• Journal of Ginseng Research
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• v.37 no.3
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• pp.371-378
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• 2013

Serum and liver metabolites in rats fed red ginseng (RG) were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The mass data were analyzed by partial least squares-discriminant analysis (PLS-DA) to discriminate between control and RG groups and identify metabolites contributing to this discrimination. The RG group was clearly separated from the control group on PLS-DA scores plot for serum samples, but not liver samples. The major metabolites contributing to the discrimination included lipid metabolites (lysophosphatidylcholine, acyl-carnitine, and sphingosine), isoleucine, nicotinamide, and corticosterone in the serum; the blood levels of all but isoleucine were reduced by RG administration. Not all metabolites were positively correlated with the health benefits of RG. However, the blood levels of lysophosphatidylcholine, which stimulate various diseases, and long-chain acylcarnitines and corticosterone, which activate the stress response, were reduced by RG, suggesting long-term RG might relieve stress and prevent physiological and biological problems.

• Mass Spectrometry Letters
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• v.5 no.2
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• pp.49-51
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• 2014

The effectiveness of tertiary matrices composed of the combination of three common matrices (dihydrobenzoic acid (DHB), ${\alpha}$-cyano-4-hydroxycinnamic acid (CHCA), and sinapinic acid (SA)) was compared with that of single or binary matrices in the analysis of polyethylene glycol (PEG) polymers ranging from 1400 to 10000 Da using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A tertiary matrix of 2,5-DHB+CHCA+SA was the most effective in terms of S/N ratios. CHCA and CHCA+SA produced the highest S/N ratios among the single matrices and the binary matrices, respectively. The improvement observed when using a tertiary matrix in analyses of PEG polymers by MALDI-TOF MS is believed to be due to the uniform morphology of the MALDI sample spots and synergistic effects arising from the mixture of the three matrix materials.

• Mass Spectrometry Letters
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• v.14 no.1
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• pp.1-8
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• 2023

Eutylone, dibutylone, and dimethylone are potential psychotropic designer drugs. The purpose of this study was to investigate the in vitro metabolic pathways of synthetic cathinones with methylenedioxy groups. The three methylenedioxy derivatives were incubated with human liver microsomes. The metabolites were characterized based on liquid chromatography and quadrupole-time-of-flight mass spectrometry. Eutylone, dibutylone, and dimethylone were metabolized to yield three, six, and four metabolites, respectively. Reduction and demethylenation were the major metabolic pathways for all three drugs tested. However, dibutylone and dimethylone showed an additional metabolite generated via N-oxidation. These results provide evidence for the in vivo metabolism of methylenedioxy synthetic cathinones, and could be applied to the analysis of synthetic cathinones and their relevant metabolites in biological samples.

• Mass Spectrometry Letters
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• v.8 no.1
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• pp.14-17
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• 2017

The effect of cationization agent concentration on glycan detection via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was investigated using $Na^+$ ions in the form of NaCl as the cationization agent. NaCl solution concentrations ranging from 1 mM to 1 M were investigated. Glycans from ovalbumin were mixed with the cationization agent solution and the 2,5-dihydroxybenzoic acid (2,5-DHB) matrix solution in a volume ratio of 1:1:1. The resulting mixture was loaded onto the MALDI plate. Two MALDI-TOF MS instruments (Voyager DE-STR MALDI-TOF MS and Tinkerbell RT MALDI-TOF MS) were used for detection of glycans. The best detection, in terms of the number of identified glycans, the peak intensity, and the signal-to-noise (S/N) ratio, was obtained with NaCl concentrations of 0.01-0.1 M for both MALDI-TOF MS instruments.

• Mass Spectrometry Letters
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• v.4 no.1
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• pp.21-23
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• 2013

The effects of trifluoroacetic acid (TFA) were evaluated on the generation of multiply charged ions of cytochrome c in a 2-nitrophloroglucinol (2-NPG) matrix in high-vacuum, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The presence of 1% TFA in the 2-NPG matrix solution was more effective in generating multiply charged protein ions than matrix solutions containing 0.1% or 0% TFA. Regarding the matrix itself, with 1% TFA, 2-NPG was significantly more effective in generating multiply charged ions than 2,5-dihydroxybenzoic acid (2,5-DHB). The maximum charge state of cytochrome c was +8 when using a 2-NPG matrix containing 1% TFA.

