• Biomolecules & Therapeutics
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• v.3 no.1
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• pp.91-96
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• 1995

The effects of toluene inhalation on the contents of amino acid neurotransmitters in rat brain were investigated and blood toluene concentrations inducing changes of behavior and amino acid neurotransmitter contents in rat brain were observed. Male wistar rats were exposed to toluene vapor (single dose : 1700, 5000 and 10000 ppm for 2 hrs, repeated dose : 1700 and 5000 ppm for 2 hrs/day$\times$6 days). Toluene concentrations in blood and the inhalation chamber were assayed by GC with headspace sampler. HPLC method following PITC derivatization was used to measure the amino acid contents in brain tissues such as frontal cortex, caudate, hippocampus, cerebellum and brain stem. Glutamic acid and aspartic acid levels were increased by single inhalation of toluene (5000 ppm) in all the brain areas assayed in this experiment. In caudate and cerebellum, taurine levels were decreased by single inhalation of low dose toluene (1700 ppm), but increased by repeated administration. At high blood toluene concentration, GABA levels were increased in all the brain areas assayed in this experiment and the increasing extents of inhibitory amino acid contents measured in caudate and hippocampus were greater than those of excitatory amino acids. These results suggest that the changes of amino acid neurotransmitter contents in brain by exposure to toluene may modulate toluene-induced behaviors.

• Toxicological Research
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• v.31 no.3
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• pp.273-278
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• 2015

The aim of this study was to develop an efficient quantitative method for the determination of acetaldehyde (AA) and formaldehyde (FA) contents in solid and liquid food matrices. The determination of those compounds was validated and performed using gas chromatography-mass spectrometry combined by solid phase micro-extraction after derivatization with O-(2,3,4,5,6-pentafluoro-benzyl)-hydroxylamine hydrochloride. Validation was carried out in terms of limit of detection, limit of quantitation, linearity, precision, and recovery. Then their contents were analyzed in various food samples including 15 fruits, 22 milk products, 31 alcohol-free beverages, and 13 alcoholic beverages. The highest contents of AA and FA were determined in a white wine (40,607.02 ng/g) and an instant coffee (1,522.46 ng/g), respectively.

• Environmental Analysis Health and Toxicology
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• v.15 no.1_2
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• pp.53-59
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• 2000

The purpose of this study is the development of the simple and precise determination method of ethyl isocyanate (EIC) and propyl isocyanate (PIC) through derivatization using secondary aliphatic amines by gas chromatography with flame ionization detector. The urea derivatives are quantitatively and simultaneously derived from EIC and PIC with secondary aliphatic amines such as dipropylamine, dibutylamine. and dipentylamine in methylene chloride, and confirmed by thin layer chromatography and gas chromatography with mass selective detector. For GC/FID, according to the increasing carbon atom of the amines, the retention time and peak area of the urea derivatives are increased. The instrumental detection limits for EIC and PIC were about 23.3∼34.8 $\mu\textrm{g}$ and 21.6∼28.9 $\mu\textrm{g}$, respectively.

• Environmental Engineering Research
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• v.12 no.3
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• pp.93-100
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• 2007

I improved an analytical method for determining trace amounts of eleven phenolic endocrine-disrupting chemicals (11 phenolic EOCs) in human urine. The 11 phenolic EOCs were subjected to hydrolysis and then to solid phase extraction with a XAD-4 column. Alkylphenols, chlorophenols, and bisphenol A in XAD-4 column were eluted with acetonitrile, and the eluate was concentrated under a nitrogen stream, and then tert-butyldimethylsilylation. Separation and determination were done by gas chromatography, using mass spectrometry operating in the selective ion monitoring mode for quantitation. For tert-butyldimethylsily (TBDMS) derivatization the recoveries were $91.2{\sim}125.9%$, the limits of quantitation (LOQ) for the 11 phenolic EOCs in the nanogram-per-milliliter range ($0.025{\sim}1.000\;ng/mL$) were thus achieved by using 1 mL of urine, and the SIM responses were linear with the correlation coefficient varying by $0.9300{\sim}0.9943$. Based on the results for urine samples from unexposed individuals, 4-tert-octylphenol and pentachlorophenol were detected in hydrolysed urine sample. Other alkylphenols, chlorophenols and bisphenol A were not detected.

• YAKHAK HOEJI
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• v.47 no.3
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• pp.142-147
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• 2003

Gas chromatography-mass spectrometric (GC-MS) procedure is presented for the simultaneous qualification and quantitation of methamphetamine (MA), amphetamine (AMP), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxyethylamphetamine (MDEA) in human hair. The method procedure involves decontamination of hair with distilled water and acetone, acidic hydrolysis, extraction in the presence of deuterated internal standards, and GC-MS analysis after derivatization with trifluoroacetic anhydride (TFAA) in ethylacetate. The limit of detection for 5 drugs were about 0.1∼0.15 ng/mg using 30 mg hair sample. Coefficient variations of correlation ranged from 0.9941 to 0.9993. The recoveries of these drugs were found to be 93.4∼104.4％. The concentrations of AMP, MA, MDA, and MDMA in abusers' hair samples were measured 0.17∼2.88, 2.09∼18.34, 0.24∼3.83, and 3.10∼22.81 ng/mg, respectively. The ratios of MA/AMP and MDMA/MDA ranged 5.67∼49.57 and 4.78∼54.31, respectively. This assay has been successfully utilized in the evaluation of the deposition of amphetamine-type stimulants (ATS) in human hair.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2921-2924
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• 2013

