• Analytical Science and Technology
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• v.15 no.1
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• pp.26-30
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• 2002

In order to determine the contents of ethyl carbamate in Korean traditional alcoholic beverages and general beverages, GC/MS-SIM method was used after extraction of beverages with dichloromethane. The contents of ethyl carbamate in Korean traditional alcoholic beverages, non-distilled alcohol, and whisky were detected in the range of $4.6-50.2{\mu}g/L$, $27.8-45.4{\mu}g/L$, and $24.8-55.1{\mu}g/L$, respectively. The recoveries were ranged from 83.3 to 104.8 %. The values of relative standard deviation were ranged from 1.8 to 14.8 % and the detection limit was $0.3{\mu}g/L$.

• Analytical Science and Technology
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• v.14 no.1
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• pp.21-27
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• 2001

In this work, analytical performance of a laboratory built double membrane desolvator (DMD) was studies using perfluoroalkoxy (PFA) nebulizer and microconcentirc nebulizer (MCN) in inductively coupled plasma atomic emission spectrometry. Compared with MCN, PFA nebulizer coupled to DMD showed similar analytical sensitivity for aqueous solution and better sensitivity for isopropyl alcohol. Since PFA resisted various acids, HCI, $H_2SO_4$ and HF solution were analyzed with less than 2% RSD. Rinse-out time for the signal reduction to 1% was obtained to be 35 s for PFA but about 45 s for MCN.

• Analytical Science and Technology
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• v.24 no.5
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• pp.360-367
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• 2011

Optical purities of 10 commercialized naproxens prepared from eight Korean drug companies were examined by an optimized chiral HPLC condition. The Chiralcel OD-H column and ChiralHyun-LE(S)-1 column were used as chiral stationary phases and the mixed eluent of hexane/isopropanol/acetic acid as 100:2.85:0.1 was used as a mobile phase for effective enantioseparation. Optical purity values of most samples were higher than 97 percents, only one of them was about 95 percents. The average relative standard deviation of them appeared very small (0.034%).

• Journal of Food Hygiene and Safety
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• v.23 no.1
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• pp.26-30
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• 2008

Polycyclic Aromatic Hydrocarbons(PAHs) contamination arises from several source including processing of food(smoking, direct drying, cooking) and environmental contamination of air, water or soil. A red ginseng is produced by steaming the root followed by drying. The methodology involved extraction with n-hexane and washing with water, clean-up on Sep-Pak Florisil Cartridges and determination by HPLC/FLD. The mobile phase was a mixture of acetonitrile and water in 8:2 by the isocratic elution and the excitation wavelength of fluorescence detector was 294 nm and its emission wavelength was 404 nm. The average recovery was about 105% and the relative standard deviation was 0.5. The levels of benzopyrene in the selected red ginseng beverage samples were not detected.

• Analytical Science and Technology
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• v.13 no.3
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• pp.315-322
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• 2000

The response characteristics of the bioelectrode developed by the co-immobilization of spinach root tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined (-0.3~0.0V vs. Ag/AgCl). the response time was relatively short ($t_{95%}=11.8$ sec) and it responded in the wide range of pH. Also, its detection limit was $2.25{\times}10^{-6}M$ (S/N=3) and a relative standard deviation of the measurements which were repeated 15 times using $1.0{\times}10^{-3}M$ hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 40% of the original value in 19 days of continuous use.

• Analytical Science and Technology
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• v.23 no.1
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• pp.97-101
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• 2010

(R)-N-3,5-dinitrobenzoyl (DNB) phenylglycinol derived chiral selector was used as a HPLC chiral stationary phase (CSP) for the resolution of racemic N-acylnaphthylalkylamines. In this study, determination of optical purity was performed by both chiral chromatography and NMR spectroscopy by using the (R)-phenylglycinol derived chiral selector. The data of accuracy and precision of each optical purity value are calculated from the results of NMR and HPLC experiments by comparing with true value. Average error of the NMR method was +2.2% with average RSD of 4.54%, while that of HPLC method was -3.5% with average RSD of 3.23%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1349-1356
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• 1994

The results of laboratory experiments on the clear-water scour of cohesionless bed sediment for three types of pier shape were presented. According to the experimental data, the local scouring around the pier was initiated at $V/V_c=0.4{\sim}0.5$ and $Fr_p{\fallingdotseq}0.2$, and the relative local scour depths linearly increased with respect to the velocity ratio and the pier Froude number. The relative scour depth had the linear relationship with ${\tau}_r$ for ${\tau}_r$ < $10^{-4}$, but it tends to become constant for ${\tau}_r$ > $10^{-4}$, irrespective of ${\tau}_r$. And also the relative scour depths showed the close relationship with both the geometric standard deviation and the pier shape.

• Economic and Environmental Geology
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• v.20 no.1
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• pp.77-82
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• 1987

An analysis is made for the relative effectiveness in detecting a subsurface thin layer by four electromagnetic depth sounding systems; horizontal coplanar loops, perpendicular loops, vertical coplanar loops and vertical coaxial loops. The moduli and phases of mutual coupling ratios over a three-layered earth for the four systems are evaluated rapidly by the related convolution technique. Root mean square differences between the responses from the three-layered and the homogeneous earths are used to compare the relative effectiveness of the systems quantitatively. Comparing the all systems, it is found that the perpendicular loop system appears to be the most superior to the other systems.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.506-511
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• 1991

A sensitive adsorptive stripping voltammetric study was investigated on the complex of indium with morin at a hanging mercury drop electrode in 0.1 M acetate buffer (pH 3.20) solution. The adsorption phenomena were observed by differential-pulse voltammetry. The effects of various analytical conditions were discussed on the reduction peak current of the adsorbed complex on the surface of HMDE. Interferences by other trace metals and surfactant were also discussed. Detection limit was 2.6 nM of indium after 90 second deposition time, and the relative standard deviation (n = 7) at 4TEX>${\mu}g$/l indium was 2.0%.

• Analytical Science and Technology
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• v.16 no.6
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• pp.499-503
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• 2003

A high performance liquid chromatography gradient elution method with fluorescence detection for the determination of biotin in pure form and pharmaceutical preparations has been developed. BrMDMC gives intense fluorescence and the fluorescence was monitored with excitation at 360 nm and emission at 410 nm. The calibration curve for biotin shows good linearity over the range of 5 ~ 400 ng with correlation coefficient of 0.999. The detection limit of biotin was 2 ng and the result of recovery was 98.75% with relative standard deviation of 1.1%.