• YAKHAK HOEJI
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• v.42 no.6
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• pp.576-582
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• 1998

Fenfluramine, an anorectic agent, is widely abused as a diet pill in Korea because it is freely marketed in China without any regulation. The optical isomers of fenfluramine hav e different phamacological actions: d-form is used as an anorectic agent, while l-form as a neuroleptic agent. To investigate the metabolism when racemic fenfluramine was administered orally, the urinary excretion of fenfluramine was studied in rats. The enantiomeric separation of fenfluramine was performed on achiral column by gas chromatography using (S)-N-(trifluoroacetyl)-l-prolyl chloride (TFP) as a derivatizing agent. After administration of 15mg/kg of racemic fenfluramine to rats, d-, l-fenfluramine and its metabolites d- and l norfenfluramine in urine were determined by chromatographic separation of TFP derivatives on DB-1 at retention time of 11.2, 11.8, 8.4 and 8.6 min respectively. Urinary recoveries of d and l-fenfluramine in rat were 0.42-5.9O% and 0.18-1.20% respectively in urine specimens collected during first 24hr. The comparison in the levels of isomers showed that d- fenfluramine were higher than l-form, while d-norfenfluramine were lower than l-form. The ratios between parent compound and metabolite revealed that d-norfenfluramine to d-fenfluramine ranged from 1.0 to 4.4, while the ratio of l-norfenfluramine to l-fenfluramine was 8.2-21.1 indicating that l-fenfluramine is metabolized faster than the d-isomer.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.612-617
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• 1995

Changes in titratable acidity, pH, viable cells, sensory properties and volatile aroma compounds of yogurt during lactic fermentation in milk added with egg white powder (EWP) have been studied. Milk added with 1% or 2% (W/V) of EWP was fermented with Lactobacillus acidophilus for 30 hr. Acidity of milk added with EAT increased gradually during lactic fermentation for 30 hr, pH dropped gradually and number of viable cells increased and reached stationary phase at about 9 hr. Addition of EWP significantly stimulated acid production by lactic acid bacteria and stimulating effect of 2% EWP addition on acid production was slightly higher than that of 1% EWP addition. Sensory evaluation showed that optimum fermentation time of yogurt prepared from milk added with 2% of EWP was about 15 hr. Gas chromatographic analysis showed that the amount of acetone and butanol decreased gradually and that of ethanol increased until 30 hr. Diacetyl and acetoin were first detected after 6hr and 9hr, respectively, and then increased until 30 hr.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.458-463
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• 1995

A curd yogurt was prepared from milk added with skim milk powder or egg white powder(EWP). The effects of EWP addition on growth and acid production by lactic acid bacteria in milk were studied. The effects of EWP addition on quality of curd yogurt in point of apparent viscosity, sensory property and volatile aroma compounds were also investigated. Addition of PAT markedly stimulated acid production by lactic acid bacteria and stimulating effect of EWP on acid production was proportional to the amount of addition. Apparent viscosity of curd yogurt added with EWP was generally higher than that of control. Curd yogurt fermented with L. acidophilus showed thixotropic characteristics. Sensory property of curd yogurt added with EWP was evaluated as better than reference sample and sample added with EWP at 2% level was evaluated as better than other samples. Acetone, ethanol, diacetyl, butanol and acetoin were detected by gas chromatographic analysis.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.427-431
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• 1997

A simultaneous and rapid gas chromatographic determination of organophosphorus, organo-chlorine, carbamate, and pyrethroid pesticides in polished rice was developed. The pesticides were extracted from samples with acetone by automated soxhlet apparatus and this extract was evaporated to dryness. The residue was dissolved in hexane, the solvent was applied to a Sep-Pak florisil catridge, was eluted with 50% ethyl acetate in n-hexane, and was injected to dual GC-ECD/NPD system. This simple method affords a high recovery of hydrophilic pesticides, allows rapid analysis, and is cheap to perform. Except for dichlorvos and captan, recoveries of 46 pesticides were over 60%.

• Preventive Nutrition and Food Science
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• v.16 no.3
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• pp.267-271
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• 2011

Static Headspace Gas Chromatographic analysis was used to study the partitioning behavior of five organic printing ink solvents between chocolate cookie/air systems. Three cookie sample formulations varied with respect to chocolate type and overall percentage of constituents. Major considerations involved differences in fat content and type and resulting variability in chemical and physical structure. Each of the solvents studied (ethyl acetate, hexane, isopropanol, methyl ethyl ketone, toluene) represents a general class of printing ink solvents based on predominate functional group. Values of the partitioning coefficient (Kp) were determined at equilibrium using measured quantities of both solvent and cookie sample in closed systems at temperature of 25, 35, and $45^{\circ}C$. In each of the three cookies at the three test temperatures, toluene always exhibited the greatest value of partitioning to cookie and hexane always exhibited the least. Results also showed that the partitioning behavior of solvents is generally inversely related to temperature and that solvent affinity, though constant for a particular cookie type over all test temperatures, varies significantly among the three cookie types. The preference of each of the five solvents for each cookie sample was also found to vary with temperature. No correlation was found between the extent of partitioning and cookie formulation or physical characteristic of solvent. The Hildebrand parameter, related to ${\Delta}Hmix$ (heat of mixing), may be used to describe differences in partitioning based on the overall potential of a solvent/cookie interaction to occur. The potential for interaction is dependent upon the chemical structure of the cookie sample and thus the availability of 'active-sites' required for a given solvent.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.106-109
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• 1965

The effects of methyl borate, iodine and potassium iodide on the Co-60 gamma radiolysis of methanol have been reinvestigated at room temperature, utilizing an experimental technique based on gas chromatographic determinations of the gaseous products of the radiolysis. The presence of methyl borate reduces the yield for ethylene glycol to some extent, with slight reductions of the yields for hydrogen and formaldehyde. The presence of iodine causes appreciable reduction of the yields for hydrogen, formaldehyde and ethylene glycol, with a slight reduction of the yield for methane. The presence of potassium iodide reduces the yields for hydrogen and ethylene glycol but increases that for formaldehyde. A mechanism of the radiolysis reaction is discussed, on the basis of the observed data.

