The Experts below are selected from a list of 4320 Experts worldwide ranked by ideXlab platform
Masayuki Yasuno - One of the best experts on this subject based on the ideXlab platform.
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Influence of Chaoborus density on the effects of an Insecticide on zooplankton communities in ponds
Hydrobiologia, 1990Co-Authors: Takayuki Hanazato, Masayuki YasunoAbstract:Zooplankton communities with a high or low density of Chaoborus larvae were established in outdoor concrete ponds, to which a Carbamate Insecticide, carbaryl, was applied at 0.1 or 0.5 mg l^−1. The lower concentration of the chemical was harmful only to Cladocera. The higher concentration damaged Chaoborus , Copepoda, and some rotifer species, as well as Cladocera. In the ponds with a low density of Chaoborus , chemical application altered the cladoceran community from dominance by Daphnia to that by Bosmina and Moina . In the ponds with a high density of Chaoborus , Chaoborus excluded cladocerans from the zooplankton community presumably by predation, and supported the dominance of rotifers. Cladocera did not recover after application of the chemical, even when Chaoborus was eliminated by the higher concentration of chemical. The relatively rapid recovery of Chaoborus seemed to interrupt the recovery of Cladocera.
Takayuki Hanazato - One of the best experts on this subject based on the ideXlab platform.
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Influence of Chaoborus density on the effects of an Insecticide on zooplankton communities in ponds
Hydrobiologia, 1990Co-Authors: Takayuki Hanazato, Masayuki YasunoAbstract:Zooplankton communities with a high or low density of Chaoborus larvae were established in outdoor concrete ponds, to which a Carbamate Insecticide, carbaryl, was applied at 0.1 or 0.5 mg l^−1. The lower concentration of the chemical was harmful only to Cladocera. The higher concentration damaged Chaoborus , Copepoda, and some rotifer species, as well as Cladocera. In the ponds with a low density of Chaoborus , chemical application altered the cladoceran community from dominance by Daphnia to that by Bosmina and Moina . In the ponds with a high density of Chaoborus , Chaoborus excluded cladocerans from the zooplankton community presumably by predation, and supported the dominance of rotifers. Cladocera did not recover after application of the chemical, even when Chaoborus was eliminated by the higher concentration of chemical. The relatively rapid recovery of Chaoborus seemed to interrupt the recovery of Cladocera.
Apichai Santalad - One of the best experts on this subject based on the ideXlab platform.
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reversed electrode polarity stacking sample preconcentration combined with micellar electrokinetic chromatography for the analysis of Carbamate Insecticide residues in fruit juices
Food Analytical Methods, 2012Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana BurakhamAbstract:Reversed electrode polarity stacking mode (REPSM) coupled to micellar electrokinetic chromatography (MEKC) was employed for the simultaneous determination of Carbamate Insecticide residues in fruit juice samples. A mixture of the studied Insecticides (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in 10 mmol L−1 phosphate buffer (pH 7.0) was introduced into the capillary tube by hydrodynamic injection at 0.5 psi for 30 s followed by removal of the sample matrix at −15 kV for 0.5 min. The analytes were successfully separated within 8 min using 10 mmol L−1 borate buffer containing 60 mmol L−1 sodium dodecyl sulfate at pH 9.5, and photodiode array detection at 205, 214, and 225 nm. The REPSM–MEKC gave stacking enhancement factors of about 4–13, compared to that without stacking. The limits of detection were in the range 0.01–0.10 mg L−1, which is acceptable with respect to the maximum residue limits. Good precisions were obtained with relative standard deviation lower than 1.8% (for migration time) and 10% (for peak area). The recoveries for most fruit juice samples were acceptable (>80%). No contamination of the studied Carbamates was observed in any sample. The proposed method is simple and effective for preconcentration and removal of matrix interferences in a single step for the determination of the studied Carbamate Insecticides.
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Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of Carbamate Insecticide residues in fruits.
Analytical and Bioanalytical Chemistry, 2009Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana Burakham, Jeremy D. Glennon, Richard L. DemingAbstract:A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of Carbamate Insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six Carbamate Insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of
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cloud point extraction and reversed phase high performance liquid chromatography for the determination of Carbamate Insecticide residues in fruits
Analytical and Bioanalytical Chemistry, 2009Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana Burakham, Jeremy D. Glennon, Richard L. DemingAbstract:A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of Carbamate Insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six Carbamate Insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of <3% for retention time and <9% for peak area. Limits of detection in the studied fruit samples were in the range of 0.1–1.0 mg kg−1. No Carbamate Insecticides were detected in the studied fruit samples. The high recoveries of the spiked fruit samples were obtained in the range 80.0–107%. The CPE method has been shown to be a potential useful methodology for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environmental friendly.
