• Analytical Science and Technology
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• v.20 no.2
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• pp.138-146
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• 2007

A simple and sensitive method for the determination of paroxetine in canine plasma was developed and validated by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-/MS/MS). Fluoxetine was used as an internal standard. Paroxetine and internal standard in plasma samples were extracted using TBME (tert-butyl methyl ether). A centrifuged upper layer was then evaporated and reconstituted with mobile phase of 50% acetonitrile adjusted to pH 3 by formic acid. The reconstituted samples were injected into a Capcell Pak UG120 ($2.0{\times}150mm$, $5{\mu}m$) column. Using MS/MS with SRM (selective reaction monitoring) mode, the transitions (precursor to product) monitored were m/z $330{\rightarrow}192$ for paroxetine, and m/z $310{\rightarrow}148$ for internal standard. Linear detection responses were obtained for paroxetine concentration range of 0.02~5 ng/mL. A correlation coefficient of linear regression ($R^2$) was 0.9993. Detection of paroxetine in canine plasma was accurate and precise, with limit of quantification at 0.02 ng/mL. The method has been successfully applied to pharmacokinetic study of paroxetine in healthy beagle dogs.

• YAKHAK HOEJI
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• v.28 no.5
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• pp.287-291
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• 1984

A rapid and accurate NMR procedure for the analysis of a mixture of sulfametrol, sulfalene and sulfameter in $CDCl_3$ and $dimethylsulfoxide-d_6$ was developed. Thioacetamide was used as an internal standard. The signals chosen for the analysis were a singlet of 4.03ppm due to the methoxyl group of sulfametrol, a singlet of 3.98ppm due to the methoxyl group of sulfalene and a singlet of 3.83ppm due to the methoxyl group of sulfameter. The quantification of the characteristic peak was done by the integration method and the peak height method. The variation coefficient of sulfametrol, sulfalene and sulfameter were 1.7(n=6), 1.7(n=6) and 1.4%(n=6), respectively in the peak height method and 8.9(n=6), 9.4(n=6) and 7.0(n=6), respectively in the integration method.

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.662-667
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• 2023

Allantoin is an abundant component of yams and has been known as a skin protectant due to its pharmacological activities. In previous methods for allantoin determination using high-performance liquid chromatography (HPLC), the separation was unsatisfactory. We herein developed a ¹H quantitative nuclear magnetic resonance (qNMR) method for quantification of allantoin in the flesh and peel of yams. The method was carried out based on the relative ratio of signals integration of allantoin to a certain amount of the internal standard dimethyl sulfone (DMSO₂) and validated in terms of specificity, linearity (range 62.5-2000 ㎍/ml), sensitivity (limit of detection (LOD) and quantification (LOQ) 4.63 and 14.03 ㎍/ml, respectively), precision (RSD% 0.02-0.26), and recovery (86.35-92.11%). The method was then applied for the evaluation of allantoin in flesh and peel extracts of four different yams cultivated in Korea.

• The Korean Journal of Nuclear Medicine
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• v.6 no.2
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• pp.41-47
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• 1972

The radioimmunoassay of human thyrotropin was performed in various thyroid states, utilizing the anti-h-T.S.H. antibody and purified human thyrotropin supplied from National Institute of Arthritis and Metabolic Diseases, Bethesda, Ma., U.S.A., and human thyrotropin standard-A obtained from National Institute for Biologic Standards, Mill Hill, London, England. $^{131}I$ labelled h-TSH was prepared after the Chloramine-T method of Greenwood et al. This double antibody system had a assay sensitivity of about $1.0{\mu}U/ml$ of plasma HTS-A and could detect the plasma h-TSH level in the euthyroid patients. Plasma h-TSH level of the normal 26 Korean was $1.1{\pm}0.83{\mu}U/ml$, and that of the 8 hypothyroidisms were 8.3 to $67.5{\mu}U/ml$. In hyperthyroidisms, no cases showed the plasma h-TSH levels over $1.0{\mu}U/ml$. Between the hypothyroidism and euthyroidsm, no overlap is noticed on plasma h-TSH levels. A case of transient hypothyroid state identified by determination of plasma h-TSH level is presented. These results revealed that the radioimmunoassay of h-TSH in plasma could be a sensitive method to diagnose the hypothyroidsm, if not caused by a pituitary disease.

