• Applied Biological Chemistry
• /
• v.21 no.1
• /
• pp.11-15
• /
• 1978

Alloisoleucine from the plasma of maple syrup disease affected patients was separated from isolecine and identified by gas liquid chromatography and mass spectrometry.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.6
• /
• pp.878-880
• /
• 2004

Revered-phase LC-electrospray ionization mass spectrometry was used to selectively determine enalapril from plasma with minimal sample preparation. Detection limit of the method was 1 ng/mL. Precision (within day and between days) and accuracy of the method at various concentrations were acceptable. The analytical technique was used for pharmacokinetic studies after administration of enalapril to human test subjects.

• Mass Spectrometry Letters
• /
• v.12 no.4
• /
• pp.137-145
• /
• 2021

Herein we report multiple ion mobility (IM) peaks in electrospray ionization IM mass spectrometry (ESI-IM-MS) produced by glutamine residue in peptide. The mobility features of 147 peptides were investigated using ESI-IM-MS combined with liquid chromatography. Of these peptides, 66 presented multiple IM peaks, and analysis of their sequence using collision induced dissociation (CID) revealed that glutamine (Gln), as well as proline (Pro), plays a critical role in generating multiple IM peaks. Mutant-based investigations using Gln-containing peptides indicate that the side chain of Gln promotes intermolecular interactions, inducing multiple structures of the peptide ions in the gas phase. Consequently, the present study demonstrates that the distinct ion mobility signatures identified herein can potentially be used to characterize glutamine-containing peptide ions.

• Food Science of Animal Resources
• /
• v.37 no.6
• /
• pp.847-854
• /
• 2017

A rapid, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of four barbiturates (phenobarbital, pentobarbital, amobarbital and secobarbital) in raw milk. The barbiturates were extracted using liquid-liquid extraction, ultrasonication and centrifugation, and purified on an SPE column. Analytes were separated by HPLC on a CSH C18 column eluted using an acetonitrile-water system with a linear gradient dilution programme, and detected by MS/MS. The recoveries of the barbiturates were 85.0-113.5%, and the intra- and inter-assay RSDs were less than 9.8% and 7.3%, respectively. The limit of detection was 5 ng/mL for all four of the barbiturates. The analytical method exhibited good linearity from 10 to 1000 ng/mL; the correlation coefficient ($r^2$) was greater than 0.9950 for each barbiturate. This method was also applied to the determination of barbiturates in real milk samples and was found to be suitable for the determination of veterinary drug residues in raw milk.

• Journal of Pharmaceutical Investigation
• /
• v.39 no.5
• /
• pp.367-372
• /
• 2009

A rapid liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay method was developed for the determination of topotecan levels in rat serum. The assay utilized a single liquid-liquid extraction with a mixture of ethy l acetate and acetonitrile (6:1 v/v) and isocratic elution. The multiple reaction monitoring was based on the transition of m/z 422.0$\rightarrow$376.5 for topotecan and 315.1$\rightarrow$226.6 for clomipramine (internal standard). The developed assay was validated to demonstrate the specificity, recovery, lower limit of quantification (LLOQ), accuracy and precision. The assay was linear over a concentration range from 0.5-100 ng/mL, with LLOQ being 0.5 ng/mL using a small volume of rat serum (0.1 mL). The mean intra- and inter-day assay accuracy was 87.7-111.0% and 97.8-108.3, respectively, and the mean intra- and interday precision was between 1.6-4.3% and 3.8-10.3, respectively. The developed assay was applied to a pharmacokinetic study after a bolus i.v. injection of topotecan in rats.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.10
• /
• pp.1517-1520
• /
• 2003

• Applied Biological Chemistry
• /
• v.50 no.3
• /
• pp.238-243
• /
• 2007

The contents of limonin, nomilin and limonin glucoside in different tissues of dangyuja (Citrus spp.) were measured during fruit growth and maturation by liquid chromatography-mass spectrometry(LC-MS). Both nomilin and limonin contents increased from June, peaked in October and in December, respectively, and then decreased afterwards. In contrast, the content of limonin glucoside increased from October and remained at high levels throughout the maturation. The contents of limonin, nomilin and limonin glucoside in peel decreased gradually throughout the growth and the trends of changes were similar to each other. However, all three limonoid contents in juice sac increased dramatically at the end of fruit maturation. The highest concentration of limonin and nomilin was observed in seed, followed by segment membrane, whereas the highest limonin glucoside concentration was observed in segment membrane, followed by juice sac.

