Lee HK

References (14)

Title : Electrochemical and fluorescent dual-mode sensor of acetylcholinesterase activity and inhibition based on MnO(2)@PD-coated surface - Kim_2023_Anal.Chim.Acta_1257_341171
Author(s) : Kim SG , Lee HK , Subba SH , Oh MH , Lee G , Park SY
Ref : Anal Chim Acta , 1257 :341171 , 2023
Abstract : We developed an electrochemical and fluorescent dual-mode sensor for assessing acetylcholinesterase (AChE) activity and inhibition by taking advantage of the high redox sensitivity of surface-coated mesoporous MnO(2)@polymer dot (MnO(2)@PD) towards AChE. The following phenomena constitute the basis of the detection mechanism: fluorescence resonance energy transfer (FRET) effect between MnO(2) and PD; catalytic hydrolysis of acetylthiocholine (ATCh) to thiocholine (TCh) by AChE expressed by PC-12 cells, inducing fluorescence restoration and change in the conductivity of the system due to MnO(2) decomposition; the presence of the inhibitor neostigmine preventing the conversion of ATCh to TCh. The surface-coated biosensor presents both fluorescence-based and electrochemical approaches for effectively monitoring AChE activity and inhibition. The fluorescence approach is based on the fluorescent "on/off" property of the system caused by MnO(2) breakdown after interaction with TCh and the subsequent release of PDs. The conductivity of the coated electrode decreased dramatically as AChE concentration increased, resulting in electrochemical sensing of AChE activity and inhibition screening. Real-time wireless sensing can be conducted using a smartphone to monitor the resistance change, investigating the potential use of MnO(2)@PD nanocomposites in biological studies, and offering a real-time redox-fluorescent test for AChE activity monitoring and inhibitor screening.
ESTHER : Kim_2023_Anal.Chim.Acta_1257_341171
PubMedSearch : Kim_2023_Anal.Chim.Acta_1257_341171
PubMedID: 37062569

Title : Unique binding mode of Evogliptin with human dipeptidyl peptidase IV - Lee_2017_Biochem.Biophys.Res.Commun_494_452
Author(s) : Lee HK , Kim MK , Kim HD , Kim HJ , Kim JW , Lee JO , Kim CW , Kim EE
Ref : Biochemical & Biophysical Research Communications , 494 :452 , 2017
Abstract : Evogliptin ((R)-4-((R)-3-amino-4-(2,4,5-trifluorophenyl)butanoyl)-3-(tert-butoxymethyl) piperazine-2-one)) is a highly potent selective inhibitor of dipeptidyl peptidase IV (DPP4) that was approved for the treatment of type 2 diabetes in South Korea. In this study, we report the crystal structures of Evogliptin, DA-12166, and DA-12228 (S,R diastereomer of Evogliptin) complexed to human DPP4. Analysis of both the structures and inhibitory activities suggests that the binding of the trifluorophenyl moiety in the S1 pocket and the piperazine-2-one moiety have hydrophobic interactions with Phe357 in the S2 extensive subsite, and that the multiple hydrogen bonds made by the (R)-beta-amine group in the S2 pocket and the contacts made by the (R)-tert-butyl group with Arg125 contribute to the high potency observed for Evogliptin.
ESTHER : Lee_2017_Biochem.Biophys.Res.Commun_494_452
PubMedSearch : Lee_2017_Biochem.Biophys.Res.Commun_494_452
PubMedID: 29061303
Gene_locus related to this paper: human-DPP4

