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엄한영,김형성,한상범 사단법인 한국질량분석학회 2014 Mass spectrometry letters Vol.5 No.1
An advanced and reliable high performance liquid chromatography (HPLC)/ultraviolet detector (UV)/ion-trap timeof-flight (IT-TOF) mass spectrometry was developed for the simultaneous quantification of 19 marker compounds in Bangpoong-tong-sung-san (BPTS), a traditional oriental prescription. Various parameters affecting HPLC separation and IT-TOFdetection were investigated, and optimized conditions were identified. The separation was achieved on a Capcell PAK C18 column(1.5 mm × 250 mm, 5 μm particle size) using a gradient elution of acetonitrile and water containing 0.1% formic acid at aflow rate of 0.1 mL/min. The column temperature was maintained at 40oC and the injection volume was 2 μL. IT-TOF systemwas equipped with an electrospray ion source (ESI) operating in positive or negative ion mode. The optimized electrospray ionizationparameters were as follows: ion spray voltage, +4.5 kV (positive ion mode), or -3.5 kV (negative ion mode); drying gas(N2), 1.5 L/min; heat block temperature, 200oC. Automatic MSn (n = 1~3) analyses were carried out to obtain structural informationof analytes. Elemental compositions and their mass errors were calculated based on their accurate masses obtained from aformula predictor software. The marker compounds in BPTS were identified by comparisons between MSn spectra from standardsand those from extracts. Moreover, the libraries of MS2 and MS3 spectra and accurate masses of parent and fragment ionsfor marker compounds were constructed. The developed method was successfully applied to the BPTS extracts and identified 17out of 19 marker compounds in the BPTS extracts.
엄한영,양동혁,서준혁,Han Young Eom,김운용,Junghyun Kim,Seul Gi Lee,Hyun-Deok Cho,한상범 대한약학회 2013 Archives of Pharmacal Research Vol.36 No.3
A simple, robust and reliable method for thedetermination of residual robenidine in chicken muscleusing high performance liquid chromatography with ultraviolet(UV) detection was developed and validatedaccording to the Codex Alimentarius Commission guidelines. Chicken muscle was extracted by acetonitrile/formicacid (98:2, v/v) and defatted with hexane. Analytes wereisocratically separated on a Luna C18 column(4.6 9 150 mm, 5 lm) using 70 % methanol in watercontaining 0.1 % trifluoroacetic acid at a flow rate of1.0 mL/min at 30 C. UV detection was performed at312 nm. The method was validated by assessing performanceparameters including selectivity, linearity, limit ofquantification (LOQ), precision, accuracy, recovery, stabilityand robustness. A calibration curve that was constructedover 0.05–0.5 lg/g showed correlation coefficientsof more than 0.999. The intra- and inter-day precisions (ascoefficient of variation) were 1.45–3.32 and 2.63–4.99 %,respectively. The intra- and inter-day accuracies were99.4–105.3 and 98.3–101.6 %, respectively. The recoverieswere in the range of 76.6–81.8 %and the LOQwas 0.05 lg/g. The developed method showed suitable performance for thedetermination of robenidine residues in chicken muscle.
서준혁,양동혁,Byung Kyu Lee,엄한영,김운용,Junghyun Kim,Hyeyeon Lee,한상범 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.8
A simple HPLC-DAD method was developed and validated to determine B group vitamin content (thiamine,riboflavin, nicotinamide, pantothenic acid, pyridoxine and folic acid) in supplemented food samples, i.e., infant formula, cereal, low-calorie food, a multi-vitamin pill and a vitamin drink. In this study, the most significant advantages were simultaneous determination of the six B group vitamins in various food matrices and a small number of sample treatment steps that required only an organic solvent, acetonitrile. Moreover, this method prevents reduction of column durability, because the mobile phase does not contain ion-pairing reagents. Analytes were separated on a Develosil RPAQUEOUS C_30 (4.6 mm × 250 mm, 5 μm particle size) column with a gradient elution of acetonitrile and 20 mM phosphate buffer (pH 3.0) at a flow rate between 0.8 and 1.0mL/min. Detection was performed at 275 nm, except for that of pantothenic acid (205 nm). The calibration curves for all six vitamins showed good linearity with correlation coefficients (r^2) higher than 0.995. The developed method was validated with respect to linearity, intra- and inter-day accuracy and precision, limit of quantification (LOQ), recovery and stability. The method showed good precision and accuracy, with intra- and inter-assay coefficients of variation less than 15% at all concentrations. The recovery was carried out according to the standard addition procedure, with yields ranging from 89.8 to 104.4%. This method was successfully applied to the determination of vitamin B groups in supplemented food products.
