• Mass Spectrometry Letters
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• v.3 no.4
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• pp.101-103
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• 2012

The ultraviolet (UV) degradation products of photochromic naphthoxazine and naphthopyran derivatives in acetonitrile were separated and identified using liquid chromatography-mass spectrometry (LC-MS). Photodegradation resulted in oxidation of products.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.61-66
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• 2009

An analytical method based on solid-phase extraction and gas chromatography / mass spectrometry has been developed for measurement of acaricides (amitraz, bromopropylate, coumaphos, cymiazole, and tetradifon) in honey sample. In the stability test of acaricides in honey, amitraz underwent a rapid degradation into 2,4-dimethylaniline (DMA), 2,4-dimethylphenylformamide (DMPF), and N-(2,4-dimethylphenyl)-N'-methylformamidine (DMPMF), whileas other acaricides were found to be stable even for over three months. Extraction of five acaricides from 5g of honey sample was carried out by liquid-liquid extraction using 20mL of ethylacetate. For purification, Florisil-SPE cartridge with elution of 5mL of n-hexane/ acetone (55:45, v/v) was found to remove interferences effectively. Quantification was performed using gas chromatography / mass spectrometry in the selected ion monitoring mode. Spiking experiments were carried out to determine the recovery, precision, and limits of detection (LODs) of the method. The overall recovery values from honey spiked at 0.02 and 0.20 ${\mu}g/g$ levels, respectively, were found to be greater than 75% for all acaricides. The method detection limits for acaricides were ranged from 0.1 to 3 ppb. The developed method in this study was applied for the monitoring of acaricides in honey products collected from urban markets in Korea.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.217-226
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• 2015

Metabolite profiles of seven commercial vinegars and two traditional vinegars were performed by gas chromatography time-of-flight mass spectrometry with multivariate statistical analysis. During alcohol fermentation, yeast, nuruk, and koji were used as sugars for nutrients and as fermentation substrates. Commercial and traditional vinegars were significantly separated in the principal component analysis and orthogonal partial least square discriminant analysis. Six sugars and sugar alcohols, three organic acids, and two other components were selected as different metabolites. Target analysis by ultra-performance liquid chromatography quadruple-time-of-flight mass spectrometry and liquid chromatography-ion trap-mass spectrometry/mass spectrometry were used to detect several metabolites having antioxidant activity, such as cyanidin-3-xylosylrutinoside, cyanidin-3-rutinoside, and quercetin, which were mainly detected in Rural Korean Black raspberry vinegar (RKB). These metabolites contributed to the highest antioxidant activity measured in RKB among the nine vinegars. This study revealed that MS-based metabolite profiling was useful in helping to understand the metabolite differences between commercial and traditional vinegars and to evaluate the association between active compounds of vinegar and antioxidant activity.

• Journal of the Korean Chemical Society
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• v.21 no.3
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• pp.193-203
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• 1977

Three sterol fractions; 4-desmethyl-, 4-monomethyl-, and 4,4-dimethylsterol, separated by thin layer chromatography from the unsaponifiables of five Cucurbitaceae (cucumber, watermelon, sponge cucumber, gourd and snake gourd) seed oils were analyzed by gas liquid chromatography and combined gas liquid chromatography-mass spectrometry. ${\alpha}$-Spinasterol, ${\Delta}^{7,22,25}$-stigmastatrienol and ${\Delta}^{7,25}$-stigmastadienol isolated from the 4-desmethylsterol fraction were identified by IR, NMR and mass spectrometry.

• 대한임상약리학회:학술대회논문집
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• 2006.11a
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• pp.102-102
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• 2006

• Bulletin of Food Technology
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• v.24 no.1
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• pp.44-52
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• 2011

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1221-1227
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• 2011

Ethyl pyruvate (EP) is known as a scavenger of reactive oxygen species (ROS) in the body through its role in the donation of diketone groups to metals to form an EP-metal complex. In order to develop a method for the quantification of EP in biological media, a sensitive and specific, high-performance liquid chromatographyelectrospray ionization-mass spectrometry (HPLC-ESI/MS) method is used to determine the EP-alkali metal ion binding species. The analyte was separated on a ZORBOX SB-C8 ($3.5{\mu}m$, $30mm{\times}2.1mm$ I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the m/z 255 $[2M + Na]^+$ ion. The method was validated over the concentration range of $0.5-60.0\;{\mu}g$/mL under 1/9 (v/v) of acetonitrile/methanol solvent system with flow rate 0.05 mL/min. The limit of quantification (LOQ) was $0.5{\mu}g$/mL.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.217.2-217.2
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• 2003

A liquid chromatography-tandem mass spectrometric (LC/MS/MS) method was developed for the determination of a new anti-angiogenic drug KR-31831 in rat plasma. KR-31831 and internal standard, KR-31543 were extracted from rat plasma with dichloromethane at basic pH. A reverse-phase LC separation was performed on Luna C8 column with the mixture of acetonitrile-ammonium formate (10 mM, pH 4.5) (67:33, v/v) as mobile phase. The detection of analytes was performed using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. (omitted)

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.109-114
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• 2004

A sensitive method for quantitation of glimepiride in human plasma has been established using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS). Glipizide was used as an internal standard. Glimepiride and internal standard in plasma sample was extracted using diethyl etherethyl acetate (1 : 1). A centrifuged upper layer was then evaporated and reconstituted with the mobile phase of acetonitrile-5 mM ammonium acetate (60:40, pH 3.0). The reconstituted samples were injected into a $C_{18}$ reversed-phase column. Using MS/MS in the multiple reaction monitoring (MRM) mode, glimepiride and glipizide were detected without severe interference from human plasma matrix. Glimepiride produced a protonated precursor ion ([M+H]$^+$) at m/z 491 and a corresponding product ion at m/z 352. And the internal standard produced a protonated precursor ion ([M+H]]$^+$) at m/z 446 and a corresponding product ion at m/z 321. Detection of glimepiride in human plasma by the LC-ESI/MS/MS method was accurate and precise with a quantitation limit of 0.1 ng/mL. The validation, reproducibility, stability, and recovery of the method were evaluated. The method has been successfully applied to pharmacokinetic studies of glimepiride in human plasma.

• Mass Spectrometry Letters
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• v.12 no.3
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• pp.112-117
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• 2021

α-Amanitin and β-amanitin are highly toxic bicyclic octapeptides responsible for the poisoning of poisonous mushrooms such as Amanita, Galerina, and Lepiota by inhibiting RNA polymerase II, DNA transcription, and protein synthesis. A sensitive, simple, and selective liquid chromatography-high resolution mass spectrometric method using parallel reaction monitoring mode was developed and validated for the simultaneous determination of α- and β-amanitin in mouse plasma to evaluate the toxicokinetics of α- and β-amanitin in mice. Protein precipitation of 5 μL mouse plasma sample with methanol as sample clean-up procedure and use of negative electrospray ionization resulted in better sensitivity and less matrix effect. The calibration curves for α- and β-amanitin in mouse plasma were linear over the range of 0.5-500 ng/mL. The intra- and inter-day coefficient of variations and accuracies for α- and β-amanitin at four quality control concentrations were 3.1-14.6% and 92.5-115.0%, respectively. The present method was successfully applied to the toxicokinetic study of α- and β-amanitin after an oral administration of α- and β-amanitin at 1.5 mg/kg dose to male ICR mice.