Title : Single-Nucleotide Polymorphisms in Pig EPHX1 Gene are Associated with Pork Quality Traits - Cho_2015_Anim.Biotechnol_26_237
Author(s) : Cho HR , Ha J , Kwon SG , Hwang JH , Park da H , Kim TW , Lee HK , Song KD , Kim SW , Kim CW
Ref : Anim Biotechnol , 26 :237 , 2015
Abstract : Epoxide hydrolase 1 (EPHX1) plays an important role in both the activation and detoxification of exogenous chemicals. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that the highest level of EPHX1 expression occurred in Berkshire liver, which is an organ that plays a key role in detoxification. We examined EPHX1 SNPs to analyze effect on increased expression of EPHX1 gene in Berkshire liver by total of 192 pigs of a pure Berkshire line (males = 97; females = 95). As a result, two nonsynonymous SNPs (nsSNPs) of EPHX1 were found from c.685T>G and c.776C > T, and located in 5th and 6th exons, respectively, which constitute the A/b hydrolase 1 domain of epoxide hydrolase. The nsSNP c.685T > G was significant differences in meat color, protein content, collagen content, and pH24 hr. Especially, T and G alleles of the nsSNP c.685T > G were significantly associated with CIE a*/CIE b* and protein content/pH24 hr, respectively. The nsSNP c.776C > T was significant differences in drip loss and protein content. Among meat quality traits to associate with SNPs, the protein content was only significantly associated with sex. Therefore, it is suggested that nsSNP c.685T > G in EPHX1 gene is a potential to apply as appropriate DNA markers for improvement of porcine economic traits.
ESTHER : Cho_2015_Anim.Biotechnol_26_237
PubMedSearch : Cho_2015_Anim.Biotechnol_26_237
PubMedID: 25927171

Title : The effects of Betula platyphylla bark on amyloid beta-induced learning and memory impairment in mice - Cho_2014_Food.Chem.Toxicol_74_156
Author(s) : Cho N , Lee HK , Jeon BJ , Kim HW , Kim HP , Lee JH , Kim YC , Sung SH
Ref : Food & Chemical Toxicology , 74 :156 , 2014
Abstract : Alzheimer's disease (AD) is closely associated with amyloid beta (Abeta)-induced neurotoxicity and oxidative stress in the brain. Betula platyphylla, which has been used to treat various oxidative-stressed related diseases, has recently received attention for its preventive activity on age-related neurodegenerative diseases. In this study, we attempted to investigate the effects of B. platyphylla bark (BPB-316) on Abeta1-42-induced neurotoxicity and memory impairment. Oral treatment using BPB-316 significantly attenuated Abeta-induced memory impairment which was evaluated by behavioral tests including the passive avoidance, Y-maze and Morris water maze test. BPB-316 also inhibited the elevation of beta-secretase activity accompanying the reduced Abeta1-42 levels in the hippocampus of the brain. Furthermore, BPB-316 significantly decreased the acetylcholinesterase activity and increased the glutathione content in the hippocampus. In addition, we confirmed that the expression of both cAMP responsive element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus of Abeta1-42-injected mice were markedly upregulated by the treatment of BPB-316. Our data suggest that the extracts of B. platyphylla bark might be a potential therapeutic agent against AD.
ESTHER : Cho_2014_Food.Chem.Toxicol_74_156
PubMedSearch : Cho_2014_Food.Chem.Toxicol_74_156
PubMedID: 25301235