Maureen Coetzee - One of the best experts on this subject based on the ideXlab platform.
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vectorial status and Insecticide resistance of anopheles funestus from a sugar estate in southern mozambique
Parasites & Vectors, 2011Co-Authors: Maureen Coetzee, Graham R Kloke, Eduardo Nhamahanga, R. H. HuntAbstract:Background The dual problems of rising Insecticide resistance in the malaria vectors and increasing human malaria cases since 2001 in southern Mozambique are cause for serious concern. The selection of Insecticides for use in indoor residual spraying (IRS) programmes is highly dependent on the extent to which local mosquitoes are susceptible to the approved classes of Insecticides. The Insecticide resistance status and role in malaria transmission of Anopheles funestus was evaluated at the Maragra Sugar Estate in southern Mozambique where an IRS vector control programme has been in operation for seven years using the Carbamate Insecticide bendiocarb.
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bioassay and biochemical analyses of Insecticide resistance in southern african anopheles funestus diptera culicidae
Bulletin of Entomological Research, 2001Co-Authors: Basil D Brooke, Lizette L Koekemoer, Graham R Kloke, M E Taylor, Graham J Small, R. H. Hunt, Janet Hemingway, Maureen CoetzeeAbstract:Abstract Anopheles funestus Giles has been implicated as a major malaria vector in sub-Saharan Africa where pyrethroid Insecticides are widely used in agriculture andpublic health. Samples of this species from northern Kwazulu/Natal in SouthAfrica and the Beluluane region of southern Mozambique showed evidence ofresistance to pyrethroid Insecticides. Insecticide exposure, synergist andbiochemical assays conducted on A. funestus suggested that elevated levels ofmixed function oxidases were responsible for the detoxification of pyrethroids inresistant mosquitoes in these areas. The data suggested that this mechanism wasalso conferring cross-resistance to the Carbamate Insecticide propoxur. Introduction The World Health Organization (WHO) estimatesapproximately 500 million malaria cases per annumresulting in two to three million deaths (WHO, 1996). Morerecent estimates for the African region suggestapproximately one million deaths resulting from 250 millioncases. Mortality in African children ranges from 0.43–0.68million of the ~66 million children aged 0–4 years infectedeach year (Snow
Rodjana Burakham - One of the best experts on this subject based on the ideXlab platform.
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reversed electrode polarity stacking sample preconcentration combined with micellar electrokinetic chromatography for the analysis of Carbamate Insecticide residues in fruit juices
Food Analytical Methods, 2012Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana BurakhamAbstract:Reversed electrode polarity stacking mode (REPSM) coupled to micellar electrokinetic chromatography (MEKC) was employed for the simultaneous determination of Carbamate Insecticide residues in fruit juice samples. A mixture of the studied Insecticides (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in 10 mmol L−1 phosphate buffer (pH 7.0) was introduced into the capillary tube by hydrodynamic injection at 0.5 psi for 30 s followed by removal of the sample matrix at −15 kV for 0.5 min. The analytes were successfully separated within 8 min using 10 mmol L−1 borate buffer containing 60 mmol L−1 sodium dodecyl sulfate at pH 9.5, and photodiode array detection at 205, 214, and 225 nm. The REPSM–MEKC gave stacking enhancement factors of about 4–13, compared to that without stacking. The limits of detection were in the range 0.01–0.10 mg L−1, which is acceptable with respect to the maximum residue limits. Good precisions were obtained with relative standard deviation lower than 1.8% (for migration time) and 10% (for peak area). The recoveries for most fruit juice samples were acceptable (>80%). No contamination of the studied Carbamates was observed in any sample. The proposed method is simple and effective for preconcentration and removal of matrix interferences in a single step for the determination of the studied Carbamate Insecticides.
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Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of Carbamate Insecticide residues in fruits.
Analytical and Bioanalytical Chemistry, 2009Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana Burakham, Jeremy D. Glennon, Richard L. DemingAbstract:A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of Carbamate Insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six Carbamate Insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of
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cloud point extraction and reversed phase high performance liquid chromatography for the determination of Carbamate Insecticide residues in fruits
Analytical and Bioanalytical Chemistry, 2009Co-Authors: Apichai Santalad, Supalax Srijaranai, Rodjana Burakham, Jeremy D. Glennon, Richard L. DemingAbstract:A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of Carbamate Insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six Carbamate Insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of <3% for retention time and <9% for peak area. Limits of detection in the studied fruit samples were in the range of 0.1–1.0 mg kg−1. No Carbamate Insecticides were detected in the studied fruit samples. The high recoveries of the spiked fruit samples were obtained in the range 80.0–107%. The CPE method has been shown to be a potential useful methodology for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environmental friendly.