Immunoliposomes (antibody-conjugated liposomes) are highly useful as both a drug carrier in drug delivery and as a reporting probe in immunodiagnostics. However, antibody conjugation is lengthy and cumbersome, because this includes several steps such as derivatization of the antibody, conjugation of the derivatized antibody to liposomes, and separation of the unbound antibodies from immunoliposomes. Recently, liposome preparation steps have simplified by using microfluidic devices (${\mu}FDs$) where liposomes are formed when a stream of lipids in solvent is hydrodynamically focused between two oblique buffer streams in a microchannel. Herein, we report a simple method for the production of immunoliposomes (rabbit IgG-conjugated liposomes) using microvalve-controlled ${\mu}FD$. The presence of antibody on the liposome was verified by observing the binding of immunoliposomes to rabbit IgG on the surface. The results suggest that immunoliposomes can be easily prepared through sequential mixing of antibody, conjugation reagents, preformed liposomes using microvalve-controlled ${\mu}FD$.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.2083-2088
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• 2007

Biosensor based on rugate PSi interferometer for the detection of avidin has been described. Rugate PSi fabricated by applying a computer-generated pseudo-sinusoidal current waveform has been prepared for the application as a label-free biosensor based on porous silicon interferometer. The fabrication, optical characterization, and surface derivatization of a rugate PSi has been described. The method to fabricate biotinderivatized rugate PSi has been investigated. The surface and cross sectional morphology of rugate PSi are obtained with SEM. FT-IR spectroscopy is used to characterize the oxidation and functionalization reaction of rugate PSi sample. Binding of the avidin into the biotin-derivatized rugate PSi induces a change in refractive index. A red-shift of reflectivity by 18 nm in the reflectivity spectrum is observed, when the biotin-modified rugate PSi was exposed to a flow of avidin.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.685-688
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• 2001

A gas chromatography/mass spectrometric assay method has been developed for the simultaneous determination of benzidine (BZ), N-acetyl benzidine (ABZ) and N,N-diacetyl benzidine (DABZ) in rat urine. BZ, ABZ and DABZ were extracted from urine at pH 8 with ethyl ether. Conjugated urinary metabolites were extracted at pH 8 after hydrolysis with 1 M HCl for 30 min at 100 $^{\circ}C.$ The dried extract was dissolved in 100 ${\mu}{\ell}$ of ethylacetate and then injected in gas chromatography-mass spectrometric (GC-MS) system without further purification or modification. BZ, ABZ and DABZ have good chromatographic properties and offer very sensitive response for the EI-MS (SIM) without any derivatization. The recoveries for BZ, ABZ and DABZ were about 98.0, 81.8 and 71.4%, respectively, at pH 8.0 and the concentration of 5.0 ng/mL. The coefficients of variation of BZ and ABZ were less than 9.5% from 0.1 to 100 ng/mL and that of DABZ was less than 13% in the same concentration range. The detection limits of the assay were 0.01 ng/mL for both BZ and ABZ, and 0.05 ng/mL for DABZ in urine or plasma 1.0 mL.

• YAKHAK HOEJI
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• v.36 no.4
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• pp.370-378
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• 1992

A simple and sensitive high performance liquid chromatographic method to quantitate ${\alpha}-keto$ acids in serum and urine was investigated. ${\alpha}-Keto$ acids react with 1,2-diamino-4,5-methylenedioxybenzene (DMB) in the presence of 2-mercapto-ethanol and sodium hydrogen sulfite to form highly fluorescent derivatives, substituted 6,7-methylenedioxyquinoxalinol. The derivatization procedure was performed in water bath at $100^{\circ}C$, and completed within 50 min. By the use of a reversed-phase column and multi-step gradient with two solvents, a mixture containing twelve of these derivatives were efficiently resolved within 35 minutes. The optimal wavelengh of the fluorescence detector are ${\lambda}_{ex}=364\;nm$ and ${\lambda}_{em}=445\;nm$. The quantitation of the individual ${\alpha}-Keto$ acids was reproducible with relative standard deviation of $3.0{\sim}7.9%$ and had a detection limits of $10{\sim}60$ fmol, except for p-hydroxyphenylpyruvic acid (960 fmol).

• Archives of Pharmacal Research
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• v.23 no.3
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• pp.226-229
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• 2000

To obtain the standard compounds of metoprolol for a pharmacokinetic study, a convenient synthetic procedure to prepare enantiomers of metoprolol (3a) and its major metaboites, 2-4-(2-hydroxy-3-isopropylamino)propoxyphenylathanol (3b) and 4-(2-hydroxy-3- isopropylamino) pro-poxyphenylacetic acid (4), was developed from their respective starting materials, 4-(2-methoxyethyl)phenol (1a), 4-(2-hydroxyethyl)phenol (1b) and methyl 4-hydroxyphenylacetate (1c). These phenolic compounds (1a, b, c) were converted in situ to their corresponding phenoxides with sodium hydroxide treatment followed by (R)- or (S)-epichlorohydrin treatment. The resulting epoxides 2 were transformed to 3 through reaction with isopropylamine. Ester 3c was hydrolyzed to the metabolite 4. Measured using the HPLC method on chiral column without any derivatization, the optical purity of enantiomers of metoprolol and o-demethylated metabolite 3b ranged between 96-99 ％ ee and that of enantiomers of carboxylic acid metabolite 4 ranged 91％ ee.