Title : The effects of lignan-riched extract of Shisandra chinensis on amyloid-beta-induced cognitive impairment and neurotoxicity in the cortex and hippocampus of mouse - Jeong_2013_J.Ethnopharmacol_146_347
Author(s) : Jeong EJ , Lee HK , Lee KY , Jeon BJ , Kim DH , Park JH , Song JH , Huh J , Lee JH , Sung SH
Ref : J Ethnopharmacol , 146 :347 , 2013
Abstract : ETHNOPHARMACOLOGICAL RELEVANCE: The fruits of Schisandra chinensis (Trucz.) Baill. (Schisandraceae) which have been used as a tonic especially for kidney yin deficiency in Chinese traditional medicine are recently receiving attention for its preventive activity on age-related neurodegenerative diseases. A variety of studies demonstrated the cognitive-enhancing effects of Schisandra chinensis through animal tests and also in clinical trials. AIM OF STUDY: In this study, we attempted to investigate the effects of the lignan-riched extract of Schisandra chinensis fruits (ESP-806) on neurotoxicity and memory impairment induced by Abeta1-42 injection in mice. MATERIALS AND
METHODS: The fruits of Schisandra chinensis were extracted with the mixture of n-hexane:ethanol (9:1), which is riched with bioactive dibenzocyclooctadiene lignans, schizandrin, gomisin N, wuweigisu C. After oral treatment of ESP-806 (100 mg/kg body weight) followed by injection of Abeta1-42 (2 mug/mouse, i.c.v.), novel object recognition and passive avoidance tests were evaluated. To verify the cognition enhancing effects of ESP-806, we examined the effects of ESP-806 on the activities of beta-secretase and acetylcholinesterase, and the contents of Abeta and the reduced glutathione within the cortex and hippocampus of Abeta-injected mice.
RESULTS: Oral treatment of ESP-806 (100 mg/kg body weight) significantly attenuated Abeta1-42-induced memory impairment evaluated by behavioral tests. Furthermore, the treatment of ESP-806 attenuated the elevation of beta-secretase activity accompanying the reduced level of Abeta1-42 in the cortex and hippocampus of the brain. ESP-806 also significantly inhibited the acetylcholinesterase activity in the hippocampus and increased the content of the reduced glutathione in the cortex and hippocampus of mouse brain.
CONCLUSIONS: These data suggested that the extract of Schisandra chinensis fruits riched with dibenzocyclooctadiene lignans may be useful in the prevention and treatment of Alzheimer's disease.
ESTHER : Jeong_2013_J.Ethnopharmacol_146_347
PubMedSearch : Jeong_2013_J.Ethnopharmacol_146_347
PubMedID: 23333311

Title : Neuroprotective effects of Eucommia ulmoides Oliv. Bark on amyloid beta(25-35)-induced learning and memory impairments in mice - Kwon_2011_Neurosci.Lett_487_123
Author(s) : Kwon SH , Lee HK , Kim JA , Hong SI , Kim SY , Jo TH , Park YI , Lee CK , Kim YB , Lee SY , Jang CG
Ref : Neuroscience Letters , 487 :123 , 2011
Abstract : In the present study, we examined whether aqueous extract of Eucommia ulmoides Oliv. Bark (EUE) with graded doses exerted its neuroprotective effects on amyloid beta(25-35) (Abeta(25-35))-induced learning and memory impairments in mice. Mice received a single intracerebroventricular (i.c.v.) injection of Abeta(25-35) 6 nmol as the critical factor in Alzheimer's disease (AD), cognition was evaluated using Y-maze, passive avoidance, and Morris water maze tests. EUE significantly improved the Abeta(25-35)-induced memory deficit in the Y-maze test. Also, EUE increased step-through latency time with Abeta(25-35)-induced learning and memory deficits in the passive avoidance test. In addition, EUE decreased the escape latencies with Abeta(25-35)-induced cognitive impairments in the Morris water maze test. In the probe trial session, EUE increased time spent in the target quadrant. In the in vitro study, EUE was found to inhibit acetylcholinesterase (AChE) activity in a dose-dependent manner (IC50 value; 172 mug/ml). Ex vivo study, EUE significantly inhibited AChE activity in the hippocampus and frontal cortex. These results demonstrate that EUE possesses potent neuroprotective effects and that its beneficial effects are mediated, in part, by AChE inhibition, and therefore, might be a potential candidate in neurodegenerative diseases such as AD.
ESTHER : Kwon_2011_Neurosci.Lett_487_123
PubMedSearch : Kwon_2011_Neurosci.Lett_487_123
PubMedID: 20974223

