel approach avoids the centrifugation step, typically off-line and time consuming, opening-up a new horizon on DLLME automation. The suitability of the proposal is evaluated by means of the determination of non-steroidal anti-inflammatory drugs in urine by liquid chromatography/ultraviolet detection. In the presented approach an ionic liquid is used as extractant. The target drugs can be determined in urine within the concentration range 0.02-10 microg mL(-1), allowing their determination at therapeutic and toxic levels. Limits of detection were in the range from 8.3 ng mL(-1) (indomethacin) to 32 ng mL(-1) (ketoprofen). The repeatability of the proposed method expressed as RSD (n=5) varied between 2.5% (for ketoprofen) and 8.6% (for indomethacin).

  14. Determination of pyrethroid pesticides in tomato using ionic liquid-based dispersive liquid-liquid microextraction.

    PubMed

    Han, Dandan; Tang, Baokun; Row, Kyung Ho

    2014-03-01

    A sensitive determination method was developed for the analysis of pyrethroid pesticide residues in tomato samples using ionic liquid-based dispersive liquid-liquid microextraction. A hydrophobic ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) and acetonitrile were used as the extraction solvent and dispersive solvent, respectively. The following experimental parameters affecting the extraction efficiency were examined: types of extraction solvent and volume of extraction solvent, types of dispersive solvent and volume of dispersive solvent and pH and ion strength of the sample solution. Under the optimum conditions, the extraction recoveries ranged from 83.9 to 96.7%. Moreover, the enrichment factors for esbiothrin, fenpropathrin and cyhalothrin were 42, 48 and 45, respectively. The calibration curves were linear with correlation coefficients ranging from 0.9997 to 0.9999 at concentrations of 0.05-1.5 µg/kg. The relative standard deviation (n = 5) was 1.7-4.5%. The limits of detection for esbiothrin, fenpropathrin and cyhalothrin were 8.1, 9.9 and 14.3 µg/kg, respectively.

  15. Evaluation of electrochemically synthesized sulfadimethoxine-imprinted polymer for solid-phase microextraction of sulfonamides.

    PubMed

    Díaz-Álvarez, Myriam; Mazzotta, Elisabetta; Malitesta, Cosimino; Martín-Esteban, Antonio

    2014-06-01

    Solid-phase microextraction (SPME) is widely used in analytical laboratories for the analysis of organic compounds, thanks to its simplicity and versatility. In the present work, the synthesis and evaluation of imprinted films for SPME by electropolymerisation of pyrrole alone or in the presence of ethylene glycol dimethacrylate is proposed. Sulfadimethoxine (SDM), a sulfonamide antibiotic, was used as template molecule. Initially, a molecularly imprinted polymer film was prepared by electropolymerisation of pyrrole onto a platinum foil, using SDM as template. The SDM template was removed by overoxidation. The behaviour of SDM on imprinted and non-imprinted polymers was investigated by differential pulse voltammetry, and a clear imprinting effect was observed, which was confirmed by rebinding experiments using both conventional and electrochemically enhanced-SPME. However, in general, the extraction efficiency was rather low (<6%) and unspecific interactions are too high. Attempts to increase extraction efficiency were unsuccessful, but the incorporation of ethylene glycol dimethacrylate to the films reduced unspecific interactions to a certain extent.

  16. Sol-gel molecularly imprinted polymer for selective solid phase microextraction of organophosphorous pesticides.

    PubMed

    Wang, Yu-Long; Gao, Yuan-Li; Wang, Pei-Pei; Shang, Huan; Pan, Si-Yi; Li, Xiu-Juan

    2013-10-15

    A sol-gel technique was applied for the preparation of water-compatible molecularly imprinted polymer (MIP) for solid phase microextraction (SPME) using diazinon as template and polyethylene glycol as functional monomer. The MIP-coated fiber demonstrated much better selectivity to diazinon and its structural analogs in aqueous cucumber sample than in distilled water, indicating its potential in real samples. Thanks to its specific adsorption as well as rough and porous surface, the coating revealed rather larger extraction capability than the non-imprinted polymer and commercial fibers. In addition, the fiber exhibited excellent thermal (about 350°C) and chemical stability (organic and inorganic). After optimization of several parameters affecting extraction efficiency, a method based on MIP-SPME combined with gas chromatography was developed for the determination of organophosphorus pesticides (OPPs) in vegetable samples. The limits of detection for the tested OPPs were in the range of 0.017-0.77 μg kg(-1). The proposed method was applied to evaluate OPPs in spiked cucumber, green pepper, Chinese cabbage, eggplant and lettuce samples, and recoveries of 81.2-113.5% were obtained by the standard addition method with three spiking levels in each kind of vegetable.

