• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1729-1734
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• 2007

The electrochemical behaviors of estrone in the presence of various surfactants were examined with great details. It is found that a cationic surfactant, cetyltrimethylammonium bromide (CTAB), obviously facilitates the electro-oxidation of estrone at carbon paste electrode (CPE) from the significant peak current enhancement and the negative shift of peak potential. Additionally, chronocoulometry and electrochemical impedance spectroscopy (EIS) were also used for further investigation of the electrode process of estrone, indicating that low concentration of CTAB exhibits excellent enhancement effects on the electrochemical oxidation of estrone, greatly enhances the diffusion coefficient and the electron transfer rate. Based on this, an electrochemical method was proposed for the determination of estrone. The oxidation peak current is proportional to the concentration of estrone in the ranges over 9.0 × 10?8 - 8.0 × 10?6 mol/L, and a low detection limit of 4.0 × 10?8 mol/L was obtained for 180s accumulation at open circuit (S/N = 3). Finally, this proposed method was demonstrated using estrone tablets with good satisfaction.

• Journal of Nutrition and Health
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• v.4 no.3
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• pp.1-4
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• 1971

Zinc is an essential trace element. Previos methods for the determination of zinc in serum have been difficult and reported findings must be treated with caution. The normal range of zinc in serum varies significantly according to different methods and author. The scope of this work was to establish the normal range of zinc in serum values in healthy Korean persons. Methods are described for the determination of zinc in serum diluted ten-fold with deionised water using Hitachi Model 207, atomic absorption spectrophotometer. The values of zinc in serum of 23 healthy Korean persons by atomic absorption spectroscopy ranged from 87.6 to $131.2\;{\mu}g/100\;ml$ with the mean value $109.1\;{\mu}g/100\;ml$ and standard deviation 10.86. In this method, satifactory result was obtained with regard to the coefficient variation and recoveries of added zinc in the measurenents.

• YAKHAK HOEJI
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• v.33 no.3
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• pp.156-160
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• 1989

A gas-chromatographic determination method of thiamin which use a quantitative cleavage of thiamin to 4-methyl-5-(2-hydroxyethyl)thiazol [I] and solvent extraction of the analyte prior to GC injection was modified. A column chromatographic procedure using a reversed phase, high capacity solid phase cartridge was applied to the clean-up of the analyte. Thiazol derivative[I] was quantitatively recovered upon the column method. Acetanilide, an internal standard, has a good recovery through the analytical procedure. The method has analytical precision of 2% or less in the coefficient of variation.

• Analytical Science and Technology
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• v.8 no.4
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• pp.469-475
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• 1995

Di-2-pyridylmethanon 2-thiophenecarboxylie hydrazone(DPMTCH) was synthesized and used as a chromogenic reagent in the spectrophotometric determination of nickel in steel. The proton disc spectrophotometrically, were $pK_{a1}= 2.66$ and $pK_{a2}= 10.98$ ${\mu}=0.5(NaCl)$. Nickel(II) reacts with DPMTCH to form a 1:2 metal-2-ligand ratio complex, the xylene solution of which has an absorption maximum at 417 nm. Beer's law is obeyed over the range $0-1.17\;mg\;ml^{-1}$ of nickel(II). The molar absorptivity of the nickel(II) complex is $4.17{\times}10^4l\;mol^{-1}\;cm^{-1}$. The precision of the method was estimated for 4.7 mg of nickel(II), the coefficient of variation for 15 replicate determinations being 0.34%.

• Herbal Formula Science
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• v.18 no.2
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• pp.251-257
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• 2010

Objectives : To develop and validate High-performance liquid chromatography-photodiode array methods for simultaneous determination of two constituents in Oryeong-san(ORS). Methods : Reverse-phase chromatography using a Gemini C18 column operating at $40^{\circ}C$, and photodiode array(PDA) detection at 280 nm, were used for quantification of the two marker components of ORS. The mobile phase using a gradient flow consisted of two solvent systems. Solvent A was $H_2O$ and solvent B was acetonitrile. Results : Calibration curves were acquired with correlation coefficient ($r^2$)>0.9999, and the relative standard deviation(RSD) values(%) for intra- and inter-day precision were not exceed 1.0%. The recovery rate of each compound was in the range of 93.01-104.16%, with an RSD less than 2.0%. The contents of two compounds in ORS were 1.10-3.72 mg/g. Conclusions : The established HPLC method will be helpful to improve quality control of ORS.