Title : Neuroprotective effects of chlorogenic acid on scopolamine-induced amnesia via anti-acetylcholinesterase and anti-oxidative activities in mice - Kwon_2010_Eur.J.Pharmacol_649_210
Author(s) : Kwon SH , Lee HK , Kim JA , Hong SI , Kim HC , Jo TH , Park YI , Lee CK , Kim YB , Lee SY , Jang CG
Ref : European Journal of Pharmacology , 649 :210 , 2010
Abstract : Chlorogenic acid is a major polyphenolic component of many plants and beverages, and is particularly abundant in coffee. We evaluated the neuroprotective effects of chlorogenic acid on learning and memory impairment induced by scopolamine (0.5 mg/kg, i.p.), a muscarinic antagonist, using the Y-maze, passive avoidance, and Morris water maze tests. The chlorogenic acid significantly improved the impairment of short-term or working memory induced by scopolamine in the Y-maze test, and significantly reversed cognitive impairments in mice as measured by the passive avoidance test. In addition, chlorogenic acid decreased escape latencies in the Morris water maze test. In a probe trial session, chlorogenic acid increased the latency time in the target quadrant in a dose-dependent manner. Ex vivo, chlorogenic acid inhibited acetylcholinesterase activity in the hippocampus and frontal cortex. Chlorogenic acid also decreased malondialdehyde levels in the hippocampus and frontal cortex. In vitro, chlorogenic acid was found to inhibit acetylcholinesterase activity (IC(5)(0)=98.17 mug/ml) and free radical scavenging activity (IC(5)(0)=3.09 mug/ml) in a dose-dependent manner. These results indicate that chlorogenic acid may exert anti-amnesic activity via inhibition of acetylcholinesterase and malondialdehyde in the hippocampus and frontal cortex.
ESTHER : Kwon_2010_Eur.J.Pharmacol_649_210
PubMedSearch : Kwon_2010_Eur.J.Pharmacol_649_210
PubMedID: 20854806

Title : Long-term suppression of tyrosinase by terrein via tyrosinase degradation and its decreased expression - Park_2009_Exp.Dermatol_18_562
Author(s) : Park SH , Kim DS , Lee HK , Kwon SB , Lee S , Ryoo IJ , Kim WG , Yoo ID , Park KC
Ref : Exp Dermatol , 18 :562 , 2009
Abstract : Previously, we reported that a fungal metabolite, terrein, decreases melanin synthesis via downregulation of microphthalmia-associated transcription factor (MITF). In the present study, we further investigated the long-term hypopigmenting action of terrein in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment with terrein at a concentration of 50 mum strongly decreased melanogenesis in a time-dependent manner. Interestingly, the decreased tyrosinase protein levels lasted for at least 7 days, even though the MITF protein levels were restored after 3 days of treatment. In accordance with the results of Western blot analyses, the tyrosinase mRNA levels were found to be continuously decreased for at least 7 days, even though recovery of the MITF mRNA levels began after 3 days of terrein treatment. Therefore, we evaluated tyrosinase downregulation to determine if it is caused by proteasomal degradation. We found that the reduction in tyrosinase levels that was induced by terrein was clearly recovered by MG-132, a proteasome inhibitor. Moreover, ubiquitination of tyrosinase increased following treatment with terrein in the presence of MG-132. Taken together, these results suggest that terrein decreases melanogenesis through ubiquitin-dependent proteasomal degradation as well as via decreased expression of its mRNA.
ESTHER : Park_2009_Exp.Dermatol_18_562
PubMedSearch : Park_2009_Exp.Dermatol_18_562
PubMedID: 19493001
Gene_locus related to this paper: aspte-AT1

