• Food Science of Animal Resources
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• v.36 no.2
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• pp.254-261
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• 2016

The purpose of this study was to analyze oxidized methionines in the myosin isoforms of porcine longissimus thoracis, psoas major, and semimembranosus muscles by liquid chromatography (LC) and mass spectrometry (MS). A total of 836 queries matched to four myosin isoforms (myosin-1, -2, -4, and -7) were analyzed and each myosin isoform was identified by its unique peptides (7.3-13.3). Forty-four peptides were observed from all three muscles. Seventeen peptides were unique to the myosin isoform and the others were common peptides expressed in two or more myosin isoforms. Five were identified as oxidized peptides with one or two methionine sulfoxides with 16 amu of mass modification. Methionines on residues 215 (215), 438 (438), 853 (851), 856 (854), 1071 (1069), and 1106 (1104) of myosin-1 (myosin-4) were oxidized by the addition of oxygen. Myosin-2 had two oxidized methionines on residues 215 and 438. No queries matched to myosin-7 were observed as oxidized peptides. LC-MS/MS allows analysis of the oxidation of specific amino acids on specific residue sites, as well as in specific proteins in the food system.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.296-313
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• 2014

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) multiresidue method was developed for the simultaneous analysis of 124 pesticides in soil by LC-MS. The procedure involved liquid extraction of soil immersed with 0.2N $NH_4Cl$ by acetonitrile with 1% acetic acid, followed by anhydrous $MgSO_4$ and sodium acetate, and dispersive SPE cleanup with $MgSO_4$, primary secondary amine (PSA) and $C_{18}$. The extracts were analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.99. Recovery studies for the validation were carried out using two type soils, loam and sandy loam, at four concentration levels (0.005, 0.01, 0.02, and 0.1 mg/kg). The recoveries of pesticides were in the range of 70-120% with < 20% RSD except 4 pesticides, Benfuracarb, Ethiofencarb, Pymetrozine, and Pyrethrin. This result indicated that the method using QuEChERS and LC-MS/MS could be applied for the simultaneous determination of pesticide residues in soils.

• Journal of Food Hygiene and Safety
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• v.35 no.4
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• pp.326-333
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• 2020

In this work, we developed an analytical method for determining 11 illicit compounds in dietary supplements using high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry. Eleven target compounds, including those meant for weight loss (7-keto-dihydroepiandrosterone, buformin, metformin, phenformin, salbutamol, and tolbutamide), sexual enhancement (dihydroepiandrosterone), and relaxation (asarone, kavain, magnoflorine, and picamilon) were screened and confirmed in dietary supplements. Method validation was performed by evaluating the selectivity, linearity, limit of quantification (LOQ), accuracy, and precision according to the Association of Official Analytical Chemists guidelines. The linearity was > 0.993 for all analytes. The LOQs were ranged in 2.1-9.9 ㎍/mL (HPLC-DAD) and 0.002-0.008 ㎍/mL (LC-MS/MS). The accuracies (expressed as recovery) were 90.0-106% (HPLC-DAD) and 83.0-114% (LC-MS/MS). The precision (expressed as the relative standard deviation) was below 10% using HPLC and LC-MS/MS. The proposed method can be used for the surveillance of illicit compounds in dietary supplements.

• Korean Journal of Pharmacognosy
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• v.49 no.3
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• pp.270-277
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• 2018

Pyungwi-san has been used to treat the digestive system diseases, physconia, nausea, anorexia, and dyspepsia in Korea. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS) method was optimized for simultaneous determination of the 14 marker components, spinosin, liquiritirn apioside, liquiritin, narirutin, 6'''-feruloylspinosin, hesperidin, liquiritigenin, glycyrrhizin, 6-gingerol, atractylenolide III, honokiol, atractylenolide II, magnolol, and atractylenolide I in Pyungwi-san extract. All analytes were separated on a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) with maintained at $45^{\circ}C$. The mobile phase consisted of 0.1% (v/v) aqueous formic acid and acetonitrile. The MS conditions were as follows: capillary voltage 3.3 kV, extractor voltage 3.0 V, RF lens voltage 0.3 V, source temperature $120^{\circ}C$, desolvation temperature $300^{\circ}C$, desolvation gas 600 L/h, cone gas 50 L/h and collision gas 0.14 mL/min. The coefficient of determination of 14 analytes was 0.9989-1.0000. The limits of detection and quantification values of the all analytes were 0.04-2.56 and 0.13-7.69 ng/mL, respectively. As a result of the analysis using the established LC-ESI-MS/MS method, the 5 components, spinosin, 6'''-feruloylspinosin, atractylenolide III, II, and I derived from Zizyphi Fructus and Atractylodis Rhizoma, were not detected in this extract. On the other hand, the 9 components except for the 5 components were 4.15-498.87 mg/kg in lyophilized Pyungwi-san extract. Among these components, glycyrrhizin, marker compound of Glycyrrhizae Radix et Rhizoma, was detected the most amount as a 498.87 mg/kg.