• Mass Spectrometry Letters
• /
• v.2 no.1
• /
• pp.8-11
• /
• 2011

Two types of glycerolipids [monoacylglycerols (MAG) and cyclitols] were isolated by reversed phase high-performance liquid chromatography from the methanol extracts of a marine sponge, and analyzed by fast atom bombardment mass spectrometry (FAB-MS) in positive-ion mode. FAB mass spectra of these compounds yielded protonated molecules $[M + H]^+$ and abundant sodiated molecules $[M + Na]^+$ from a mixture of 3-nitrobenzyl alcohol and NaI. The structures of these compounds were elucidated by FAB-collisional-induced dissociation (CID)-tandem mass spectrometry. We carried out collision-indused dissociation (CID) of these lipids in B/E-linked scan mode. The CID B/E-linked scan of $[M + H]^+$ and $[M + Na]^+$ precursor ions resulted in the formation of numerous characteristic product ions through a series of dissociative processes. The product ions formed by charge-remote fragmentation (CRF) provided important information for the identification of the acyl chain structure substituted at the glycerol backbone. Some of the product the ions were diagnostic for the presence of a glycerol backbone or acyl chain structure.

• Mass Spectrometry Letters
• /
• v.10 no.1
• /
• pp.18-26
• /
• 2019

We developed a bioanalytical method for simultaneous determination of nine NBOMe derivatives (25H-NBOMe, 25B-NBOMe, 25E-NBOMe, 25N-NBOMe, 25C-NBOH, 25I-NBOH, 25B-NBF, 25C-NBF, and 25I-NBF) in human plasma using liquid chromatography tandem mass spectrometry (LC-MS/MS). Human plasma samples were pre-treated using solid-phase extraction. Separation was achieved on a C18 column under gradient elution using a mobile phase containing 0.1% formic acid in acetonitrile and 0.1% formic acid in water at a flow rate of 0.3 mL/min. Mass detection was performed in the positive ion mode using multiple reaction monitoring. The calibration range was 1-100 ng/mL for all quantitative analytes, with a correlation coefficient greater than 0.99. The intra- and inter-day precision and accuracy varied from 0.85 to 6.92% and from 90.19 to 108.69%, respectively. The recovery ranged from 86.36 to 118.52%, and the matrix effects ranged from 27.09 to 99.72%. The stability was acceptable in various conditions. The LC-MS/MS method was validated for linearity, accuracy, precision, matrix effects, recovery and stability in accordance with the FDA guidance. The proposed method is suitable for reliable and robust routine screening and analysis of nine NBOMe derivatives in forensic field.

• Archives of Pharmacal Research
• /
• v.26 no.8
• /
• pp.606-611
• /
• 2003

Byakangelicin, 9-(2,3-dihydroxy-2-methylbutoxy)-4-methoxy-7H- furo[3,2-g][l]benzopyran-7-one (BKG), a component of Angelicae dahuricae Radix, is considered to be an inhibitor of aldose reductase for the treatment of diabetic cataract. An analytical method for the isolation of BKG developed by high-performance liquid chromatography has been reported. No literature on the metabolism of BKG, however, has been found. With the purpose of identifying new metabolites of BKG, BKG (100 mg/kg) was orally administered to Sprague-Dawley rats via a gavage. Using a metabolic cage, urine was collected for 24 h, and the urine samples were extracted by liquid-liquid extraction. For structural identification of new urinary metabolites of BKG, various instrumental analyses were conducted by gas-chromatography/mass spectrometry, high-performance liquid chromatography/diode array detector, liquid chromatography/mass spectroscopy with thermospray interface and $^1H$ nuclear magnetic resonance spectroscopy. Two metabolites produced from the Ο-demethylation or Ο-dealkylation of BKG were newly identified, and another new but unknown metabolite was assumed to be the hydroxylated form of BKG. These results indicate that the major metabolic products of BKG are formed by Ο-demethylation or Ο-dealkylation of BKG side chains.