• Journal of computational fluids engineering
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• v.19 no.4
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• pp.68-74
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• 2014

This computational study features the transient compressible and inviscid flow analysis on a metallic plasma discharge from the opposing composite electrodes which is subjected to pulsed electric power. The computations have been performed using the flux corrected transport algorithm on the axisymmetric two-dimensional domain of electrode gap and outer space along with the calculation of plasma compositions and thermophysical properties such as plasma electrical conductivity. The mass ablation from aluminum electrode surfaces are modeled with radiative flux from plasma column experiencing intense Joule heating. The computational results shows the highly ionized and highly under-expanded supersonic plasma discharge with strong shock structure of Mach disk and blast wave propagation, which is very similar to muzzle blast or axial plasma jet flows. Also, the geometrical effects of composite electrodes are investigated to compare the amount of mass ablation and penetration depth of plasma discharge.

• Archives of Pharmacal Research
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• v.29 no.4
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• pp.339-342
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• 2006

A simple high performance liquid chromatographic (HPLC) method was developed for the determination of tolperisone in human plasma. Tolperisone and internal standard (chlorphenesin) were isolated from 1 mL of plasma using 8 mL of dichlormethane. The organic phase was collected and evaporated under nitrogen gas. The residue was then reconstituted with 300 mL aliquot of mobile phase and a 100 mL aliquot was injected onto the $C_{18}$ reverse-phased column. The mobile phase, $45\%$ methanol containing $1\%$ glacial acetic acid and $0.05\%$ 1-hexanesulfonic acid was run at a flow rate of 1 mL/min. The column effluent was monitored using UV detector at 260 nm. The retention times for tolperisone and the internal standard were approximately 7.1 and 8.4 min, respectively. The standard curve was linear with minimal intra-day and inter-day variability. The quantification limit of tolperisone in human plasma was 10 ng/ mL. The proposed method has been applied to the determination of pharmacokinetic profile of tolperisone in Koreans. The T max of tolperisone in Koreans $(0.94{\pm}0.42\;h)$ was not significantly differ from that reported in Europeans (0.5-1 h), but the mean half-life in Koreans $(1.14{\pm}0.27\;h)$ was shorter than that in Europeans $(2.56{\pm}0.2\;h)$. The proposed HPLC method is simple, accurate, reproducible and suitable for pharmacokinetic study of tolperisone.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.276.1-276.1
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• 2003

This study describes a simple and sensitive semi-micro HPLC method with UV detection and direct deproteinization. The plasma protein was precipitated using perchloric acid (60％) and the supernatant was directly injected onto the semi-micro HPLC system. The separation was achieved on a C18 (25 mm ${\times}$ 2.0 mm I.D) analytical column with a mobile phase of sodium acetate buffer (pH 3.5, 50 mmol) - acetonitrile (60:40, V/V). (omitted)

• Archives of Pharmacal Research
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• v.22 no.1
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• pp.86-88
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• 1999

An advance d and sensitive high-performance liquid chromatographic (HPLC) method for determination of omeparzole in human plasma has been developed. After omeprazole was extracted from plasma with diethylether, the organic phase was transferred to another tube and trapped back with 0.1 N NaOH solution. The alkaline aqueous layer was injected into a reversed-phase C8 column. Lansoprazole was used as an internal standard. The mobile phase consisted of 30% of acetonitrile and 70% of 0.2 M $ KH_{2}PO_{4}$, pH 7.0. Recoveries of the analytes and internal standard were >75.48%. The coefficients of variation of intra- and inter-day assay were <5.78 and 4.59% for plasma samples. The detection limit in plasma was 2 ng/ml. The clinical applicability of this assay method was evaluated by determining plasma concentration-time courses of the respective analytes in 24 healthy volunteers after oral administration 40 mg of omeprazole. The present assay is considered to be simple, accurate, economical and suitable for the study of the kinetic disposition of omeprazole in the body.

• Archives of Pharmacal Research
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• v.21 no.6
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• pp.651-656
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• 1998

A sensitive high-performance liquid chromatographic (HPLC) method for the determination of aloesin in plasma was developed. After solid-phase extraction from plasma and derivatization of aloesin and compound AD-1, which was prepared from aloesin as a internal standard, with 9-anthroylnitrile in the presence of quinuclidine, the derivatives were separated on a Inertsil ODS-3 column using acetonitrile/methanol/water (3:1:6) as a mobile phase, and detected fluorimetrically at 460nm with excitation at 360nm. The detection limit of aloesin was 3.2ng/ml in plasma (S/N=3).

