• Analytical Science and Technology
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• v.23 no.4
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• pp.405-413
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• 2010

A new method for the simultaneous determination of six glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, methylprednisolone, and flumethasone) in meats (bovine muscle, bovine liver) were established. Samples were effectively extracted using C18 cartridge with ethylacetate. Chromatographic separation was achieved using C18 column and negative electrospray ionization mass spectrometry was performed in the Multiple Reaction Monitoring mode for the effective quantitation and qualification of glucocorticoids. Acetonitrile and water (0.1% formic acid) were used as mobile phase and additive for effective electrospray ionization, and gave good chromatographic separation and mass spectrometric sensitivity. The limit of detection (LODs) and the limit of quantitation (LOQs) in spiked blank samples depending on types of matrix and pharmaceuticals were ranged from 0.2 to $1.0\;{\mu}g$/kg and 0.8 to $3.4\;{\mu}g$/kg, respectively. And the recoveries were between 89.5 to 119.6%. The established method showed good recoveries, accuracies, precisions and fast sample preparation and it will be applied to assay of glucocorticoids residues in meat.

• Journal of Conservation Science
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• v.34 no.5
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• pp.369-377
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• 2018

In order to examine the constituents and weathered state of a lacquer specimen, analysis of the organic materials was conducted using py/GC/MS(pyrolysis-gas chromatography-mass spectrometry). The samples were obtained from the lacquered wooden sheath of a long ring-pommel sword excavated in the Imdang No.1 ancient tomb constructed around the Proto-Three Kingdoms period. In direct py/GC/MS, the sample and the dried Asian lacquer showed similar chromatograms, while the characteristic compounds of Asian lacquer such as 1,2-dimethoxy-3-pentadecylbenzene were observed in THM(thermally assisted hydrolysis and methylation)-py/GC/MS. In addition, compounds like dimethyl nonanedioate, which presumably originated from drying oil, were also detected. Furthermore, the detection of oxidized catechols in considerable amount indicated that the degradation of lacquer is estimated to result from the oxidation of urushiol. Therefore, it is suggested that the lacquered wooden sheath was prepared using Asian lacquer and drying oil, and that the lacquer layer was considerably oxidized over the long burial time.

• YAKHAK HOEJI
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• v.60 no.3
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1232-1236
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• 2013

The Cu cation binding sites of $[Cu(I){\cdot}d(CpG){\cdot}d(CpG)-2H]^{-1}$ complex have been investigated to explain the $[Cu{\cdot}DNA]$ biological activity caused by the Cu association to DNA. The structure of $[Cu(I){\cdot}d(CpG){\cdot}d(CpG)-2H]^{-1}$ complex was investigated by electrospray ionization mass spectrometry (ESI-MS). The fragmentation patterns of $[Cu(I){\cdot}d(CpG){\cdot}d(CpG)-2H]^{-1}$ complex were analyzed by MS/MS spectra. In the MS/MS spectra of $[Cu(I){\cdot}d(CpG){\cdot}d(CpG)-2H]^{-1}$ complex, three fragment ions were observed with the loss of d(CpG), {d(CpG) + Cyt}, and {d(CpG) + Cyt + dR}. The Cu cation binds to d(CpG) mainly by substituting the $H^+$ of phosphate group. Simultaneously, the Cu cation prefers to bind to a guanine base rather than a cytosine base. Five possible geometries were considered in the attempt to optimize the $[Cu(I){\cdot}d(CpG){\cdot}d(CpG)-2H]^{-1}$ complex structure. The ab initio calculations were performed at B3LYP/6-31G(d) level.

• Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.213-219
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• 2005

Vitellogenin (VTG) was purified from the blood plasma of estradiol-17$\beta$ ($E_2$)-treated male marbled sole (Limanda yokohamae) using gel filtration and anion exchange chromatography. The purity of the marbled sole VTG (msVTG) was confirmed by polyacrylamide gel electrophoresis (SDS-PAGE) and N-terminal amino acid sequencing. The purified msVTG was used to produce monoclonal and polyclonal antibodies in mice and rabbits, respectively, and the specificity of the polyclonal antisera for msVTG was confirmed by Western blot analysis. The antibodies cross­reacted with a protein of molecular mass approximately 160 kDa in the plasma samples of mature female marbled sole. No cross-reactivity was observed with the plasma of male fish. A direct non-competitive sandwich enzyme-linked immunosorbent assay (ELISA) was developed using the monoclonal anti-msVTG and polyclonal anti-msVTG antibodies, with purified msVTG as the standard protein. The values of the intra- and inter-assay variations were within the ranges of $8.l-9.8\%$ and $8.5-12.2\%$, respectively. The sensitivity was about 0.3 ng/mL. Serial dilutions of plasma from mature female sole reacted with the msVTG-antibodies in the sandwich ELISA, whereas the plasma from male fish did not. The results indicate that the maturation status of female marbled sole can be identified using a sandwich ELISA for msVTG.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.69-75
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• 2004

This work proposes an 8b 220 MS/s 230 mW 3-stage pipeline CMOS ADC with on-chip filers for temperature- and power- insensitive voltage references. The proposed RC low-pass filters improve switching noise performance and reduce reference settling time at heavy R & C loads without conventional off-chip large bypass capacitors. The prototype ABC fabricated in a 0.25 um CMOS occupies the active die area of 2.25 $\textrm{mm}^2$ and shows the measured DNL and INL of maximum 0.43 LSB and 0.82 LSB, respectively. The ADC maintains the SNDR of 43 dB and 41 dB up to the 110 MHz input at 200 MS/s and 220 MS/s, respectively, while the SNDR at the 500 MHz input is degraded as much as only 3 dB than the SNDR at the 110 MHz input.

