The Experts below are selected from a list of 3576 Experts worldwide ranked by ideXlab platform
Supalax Srijaranai - One of the best experts on this subject based on the ideXlab platform.
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vortex assisted low density solvent liquid liquid microextraction and salt induced demulsification coupled to high performance liquid chromatography for the determination of five organophosphorus pesticide residues in fruits
Talanta, 2015Co-Authors: Ketsarin Seebunrueng, Yanawath Santaladchaiyakit, Supalax SrijaranaiAbstract:Abstract A simple and rapid microextraction method, vortex-assisted low density solvent liquid–liquid microextraction and salt-induced demulsification (VLLME–SID) coupled to high performance liquid chromatography (HPLC) was developed for the determination of organophosphorus pesticide (OPP) residues in fruits. The studied OPPs were azinphos-Methyl, Parathion-Methyl, fenitrothion, diazinon and chlorpyrifos. For VLLME–SID, a mixture of low density solvents (1-dodecanol and hexane) was used as the extraction solvent under vortex agitation for enhancing dispersion. After complete dispersion, the emulsion was formed and the OPPs were extracted into extraction solvent droplets. Then, the emulsion was quickly broken up into two clear phases after the addition of AlCl3 as a demulsifier. Centrifugation was not required in this procedure. Under the optimal conditions, high enrichment factors (180–282), low limit of detections (LODs) (0.05–1 ng mL−1) and good precision (RSD≤7% for retention time and peak area) were obtained. The proposed method was successfully applied to the analysis of OPP residues in fruit samples (watermelon, grape, and cantaloupe). The LODs for samples were in the range 0.0006–0.0015 mg kg−1 which are below the established EU-MRLs (0.01–0.3 mg kg−1). Good recoveries were also obtained (80–104%).
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vortex assisted low density solvent based demulsified dispersive liquid liquid microextraction and high performance liquid chromatography for the determination of organophosphorus pesticides in water samples
Chemosphere, 2014Co-Authors: Ketsarin Seebunrueng, Yanawath Santaladchaiyakit, Supalax SrijaranaiAbstract:Abstract A simple, rapid, effective and eco-friendly preconcentration method, vortex-assisted low density solvent based solvent demulsified dispersive liquid–liquid microextraction (VLDS–SD–DLLME), followed by high performance liquid chromatography–diode array detector (HPLC–DAD) analysis, has been developed for the first time for the determination of four organophosphorus pesticides (OPPs) (e.g., azinphos-Methyl, Parathion-Methyl, fenitrothion and diazinon) in environmental water samples. In this preconcentration procedure, an emulsion was obtained after the mixture of extraction solvent (1-dodecanol) and dispersive solvent (acetonitrile, ACN) was injected rapidly into 10 mL of the sample solution. The vortex agitator aided the dispersion of the extraction solvent into the sample solution. After the formation of an emulsion, the demulsifier (ACN) was added, resulting in the rapid separation of the mixture into two phases without centrifugation. Under optimal conditions, the proposed method provided high extraction efficiency (90–99%), good linearity range (0.5–500 ng mL −1 ), low limits of detection (0.25–1 ng mL −1 ) and good repeatability and recoveries were obtained.
Nikolaos V Kyriakidis - One of the best experts on this subject based on the ideXlab platform.
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rapid multi residue method for the determination of azinphos Methyl bromopropylate chlorpyrifos dimethoate Parathion Methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology
Journal of Chromatography A, 2003Co-Authors: Konstantinos S. Liapis, P Apladasarlis, Nikolaos V KyriakidisAbstract:Abstract A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid–liquid partition with a mixture of dichloromethane and light petroleum (40–60 °C) and subsequent determination by a gas chromatographic–mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2–2.0 mg/kg were 97.3±6.7 to 120±1.0%, while the recoveries of chlorpyrifos and Parathion Methyl examined in the concentration range 0.02–0.2 mg/kg were 95.5±7.5 to 145±3.6%, the recoveries of azinphos Methyl in the range 0.05–0.5 mg/kg were 74.8±29.6 to 96.5±13% and those of dimethoate in the range 0.1–1.0 mg/kg were 73.1±5.7 to 92.8±2.8% for n=3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and Parathion Methyl, 0.05 mg/kg for azinphos Methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).
