• The Korea Journal of Herbology
• /
• v.23 no.4
• /
• pp.45-49
• /
• 2008

Objectives: To investigate the quantitative determination of marker constituents of Dioscoreae Rhizoma by the packaging methods Methods: HPLC for the determinations of allatoin in the Dioscoreae Rhizoma. the separation method was performed on an Luna $NH_2$ column($250mm{\times}4.6mm,\;5{\mu}m$, Phenomenes) using solvent water-acetonitrile(2:8, v/v%) with photo diode array detector(210nm). The flow rate was 2.0 mL/min. Results: Retention time of allatoin in HPLC chromatogram was about 4.8 min and calibration curve showed good linearity($R^2$=0.9994) at concentrations from 50.0 to 1000.0 ${\mu}g/mL$ of allantoin. Average content of allantoin by packaging methods was $0.16{\sim}0.40%$. In addition. weight loss rate(%) of Dioscoreae Rhizoma according to the packaging methods was $-0.60{\sim}1.80%$. Conclusions: The variation on content of the marker constituent of Dioscoreae Rhizoma by the packaging methods didn't show difference.

• BMB Reports
• /
• v.43 no.11
• /
• pp.761-765
• /
• 2010

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-$d_3$ as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9：00-11：00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.3
• /
• pp.498-506
• /
• 2002

Improvements of fuel properties have become essential for exhaust emission reduction as well as for optimization of directly-related design factors and exhaust gas aftertreatment. In this study, the potential possibility of oxygenated fuel such as ethylene glycol mono-n-butyl ether(EGBE) was investigated for the sake of smoke reduction from diesel engine. Because EGBE include oxygen content approximately 27%, it is a kind of effective oxygenated fuel that the smoke emission of EGBE is reduced remarkably in comparison with commercial diesel fuel, that is, it can supply oxygen component sufficient at high load and speed in diesel engine. And, it was tried to analyze the quantities of the low and high boiling point hydrocarbon among the exhaust emissions in diesel engine. It have been investigated by the quantitative analysis of the hydrocarbon $C_1$~ $C_{6}$ using the gas chromatography. This study was carried out by comparing the chromatogram with diesel fuel and diesel fuel blended EGBE 20vo1-%. The results of this study show that the hydrocarbon $C_1$~C$_{6}$ among the exhaust emission of the mixed fuels are exhausted lower than those of the diesel fuel at the all load and speed. In particular, high boiling point hydrocarbons such as $C_{5}$ and $C_{6}$ were reduced remarkably at high speed and load.d.

• KSBB Journal
• /
• v.11 no.5
• /
• pp.529-535
• /
• 1996

Methyl frucloside was purified from the aqueous sugar/methyl fructoside solution by liquid chromatography using Amberlite IRA-900, strong anion-exchange resin. The optimum operating conditions, resolution and productivity of methyl fructoside were discussed to evaluate the practical feasibility of the proposed chromatographic separation process of methyl fructoside which is useful as a new starting material for sugar ester synthesis. The linear chromatography model with HETP was well applied to the chromatographic separation process of methyl fructoside and the theoretical solution successfully predicted the elution chromatogram of methyl fructoside and sucrose at different superficial linear velocity of eluent for rectangular feed with different loading volume of packed bed. The optimum operating conditions were found to be 75% with the loading volume of packed bed at 1.13 cm/min of the superficial linear velocity at $60^{\circ}C$, and gave the productivity of methyl fructoside of 7 mg/g-resin/h with the resolution of 1.1.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.3
• /
• pp.353-358
• /
• 2006

Flavonoid and limonoid compounds were determined by HPLC on the methanol and ethanol extracts from citron seeds. The quantities of the compounds in these categories were higher in the ethanol extract than methanol extract. The types of these compounds were detected in larger numbers in the ethanol extract. The content of limonin was the largest in both methanol and ethanol extract among the detectable compounds ; 140.34 mg/100g and 170.98 mg/100g, respectively, and the contents of other compounds, caffeic acid, naringin, lutin, nomilin, were found in large amount in this order. The molecular weights of forty two compounds in ethanol extract were determined with mass spectrums and extracted ion current chromatograms by HPLC/MS.

• Microbiology and Biotechnology Letters
• /
• v.1 no.1
• /
• pp.13-18
• /
• 1973

For the production of Nucleic acid derivatives by microorganisms, adenineless mutants were induced from Bacillus subtilis with the mutagens, ultraviolet rays and diethylsulfate. And total strains of 62 adenineless mutants were isolated. These mutants were found to have an ability of accumulating u. v. absorbing substances in the culture broth. They were analyzed to be hypoxanthine, uracil, and other unknown compound by means of two dimensional thin layer chromatography, u. v. absorption spectra, and I. R. absorption spectrum. Mutant BS-137 was screened out to accumulate hypoxanthine, which was isolated from the culture broth through activated carbon column and recrystallize from cold water. The effect of the medium compositions on hypoxanthine accumulation were examined for the mutant BS-137. Glucose appeared to be the best carbon source, but molasses could be substitute for it, NaNO$_3$ and yeast extract were especially good sources of nitrogen.