• Analytical Science and Technology
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• v.24 no.1
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• pp.15-23
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• 2011

An accurate mass and isotope ratio were determined using a gas chromatography/time of flight mass spectrometer in CI positive mode for the identification of unknown metabolites. High mass tune was used to improve the ion intensity of $[M+H]^+$. Chromatographic resolution and dynamic range enhancement were performed to obtain more reliable accurate masses and correct isotope abundance ratios. Average absolute errors of mass and isotope ratios for 24 reference metabolite -TMS (trimethylsilyl) derivatives were 6.8 ppm, 1.5% of (M+1/M ratio) and 1.7% of (M+2/M ratio), respectively. The correct formulas of twenty one compound were retrieved within top-2 hit from the heuristic algorithm for elemental composition using each accurate mass and isotope abundance ratio.

• Archives of Pharmacal Research
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• v.29 no.4
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• pp.339-342
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• 2006

A simple high performance liquid chromatographic (HPLC) method was developed for the determination of tolperisone in human plasma. Tolperisone and internal standard (chlorphenesin) were isolated from 1 mL of plasma using 8 mL of dichlormethane. The organic phase was collected and evaporated under nitrogen gas. The residue was then reconstituted with 300 mL aliquot of mobile phase and a 100 mL aliquot was injected onto the $C_{18}$ reverse-phased column. The mobile phase, $45\%$ methanol containing $1\%$ glacial acetic acid and $0.05\%$ 1-hexanesulfonic acid was run at a flow rate of 1 mL/min. The column effluent was monitored using UV detector at 260 nm. The retention times for tolperisone and the internal standard were approximately 7.1 and 8.4 min, respectively. The standard curve was linear with minimal intra-day and inter-day variability. The quantification limit of tolperisone in human plasma was 10 ng/ mL. The proposed method has been applied to the determination of pharmacokinetic profile of tolperisone in Koreans. The T max of tolperisone in Koreans $(0.94{\pm}0.42\;h)$ was not significantly differ from that reported in Europeans (0.5-1 h), but the mean half-life in Koreans $(1.14{\pm}0.27\;h)$ was shorter than that in Europeans $(2.56{\pm}0.2\;h)$. The proposed HPLC method is simple, accurate, reproducible and suitable for pharmacokinetic study of tolperisone.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.246-252
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• 2019

In the system of GC-OTC/FID (Gas chromatography-Open Tubular Column/Flame Ionization Detector), DMSO (Dimethyl sulfide) solvent was used to separate the polar solvents (Alcohols). In this system DMSO was eluted later than the separated polar solvents. At this system to calculate chromatographic factors [adjusted retention time ($t_R^{\prime}=t_R-t_O$), capacity factor{$k^{\prime}=(t_R-t_O)/t_O$} and separation factor {${\alpha}=(t_{R2}-t_O)/(t_{R1}-t_O)$}], dead time($t_O$) is necessary, but the method to calculate it has not been reported yet. Therefore, we have tried to develop $t_O$. To calculate $t_O$, we conversed DMSO retention time (DMSO $t_R$) to logarithm ($f(x)={\log}\;t_{R(DMSO)}{\rightarrow}t_O$, $t_O={\log}$ 9.551=0.980). To confirm the optimization of the developed method, we compared with $CH_4\;t_R$ and ${\ln}\;t_{R(DMSO)}$. Both of the values calculated by $CH_4\;t_R$ and ${\ln}\;t_{R(DMSO)}$ were not suitable in the calculation k' and ${\alpha}$. The developed method in this study{${\log}\;t_{R(DMSO)}$} has satisfied both of the values k' criteria (1${\alpha}(1<{\alpha}<2)$. The developed calculation method in this study was easy and convenient, therefore it can be expected to be applied to these similar systems.

• Korean Journal of Food Science and Technology
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• v.24 no.3
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• pp.272-278
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• 1992

Takju, a Korean traditional wine, was prepared by using nuruk and Koji which were inoculated with Aspergillus kawachii and Aspergillus shirousamii. Those chemical composition such as alcohols and organic acids were determined with gas chromatography to investigate the variation of its content by the fermentation. Alcohol such as methyl, ethyl, n-propyl, i-butyl, i-amyl alcohol were detected in the most takju mash samples. Alcohol contents in the groups fermented with KNR and SNR were slightly higher than KKR, SKR groups. Lactic acid were concentrated and organic acids such as pyruvic, oxalic, malonic, succinic, maleic, malic, ${\alpha}-keto$ glutaric acid were also detected in the most samples. The pH was lowest in the KKR group. The total acid content was slightly decreased at the later fermentation and was highest in KKR. The content of minerals were highest in the WNR and BNR groups. Throughout fermentation the content of potassium and magnesium varied greatly with the tested groups.