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rapid multi residue method for the determination of azinphos Methyl bromopropylate chlorpyrifos dimethoate Parathion Methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology
Journal of Chromatography A, 2003Co-Authors: Konstantinos S. Liapis, P Apladasarlis, Nikolaos V KyriakidisAbstract:A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid-liquid partition with a mixture of dichloromethane and light petroleum (40-60 degrees C) and subsequent determination by a gas chromatographic-mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2-2.0 mg/kg were 97.3 +/- 6.7 to 120 +/- 1.0%, while the recoveries of chlorpyrifos and Parathion Methyl examined in the concentration range 0.02-0.2 mg/kg were 95.5 +/- 7.5 to 145 +/- 3.6%, the recoveries of azinphos Methyl in the range 0.05-0.5 mg/kg were 74.8 +/- 29.6 to 96.5 +/- 13% and those of dimethoate in the range 0.1-1.0 mg/kg were 73.1 +/- 5.7 to 92.8 +/- 2.8% for n = 3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and Parathion Methyl, 0.05 mg/kg for azinphos Methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).
Wilfred Chen - One of the best experts on this subject based on the ideXlab platform.
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biosensor for direct determination of organophosphate nerve agents 1 potentiometric enzyme electrode
Biosensors and Bioelectronics, 1999Co-Authors: Priti Mulchandani, Irina Kaneva, Ashok Mulchandani, Wilfred ChenAbstract:Abstract A potentiometric enzyme electrode for the direct measurement of organophosphate (OP) nerve agents was developed. The basic element of this enzyme electrode was a pH electrode modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking OPH with bovine serum albumin (BSA) and glutaraldehyde. OPH catalyses the hydrolysis of organophosphorus pesticides to release protons, the concentration of which is proportional to the amount of hydrolysed substrate. The sensor signal and response time was optimized with respect to the buffer pH, ionic concentration of buffer, temperature, and units of OPH immobilized using paraoxon as substrate. The best sensitivity and response time were obtained using a sensor constructed with 500 IU of OPH and operating in pH 8.5, 1 mM HEPES buffer. Using these conditions, the biosensor was used to measure as low as 2 μM of paraoxon, ethyl Parathion, Methyl Parathion and diazinon. The biosensor was completely stable for at least one month when stored in pH 8.5, 1 mM HEPES +100 mM NaCl buffer at 4°C.
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biosensor for direct determination of organophosphate nerve agents 1 potentiometric enzyme electrode
Biosensors and Bioelectronics, 1999Co-Authors: Priti Mulchandani, Irina Kaneva, Ashok Mulchandani, Wilfred ChenAbstract:A potentiometric enzyme electrode for the direct measurement of organophosphate (OP) nerve agents was developed. The basic element of this enzyme electrode was a pH electrode modified with an immobilized organophosphorus hydrolase (OPH) layer formed by cross-linking OPH with bovine serum albumin (BSA) and glutaradehyde. OPH catalyses the hydrolysis of organophosphorus pesticides to release protons, the concentration of which is proportional to the amount of hydrolysed substrate. The sensor signal and response time was optimized with respect to the buffer pH, ionic concentration of buffer, temperature, and units of OPH immobilized using paraoxon as substrate. The best sensitivity and response time were obtained using a sensor constructed with 500 IU of OPH and operating in pH 8.5, 1 mM HEPES buffer. Using these conditions, the biosensor was used to measure as low as 2 microM of paraoxon, ethyl Parathion, Methyl Parathion and diazinon. The biosensor was completely stable for at least one month when stored in pH 8.5, 1 mM HEPES + 100 mM NaCl buffer at 4 degrees C.
Ketsarin Seebunrueng - One of the best experts on this subject based on the ideXlab platform.