• Korean Circulation Journal
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• v.54 no.7
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• pp.382-394
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• 2024

Background and Objectives: Fractional flow reserve (FFR) is an invasive standard method to identify ischemia-causing coronary artery disease (CAD). With the advancement of technology, FFR can be noninvasively computed from coronary computed tomography angiography (CCTA). Recently, a novel simpler method has been developed to calculate onsite CCTA-derived FFR (CT-FFR) with a commercially available workstation. Methods: A total of 319 CAD patients who underwent CCTA, invasive coronary angiography, and FFR measurement were included. The primary outcome was the accuracy of CT-FFR for defining myocardial ischemia evaluated with an invasive FFR as a reference. The presence of ischemia was defined as FFR ≤0.80. Anatomical obstructive stenosis was defined as diameter stenosis on CCTA ≥50%, and the diagnostic performance of CT-FFR and CCTA stenosis for ischemia was compared. Results: Among participants (mean age 64.7±9.4 years, male 77.7%), mean FFR was 0.82±0.10, and 126 (39.5%) patients had an invasive FFR value of ≤0.80. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR were 80.6% (95% confidence interval [CI], 80.5-80.7%), 88.1% (95% CI, 82.4-93.7%), 75.6% (95% CI, 69.6-81.7%), 70.3% (95% CI, 63.1-77.4%), and 90.7% (95% CI, 86.2-95.2%), respectively. CT-FFR had higher diagnostic accuracy (80.6% vs. 59.1%, p<0.001) and discriminant ability (area under the curve from receiver operating characteristic curve 0.86 vs. 0.64, p<0.001), compared with anatomical obstructive stenosis on CCTA. Conclusions: This novel CT-FFR obtained from an on-site workstation demonstrated clinically acceptable diagnostic performance and provided better diagnostic accuracy and discriminant ability for identifying hemodynamically significant lesions than CCTA alone.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.3
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• pp.163-175
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• 2011

Though polycyclic aromatic hydrocarbon compounds (PAHs) in marine sediment has been produced by many colleges and institution in Korea, it is difficult to compare PAHs data in a study area with those in other areas due to the lack of confidence for the quality of data from the other organization. Therefore, we suggested the protocol for PAHs analysis in marine sediment through examining the method of PAHs analysis described in over twenty scientific papers and reports. When a known amount of 23 PAHs were spiked into a sediment and anlyzed following this new protocol, very good recoveries were obtained. In addition, for college and institution with their own method to analyze PAHs can keep producing PAHs data without exchanging to this new PAHs protocol, the method to get a full confidence through the QA/QC for the PAHs data produced by these organization is included to the protocol.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.821-827
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• 2014

An isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) method has been developed and applied to the determination of arsenobetaine (AsB, ${(CH_3)_3}^+AsCH_2COO^-$) from oyster candidate certified reference material (CRM). The exact matching isotope dilution approach was adopted for accurate determination of AsB using $^{13}C_2$-labeled AsB as an internal standard. Efficiencies of different AsB extraction methods were evaluated using a codfish reference material and a simple sonication method was selected as the method of choice for the certification of the oyster candidate CRM. The hydrophilic interaction liquid chromatography (HILIC) combined with electrospray ionization tandem mass spectrometry (ESI/MS/MS) in selected reaction monitoring (SRM) mode was optimized for adequate chromatographic retention and robust quantification of AsB from codfish and oyster samples. By analyzing 12 subsamples taken from each 12 bottles systematically selected from the whole oyster CRM batch, the certified value of AsB was determined as $6.60mg{\cdot}kg^{-1}{\pm}0.31mg{\cdot}kg^{-1}$ and it showed excellent between-bottle homogeneity of less than 0.42%, which is represented by relative standard deviation of 12 bottles from the CRM batch. The major source of uncertainty was the certified value of the AsB standard solution.

