Tae Woong Na
Chonnam National University
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Featured researches published by Tae Woong Na.
Food Chemistry | 2012
Md. Musfiqur Rahman; Jeong-Heui Choi; A. M. Abd El-Aty; Morad Dirhem Naji Abid; Jong-Hyouk Park; Tae Woong Na; Yong-Doo Kim; Jae-Han Shim
During gas chromatography (GC), the matrix can deactivate the active site during the transport of the compound from the injector to the detector. This deactivation capacity varies among matrices, as it is dependant on the concentrations of the different constituent compounds of each matrix. During the analysis of terbufos and its metabolites, two of its metabolites were highly thermolabile, and were readily decomposed inside the GC system. As the matrix can mask the active site, we carried out a matrix-matched calibration in an effort to protect the analyte against decomposition. As a component of our analysis, the pepper matrix was the first to be matched; however, it failed to completely protect the metabolites. Subsequently, a variety of different compounds, including 3-ethoxy-1,2-propanediol, gulonolactone, and sorbitol at 10, 1, and 1mg/mL were tested; however, none of these generated the desired effect. We surmised that some of the compounds may have decomposed inside the injection port, so we introduced a carbofrit inlet liner, which is highly inert. But, this step did not improve the protective qualities of the matrices. Finally, pepper leaf matrix was added to the pepper matrix, and we observed a profound protective effect for almost all of the analytes tested. A selective detector (flame photometric detector with phosphorus filter) was used to facilitate a high matrix concentration without interaction with the analyte. After resolving the problem of these two metabolites, terbufos and its five toxic metabolites were analyzed in pepper and pepper leaf samples. The recovery rates for terbufos and its metabolites were 73-114.5% with a relative standard deviation of <12%. This method was successfully applied to field samples, and terbufos sulfone, terbufos sulfoxide, and terbufoxon sulfoxide were found as residues in the suspected pepper and pepper leaf samples.
Food Chemistry | 2012
Ki Hun Park; Jeong-Heui Choi; A. M. Abd El-Aty; Soon-Kil Cho; Jong-Hyouk Park; Bo Mi Kim; Angel Yang; Tae Woong Na; Md. Musfiqur Rahman; Geon-Jae Im; Jae-Han Shim
In this study, a simultaneous method was developed for the determination of spinetoram (XDE-175-J and XDE-175-L) and its demethyl metabolites (N-demethyl-175-J and N-demethyl-175-L) and formyl metabolites (N-formyl-175-J and N-formyl-175-L) in the minor crops; amaranth and parsley. The method uses quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction. Afterwards, the analytes were quantified and confirmed via liquid chromatography-electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). Calibration curves were linear over the calibration ranges for all the analytes tested with r(2)>0.993. Limits of detection and quantitation were 0.01 and 0.03 mg/kg for all the tested analytes in amaranth and parsley, respectively. Recovery values, at spiking levels 0.05 and 0.25 mg/kg, ranged from 71.0% to 115.2% with relative standard deviations <15%, except for N-formyl-175-J in both amaranth and parsley. This method was applied to field-incurred samples and was shown to provide an adequate sensitivity and performance for the simultaneous determination of spinetoram and metabolites. To the best of our knowledge, this is the first time spinetoram and its metabolites were quantified using LC-MS/MS in minor crops.
Journal of The Korean Society for Applied Biological Chemistry | 2012
Tae Woong Na; Md. Musfiqur Rahman; Jong-Hyouk Park; Angel Yang; Ki Hun Park; A. M. Abd El-Aty; Jae-Han Shim
Persistence and degradation behaviors of acequinocyl and hydroxyacequinocyl were determined in perilla leaf grown under greenhouse conditions. Acequinocyl (15%, SC) was sprayed on perilla leaf at the recommended dose rate of 37.5 g/250 L water/10a with single and double dose applications. Leaf samples were collected randomly at 0 (2 h after application), 1, 3, 5, and 7 days post-application from two different plots. The samples were extracted with acetonitrile, purified through a solid phase extraction procedure, and analyzed via ultra performance liquid chromatography coupled with photo diode array detector (UPLCPDA). Residues were confirmed via liquid chromatography tandem mass spectrometry (LC-MS/MS) in positive-ion electrospray ionization (ESI+) mode. Calibration curves were linear over the concentration ranges for the analytes with r2 ≥0.992. The limits of detection and quantification were 0.05 and 0.165 mg/kg for both acequinocyl and hydroxyacequinocyl. The method was validated in triplicate at two fortification concentrations in the matrix. Good recoveries were observed for the target analytes, ranging between 94.95 and 113.26% with relative standard deviations less than 6%. The rates of disappearance of total acequinocyl on perilla leaf for single and double doses were described as first-order kinetics with half-lives of 2.8 and 3.1-days, respectively.