Cheol-Woo Lee,Jeongmi Lee,Jaehyun Lee,엄한영,Min Kyung Kim,서준혁,Hyesun Yeom,김운용,염정록,한상범 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.9
Toluene, xylene and styrene are volatile organic solvents that are commonly used in mixtures in many industries. Because these solvents are metabolized and then excreted in urine, their urinary metabolites are thought to be biomarkers of occupational exposure to these solvents. Therefore, a simple, rapid, and yet reliable analytical method for determining the metabolites is required for accurate biological monitoring. In the present study, a simple and rapid HPLC-UV method was developed for the simultaneous determination of eight major metabolites of toluene, xylene and styrene: hippuric acid (HA), mandelic acid (MA), o-, m- and p-methylhippuric acids (o-, m- and p-MHAs), and o-, m- and p-cresols. A monolithic column was employed as the stationary phase and several conditions, including flow rate, composition of mobile phase and column temperature, were variables for the optimization of the chromatographic resolution. All eight metabolites were successfully resolved within 5 minutes in 10% aqueous ethanol containing 0.3% acetic acid and 1.6% β-cyclodextrin, using a flow rate gradient of 1.0 - 5.0 mL/min at 25 oC. The performance of this method was validated by linearity, intra- and inter-day accuracy, and precision. The linearity was observed with correlation coefficients of 0.9998 for HA, 0.9999 for MA, 0.9989 for o-MHA, 0.9998 for m-MHA, 0.9991 for p-MHA, 0.9997 for o-cresol, 0.9998 for m-cresol, and 0.9986 for p-cresol. The intra- and inter-day precision of the method were less than 5.89% (CV) and the accuracy ranged from 92.95 to 106.62%. The validity was further confirmed by analysis of reference samples that were prepared by the inter-laboratory quality assurance program of the Korea Occupational Safety and Health Agency (KOSHA, Seoul, Korea). All measured concentrations of the analytes agreed with the certified values.
Hyun Du Shin,서준혁,Junghyun Kim,Hyeyeon Lee,엄한영,김운용,양동혁,한상범,염정록 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.2
A simple new method was developed for the determination of betaine in Fructus Lycii using hydrophilic interaction liquid chromatography with evaporative light scattering detection (HILIC-ELSD). Good chromatographic separation and reasonable betaine retention was achieved on a Kinetex HILIC column (2.1 × 100 mm,2.6 μm) packed with fused-core particle. The mobile phase consisted of (A) acetonitrile and (B) 10 mM ammonium formate (pH 3.0)/acetonitrile (90/10, v/v). It was used with gradient elution at a flow rate of 0.7 mL/min. The column temperature was set at 27.5 °C and the injection volume was 10 μL. The ELSD drift tube temperature was 50 °C and the nebulizing gas (nitrogen) pressure was 3.0 bar. Stachydrine, a zwitterionic compound, was used as an internal standard. Calibration curve over 10-250 μg/mL showed good linearity (R2> 0.9992) and betaine in the 70% methanol extract of Fructus Lycii was well separated from other peaks. Intraand inter-day precision ranged from 1.1 to 3.0% and from 2.4 to 5.3%, respectively, while intra- and inter-day accuracy ranged from 100.0 to 107.0% and from 94.3 to 103.9%, respectively. The limit of quantification (LOQ) was 10 μg/mL and the recoveries were in the range of 98.2-102.7%. The developed HILIC-ELSD method was successfully applied to quantitatively determine the amount of betaine in fourteen Fructus Lycii samples from different locations, demonstrating that this method is simple, rapid, and suitable for the quality control of Fructus Lycii.