• Archives of Pharmacal Research
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• v.9 no.4
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• pp.211-214
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• 1986

A simultaneous determination method of alkaline earth metals was attempted with the conventional high performance liquid chromatographic system. Four cations, namely, magnesium, calcium, strontium and barium ion, were injected directly as aqueous solution into an eluent containing copper chloride solution and and were successfully separated and determined on a separating column (Zipax SCX, 4.6 mm i.d. ${\times}25$ cm length, Du Pont, USA) by using a variable wavelength UV detector. The linear calibration curves were obtianed in the range from $1.0{\times}10^{-4}M$ to $5.0{\times}10^{-4}M$ and the correlation coefficient of the calibration curve for each metal of magnesium and calcium in tap water. Alkaline earth metals were determined with the conventional high performance liquid chromatographic system.

• Journal of Families and Better Life
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• v.24 no.1 s.79
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• pp.71-82
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• 2006

The purpose of this study was to develop a standardized scale to measure consumers' motivation to purchase based on a self-determination theory. A preliminary 27-item scale was developed through literature review, diary analysis, and FGI. A questionnaire survey was conducted among 1,000consumers on internet using the preliminary scale. Then a series of tests, such as test-retest, item analysis, item-to-total correlation, Cronbach's reliability coefficient, and factor analysis, were conducted using the survey data. The final scale with21 items was constructed in the end. The Purchase Motivation Scale for Consumers consisted of five factors: (1) external motivation, (2) introjected motivation, (3) identified motivation I: self-respect, (4) identified motivation II: pursuit of harmony, and (5) internal motivation.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.31-36
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• 2010

This paper introduces a practical determination method for soil parameters adopted in the new performance based design code for port and harbour facilities in Japan. In the new port-design code, the depth profile of the derived values is modeled as the profile of the estimated values so as to be either the mean value or the regression line, then the correction factors are multiplied to the estimated value according to the coefficient of variation (if COV > 0.1) and the number of the data entries (if n < 10). The new port-design code is applied to the unconfined compression test results for the Hiroshima Port clay in order to evaluate the undrained shear strengths. From the discussion, it is emphasized that not only the statistic treatment but also the engineering judgment are required in the procedure of the soil parameter determination for the reliability design.

• Journal of Pharmaceutical Investigation
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• v.21 no.2
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• pp.79-84
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• 1991

The agar diffustion method using Escherichia coli was investigated for determination of Vitamin $B_{l2}$ instead of turbidimetric method using Lactobacillus leichannii (USP XXII method). The turbidimetric method is difficult to control the test organism and it has complicated procedure. From this study, it was found that the agar diffusion method on the determination of Vitamin $B_{12}$ in pharamaceutical preparation is simple and convenient as compared with turbidimetric method. Also we found that the coefficient of variation in reproducibility and the standard error in recovery were 2.18% and 1.83%, respectively.

• YAKHAK HOEJI
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• v.24 no.2
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• pp.117-122
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• 1980

A new application of high pressure liquid chromatography for the determination of fenitrothion and cis- and trans-neopynamin in insecticidal preparations was investigated. Optimum conditions for a good separation and determination were determined; solvent system: dichloromethane + n-hexane = 17 + 83; Bow rate: 0.5ml/min; column: u-porasil ($4mm{\times}3Ocm$); absorbance wavelength: 254nm; 0.05 AUFS and sample size: 30 ul. Recovery of fenicrothion, cis- and trans-neopynamin from mixed artificial preparations was 99.6%, 99.7% and 99.8% respectively. Also reproducibility tests showed that the coefficient of variation was 0.89% for fenitrothion, 0.74% cis-neopynamin and 1.1% for trans-neopynamin. There was no interference with insecticidal preparation containing DDVP, allethrin, S-421 and kerosene. HPLC method was rapid, accurate and it gave better reproducibility and higher sensitivity than any other analytical method. It was considered that HPLC could be greatly applied to the analysis of fenitrothion and neopynamin in insecticidal preparations.