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vortex assisted low density solvent liquid liquid microextraction and salt induced demulsification coupled to high performance liquid chromatography for the determination of five organophosphorus pesticide residues in fruits
Talanta, 2015Co-Authors: Ketsarin Seebunrueng, Yanawath Santaladchaiyakit, Supalax SrijaranaiAbstract:Abstract A simple and rapid microextraction method, vortex-assisted low density solvent liquid–liquid microextraction and salt-induced demulsification (VLLME–SID) coupled to high performance liquid chromatography (HPLC) was developed for the determination of organophosphorus pesticide (OPP) residues in fruits. The studied OPPs were azinphos-Methyl, Parathion-Methyl, fenitrothion, diazinon and chlorpyrifos. For VLLME–SID, a mixture of low density solvents (1-dodecanol and hexane) was used as the extraction solvent under vortex agitation for enhancing dispersion. After complete dispersion, the emulsion was formed and the OPPs were extracted into extraction solvent droplets. Then, the emulsion was quickly broken up into two clear phases after the addition of AlCl3 as a demulsifier. Centrifugation was not required in this procedure. Under the optimal conditions, high enrichment factors (180–282), low limit of detections (LODs) (0.05–1 ng mL−1) and good precision (RSD≤7% for retention time and peak area) were obtained. The proposed method was successfully applied to the analysis of OPP residues in fruit samples (watermelon, grape, and cantaloupe). The LODs for samples were in the range 0.0006–0.0015 mg kg−1 which are below the established EU-MRLs (0.01–0.3 mg kg−1). Good recoveries were also obtained (80–104%).
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vortex assisted low density solvent based demulsified dispersive liquid liquid microextraction and high performance liquid chromatography for the determination of organophosphorus pesticides in water samples
Chemosphere, 2014Co-Authors: Ketsarin Seebunrueng, Yanawath Santaladchaiyakit, Supalax SrijaranaiAbstract:Abstract A simple, rapid, effective and eco-friendly preconcentration method, vortex-assisted low density solvent based solvent demulsified dispersive liquid–liquid microextraction (VLDS–SD–DLLME), followed by high performance liquid chromatography–diode array detector (HPLC–DAD) analysis, has been developed for the first time for the determination of four organophosphorus pesticides (OPPs) (e.g., azinphos-Methyl, Parathion-Methyl, fenitrothion and diazinon) in environmental water samples. In this preconcentration procedure, an emulsion was obtained after the mixture of extraction solvent (1-dodecanol) and dispersive solvent (acetonitrile, ACN) was injected rapidly into 10 mL of the sample solution. The vortex agitator aided the dispersion of the extraction solvent into the sample solution. After the formation of an emulsion, the demulsifier (ACN) was added, resulting in the rapid separation of the mixture into two phases without centrifugation. Under optimal conditions, the proposed method provided high extraction efficiency (90–99%), good linearity range (0.5–500 ng mL −1 ), low limits of detection (0.25–1 ng mL −1 ) and good repeatability and recoveries were obtained.
Konstantinos S. Liapis - One of the best experts on this subject based on the ideXlab platform.
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rapid multi residue method for the determination of azinphos Methyl bromopropylate chlorpyrifos dimethoate Parathion Methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology
Journal of Chromatography A, 2003Co-Authors: Konstantinos S. Liapis, P Apladasarlis, Nikolaos V KyriakidisAbstract:Abstract A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid–liquid partition with a mixture of dichloromethane and light petroleum (40–60 °C) and subsequent determination by a gas chromatographic–mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2–2.0 mg/kg were 97.3±6.7 to 120±1.0%, while the recoveries of chlorpyrifos and Parathion Methyl examined in the concentration range 0.02–0.2 mg/kg were 95.5±7.5 to 145±3.6%, the recoveries of azinphos Methyl in the range 0.05–0.5 mg/kg were 74.8±29.6 to 96.5±13% and those of dimethoate in the range 0.1–1.0 mg/kg were 73.1±5.7 to 92.8±2.8% for n=3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and Parathion Methyl, 0.05 mg/kg for azinphos Methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).
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rapid multi residue method for the determination of azinphos Methyl bromopropylate chlorpyrifos dimethoate Parathion Methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology
Journal of Chromatography A, 2003Co-Authors: Konstantinos S. Liapis, P Apladasarlis, Nikolaos V KyriakidisAbstract:A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid-liquid partition with a mixture of dichloromethane and light petroleum (40-60 degrees C) and subsequent determination by a gas chromatographic-mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2-2.0 mg/kg were 97.3 +/- 6.7 to 120 +/- 1.0%, while the recoveries of chlorpyrifos and Parathion Methyl examined in the concentration range 0.02-0.2 mg/kg were 95.5 +/- 7.5 to 145 +/- 3.6%, the recoveries of azinphos Methyl in the range 0.05-0.5 mg/kg were 74.8 +/- 29.6 to 96.5 +/- 13% and those of dimethoate in the range 0.1-1.0 mg/kg were 73.1 +/- 5.7 to 92.8 +/- 2.8% for n = 3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and Parathion Methyl, 0.05 mg/kg for azinphos Methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).