Biomedical Chromatography | 2011
Jong Hyouk Park; M. I. R. Mamun; A. M. Abd El-Aty; Tae Woong Na; Jeong-Heui Choi; M. W. Ghafar; Kap Soon Kim; Sang Don Kim; Jae-Han Shim
In this study, a multiresidue analytical method for the detection of 37 pesticides in a soil matrix was developed and validated. The soil sample was fortified with a known quantity of pesticides at two different concentration levels (0.1 and 0.01 µg/g) and the analytes were extracted via a liquid-solid extraction method. The pesticides were separated on an HP5 capillary column and were analyzed with a gas chromatograph coupled to a nitrogen-phosphorous detector (GC-NPD). Method validation was accomplished with good linearity (r(2) = 0.994-0.999) within a considerable range of concentrations. Satisfactory recoveries (70.5-110.4%) were obtained with 32 pesticides at both spiking concentration levels, whereas five pesticides-dimepiperate, buprofezin, prometryn, pirimicarb, and fludioxonil-were recovered at relatively low levels (43.6-61.8%). The applicability of the method was demonstrated by analyzing field samples collected from 24 different sites around Yeongsan and Sumjin rivers in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples. The developed method could be employed as a simple and cost-effective method for the routine detection and analysis of 37 pesticides in soil samples.
Journal of Separation Science | 2016
Md. Musfiqur Rahman; Sung-Woo Kim; Tae Woong Na; A. M. Abd El-Aty; Young-Jun Lee; Joon-Seong Park; Amer Ramadan; Han Sol Lee; Hyung Suk Chung; Jeong-Heui Choi; Ho-Chul Shin; Jae-Han Shim
An analytical method to detect phorate and its metabolites, including phorate sulfone, phorate sulfoxide, phoratoxon, phoratoxon sulfone, and phoratoxon sulfoxide, in porcine and chicken muscles and table eggs was developed and validated. Extraction was performed using a quick, easy, cheap, effective, rugged, and safe method and analysis was conducted using ultra-high performance liquid chromatography-tandem mass spectrometry. Matrix-matched calibrations were linear over the tested concentrations, with determination coefficient ≥ 0.995 for all tested analytes in the different matrices. The limits of detection and quantification were 0.001 and 0.004 mg/kg, respectively. The calculated recovery rates at three fortification levels were satisfactory, with values between 74.22 and 119.89% and relative standard deviations < 10%. The method was applied successfully to commercial samples collected from locations throughout the Korean Peninsula, and none of them showed any traces of the tested analytes. Overall, the developed method is simple and versatile, and can be used for monitoring phorate and its metabolites in animal products rich in protein and fat.
Biomedical Chromatography | 2011
Jeong-Heui Choi; Tae Woong Na; M. I. R. Mamun; A. M. Abd El-Aty; Eun-Ho Shin; Jong-Hyouk Park; Jae-Han Shim
In this study, a method for the detection of sarafloxacin in pig and chicken muscles was developed using HPLC-FLD as a regulatory residue technique. Good extraction efficiency was achieved using a mixture of 1% orthophosphoric acid-0.2 m MgCl(2) in water and acetonitrile as an extraction solvent, and n-hexane partitioning and centrifugation for cleanup was used in the absence of dehydration. Specificity, linearity, detection and quantification limits, recovery, accuracy and precision were all validated, and all results were sufficient for the SARA regulatory residue method in pig and chicken muscles. The method developed and described herein was not only simple but also reliable, and was applied to market samples to determine their residue contents.
Biomedical Chromatography | 2011
Jong Hyouk Park; M. I. R. Mamun; A. M. Abd El-Aty; Tae Woong Na; Jeong-Heui Choi; M. W. Ghafar; Woo Jung Choi; Kap Soon Kim; Sang Don Kim; Jae-Han Shim
In a continuation of our earlier work, a multiresidual analytical method using 48 frequently used neutral pesticides in a water matrix was developed and validated in this study. The samples were extracted with dichloromethane and the pesticides were analyzed via GC-NPD followed by confirmation with GC-MS. Good linearity was detected over a concentration range of 0.01-1.0 microg/mL with correlation coefficients (r(2) ) in excess of 0.982. The recoveries were measured between 70.7 and 111.4% for the majority of the targeted pesticides with relative standard deviations (RSDs) of less than 20%. The LODs and LOQs were in ranges of 0.1-2 and 0.33-6.6 microg/L, respectively. A total of 66 water samples were collected from different locations in Yeongsan and the Sumjin River, Republic of Korea, and were analyzed in accordance with the developed method. None of the water samples were determined to contain any of the targeted pesticides. The method has been shown to be simpler, faster, and more cost-effective than the method established by the Environmental Protection Agency (EPA).
Food Chemistry | 2012
Bo Mi Kim; Joon-Seong Park; Jeong-Heui Choi; A. M. Abd El-Aty; Tae Woong Na; Jae-Han Shim
Environmental Monitoring and Assessment | 2013
Md. Musfiqur Rahman; Tae Woong Na; A. M. Abd El-Aty; Jong-Hyouk Park; M. N. U. Al Mahmud; Angel Yang; Ki Hun Park; Jae-Han Shim
Biomedical Chromatography | 2017
Sung-Woo Kim; Md. Musfiqur Rahman; A. M. Abd El-Aty; Md. Humayun Kabir; Tae Woong Na; Jeong-Heui Choi; Ho-Chul Shin; Jae-Han Shim