  17. Preparation of novel polydimethylsiloxane solid-phase microextraction film and its application in liquid sample pretreatment.

    PubMed

    Wei, Fang; Zhang, Fang-Fang; Liao, Hui; Dong, Xu-Yan; Li, Yan-Hua; Chen, Hong

    2011-02-01

    In this paper, an extraction approach based on the use of a novel polydimethylsiloxane (PDMS) film as the extraction medium was described. Two kinds of PDMS films with smooth surface and frosted surface were prepared and were practically evaluated for extraction. A model analytical problem, the determination of organochlorine pesticides in water samples, was selected for practical evaluation of the film extraction procedure by direct extraction and solvent desorption, followed by gas chromatography (GC) analysis with electron capture detection (ECD). The main variables affecting the extraction process such as the extraction time, the extraction temperature, the elution conditions, etc. were studied. The method was characterized on the basis of its linearity, precision, and limits of detection. The novel approach was sensitive and precise enough for the detection of the target analytes in the low nanogram per liter range using 5 mL of sample. In fact, limits of detection ranging from 0.77 to 10.25 ng/L were obtained. Compared with the solid-phase microextraction (SPME) fiber, the robust extraction film has a large extraction capacity, low cost of preparation. Besides, owing to the simplicity of the extraction procedures, in-site sample preparation for environmental monitor may be realized.

  18. HPLC assay of tomato carotenoids: validation of a rapid microextraction technique.

    PubMed

    Sérino, Sylvie; Gomez, Laurent; Costagliola, Guy; Gautier, Hélène

    2009-10-14

    Carotenoids are studied for their role as pigments and as precursors of aromas, vitamin A, abscisic acid, and antioxidant compounds in different plant tissues. A novel, rapid, and inexpensive analytical protocol is proposed to enable the simultaneous analysis of four major tomato carotenoids: lutein, lycopene, beta-carotene, and phytoene. Microextraction is performed in the presence of sodium chloride, n-hexane, dichloromethane, and ethyl acetate on fresh tomato powder that has been finely ground in liquid nitrogen. The carotenoids are extracted by agitation and centrifugation and then analyzed by HPLC using a diode array detector. The principal advantage of this extraction resides in the absence of an evaporation step, often necessary to assay tomato carotenoids other than lycopene. Whatever the carotenoid, tests for accuracy, reproducibility, and linearity were satisfactory and indicative of the method's reliability. The stability of extracts over time (several days at -20 degrees C) as the satisfactory sensitivity of the assay whatever the fruit ripeness had a part in the robustness of the method. Reliable, rapid, simple, and inexpensive, this extraction technique is appropriate for the routine analysis of carotenoids in small samples.

  19. Theoretical analysis and experimental evaluation of headspace in-drop derivatisation single-drop microextraction using aldehydes as model analytes.

    PubMed

    Fiamegos, Yiannis C; Stalikas, Constantine D

    2007-09-05

    In-drop derivatisation single-drop microextraction approach can constitute, to a certain degree, a low-cost reasonable alternative to the well-known on-fibre solid-phase microextraction. The headspace mode integrates extraction, preconcentration and derivatisation into a single step from the headspace of a sample. In this study, two low-molecular-weight aldehydes are derivatised in a hanging drop containing 2,4,6-trichlorophenylhydrazine, in a headspace single-drop microextraction configuration system. The single organic drop, dispersed in gas phase, is well covered in this study as a locale of the main reaction. The measurement of diffusion and kinetic parameters and their relationship were designed to reveal, for the first time, inherent mechanistic aspects in such an analytical system. The two-film theory of mass transfer is used to discuss the mechanism along with the calculation of characteristic times and specific rates of absorption. All these, together with certain experimental data may ascertain whether the overall process is reaction rate dependent or limited by mass transfer in the gas phase, at the air-water and air-organic interface or in the organic phase. The descriptors of mass transfer and chemical reaction in a single drop are critically reviewed and reconsidered and the practical aspects for the analysis of volatile organic compounds are highlighted. Relative standard deviations for both aldehydes were 3.4% (n=5) and 4.9% (n=5) for 1 microM of hexanal and 0.3 microM of formaldehyde, respectively. Detection limits for aqueous samples were 0.1 and 0.03 microM for formaldehyde and hexanal, respectively.