Title : Investigating the role of protein folding and assembly in cell-type dependent expression of alpha7 nicotinic receptors using a green fluorescent protein chimera - Lee_2009_Brain.Res_1259_7
Author(s) : Lee HK , Gwalani L , Mishra V , Anandjiwala P , Sala F , Sala S , Ballesta JJ , O'Malley D , Criado M , Loring RH
Ref : Brain Research , 1259 :7 , 2009
Abstract : To test the hypothesis that cell-dependent expression of alpha7 receptors is due to differences in protein folding or assembly, we constructed a chimeric rat alpha7 subunit with green fluorescent protein (GFP) at the receptor C-terminal. Expression of alpha7-GFP in Xenopus oocytes resulted in currents that were indistinguishable from wild type receptors but were only 33% of control. (125)I-alpha-bungarotoxin (alphaBGT) binding at the oocyte surface was reduced to 23% of wild type. Transfection of alpha7-GFP into GH4C1 cells produced fluorescence that was less intense than GFP alone, but showed significant alpha-BGT binding compared to transfection with GFP. In contrast, alpha7-GFP transfection in SH-EP1, HEK293 and CHO-CAR cells produced fluorescence without alphaBGT binding. Flow cytometry of cells transfected with alpha7-GFP indicated fluorescence in both SH-EP1 and GH4C1 cells, but surface toxin binding sites and sites immunoprecipitated using anti-GFP antibodies were undetectable in SH-EP1 cells, suggesting a problem in folding/assembly rather than trafficking. Surprisingly, integrated fluorescence intensities in GH4C1 cells transfected with alpha7-GFP did not correlate with amounts of cell surface or immunoprecipitable alphaBGT binding. Therefore, GFP folding at the C-terminal of the alpha7-GFP chimera is cell-line independent, but toxin binding is highly cell-line dependent, suggesting that if altered protein folding is involved in the cell-type dependence of alpha7 receptor expression, the phenomenon is restricted to specific protein domains. Further, C-terminal GFP-labeled alpha7 receptors decreased the efficiency of folding/assembly not only of chimeric subunits, but also wild-type subunits, suggesting that the C-terminal is an important domain for alpha7 receptor assembly.
ESTHER : Lee_2009_Brain.Res_1259_7
PubMedSearch : Lee_2009_Brain.Res_1259_7
PubMedID: 19368825

Title : Ion-pair liquid-liquid-liquid microextraction of nerve agent degradation products followed by capillary electrophoresis with contactless conductivity detection - Xu_2008_J.Chromatogr.A_1205_158
Author(s) : Xu L , Gong XY , Lee HK , Hauser PC
Ref : Journal of Chromatography A , 1205 :158 , 2008
Abstract : The four nerve agent degradation products methylphosphonic acid (MPA), ethyl methylphosphonic acid (EMPA), isopropyl methylphosphonic acid (IMPA) and cyclohexyl methylphosphonic acid (CMPA) have been successfully extracted from aqueous sample solution by ion-pair liquid-liquid-liquid microextraction. In this procedure, the target analytes in the sample solution were converted into their ion-pair complexes with tri-n-butyl amine and then extracted by an organic solvent (1-octanol) layer on top of the sample solution. Simultaneously, the analytes were back-extracted into a drop of an aqueous acceptor solution which was suspended in the organic phase at a microsyringe needle tip. The factors influential to extraction: type of organic solvent, type of ion-pair reagent and its concentration, pH values of sample solution and acceptor aqueous phase, stirring rate and extraction time were investigated in detail. After extraction, the drop of the acceptor solution was withdrawn into the syringe and injected into a capillary electrophoresis system for analysis. Using contactless conductivity detection, direct quantification of these compounds is possible. Moreover, large-volume sample injection was employed for further preconcentration. Improvements in the limits of detection between 2.5 and 4 orders of magnitude could be achieved and concentrations at the ng/mL level can be determined. This newly established approach was successfully applied to a spiked river water sample.
ESTHER : Xu_2008_J.Chromatogr.A_1205_158
PubMedSearch : Xu_2008_J.Chromatogr.A_1205_158
PubMedID: 18721925