• Korean Journal of Pharmacognosy
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• v.48 no.4
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• pp.320-328
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• 2017

Yongdamsagan-tang has been used to treat the urinary disorders, acute- and chronic-urethritis, and cystitis in Korea. In this study, an ultra-performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS/MS) method was established for simultaneous analysis of the 20 bioactive marker compounds, geniposidic acid, chlorogenic acid, geniposide, liquiritin apioside, acteoside, calceolarioside B, liquiritin, nodakenin, baicalin, liquiritigenin, wogonoside, baicalein, glycyrrhizin, wogonin, glycyrrhizin, wogonin, saikosaponin A, decursin, decursinol angelate, alisol B, alisol B acetate, and pachymic acid in traditional herbal formula, Yongdamsagan-tang. Chromatographic separations of all marker compounds were conducted using a Waters Acquity UPLC BEH $C_{18}$ analytical column ($2.1{\times}100mm$, $1.7{\mu}m$) at $45^{\circ}C$ using a mobile phase of 0.1% (v/v) formic acid in water and acetonitrile with gradient elution. The MS analysis was performed using a Waters ACQUITY TQD LC-MS/MS coupled with an electrospray ionization source in the positive and negative modes. The flow rate was 0.3 mL/min and injection volume was $2.0{\mu}L$. The correlation coefficient of 20 marker compounds in the test ranges was 0.9943-1.0000. The limits of detection and quantification values of the all marker components were 0.11-6.66 and 0.34-19.99 ng/mL, respectively. As a result of the analysis using the optimized LC-ESI-MS/MS method, three compounds, geniposidic acid (from Plantaginis Semen), alisol B (from Alismatis Rhizoma), and pachymic acid (from Poria Sclerotium), were not detected in this sample. While the amounts of the 17 compounds except for the geniposidic acid, alisol B, and pachymic acid were $0.04-548.13{\mu}g/g$ in Yongdamsagan-tang sample. Among these compounds, baicalin, bioactive marker compound of Scutellariae Radix, was detected at the highest amount as a $548.13{\mu}g/g$.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.809-816
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• 2010

Microbial biotransformations can be used to predict mammalian drug metabolism. The present investigation deals with microbial biotransformation of valdecoxib using microbial cultures. Thirty-nine bacterial, fungal, and yeast cultures were used to elucidate the biotransformation pathway of valdecoxib. A number of microorganisms metabolized valdecoxib to various levels to yield nine metabolites, which were identified by HPLC-DAD and LC-MS-MS analyses. HPLC analysis of biotransformed products indicated that a majority of the metabolites are more polar than the substrate valdecoxib. Basing on LC-MS-MS analysis, the major metabolite was identified as a hydroxymethyl metabolite of valdecoxib, whereas the remaining metabolites were produced by carboxylation, demethylation, ring hydroxylation, N-acetylation, or a combination of these reactions. The hydroxymethyl and carboxylic acid metabolites were known to be produced in metabolism by mammals. From the results, it can be concluded that microbial cultures, particularly fungi, can be used to predict mammalian drug metabolism.

• Journal of Environmental Health Sciences
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• v.37 no.6
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• pp.474-481
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• 2011

This study investigated urinary metabolites of polycyclic aromatic hydrocarbons (PAHs) in the urine of smokers and non-smokers by liquid chromatography triple quordrupole tandem mass spectroscopy (LC/MS/MS). Compounds analyzed for urinary biomarkers of PAHs were five mono-hydroxylated PAHs metabolites; 1-naphthol, 2-naphthol, 1-hydroxypyrene(1-OHP), 3-phenanthrol, 2-fluorenol. Urine samples were pretreated by enzymatic hydrolysis and solid phase extraction method. Smokers were composed of 17 men and five women; non-smokers 17 men and 16 women. Smoking increased urinary concentrations of five PAHs metabolites significantly higher than those of nonsmokers. Statistically significant correlations among the five PAHs metabolites were shown. The results suggest that LC/MS/MS technology should be useful in the environmental health discipline.

• Mass Spectrometry Letters
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• v.6 no.4
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• pp.99-104
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• 2015

A liquid chromatography mass spectrometry (LC-MS) system was used to identify and distinguish oligostilbene diastereoisomers. A polyphenolic extract from Neobalanocarpus heimii known to be rich in oligostilbenes of various degrees of condensation was used as test material. Fourteen oligostilbenes were isolated from this extract on a fully automated semi-preparative HPLC system. Out of these, two pairs of dimers, one pair of trimers, two pairs of tetramers and a group of four tetramers with similar skeleton were identified as diastereoisomers. Their structures and configurations were established by spectroscopic methods. All isolated compounds were subjected to an LC-MS/MS to study their fragmentation patterns. The experiments were performed on a liquid chromatography-mass spectrometry (LC-MS) with electrospray-ionization (ESI) interface in positive mode. MS/MS spectra of each pure compound were recorded by direct infusion in identical conditions and their product ion spectra were analysed. Some subtle yet significant differences were observed between the spectra of oligostilbenes from the various diastereoisomeric series.

• Mass Spectrometry Letters
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• v.2 no.2
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• pp.45-48
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• 2011

The authors describe a method for monitoring dicyclanil levels in lamb and chicken muscle tissues. The devised procedure involves dicyclanyl extraction by SPE and its detection HPLC-UV/Vis and LC/MS/MS. The method was found to have LOD and LOQ values of $0.02\;mg\;kg^{-1}$ and $0.05\sim0.06\;mg\;kg^{-1}$, respectively. The intraday precision and an accuracy of spiked samples were found to have 2.3~10.4 RSD% and 80.9~105.7%, respectively.

• Mass Spectrometry Letters
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• v.5 no.1
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• pp.30-33
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• 2014

A solid phase extraction (SPE) method was optimized for the quantitative analysis of perfluorooctanoic acid (PFOA) in serum using hydrophilic-lipophilic balance SPE and LC-MS/MS. Fetal bovine serums spiked with $^{13}C_8$-PFOA before or after SPE were used as test samples for evaluation of the SPE efficiency. Simultaneous evaluation of matrix effects and absolute SPE recovery for $^{13}C_8$-PFOA in serum using different sample pre-treatments and SPE conditions allowed optimization of SPE process efficiency with minimal matrix effect and decent SPE recovery. Introduction of protein precipitation as a sample pre-treatment procedure for serum samples before SPE generally decreased matrix effect in LC-MS/MS analysis and provided more stable recovery of PFOA.