  20. Recent progress, challenges and trends in trace determination of drug analysis using molecularly imprinted solid-phase microextraction technology.

    PubMed

    Ansari, Saeedeh; Karimi, Majid

    2017-03-01

    The quantification of drugs in biological samples is a significant task for determination of the physiological efficiency in evaluated drugs in the drug discovery. To analysis of the chemical compounds at the trace and ultratrace levels, adequate analytical procedures should be applied. Therefore, sample preparation method undoubtedly is the most important stage in the trace determination process. In spite of the great growth of analytical instrumentation during the recent years, sample preparation is still nowadays considered the impasse of the all analytical procedure, especially in drugs analysis. Because of the low concentration level of drugs in blood, plasma, and the diversity of the metabolites, the chosen extraction technique should be almost perfect. Solid-phase microextraction (SPME) is a powerful, simple, fast and an equilibrium-based sample preparation method that permits integration of sampling, sample clean-up, and pre-concentration in a single solvent-free step for chemical analysis. Molecularly imprinted polymers (MIPs) that provided by the presence of a template during their synthesis are the stable polymers with molecular recognition abilities and excellent materials which provide selectivity to sample preparation. Because of its characteristics such as easy preparation, high selectivity, and chemical stability, MIP is widely utilized in many analytical fields. Accordingly, the molecular imprinting and SPME methods combination would prepare a strong analytical instrumentation which comprises simplicity, flexibility, and the selectivity characteristics of both methods. This review focuses on the application of solid-phase microextraction method coupled with molecularly imprinted polymers, namely molecularly imprinted solid-phase microextraction (MISPME), for trace determination in drug analysis.

  1. Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography-tandem mass spectrometry.

    PubMed

    Abdel-Rehim, Abbi; Abdel-Rehim, Mohamed

    2013-09-01

    This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C8 -cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS-LC-MS/MS is reported.

  2. Optimisation of specialty malt volatile analysis by headspace solid-phase microextraction in combination with gas chromatography and mass spectrometry.

    PubMed

    Vandecan, Sem M G; Saison, Daan; Schouppe, Nina; Delvaux, Filip; Delvaux, Freddy R

    2010-06-25

    The objective of this study was to develop a technique for analysing 14 flavour components, relevant for specialty malts. Therefore, a method was developed for the analysis of these components in dry ground malt using headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. A procedure was optimised for the optimal amount of sample, fibre selection, extraction temperature and extraction time. Afterwards, the method was calibrated and validated by the quantification of the specialty malt flavour components in a colour, a caramel and a roasted malt.

  3. Determination of cocaine and cocaethylene in plasma by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Alvarez, Iván; Bermejo, Ana María; Tabernero, María Jesús; Fernández, Purificación; López, Patricia

    2007-01-01

    The present paper describes a method for the simultaneous determination of cocaine and cocaethylene in plasma. It was based in the extraction of the analytes by solid-phase microextraction (SPME), and gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring (SIM) mode. The method showed to be very simple, rapid and sensitive. The method was validated for the two compounds, including linearity (range 25-1000 ng/mL) and the main precision parameters. It was applied to ten plasma samples from cocaine and alcohol users, obtaining positive results in all cases.

  4. Determination of cadmium and lead in edible oils by electrothermal atomic absorption spectrometry after reverse dispersive liquid-liquid microextraction.

    PubMed

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2014-06-01

    The dispersive liquid-liquid microextraction of edible oils with a low volume of an acidic solution in the presence of isopropyl alcohol allows cadmium and lead to be completely separated into the aqueous phase. After centrifugation, the metals are determined by electrothermal atomization atomic absorption spectrometry using a palladium salt for chemical modification in the heating cycle. Using a 10 g oil sample, the enrichment factor is 140, which permits detection limits of 0.6 and 10 ng kg(-1) for cadmium and lead, respectively. The results agree with those obtained after sample mineralization. Data for the cadmium and lead levels for 15 samples of different characteristics are given.

  5. Characterization of three agave species by gas chromatography and solid-phase microextraction-gas chromatography-mass spectrometry.