• Mass Spectrometry Letters
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• v.10 no.3
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• pp.84-87
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• 2019

Liquid chromatography mass spectrometry is widely employed in proteomics studies. One of such instruments is the Liquid Chromatography (LC)-Matrix-assisted laser desorption ionisation (MALDI)-Time of flight (TOF) or LC-MALDI-TOF/TOF. In this study, this instrument was used to identify the membrane proteins of a protozoan parasite namely Entamoeba histolytica. It causes amoebiasis in human. The E. histolytica trophozoites were cultured prior to the membrane protein extraction using the conventional method, $ProteoPrep^{(R)}$ and $ProteoExtract^{(R)}$ kits. Then, the membrane protein extracts were trypticdigested and analysed by LC-MALDI-TOF/TOF. Approximately, 194 proteins were identified and 27.8% (54) were predicted as membrane proteins having 1 to 15 transmembrane regions and signal peptides by combining all three extraction methods. Also, this study has discovered 3 unique proteins as compared to our previous study which merit further investigation.

• Journal of Microbiology and Biotechnology
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• v.25 no.9
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• pp.1537-1541
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• 2015

Previous detection methods for Citrobacter are considered time consuming and laborious. In this study, we have developed a rapid and accurate detection method for Citrobacter species in pork products, using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). A total of 35 Citrobacter strains were isolated from 30 pork products and identified by both MALDI-TOF MS and 16S rRNA gene sequencing approaches. All isolates were identified to the species level by the MALDI-TOF MS, while 16S rRNA gene sequencing results could not discriminate them clearly. These results confirmed that MALDITOF MS is a more accurate and rapid detection method for the identification of Citrobacter species.

• Mass Spectrometry Letters
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• v.12 no.2
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• pp.47-52
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• 2021

Evaluating the impurity concentrations in semiconductor thin films using time of flight secondary ion mass spectrometry (ToF-SIMS) is an effective technique. The mass interference between isotopes and matrix element in data interpretation makes the process complex. In this study, we have investigated the doping concentration of phosphorus in, phosphorus doped silicon thin film on glass using ToF-SIMS in the dynamic mode of operation. To overcome the mass interference between phosphorus and silicon isotopes, the quantitative analysis of counts to concentration conversion was done following two routes, standard relative sensitivity factor (RSF) and SIMetric software estimation. Phosphorus doped silicon thin film of 180 nm was grown on glass substrate using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using ToF-SIMS, the phosphorus-31 isotopes were detected in the range of 10¹~10⁴ counts. The silicon isotopes matrix element was measured from p-type silicon wafer from a separate measurement to avoid mass interference. For the both procedures, the phosphorus concentration versus depth profiles were plotted which agree with a percent difference of about 3% at 100 nm depth. The concentration of phosphorus in silicon was determined in the range of 10¹⁹~10²¹ atoms/cm³. The technique will be useful for estimating distributions of various dopants in the silicon thin film grown on glass using ToF-SIMS overcoming the mass interference between isotopes.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.880-883
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• 1996

Plasma Source Ion Implantation (PSII) technique was used for the hydrophilization or hydrophobization of polymer surfaces. Polymers were modified with different plasma gases such as oxygen, nitrogen, argon, and tetrafluoromethane, and for varying lengths of treatment time. Plasma ion treatment of oxygen, nitrogen, argon and their mixtures increased significantly the hydrophilic properties of polymer surfaces. More hydrophobic surfaces of polymers were formed after the treatment with tetrafluoromethane. A study of plasma source ion implanted polymers was performed using contact angle measurements and Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS). The TOF-SIMS spectra and depth profile were used to obtain the information about the treated surfaces of polymers. The permanence of this technique could be evaluated with respect to ageing time. The surfaces treated with PSII gave better stability than other surface modification methods.

• Proceedings of the PSK Conference
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• 2000.04a
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• pp.199.2-199.2
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• 2000