• Archives of Pharmacal Research
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• v.13 no.3
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• pp.215-220
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• 1990

Two different, derivative spectrophotometric and gas-liquid chromatographic, procedures for direct quantitation of caffeine and some commonly dispensed antihistaminics in bulk forms, in their laboratory prepared mmixtures and in dosage formulations, have been investigated. The limit, sensitivity reproducibility and accuracy of each method were studied for each individual drug substance and in some usual pharmaceutical formulations.

• Journal of Korean Society of Forest Science
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• v.81 no.2
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• pp.177-182
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• 1992

Soil air $CO_2$ concentrations were measured in two soil depths (O and B horizon) by (1) the use of the Draeger direct reading chromatographic tubes and (2) syringe gas collections with gas chromatographic detection in a Spodosol supporting low elevation, commercial spruce-fir forest, Maine, USA, Mean soil air $CO_2$ concentrations(%) during the growing season of 1991 ranged from 0.11 in the O horizon by the Draeger method to 0.29 in the B horizon by the gas chromatographic method. Soil air $CO_2$ concentrations by the Draeger method were lower than those obtained using the gas chromatographic method for both soil horizons. However, data from the two methods were significantly(p<0.01) correlated and paralleled each other relative to temporal patterns. Positive and highly significant correlations existed between soil air $CO_2$ concentrations and soil temperature, although correlation coefficients only ranged from 0.13 to 0.32, depending on the method and horizon chosen.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.36-41
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• 1992

Several commercial cottonseed, corn and rapeseed oils were stored at $60^{\circ}C\;and\;70^{\circ}C$ with daily exposure of fluorescent light for 12 hours and evaluated their rancidity by headspace gas chromatographic analysis of pentanal and hexanal. The data of gas chromatographic analysis was compared with organoleptic flavor evaluation. For headspace gas chromatographic analysis, the volatile compounds were recovered by porous polymer trap and flushed into a fused silica capillary column at $250^{\circ}C$. Twenty-three GC peaks were identified on the basis of relative retention time of reference compounds and gas chromatography-mass spectrometry. The results showed that the contents of pentanal and hexanal were linearly increased during storage. A very simple linear relationship was found between organoleptic flavor scores and amounts of two volatile compounds with very high correlation coefficient. This results suggested the possible implication of pentanal and hexanal as an quality index for rancidity evaluation of cottonseed, corn and rapeseed oils.

• YAKHAK HOEJI
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• v.23 no.1
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• pp.7-10
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• 1979

A gas chromatographic determination of dienestrol in dienestrol cream has been studied. Dienestrol cream was dissolved in pyridine and silylation was done by using N, O-bis (trimethylsilyl) trifluoroacetamide. The derivative was injected into 3% silicone OV-17 column for chromatographic estimation. The dienestrol peak was found to be well separated from the other components of the cream. The detection limit was obtained to be $5.6{\times}10^{11}$ mol of dienestrol for this method. As there is no need for prior separation procedure, this experiment is extremely simple and less time consuming as compared to the conventional methods for estimation of dienestrol in cream.

• 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.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1247-1251
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• 1998

A method is developed for simultaneously determining ethanol and acetic acid in vinegars by quantitative packed-column gas chromatography. Vinegars were filtrated and directly chromatographed on a $2\;m{\times}2\;mm$ stainless steel column packed with Tenax-GC, 80/100. Ethanol, isopropy alcohol as an internal standard, and acetic acid were completely separated within 20 min of running time without any interfering peaks. The accuracy of packed column gas solid chromatography (PCGSC) was discussed compared to the analytical data by titration, high performance liquid chromatography and capillary column gas liquid chromatography (CCGLC).

• Korean Journal of Food Science and Technology
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• v.17 no.5
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• pp.355-360
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• 1985

Soybean, hydrogenated soybean and corn oils, which were exposed to fluorescent light for different periods of time, were evaluated for sensory qualities by subjective sensory evaluation and instrumental gas chromatographic analysis. Sensory evaluation was conducted in 8 laboratories using a 10-point hedonic scale with a total of 95 panel members. The correlation coefficients between sensory scores and predicted sensory scores by gas chromatographic analysis for the 8 laboratories varied from 0.10 to 0.99. However, most laboratories had better than 0.90, which was considered excellent. The correlation coefficients between sensory scores of the 95 panel members and predicted sensory scores using the amount of 2. 4-decadienal isomers in oil determined by a gas chromatographic method for soybean, hydrogenated soybean, and corn oils, were r=0.96, r=0.97, and r=0.97, respectively. The correlation study suggests that it is possible to obtain realistic results of oil flavor qualities from the instrumental evaluation by combining improved gas chromatographic analysis, sensory evaluation, and statistical analysis for practical purposes.

• Journal of the Korean Home Economics Association
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• v.7 no.1
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• pp.74-77
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• 1969

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.135-139
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• 1991

Tridecanedioic acid (DC-13), starting material of the valuable musk ethylene brassylate, was obtained from n-tridecane by the Candida tropicalis mutant. The mutants were first obtained from primary screening step using the selective medium and then solid phase extraction sampling method was used for the selective isolation of organic acids from the cultured media of mutants. The resulting acids were directly converted to volatile tert-butyldimethyl silyl delivatives, which were then analyzed by gas chromatography. The efficient GC profiling method was used for the rapid identification of the mutant producing DC-13 in large quantity, and for the optimization of the culture conditions of mutant. The optimal culture conditions were found as follows: pH 8.0, 30$^{\circ}C$, 250rpm, 48hour of culture and $(NH_4)_2HPO_4$ as nitrogen source.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.475-479
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• 1996

Diethylcarbamazine (DEC, 1-diethylcarbamyl-4-methylpiperazine) is an antiparasitic piperazine derivative used in the treatment of lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi or grugia timori. DEC-N-oxide is a major metabolite in humans and has antifilarial activity. In carrying out pharmacokinetic studies, gas chromatographic analysis of DEC in plasma can be complicated by the presence of the metabolite, since the thermally unstable DEC-N-oxide is converted back to a material which coelutes with DEC under the conditions of the analysis. We now report a method to separate DEC-N-oxide from DEC in plasma using solid phase extraction with subsequent gas chromatographic analysis using a nitrogen specific detector. One-diethylcarbamyl-4-ethylpiperazine (E-DEC) was the internal standard. The standard curve of DEC was linear in the range of 10 to 200 ng/ml as described by Y=0.0350+0.0128X, $R^2=0.999$. The limit of quantitation was 4 ng/mL. Reproducibility at 10, 100 and 200 ng/mL concentration points of the standard curve gave coefficient variations of 6.1%, 7.8% and 1.6%, respectively. The recovery following solid phase extraction was 99.3% for DEC and 94.8% for the internal standard. This sensitive and specific analytical method is suitable for pharmacokinetic studies of DEC.