    PubMed

    Peña-Alvarez, Araceli; Díaz, Laura; Medina, Alejandra; Labastida, Carmen; Capella, Santiago; Vera, Luz Elena

    2004-02-20

    Steam distillation (SD) extraction-solid-phase microextraction coupled to GC-MS was developed for the determination of terpenes and Bligh-Dyer extraction-derivatization coupled with GC for the determination of fatty acids such as ethyl esters were used. It was found that the three different Agave species have the same profile of fatty acids; the quantity of these compounds is different in each Agave variety. On the other hand, different terpenes were identified in the three Agave plants studied: nine in A. salmiana, eight in A. angustifolia and 32 in A. tequilana Weber var. azul.

  6. Application of solid-phase microextraction to the recovery of explosives and ignitable liquid residues from forensic specimens.

    PubMed

    Furton, K G; Almirall, J R; Bi, M; Wang, J; Wu, L

    2000-07-14

    A current review of the application of solid-phase microextraction (SPME) to the analysis of ignitable liquids and explosive residues is presented along with experimental results demonstrating the relative effects of controllable variables. Variables discussed include fiber chemistry, adsorption and desorption temperatures, extraction and desorption times, fiber sampling placement (direct, headspace, and partial headspace) and matrix effects, including water content. SPME is shown to be an inexpensive, rapid and sensitive method for the analysis of ignitable liquids and high explosives residues from solid debris samples and from aqueous samples. Explosives are readily detected at parts per trillion concentrations and ignitable liquids are reproducibly detected at levels below those using conventional methods.

  7. Rapid differentiation of new apple cultivars by headspace solid-phase microextraction in combination with chemometrical data processing.

    PubMed

    Schulz, Ines; Ulrich, Detlef; Fischer, Christa

    2003-04-01

    The aim of this study was to test a combination of automated headspace solid phase-microextraction gas chromatography (GC) with chemometrical data treatment for the rapid differentiation of enzyme-inactivated homogenates of new apple cultivars. The four cultivars Pinova, Piflora, Renora and Florina are characterized by different volatile patterns. Differences in the contents of volatiles were especially found for butyl acetate, ethyl butanoate, 2-methyl butanol, ethyl acetate and 6-methyl-5-hepten-2-ol. The used sample preparation method for GC coupled with pattern recognition of chromatograms is a useful tool for rapid and reliable determination of large numbers of samples.

  8. Detection of perfluorocarbons in blood by headspace solid-phase microextraction combined with gas chromatography/mass spectrometry.

    PubMed

    Mathurin, J C; de Ceaurriz, J; Audran, M; Krafft, M P

    2001-11-01

    A new method of detection of perfluorocarbon molecules (PFCs) in blood sample has been established. After an extraction and pre-concentration step performed by headspace solid-phase microextraction (HS-SPME), the PFCs are detected by gas chromatography-mass spectrometry (GC/MS) with an ion trap mass spectrometer in MS and MS/MS modes. The influence of different parameters on the SPME process is discussed. The limit of detection and the linearity of the procedure have been determined for two PFCs.

  9. Analysis of volatile components from Melipona beecheii geopropolis from Southeast Mexico by headspace solid-phase microextraction.

    PubMed

    Torres-González, Ahira; López-Rivera, Paulina; Duarte-Lisci, Georgina; López-Ramírez, Ángel; Correa-Benítez, Adriana; Rivero-Cruz, J Fausto

    2016-01-01

    A head space solid-phase microextraction method combined with gas chromatography-mass spectrometry was developed and optimised to extract and analyse volatile compounds of Melipona beecheii geopropolis. Seventy-three constituents were identified using this technique in the sample of geopropolis collected. The main compounds detected include β-fenchene (14.53-15.45%), styrene (8.72-9.98%), benzaldehyde (7.44-7.82%) and the most relevant volatile components presents at high level in the geopropolis were terpenoids (58.17%).

  10. Optimization of headspace solid-phase microextraction for the determination of pesticide residues in vegetables and fruits.

    PubMed

    Chai, Meekin; Tan, Guanhuat; Lal, Asha

    2008-02-01

    A headspace solid-phase microextraction method has been developed for the determination of 8 pesticides in vegetables and fruits by using gas chromatography with an electron capture detector. Two types of fibers (polyacrylate, 85 microm and polydimethylsiloxane, 100 microm) have been assayed and compared. The main factors: extraction and desorption parameters, ionic strength, and the effects of dilution and organic solvents, were studied and optimized. The optimized procedures resulted in more than 80% recovery for all the investigated vegetable and fruit samples with RSD values below 10%.

