• Mass Spectrometry Letters
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• v.4 no.3
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• pp.55-58
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• 2013

Dioscin is a biologically active steroidal saponin with anticancer and hepatoprotective effects. A rapid, selective, and sensitive liquid chromatographic method with electrospray ionization tandem mass spectrometry was developed for the quantification of dioscin in rat plasma. Dioscin was extracted from rat plasma using ethyl acetate at acidic pH. The analytes were separated on a Halo C18 column using gradient elution of acetonitrile and 0.1% formic acid and detected by tandem mass spectrometry in selected reaction monitoring mode. The standard curve was linear ($r^2$ = 0.998) over the concentration range of 1-100 ng/mL. The lower limit of quantification was 1.0 ng/mL using 50 ${\mu}L$ of plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.3 to 8.0% and -5.4 to 10.0%, respectively. This method was applied successfully to the pharmacokinetic study of dioscin after oral administration of dioscin at a dose of 29.2 mg/kg in male Sprague-Dawley rats.

• Mass Spectrometry Letters
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• v.14 no.3
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• pp.104-109
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• 2023

Anabolic-androgenic steroids (AAS) are used illegally to enhance muscle development and increase strength and power. In this study, a reliable, and sensitive quantitative method was developed and validated using heptafluorobutyric acid anhydride (HFPA) derivatives for the simultaneous detection of prohibited AAS (testosterone [TS], boldenone [BD], 5α-estrane-3β,17α-diol [EAD]) using gas chromatography-tandem mass spectrometry (GC-MS/MS). For processing the samples, solid phase extraction, methanolic hydrolysis, and liquid-liquid extraction were used. For detection using mass spectrometry, the multiple reaction monitoring (MRM) mode was used with the electron ionization (EI) positive mode. The method was evaluated for selectivity, linearity, lower limit of quantification, intra- and inter-day precision, accuracy, and stability. The results showed that the method was accurate and reproducible for the quantitation of the three steroids. The developed method was finally applied to the analysis of a suspect gelding urine sample received from the Asian Quality Assurance Program (AQAP).

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1134-1136
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• 1994

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.955-957
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• 2014

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.15-19
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• 1989

Mass spectral fragmentations of some s-triazine herbicides have been investigated using tandem mass spectrometry. Major pathways driven by the side chains have been confirmed. However, most of the previously proposed pathways which were thought to be characteristic of the ring have been found unlikely. A class of ring cleavage reactions characteristic of s-triazine rings with alkylamino side chains has been found and the mechanism has been proposed. In addition, tandem mass spectrometry has been utilized to differentiate tautomeric structures and to analyze the fragmentation reactions occurring from the mixture of isobaric ions.

• Mass Spectrometry Letters
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• v.10 no.3
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• pp.93-101
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• 2019

Algorithms and software for predicting tandem mass spectra have been developed in recent years. In this work, we explore how distinct in silico $MS^2$ spectra are predicted for isomers, i.e. compounds having the same formula and similar molecular structures, to differentiate between them. We used the CFM-ID 2.0/3.0 predictor with regard to (a) test compounds, whose experimental mass spectra had been randomly sampled from the MassBank of North America (MoNA) collection, and to (b) the most widespread isomers of test compounds searched in the PubChem database. In the first validation test, in silico mass spectra constitute a reference library, and library searches are performed for test experimental spectra of "unknowns". The searches led to the true positive rate (TPR) of ($46-48{\pm}10$)%. In the second test, in silico and experimental spectra were interchanged and this resulted in a TPR of ($58{\pm}10$)%. There were no significant differences between results obtained with different metrics of spectral similarity and predictor versions. In a comparison of test compounds vs. their isomers, a statistically significant correlation between mass spectral data and structural features was observed. The TPR values obtained should be regarded as reasonable results for predicting tandem mass spectra of related chemical structures.

• Clinical and Experimental Pediatrics
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• v.48 no.5
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• pp.561-564
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• 2005

Isolated deficiency of 3-methylcrotonyl CoA carboxylase is a rare disorder of the catabolic pathway for leucine and many patients have mild symptoms or no symptom. However, the introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder. We report an asymptomatic premature infant with isolated 3-methylcrotonyl CoA carboxylase deficiency detected by newborn screening program using tandem mass spectrometry. She was born at preterm, 36 weeks of gestation and her birth weight was 1,912 gm. She was delivered by Cesarian section due to maternal preeclampsia and oligohydramnios. An elevation of 3-hydroxyisovalerylcarnitine in a blood sample obtained at Seven days was detected by tandem mass screening. Massively elevated excretion of 3-hydroxyisovalerate and 3-methylcrotonylglycine was detected in the urine collected at 15 days. L-carnitine(100 mg/kg/day) was administrated orally to correct sencondary carnitine deficiency. Carnitine is conjugated with metabolites, to decrease the potential toxic effects. She is asymptomatic to date, and her growth and development are within normal limits.

• Bioinformatics and Biosystems
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• v.1 no.2
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• pp.89-94
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• 2006

Mass spectrometry (MS) is widely applied for high throughput proteomics analysis. When large-scale proteome analysis experiments are performed, it generates massive amount of data. To search these proteomics data against protein databases, fully automated database search algorithms, such as Mascot and SEQUEST are routinely employed. At present, it is critical to reduce false positives and false negatives during such analysis. In this review we have focused on aspects of automated protein identification using tandem mass spectrometry (MS/MS) spectra and validation of the protein identifications of two most common automated protein identification algorithms Mascot and SEQUEST.

• Mass Spectrometry Letters
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• v.5 no.1
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• pp.1-11
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• 2014

Lipids play important roles in biological systems; they store energy, play a structural role in the cell membrane, and are involved in cell growth, signal transduction, and apoptosis. Phospholipids (PLs) in particular have received attention in the medical and lipidomics research fields because of their involvement in human diseases such as diabetes, obesity, atherosclerosis, and many cancers associated with lipid metabolic disorders. Here I review experimental strategies for PL analysis based on nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MSn). In particular, discussed are lipid extraction methods, nanoflow LC separation of PLs, effect of ionization modifiers on the ESI of PLs, influence of chain lengths and unsaturation degree of acyl chains of PLs on MS intensity, structural determination of the molecular structure of PLs and their oxidized products, and quantitative profiling of PLs from biological samples such as tissue, urine, and plasma in relation to cancer and coronary artery disease.

• Mass Spectrometry Letters
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• v.2 no.1
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• pp.16-19
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• 2011

Oxidation products of ceftiofur were formed in hydrogen peroxide solution. The structures of the ceftiofur oxidation products were characterized by high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (HPLC/ESI/MS/MS). The products were identified as compounds oxidized at the sulfur of a cephem ring. For further analysis, experiments were performed using $O^{18}$-labeled hydrogen peroxide. In addition, density-functional calculations were carried out for six possible oxidation products to support the experimental results.