• Mass Spectrometry Letters
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• 제8권4호
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• pp.90-97
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• 2017

Androgenic anabolic steroids (AASs) are synthetic derivatives of testosterone with a common structure containing cyclopentanoperhydrophenanthrene nucleus. Their use enhances the muscle building capacity and is beneficial during performance. The AASs are one of the most abused group of substances in horse doping. Liquid chromatography tandem mass spectrometry ($LC/MS^n$) has been successfully applied to the detection of anabolic steroids in biological samples. However, the saturated hydroxysteroids viz: nandrolone, $5{\alpha}-estrane-3{\beta}$, $17{\alpha}-diol$ exhibit lower detection responses in electrospray ionisation (ESI) because of their poor ionisation efficiency. To overcome this limitation pre-column chemical derivatization has been introduced to enhance their detection responses in $LC-ESI-MS^n$ analysis. The aim of present study was to develop a sensitive method for identification and confirmation of nandrolone and its metabolite in horse urine incorporating pre-column derivatization using picolinic acid. The method consists of extraction of targeted steroid conjugates by solid phase extraction (SPE). The eluted steroid conjugates were hydrolysed by methanolysis and free steroids were recovered with liquid-liquid extraction. The resulting steroids were derivatized to form picolinoyl esters and identification was done using LC-ESI-MS/MS in positive ionization mode. The picolinated steroid adduct enhanced the detection levels in comparison to underivatized steroids.

• Journal of Nutrition and Health
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• 제3권3호
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• pp.137-140
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• 1970

한국인(韓國人) 모유(母乳)와 우유(牛乳)에 대(對)해서 GLC법(法)에 의(依)하여 지방산(脂肪酸) 조성(組成)을 구(求)하여 비교(比較)하고 또 채취(採取)한 시료(試料)에 대(對)해서의 일반조성(一般組成)의 치(値)도 기재하였다. 인유(人乳)의 지방산(脂肪酸)은 Butyric acid, Caproic acid 및 Caprylic acid 등(等)의 지방산(脂肪酸)을 거의 함유(含有)하고 있지 않은 점(點)과 우유(牛乳)의 지방산(脂肪酸)은 저급(低級) 지방산(脂肪酸)을 함유(含有)하고 있는 반면(反面) Linol산(酸)의 함량(含量)이 인유(人乳)에 비(比)해서 훨씬 적었다는 점(點)이다.

• 대한수의학회지
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• 제40권1호
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• pp.72-80
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• 2000

Lipopolysaccharides (LPS) of Pasteurella multocida (P multocida) and several Gram-negative bacterial pathogens were analyzed by methanolysis, trifluoroacetylation and gas chromatography (GC) on a fused-silica capillary column. The GC analysis indicated that LPS prepared from a strain of P multocida by phenol-water (PW) or trichloroacetic acid (TCA) extraction were quite different in chemical composition. However, LPS prepared from Salmonella enteritidis by the two extraction methods were very similar. PW-LPS extracts from different Pasteurella strains of a serotype had essentially identical GC patterns. Endotoxic LPS extracted from 16 different serotypes of P multocida by PW or by phenol-chloroform-petroleum ether procedures yielded chromatograms indicating similar composition of the fatty acid moieties but minor differences in carbohydrate content. When the chemical composition of endotoxic LPS extracted from several Gram-negative bacteria (P multocida, Pasteurella hacmolytica, Haemophilus somnus, Actinobacillus ligniersii, Brucella abortus, Treponema hyodysenteriae, Escherichia coli, Bacteriodes fragilis, Salmonella abortus equi and Salmonella enteritidis) were examined, each bacteria showed a unique GC pattern. The carbohydrate constituents in LPS of various Gram-negative bacteria were quite variable not only in the O-specific polysaccharides but also in the core polysaccharides. The LPS of closely related bacteria shared more fatty acid constituents with each other than with unrelated bacteria.

• 공업화학
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• 제20권2호
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• pp.208-212
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• 2009

동식물의 유지로부터 합성된 바이오디젤은 기존 석유디젤을 대체할 수 있는 친환경적인 연료로 알려져 있다. 하지만 바이오디젤은 석유디젤에 비해 낮은 온도에서 연료특성이 열악한 것으로 알려져 있기 때문에 다양한 원료별 바이오디젤의 저온특성 분석이 필요하다. 본 연구에서는 12종류의 다양한 식물성오일로부터 트란스에스테르화를 시킨 결과, 86~96%의 높은 수율로 바이오디젤을 얻을 수 있었다. 이렇게 합성된 바이오디젤을 운점, 유동점, 저온필터막힘점을 측정한 결과, 올레핀 함량이 높은 들기름으로부터 합성된 바이오디젤의 저온특성이 가장 우수하였다.

