• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2005년도 제28회 학술발표회 초록집
• /
• pp.57-57
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• 제25권10호
• /
• pp.1508-1512
• /
• 2004

A gas chromatography/mass spectrometric (GC/MS) method has been developed for the determination of trace mono-n-butyltin (MBT), di-n-butyltin (DBT), and tri-n-butyltin (TBT) compounds in sediments. Samples were extracted by 10% acetic acid in methanol containing 0.03% tropolone and were then derivatized for GC/MS analysis. Ethylation by sodium tetraethylborate and phenylation by sodium tetraphenylborate were evaluated as a derivatization reaction of the organotins in sample extract. n-Hexane was added into reaction media in the beginning of the reaction for the continuous extraction of derivatized organotins. Ethylation requires less than 2 hours to get proper derivatization yields for MBT, DBT, and TBT altogether and produces relatively low amounts of side reaction products. Compared to ethylation, phenylation requires much longer time but provides relatively lower yield and produces considerable amounts of side reaction products. Therefore, the ethylation reaction was applied for the analysis of organotin compounds in sediment. An isotope dilution mass spectrometric (IDMS) method based on GC/MS has been applied to the accurate determination of DBT compounds in the sediments. The IDMS results from the analyses of sediment samples showed a reasonable repeatability and a good agreement with the values obtained by IDMS based on liquid chromatography/induced coupled plasma/mass spectrometry.

• 통합자연과학논문집
• /
• 제4권3호
• /
• pp.182-186
• /
• 2011

Chemical modification of porous silicon surface has been investigated to have different physical surface properties. Porous silicon modified with dodecyl functionality exhibits hydrophobic feature, however the oxidation of porous silicon to modify with hydroxyl group displays hydrophilic properties. Surface characterization for both dodecyl and hydroxyl derivatized porous silicon was investigated by FT-IR spectroscopy. To determine the surface coverage, the amine functionalized surface was reduced by dithiothreitol (DTT) and the released 2-thiopyridone was quantified by UV/vis spectroscopy.

• Biomolecules & Therapeutics
• /
• 제31권5호
• /
• pp.566-572
• /
• 2023

A chiral derivatization strategy with phenylglycine methyl ester (PGME) was employed to develop a straightforward method to determine the absolute configurations of N,N-dimethyl amino acids. The PGME derivatives were analyzed using liquid chromatography-mass spectrometry to identify the absolute configurations of various N,N-dimethyl amino acids based on their elution time and order. The established method was applied to assign the absolute configuration of the N,N-dimethyl phenylalanine in sanjoinine A (4), a cyclopeptide alkaloid isolated from Zizyphi Spinosi Semen widely used as herbal medicine for insomnia. Sanjoinine A displayed production of nitric oxide (NO) in LPS-activated RAW 264.7 cells.

• Bulletin of the Korean Chemical Society
• /
• 제34권9호
• /
• pp.2787-2794
• /
• 2013

Cholesterol and cholesterol oxidation products (COPs) may accumulate in foods of animal origin during processing or storage. An effective and sensitive analytical method was developed by increasing the UV absorption of compounds through derivatization by attaching a chromophore to the functional groups of cholesterols (cholesterol, 20-hydroxycholesterol, 7-ketocholesterol, cholestane-$3{\beta}$-$5{\alpha}$-$6{\beta}$-triol, 25-hydroxycholesterol, and $5,6{\alpha}$-epoxycholesterol). The influences of the reaction time, volume of reaction solvent, amounts of derivatizing reagent, and extraction solvents were investigated, as they may influence the reaction and extraction yield. The derivatized COPs were analyzed simultaneously on a C18 column (2.1 mm i.d. ${\times}$ 100 mm length, $3.5{\mu}m$ particle size) using a gradient elution with water and acetonitrile. The derivatized COPs showed increased sensitivity and selectivity in HPLC/UV-Vis. The LOD and LOQ were in the concentration ranges of 0.018-0.55 mg/kg and 0.059-1.84 mg/kg from the powdered milk. And the accuracy and precision were 78.1-116.7% and 1.1-9.9%, respectively.

• 분석과학
• /
• 제12권6호
• /
• pp.571-576
• /
• 1999

소변 시료에서 비스테로이드성 소염진통제 (Non-Steroidal Anti-Inflammatory Drugs)인 Fenamates 부류의 6종에 대해서 pentafluoropropionyl 유도체화 반응을 통하여 Gas Chromatograph/Negative Chemical Ionization-Mass Spectrometer에 감응도가 높은 유도체를 만들었다. 6종의 소염 진통제 약물에 대하여 반응성이 좋은 유도체화 반응 조건과 크로마토그래피 조건을 설정하였으며 이들 약물은 동시에 분석 가능하였고 검출한계가 4-25 pg/mL 이어서 경마 경기에서 자주 사용되고 있는 NSAIDs의 미량 성분에 대한 검출 및 법과학에서의 응용이 가능하다.

• Archives of Pharmacal Research
• /
• 제20권2호
• /
• pp.184-190
• /
• 1997

A new method based on the chemical reaction has been devised for the sequential analysis of reducing oligosaccharides using 8-amino-2-naphthalenesulfonic acid (ANS), a fluorescent precolumn derivatization reagent for reducing saccharides. The procedure established includes 1) the derivatization of a reducing oligosaccharide to produce a Schiff base, 2) the reduction of the base with sodium cyanoborohydride $(NaBH_3/CN), 3)$ the methoxycarbonylation of the resultant secondary amino group, 4) the cleavage of the glycoside bond next to the reducing end, based on the intramolecular acid hydrolysis by the action of a sulfonic acid group of the ANS derivative, 5) the identification of the liberated reducing end by high-performance liquid chromatography (HPLC), and finally 6) the recovery of the resultant oligosaccharide fragment from the cleavage reaction mixture. The extensive examination of the conditions for the sequential analysis of reducing oligosaccharides resulted in the procedure of simplicity , high selectivity and high recovery. This procedure was found to be useful for the sequential analysis of di-, tri- and tetrasaccharides.

• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.3103-3106
• /
• 2014

• Bulletin of the Korean Chemical Society
• /
• 제15권9호
• /
• pp.791-795
• /
• 1994

1,3-Dimethyl and dipropyl ethers of p-t-butylcalix[4]arene and calix[4]arenes have been converted to the corresponding diesters, acetate and propionate, and their conformations are inferred based on the $^1H$ and $^{13}C$ NMR spectra. The presence of t-butyl groups is effective in maintaining the cone conformation on derivatization.

• Applied Biological Chemistry
• /
• 제40권5호
• /
• pp.442-446
• /
• 1997

감도와 재현성이 높은 quinclorac 의 토양중 잔류분석방법 개발을 위해 $CO_2$를 이용한 초임계추출후 4-bromomethyl-7-methoxycoumarin 로 형광유도체화하여 HPLC 상에서 분석하는 방법을 개발하였다. 추출변수로 추출압력과 modifier인 methanol 의 함량을 변화시켜, 100 ppb 처리토양에서 7000 psi $(80^{\circ}C)$, 30% $(methanol/CO_2\;v/v)$) 조건을 이용하여 96% 의 회수율을 얻었다. 18-crown-6-ether 를 촉매로 한 형광유도체 반응은 상온에서 30분이내에 정량적으로 완결되었으며 HPLC-형광분석검출기를 이용하여 토양중 quinclorac의 최소검출 수준을 0.5 ppb까지 낮출 수 있었다. 이 방법은 기존의 방법에 비해 간편하고 감도가 높아 carboxylic acid를 함유한 농약의 잔류분석에 이용될 수 있다고 판단된다.