Title : Temporospatial localization of acetylcholinesterase activity in the dental epithelium during mouse tooth development - Ko_2007_Life.Sci_81_1235
Author(s) : Ko SO , Kim TH , Lee HK , Lee JC , Cho ES
Ref : Life Sciences , 81 :1235 , 2007
Abstract : Acetylcholinesterase (AChE), a principal modulator of cholinergic neurotransmission, also has been demonstrated to be involved in the morphogenetic processes of neuronal and non-neuronal tissues. This study shows that AChE exhibits temporospatial activity in the dental epithelium of the developing mouse tooth. To identify the AChE activity in the mouse tooth during development, we performed enzyme histochemistry on the mouse embryos from embryonic day 13 (E13) to E18 and on the incisors and molars of the neonatal mouse at 10 days after birth (P10). In the developing molars of mouse embryos, AChE activity was not found in the dental epithelium at E13 (bud stage). AChE activity first appeared in the developing cervical loops of the enamel organ at E14 (cap stage), but was not found in the enamel knot. At E18 (bell stage), AChE activity was localized in the inner enamel epithelium except the cervical-loop area. In the incisors and molars of neonatal mice (P10), AChE activity was localized in the inner enamel epithelium of the cervical-loop and enamel-free area. Overall, AChE activity was localized in the differentiating dental epithelium while the activity of butyrylcholinesterse, another cholinesterase, was located primarily in the cells of the dental follicle. The results suggest that AChE may play a role in the histo- and cytodifferentiation of dental epithelium during tooth development.
ESTHER : Ko_2007_Life.Sci_81_1235
PubMedSearch : Ko_2007_Life.Sci_81_1235
PubMedID: 17905311

Title : Synthesis and melanin biosynthesis inhibitory activity of (+\/-)-terrein produced by Penicillium sp. 20135 - Lee_2005_Bioorg.Med.Chem.Lett_15_471
Author(s) : Lee S , Kim WG , Kim E , Ryoo IJ , Lee HK , Kim JN , Jung SH , Yoo ID
Ref : Bioorganic & Medicinal Chemistry Lett , 15 :471 , 2005
Abstract : Terrein was isolated from Penicillium sp. 20135, prepared by a practical synthetic way, and evaluated first time for its melanin biosynthesis inhibitory activity.
ESTHER : Lee_2005_Bioorg.Med.Chem.Lett_15_471
PubMedSearch : Lee_2005_Bioorg.Med.Chem.Lett_15_471
PubMedID: 15603975
Gene_locus related to this paper: aspte-AT1