  11. Application of Solid Phase Microextraction with Gas Chromatography-Mass Spectrometry as a Rapid, Reliable, and Safe Method for Field Sampling and Analysis of Chemical Warfare Agent Precursors

    DTIC Science & Technology

    2005-03-01

    Health Sciences Department of Preventive Medicine and Biometrics Dissertation and Abstract Approval...Douglas K. Parrish LT MSC USN Department of Preventive Medicine and Biometrics Uniformed Services University of...CDR Gary L. Hook, PhD, MPH, MSC USN Assistant Professor Department of Preventive Medicine and Biometrics Solid phase microextraction was

  12. Electromembrane-surrounded solid-phase microextraction coupled to ion mobility spectrometry for the determination of nonsteroidal anti-inflammatory drugs: A rapid screening method in complicated matrices.

    PubMed

    Abedi, Hamid; Ebrahimzadeh, Homeira

    2015-05-01

    A new robust method of electromembrane-surrounded solid-phase microextraction coupled to ion mobility mass spectrometry was applied for nonsteroidal anti-inflammatory drugs determination in complex matrices. This is the first time that a graphene/polyaniline composite coating is applied in electromembrane-surrounded solid-phase microextraction method. The homemade graphene/polyaniline composite is characterized by a high electrical conductivity and thermal stability. The variables affecting electromembrane-surrounded solid-phase microextraction, including extraction time; applied voltage and pH were optimized through chemometric methods, central composite design, and response surface methodology. Under the optimized conditions, limits of detection of 0.04 and 0.05 ng/mL were obtained for mefenamic acid and ibuprofen, respectively. The feasibility of electromembrane-surrounded solid-phase microextraction followed by ion mobility mass spectrometry was successfully confirmed by the extraction and determination of low levels of ibuprofen and mefenamic acid in human urine and plasma samples and satisfactory results were obtained.

  13. Dispersive liquid-liquid microextraction combined with microwave-assisted derivatization for determining lipoic acid and its metabolites in human urine.

    PubMed

    Tsai, Chia-Ju; Chen, Yen-Ling; Feng, Chia-Hsien

    2013-10-04

    This study explored dispersive liquid-liquid microextraction for extraction and concentration of lipoic acid in human urine. To improve the detection of lipoic acid by both capillary liquid chromatography (CapLC) with UV detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), microwave-assisted derivatization with 4-bromomethyl-6,7-dimethoxycoumarin was performed to render lipoic acid chromophores for UV detection and also high ionization efficiency in MALDI. All parameters that affected lipoic acid extraction and derivatization from urine were investigated and optimized. In the analyses of human urine samples, the two methods had a linear range of 0.1-20 μM with a correlation coefficient of 0.999. The detection limits of CapLC-UV and MALDI-TOF MS were 0.03 and 0.02 μM (S/N ≧ 3), respectively. The major metabolites of lipoic acid, including 6,8-bismethylthio-octanoic acid, 4,6-bismethylthio-hexanoic acid, and 2,4-bismethylthio-butanoic acid were also extracted by dispersive liquid-liquid microextraction and detected by MALDI-TOF MS. The minor metabolites (undetectable by MALDI-TOF MS), bisnorlipoic acid and tetranorlipoic acid were also extracted by dispersive liquid-liquid microextraction and identified with an LTQ Orbitrap mass spectrometer. After dispersive liquid-liquid microextraction and microwave-assisted derivatization, all lipoic acid derivatizations and metabolites were structurally confirmed by LTQ Orbitrap.

  14. Rapid determination of 54 pharmaceutical and personal care products in fish samples using microwave-assisted extraction-Hollow fiber-Liquid/solid phase microextraction.

    PubMed

    Zhang, Yi; Guo, Wen; Yue, Zhenfeng; Lin, Li; Zhao, Fengjuan; Chen, Peijin; Wu, Weidong; Zhu, Hong; Yang, Bo; Kuang, Yanyun; Wang, Jiong