• Archives of Pharmacal Research
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• v.23 no.2
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• pp.178-181
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• 2000

In order to study the simultaneous determination of (+)- and (-)-cetirizine in human urine we have developed a chiral separation method by HPLC. A chiral stationary phase of $\alpha$$_1$-acidglycoprotein, the AGP-CSP was used to separate the enantiomers. The pH of the phosphate buffer, as well as the content of the organic modifier in the mobile phase, markedly affected the chromatographic separation of (+)- and (-)-cetirizine. A mobile phase of 10 m㏖/1 phosphate buffer (pH 7.0)-acetonitrile (95 : 5, v/v) was used for the urine assays. Ultraviolet absorption was monitored at 230nm and roxatidine was employed as the internal standard for quantification. (+)-Cetirizine, (-)-cetirizine and the internal standard were eluted at retention times of 12, 16, and 32 mins, respectively. The detection limit for cetirizine enantiomers was 400 ng/$m\ell$ of urine. A pharmacokinetic study was conducted with the help of 5 healthy female volunteers who were administered with a single oral dose of racemic cetirizine (20 mg). The peak area ratios provided by the cetirizine enantiomers were linear(r>0.997) over a concentration range of 2.5-200 ${\mu}g/ml$. The peak of the excreted cetirizine enantiomers appeared in the urine sample during the period of 1-2 hrs following the administration of the oral dose. The excreted level of (+)-cetirizine was slightly higher than (-)-cetirizine but the difference was not statistically significant. However, this method appears to have applications for enantioselective pharmacokinetic studies of racemic drugs.

• The Korea Journal of Herbology
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• v.23 no.3
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• pp.27-32
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• 2008

Objectives : In this paper, we describe that $^1H-NMR$ spectroscopy may be superior to the conventional HPLC for the quantitative analysis of hesperidin from Citrus unshiu. Methods : $^1H-NMR$ spectra (400 MHz) were recorded in $DMSO-d_6$ using a Varian UNITY Inova AS 400 FT NMR spectrometer. One hundred milligram of powdered Citrus unshiu was weighed out and mixed with 1 ml of $DMSO-d_6$ with sonication for 30 min (room temperature). The extracts were filtrated through a 0.45 ${\mu}m$ PVDF filter and 0.5 ml of filtrated extract used for quantitative $^1H-NMR$ measurement (added 1 mg of dimethyl terephthalate as internal standard). The quantity of hesperidin was calculated by the ratio of the intensity of the compound to the known amount of internal standard. For HPLC analysis, the half gram of plant material was extracted with 60 ml of MeOH for 2 hours. The extracts were made 100 ml volume and analyzed by a Waters HPLC system using a YMC ODS column. The total flow rate was 1.0 ml/min with a sample volume 10 ${\mu}l$ and UV detection at 280nm. Results : The contents of hesperidin in Citrus unshiu was determined $5.33{\pm}0.06$% in the quantitative $^1H-NMR$ method and $5.15{\pm}0.12%$ in HPLC method. Using the quantitative $^1H-NMR$ the contents of hesperidin can be determined in much shorter time than the conventional HPLC measurements. Conclusions : From those results, the advantages of quantitative $^1H-NMR$ analysis are that can be analyzed to identify and quantify, and no reference compounds required for calibration curve. Besides, it allows rapid and simple quantification for hesperidin with an analysis time for only 10 min without any pre-purification steps.

• The Journal of Internal Korean Medicine
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• v.34 no.3
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• pp.278-288
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• 2013

Objectives : Methicillin-resistant Staphylococcus aureus (MRSA) has a cephalosporin and beta-lactam antibiotic-resistant strains. MRSA is one of the major pathogens causing hospital infection and the isolation ratio of MRSA has gradually increased. Consequently, increased resistance to antibiotics is causing serious problems in the world. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases. Methods : The antibacterial activities of Ipyo-san were evaluated against 2 strains of MRSA and 1 standard Methicillin-susceptible staphylococcus aureus (MSSA) strain by using the disc diffusion method, minimal inhibitory concentrations (MIC) assay, colorimetric assay using MTT test, checkerboard dilution test and time-kill assay performed under dark. Results : The MIC of Ipyo-san water extract against S. aureus strains ranged from 1000 to $2,000{\mu}g/ml$, so we confirmed that it had a strong antibacterial effect. Also, the combinations of Ipyo-san water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. We suggest that Ipyo-san water extract against MRSA has antibacterial activity so it has potential as alternatives to antibiotic agents. For the combination test, we used Triton X-100 (TX) and DCCD for measurement of membrane permeability and inhibitor of ATPase. As a result, antimicrobial activity of Ipyo-san water extract was affected by the cell membrane. Conclusions : We suggest that the Ipyo-san water extract lead the treatment of bacterial infection to solve the resistance and remaining side-effect problems that are the major weak points of traditional antibiotics.