• Tribology and Lubricants
• /
• v.33 no.2
• /
• pp.45-51
• /
• 2017

Engine oil is a substance used for the lubrication of internal combustion systems. However, in some case, defects in engine systems may contaminate engine oil with fuel. Contaminated engine oil can cause problems in the normal functioning of a vehicle. In this study, we investigate the functional properties of engine oil contaminated with diesel fuel. The test results indicate that the engine oil contaminated with diesel fuel has low flash point, pour point, density, kinematic viscosity and cold cranking simulator value. The contaminated engine oil which has low plash point can cause fire and explosion accident. Furthermore, a four ball test indicates that the contaminated engine oil increases wear scar to poor lubricity. Moreover, we investigate the GC pattern using SIMDIST (simulated distillation) for determination of diesel in engine oil. The SIMDIST analytic result, diesel was detected at earlier retention time than engine oil in chromatogram. Thus the SIMDIST method can define whether engine oil is contaminated by diesel fuel or not. We can use the SIMDIST method for the diagnosis of oil condition instead of analyzing other physical properties that require many analytic instruments, large volume of oil sample and long analysis time.

• Journal of Korean Society on Water Environment
• /
• v.23 no.6
• /
• pp.843-849
• /
• 2007

Monitoring of NOM characteristics is important for improving removal efficiency of natural organic matter (NOM) in water treatment processes. In this study, several NOM characteristics, which include specific UV absorbance (SUVA), total carbonate content, molecular weight distribution, and fluorescence properties, were measured using samples collected from a pilot-scale water treatment plant consisting of coagulation/flocculation (C/F), filtration, ozonation and granular activated carbon (GAC) processes. The highest removal of NOM was observed in C/F and filtration processes as demonstrated by the reduction of dissolved organic carbon (DOC) by 25% and 21%, respectively. Despite nearly no change in DOC, however, the lowest SUVA value and the highest total carbohydrate content were observed in the sample from ozonation process. This indicates that non-degradable aromatic compounds become depleted and biodegradable organic compounds are enriched during the process. Comparison of synchronous fluorescence spectra of the samples showed that ozoation process increased protein-like fluorescence while it decreased fulvic-like and terrestrial humic-like fluorescence. Consistently, a slight peak of protein-like fluorescence was observed in the sample from ozonation process. The greatest change in molecular weight distributions of the samples was observed in C/F process. Comparison of size exclusion chromatogram of the samples revealed that NOM fractions with the molecular weight greater than 2000 Da were reduced by over 90% after C/F process. SUVA values and total carbohydrate content of the samples were well correlated with a ratio of protein-like fluorescence and terrestrial humic-like fluorescence intensities with the correlation coefficients of 0.99 and 0.91, respectively. This suggests that synchronous fluorescence properties of NOM could be used as useful tolls for monitoring changes of some NOM characteristics during water treatment processes.

• Korean Journal of Food Science and Technology
• /
• v.6 no.3
• /
• pp.185-187
• /
• 1974

Total malonaldehyde(MA) in several dried fishery products (Alaska pollack, anchovy, white bait and squid) was determined by distillation and TBA reaction. In particular, MA in a water extract of dried anchovy was fractionated into bound and free MA on a Sephadex G-10 column. Among the three elution peaks, two peaks were found to be bound MA representing 94.5% of the total MA in the water extract and free MA constituted only a minor peak.

• Korean Journal of Microbiology
• /
• v.37 no.1
• /
• pp.66-71
• /
• 2001

An aerobic microbiological process was tested in 1.5 L stirred tank reactors for the treatment of dinitrotoluenes (DNTs)[e.g., 2.4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT)] in the test culture of Stenotrophomonas maltophilia, which had previously characterized. Both 2,4-DNT and 2,6-DNT were completely degraded within 10 days and 14 days of incubation, respectively. Addition of the secondary carbon was essential to degrade DNTs, and little degradation was achieved in the absence of the secondary carbons. The effect of additional nitrogens on the degradation of DNTs was evaluated. Complete degradation of DNTs was observed in the absence of any additional nitrogens, whereas DNTs were partially degraded in the growth media with additional nitrogens. Both HPLC and GC-MS were used to detect and verify the residual DNTs and their intermediates. As the results, the HPLC and GC-MS chromatograms demonstrated that the both parent compounds, 2, 4-DNT and 2,6-DNT, and respective intermediates, 2-amino-4-nitrotoluene and 2-amino-6-nitrotoluene, could be successfully identified under the analytical conditions.