• KSBB Journal
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• v.31 no.1
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• pp.1-7
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• 2016

Changes in the concentrations of glucosinolates and related compounds in different extracts of Dolsan leaf mustard kimchi (DLMK) and Dolsan leaf mustard pickles (DLMP) were during storage investigated. Samples were kept at 0oC for 35 days and collected at 7 day intervals. The leaves and stems of DLMK and DLMP were refluxed for 24 h with 50% acetonitrile, and the extracts were analyzed by LC-PDA/MS/MS. The main glucosinolates detected in DLMK were sinigrin, gluconapoleiferin, glucobrassicanapin, and gluconapin, whereas those in DLMP were sinigrin, gluconapoleiferin, glucobrassicanapin, glucobrassicin, and glucoerucin. Sinigrin concentrations were quantified by UV absorption at 228 nm. Sinigrin concentrations in the leaves and stems of DLMK on the day of preparation were 2.14 mg/g and 2.25 mg/g, respectively, and those on day 35 after preparation were 1.25 mg/g and 1.00 mg/g, respectively. DLMP showed a similar trend: the concentrations in the leaves and stems on the day of preparation were 2.04 mg/g and 0.29 mg/g, respectively, whereas those on day 35 after preparation were 0.59 mg/g and 0.41 mg/g, respectively. Thus, sinigrin concentrations decreased during storage.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.12.1-12.7
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• 2011

Objectives: Perchlorate is an emerging contaminant that is found everywhere, including various foods. Perchlorate is known to disturb the production of thyroid hormones and leads to mental disorders in fetuses and infants, as well as metabolic problems in adults. In this study, we attempted to establish an LC-MS/MS method for measuring perchlorate in dairy products and used this developed method to investigate perchlorate levels in Korean milk and yogurt samples. Methods: The developed method of perchlorate analysis requires a shaker and 1% acetic acid/acetonitrile as the extracting solvent. Briefly, the samples were extracted and then centrifuged (4000 rpm, 1hour), and the supernatant was then passed through a $Envi^{TM}$ Carb SPE cartridge that had been prewashed sequentially with 6 mL of acetonitrile and 6 mL of 1% acetic acid in water. The final volume of the sample extract was adjusted to 40 mL with reagent water and the final sample was filtered through a 0.20-${\mu}m$ pore size PTFE (Polytetrafluoroethylene) syringe filter prior to LC-MS/MS. Results: The average levels of perchlorate in milk and yogurt samples were $5.63{\pm}3.49\;{\mu}g/L$ and $3.65{\pm}2.42\;{\mu}g/L$, respectively. The perchlorate levels observed in milk samples in this study were similar to those reported from China, Japan, and the United States. Conclusions: The exposure of Koreans to perchlorate through the consumption of dairy products was calculated based on the results of this study. For all age groups, the calculated exposure to perchlorate was below the reference of dose (0.7 ${\mu}g/kg$-day) proposed by the National Academy of Science, USA, but the perchlorate exposure of children was higher than that of adults. Therefore, further investigation of perchlorate in other food samples is needed to enable a more exact assessment of exposure of children to perchlorate.

• Korean Journal of Environmental Agriculture
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• v.23 no.4
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• pp.197-202
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• 2004

The persistence of pendimethalin in soil and ground water has an injurious effect on ecosystem. Pendimethalin-degrading bacterium was isolated from Masan, Gyeongnam province and temporarily identified as Bacillus sp. MS202 by the analysis of API CHB50, kit, FAME, and 16S rDNA sequence. from the analysis of pnedimethalin metabolite using TLC, GC, and GC-MS, we found that the degradation of pendimethalin by Bacillus sp. MS202 did not result in the dealkylated form, but the formation of the reduced compound, 6-amino-2-nitro-N(1-ethylpropyl)-3,4-xylidine or 2- amino-6-nitro-N(1-ethylpropyl)-3,4-xylidine.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.200-205
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• 2021

Polynemoraline C, a pyridocoumarin alkaloid, exhibits anticholinergic, anti-inflammatory, antitumor, and antimicrobial activities. A sensitive analytical method of polynemoraline C in mouse plasma was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Polynemoraline C and ¹³C-caffeine (internal standard) in mouse plasma were extracted using a liquid-liquid extraction method coupled with ethyl acetate. This extraction method resulted in high and reproducible extraction recovery in the range of 73.49%-77.31% with no interfering peaks around the peak retention time of polynemoraline C and ¹³C-caffeine. The standard calibration curves for polynemoraline C were linear over the range of 0.5-200 ng/mL with r² > 0.985. The accuracy, precision, and the stability of the data were within acceptable limits on the FDA guideline. After intravenous and oral administration of polynemoraline C at doses of 5 and 30 mg/kg, respectively, the present method was successfully applied to the pharmacokinetic study of polynemoraline C. Polynemoraline C in mouse plasma showed a multi-exponential elimination pattern with a high volume of distribution values. This compound's absolute oral bioavailability was found to be 17.0%. Polynemoraline C's newly developed LC-MS/MS method can be used for further studies on the efficacy, toxicity, and biopharmaceutics of polynemoraline C, as well as its pharmacokinetic studies.