Title : Genomic blueprint of Hahella chejuensis, a marine microbe producing an algicidal agent - Jeong_2005_Nucleic.Acids.Res_33_7066
Author(s) : Jeong H , Yim JH , Lee C , Choi SH , Park YK , Yoon SH , Hur CG , Kang HY , Kim D , Lee HH , Park KH , Park SH , Park HS , Lee HK , Oh TK , Kim JF
Ref : Nucleic Acids Research , 33 :7066 , 2005
Abstract : Harmful algal blooms, caused by rapid growth and accumulation of certain microalgae in the ocean, pose considerable impacts on marine environments, aquatic industries and even public health. Here, we present the 7.2-megabase genome of the marine bacterium Hahella chejuensis including genes responsible for the biosynthesis of a pigment which has the lytic activity against a red-tide dinoflagellate. H.chejuensis is the first sequenced species in the Oceanospiralles clade, and sequence analysis revealed its distant relationship to the Pseudomonas group. The genome was well equipped with genes for basic metabolic capabilities and contained a large number of genes involved in regulation or transport as well as with characteristics as a marine heterotroph. Sequence analysis also revealed a multitude of genes of functional equivalence or of possible foreign origin. Functions encoded in the genomic islands include biosynthesis of exopolysacchrides, toxins, polyketides or non-ribosomal peptides, iron utilization, motility, type III protein secretion and pigmentation. Molecular structure of the algicidal pigment, which was determined through LC-ESI-MS/MS and NMR analyses, indicated that it is prodigiosin. In conclusion, our work provides new insights into mitigating algal blooms in addition to genetic make-up, physiology, biotic interactions and biological roles in the community of a marine bacterium.
ESTHER : Jeong_2005_Nucleic.Acids.Res_33_7066
PubMedSearch : Jeong_2005_Nucleic.Acids.Res_33_7066
PubMedID: 16352867
Gene_locus related to this paper: hahch-q2s6v8 , hahch-q2s7u4 , hahch-q2s8m0 , hahch-q2s9b5 , hahch-q2s9n3 , hahch-q2s796 , hahch-q2s803 , hahch-q2s809 , hahch-q2s829 , hahch-q2sae5 , hahch-q2sav4 , hahch-q2sbd6 , hahch-q2sc65 , hahch-q2scc5 , hahch-q2sci6 , hahch-q2sct6 , hahch-q2scw7 , hahch-q2sdy2 , hahch-q2seh8 , hahch-q2seq6 , hahch-q2sfm2 , hahch-q2sfm4 , hahch-q2sfm9 , hahch-q2sfx3 , hahch-q2sgj4 , hahch-q2sgn6 , hahch-q2sgt0 , hahch-q2sgz8 , hahch-q2shj8 , hahch-q2shp0 , hahch-q2shq5 , hahch-q2shv0 , hahch-q2shv4 , hahch-q2shz6 , hahch-q2sic0 , hahch-q2sil6 , hahch-q2sj56 , hahch-q2sje1 , hahch-q2sje8 , hahch-q2skf9 , hahch-q2skg3 , hahch-q2skl5 , hahch-q2skv5 , hahch-q2sl80 , hahch-q2sll2 , hahch-q2slq4 , hahch-q2sls7 , hahch-q2sm17 , hahch-q2sn09 , hahch-q2sn54 , hahch-q2snn5 , hahch-q2snq6 , hahch-q2snw9 , hahch-q2spi5 , hahch-q2spk1 , hahch-q2spm8 , hahch-q2sq02 , hahch-q2sqg8 , hahch-q2sqn4 , hahch-q2sqx6 , hahch-q2sjs2

Title : Optimization of microwave-assisted extraction and supercritical fluid extraction of carbamate pesticides in soil by experimental design methodology - Sun_2003_J.Chromatogr.A_1014_165
Author(s) : Sun L , Lee HK
Ref : Journal of Chromatography A , 1014 :165 , 2003
Abstract : Orthogonal array design (OAD) was applied for the first time to optimize microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE) conditions for the analysis of four carbamates (propoxur, propham, methiocarb, chlorpropham) from soil. The theory and methodology of a new OA16 (4(4)) matrix derived from a OA16 (2(15)) matrix were developed during the MAE optimization. An analysis of variance technique was employed as the data analysis strategy in this study. Determinations of analytes were completed using high-performance liquid chromatography (HPLC) with UV detection. Four carbamates were successfully extracted from soil with recoveries ranging from 85 to 105% with good reproducibility (approximately 4.9% RSD) under the optimum MAE conditions: 30 ml methanol, 80 degrees C extraction temperature, and 6-min microwave heating. An OA8 (2(7)) matrix was employed for the SFE optimization. The average recoveries and RSD of the analytes from spiked soil by SFE were 92 and 5.5%, respectively except for propham (66.3+/-7.9%), under the following conditions: heating for 30 min at 60 degrees C under supercritical CO2 at 300 kg/cm2 modified with 10% (v/v) methanol. The composition of the supercritical fluid was demonstrated to be a crucial factor in the extraction. The addition of a small volume (10%) of methanol to CO2 greatly enhanced the recoveries of carbamates. A comparison of MAE with SFE was also conducted. The results indicated that >85% average recoveries were obtained by both optimized extraction techniques, and slightly higher recoveries of three carbamates (propoxur, propham and methiocarb) were achieved using MAE. SFE showed slightly higher recovery for chlorpropham (93 vs. 87% for MAE). The effects of time-aged soil on the extraction of analytes were examined and the results obtained by both methods were also compared.
ESTHER : Sun_2003_J.Chromatogr.A_1014_165
PubMedSearch : Sun_2003_J.Chromatogr.A_1014_165
PubMedID: 14558622