• 한국자동차공학회논문집
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• 제19권3호
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• pp.122-129
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• 2011

Biodiesel produced from triglyceride which is main component of animal fats and vegetable oils by methanolysis was known for remarkable cetane number. In this study, the derived cetane number of 3 kinds of biodiesel came from vegetable oils such as soybean oil, palm oil, and perilla oil and 2 kind of biodiesel which were produced from beef tallow and pork lard were analyzed using IQT (Ignition quality tester). In IQT test result, the derived cetane number of palm- , beef tallow- and pork lard's biodiesel were more excellent than other biodiesels. After analysis of biodiesel composed molecular by gas chromatography-mass and determination of the derived cetane number of pure biodiesel components using IQT, we have found that the low olefin contented and long alkyl chained biodiesel have excellent derived cetane number.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2408-2412
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• 2009

The specific rates of solvolysis of methyl fluoroformate have been measured at $40.0\;{^{\circ}C}$ in several hydroxylic solvents. Analysis with the extended Grunwald-Winstein equation leads to sensitivities toward changes in solvent nucleophilicity (l) of $1.33\;{\pm}\;0.10$ and toward changes in solvent ionizing power (m) $0.73\;{\pm}\;0.06$. For methanolysis, a solvent deuterium isotope effect of 3.98 is compatible with the incorporation of general-base catalysis into the substitution process. For four representative solvents, studies were made at several temperatures and activation parameters determined. These observations are also compared with those previously reported for alkyl halogenoformate esters and mechanistic conclusions are drawn.

• Bulletin of the Korean Chemical Society
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• 제28권4호
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• pp.657-661
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• 2007

The specific rates of solvolysis of isopropyl fluoroformate are well correlated using the extended Grunwald-Winstein equation, with a sensitivity (l ) to changes in solvent nucleophilicity (NT) and a sensitivity (m) to changes in solvent ionizing power (YCl). The sensitivities (l = 1.59 ± 0.16 and m = 0.80 ± 0.06) toward changes in solvent nucleophilicity and solvent ionizing power, and the kF/kCl values are very similar to those for solvolyses of n-octyl fluoroformate, suggesting that the addition step of an addition-elimination mechanism is rate-determining. For methanolysis, a solvent deuterium isotope effect of 2.53 is compatible with the incorporation of general-base catalysis into the substitution process. The large negative values for the entropies of activation are consistent with the bimolecular nature of the proposed rate-determining step. These observations are also compared with those previously reported for the corresponding chloroformate and fluoroformate esters.

• Elastomers and Composites
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• 제47권2호
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• pp.96-103
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• 2012

본 논문에서는 PET를 재활용하는 최근의 기술들을 소개한다. PET가 광범위하게 사용되고 또한 썩지 않기 때문에 환경 문제를 야기하고 또한 이 물질의 폐기 및 소각은 경제적 손실이기도 하다. PET의 화학적 재활용은 이 폐기물들을 유용한 원료물질로 전환하여 PET를 재생산하는 것이 가능하게 한다. PET의 화학적 재활용은 글리콜에 의한 글리콜리시스, 메탄올에 의한 메탄올리시스, 물에 의한 가수분해 등의 반응에 의한 PET 고분자 사슬의 분해가 이루어지고, 분리정제 과정을 거쳐 MEG, DMT, PTA와 같은 단량체 혹은 폴리에스터 올리고머로 만들어진다. 이 물질들은 폴리에스터를 합성하는 데 사용될 수 있다.

• 대한화학회지
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• 제57권3호
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• pp.377-381
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• 2013

Thevetia peruviana (Yellow Oleander) seed oil was extracted with n-hexane in a soxhlet extractor. The ethanolysis and methanolysis of the oil were carried out with 50% of potassium hydroxide in ethanol and methanol respectively by weight of oil, as catalyst. The biodiesel was tested for biodegradability using E. coli. The percentage yield of the FAEE and FAME were 84.8% and 91.6% respectively. The biodegradability values of 81.4% and 86.2% were obtained for FAEE and FAME respectively after a period of 28 days. Other fuel quality parameters determined are the cetane index of 47.19 (FAEE) and 58.97 (FAME), flash point of $198^{\circ}C$ (FAEE) and $175^{\circ}C$ (FAME), kinematic viscosity at $40^{\circ}C$ of 5.21 $mm^2s^{-1}$ (FAEE) and 5.10 $mm^2s^{-1}$(FAME), pour point of $4^{\circ}C$ (FAEE) and $-2^{\circ}C$ (FAME) and a cloud point of $6^{\circ}C$ (FAEE) and $3^{\circ}C$ (FAME). Thus, Thevetia peruviana oil has a high potential for use in production of environmentally friendly biodiesel.

• 한국미생물·생명공학회지
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• 제48권4호
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• pp.480-490
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• 2020

A novel lipase gene, Lip-1420, was isolated from a metagenomic library constructed from reed marsh from Mt. Jumbong in Korea, comprising 112,500 members of recombinant plasmids. The DNA sequence of Lip-1420-subclone (5,513 bp) was found to contain at least 11 ORFs according to the GenBank database. The ORF-3 gene was inserted into the pET21a plasmid containing the C-terminal 6-His tag and transformed into E. coli BL21(DE3) to express the recombinant lipase protein. Lip-1420 was purified using a fast protein liquid chromatography system. The gene was registered in GenBank (MH628529). The values of Km and Vmax were determined as 0.268 mM and 1.821 units, respectively, at 40℃ and pH 8.0, using p-nitrophenyl palmitate as the substrate. This lipase belongs to family IV taxonomically because it has conserved HGGG and GDSAG motifs in the constitutive amino acid sequence. According to the predicted structural model, the binding sites are represented by residues H78, G81, D150, S151, A152, V181, and D236. Finally, Lip-1420 showed triolein selectivity for methanolysis between triolein (18:1) and tristearin (18:0) substrates. Further study of the selective mechanism and structure-function relationship of this new lipase could be useful for more practical applications.