    2017-04-15

    In this paper, a simple, rapid, solvent-less and environmental friendliness microextraction method, microwave-assisted extraction-hollow fiber-liquid/solid phase microextraction (MAE-HF-L/SME), was developed for simultaneous extraction and enrichment of 54 trace hydrophilic/lipophilic pharmaceutical and personal care products (PPCPs) from fish samples. A solid-phase extraction material, solid-phase microextraction (SPME) fiber, was synthesized. The SPME fiber had a homogeneous, loose structure and good mechanical properties, and they exhibited a good adsorption capacity for most PPCPs selected. The material formed the basis for the method of MAE-HF-L/SME. A method of liquid chromatography-high resolution mass spectroscopy (LC-HRMS) for analysis of 54 PPCPs. Under optimal synthesis and extraction conditions, the limits of detection (LODs, n=3) and the limits of quantitation (LOQs, n=10) for the 54 PPCPs were between 0.01-0.50μg·kg(-1) and 0.052.00μg·kg(-1), respectively. Percent recoveries and the relative standard deviations (RSDs) in spiked fish samples (n=6) were between 56.3%-119.9% and 0.3%-17.1%, respectively. The microextraction process of 54 PPCPs in MAE-HF-L/SME took approximately 12min. The method has a low matrix interference and high enrichment factor and may be applicable for determination of 54 different PPCPs in fish samples.

  15. Accelerated solvent extraction combined with dispersive liquid-liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples.

    PubMed

    Xing, Han-Zhu; Wang, Xia; Chen, Xiang-Feng; Wang, Ming-Lin; Zhao, Ru-Song

    2015-05-01

    A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9-110%. These findings indicate that accelerated solvent extraction with dispersive liquid-liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.

  16. Surface enhanced Raman spectroscopy hyphenated with surface microextraction for in-situ detection of polycyclic aromatic hydrocarbons on food contact materials.

    PubMed

    Zhang, Min; Zhang, Xiaoli; Shi, Yu-E; Liu, Zhen; Zhan, Jinhua

    2016-09-01

    Highly bioaccumulated polycyclic aromatic hydrocarbons (PAHs) have cause health concerns because of their carcinogenic properties. PAHs could migrate to food from contaminated food contact materials. In this study, a hyphenated technique combining surface enhanced Raman spectroscopy (SERS) with surface microextraction was developed for in-situ on site screening of PAHs on food contact materials. Methanol and 1-propanethiol-modified silver nanoparticles (PTH-Ag NPs) were used to perform the in-situ microextraction and detection of PAHs, respectively. The SERS spectra can be obtained by a portable Raman spectrometer. The vibration of the C-C bond of PTH at 1030cm(-1) was chosen as an internal standard peak. The PTH-Ag NPs showed high uniformity with an RSD of 2.96%. A plot of the normalized SERS intensity against fluoranthene concentration showed a linear relationship (R(2)=0.98). The detection limit could reach 0.27ngcm(-2). The in-situ microextraction-SERS hyphenated technique for the detection of three PAHs at five food contact materials was demonstrated. The method can be also applied to detect PAH mixtures. This in-situ microextraction-SERS hyphenated method demonstrated its ability to rapidly screen PAHs on contaminated food contact materials free from complex sample pretreatment.

  17. HIGH LEVELS OF MONOAROMATIC COMPOUNDS LIMIT THE USE OF SOLID-PHASE MICROEXTRACTION OF METHYL TERTIARY BUTYL ETHER AND TERTIARY BUTYL ALCOHOL

    EPA Science Inventory

    Recently, two papers reported the use of solid-phase microextraction (SPME) with polydimethylsiloxane(PDMS)/Carboxen fibers to determine trace levels of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (tBA) in water. Attempts were made to apply this technique to th...

  18. SIMPLE METHOD FOR ESTIMATING POLYCHLORINATED BIPHENYL CONCENTRATIONS ON SOILS AND SEDIMENTS USING SUBCRITICAL WATER EXTRACTION COUPLED WITH SOLID-PHASE MICROEXTRACTION. (R825368)

    EPA Science Inventory

    A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a seale...

  19. Comparison of characteristic flavor and aroma volatiles in melons and standards using solid phase microextraction (SPME) and Stir Bar Sorptive Extraction (SBSE) with GC-MS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stir bar sorptive extraction (SBSE) is a technique for extraction and analysis of organic compounds in aqueous matrices, similar in theory to solid phase microextraction (SPME). SBSE has been successfully used to analyze several organic compounds, including food matrices. When compared with SPME, ...

  20. Speciation of AsIII and AsV in fruit juices by dispersive liquid–liquid microextraction and hydride generation-atomic fluorescence spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new procedure was developed to speciate and quantify As(III) and As(V) in fruit juices. At pH 3.0, As(III) and ammonium pyrrolidine dithiocarbamate (APDC) formed a complex, which was extracted into carbon tetrachloride by dispersive liquid–liquid microextraction (DLLME) and subsequently quantified...