• Korean Journal of Clinical Pharmacy
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• v.10 no.1
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• pp.38-41
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• 2000

A high-performance liquid chromatographic method with fluorometric detection was evaluated for analysis of ofloxacin in plasma. Biological fluids (plasma, $200\;{\mu}L$) were prepared for assay by protein precipitation with chlorofurm. The detection of ofloxacin and triamterene as an internal standard were performed at 358 nm for excitation and 495 nm for emission. The HPLC separation was carried out on Ultrasphere ODS column (4.6 mm${\times}25\;cm,\;5\;{\mu} m$) with acetonitrile $(45\%)$-phosphoric acid $(1.5\%)\;containing\;0.3\%$ sodium laurylsulfate as the mobile phase. The flow-rate was 1.0 mL/min. The calibration graphs were linear from 3.0 to 80 ng/mL with r=0.998. The minimal detectable concentration in plasma was 1.5 ng/mL. The proposed technique is reproducible, selective, reliable and sensitive.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.220.1-220.1
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• 2003

A sensitive and selective liquid chromatographic method for the determination of carvedilol in human plasma was developed and validated. Analytes were separated on a XTerra C18 column with acetonitrile-methanol-30 mM KH$_2$PO$_4$ (pH 2.5) (20 : 20 : 60, v/v/v), as mobile phase. One mL plasma were pipetted into glass tubes and spiked with 0.05 mL of internal standard solution. After adding 7 mL of diethyl ether, the plasma sample was then shacked for 15 min. A centrifuged upper layer was back-extracted with 150 uL of 0.05 M sulfuric acid. (omitted)

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.36-44
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• 2010

The ambipolar diffusion equation has been solved in a fine-tube lamp of a few mm in diameter. In the diffusion of radial direction, the plasma diffuses and vanishes away at the glass wall by recombination with the characteristic time of plasma loss is given by $\tau_r\;=\;(r_0/2.4)^2/D_a$. With the radius $r_0{\sim}1\;mm$ and the ambipolar diffusion coefficient $D_a{\sim}0.01\;m^2/s$, the vanishing time is calculated $\tau_r{\sim}10\;{\mu}s$ which corresponds to the least value of frequency 30 kHz for the sustaining the plasma in the operation of high voltage AC-power. In the diffusion of longitudinal z-direction, a high density plasma generated at the area of a high voltage electrode, diffuses into the positive column with the characteristic time $\tau_z{\sim}0.1\;s$. The plasma diffusion velocity at the boundary of high density plasma is $u_D{\sim}10^2\;m/s$ at the time $t{\sim}10^{-6}$ s and the diffusion velocity becomes slow as $u_D{\sim}1\;m/s$ at $t{\sim}10^{-3}\;s$. Therefore, for the long lamp of 1 m, it takes about several seconds for the high density plasma at the area of electrode to diffuse through the whole positive column space.

• Mass Spectrometry Letters
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• v.2 no.4
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• pp.92-95
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• 2011

Pyrophosphates are the key intermediates in the biosynthesis of isoprenoids, and their concentrations could reveal the benefits of statins in cardiovascular diseases. Quantitative analysis of five pyrophosphates, including isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP), was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in negative ionization mode. After dilution with methanol, samples were separated on a 3 ${\mu}m$ particle multi-modal $C_{18}$ column ($50{\times}2$ mm) and quantified within 10 min. The gradient elution consists of 10 mM ammonium bicarbonate and 0.5% triethylamine (TEA) in water and 0.1% TEA in 80% acetonitrile was used at the flow rate of 0.4 mL/min. Overall recoveries were 51.4-106.6%, while the limit of quantification was 0.05 ${\mu}g$/mL for GPP and FPP and 0.1 ${\mu}g$/mL for IPP, DMAPP, and GGPP. The precision (% CV) and accuracy (% bias) of the assay were 1.9-12.3% and 89.6-111.8%, respectively, in 0.05-10 ${\mu}g$/mL calibration ranges ($R^2$ > 0.993). The devised LC-MS/MS technique with the multi-modal $C_{18}$ column can be used to estimate the biological activity of pyrophosphates in plasma and may be applicable to cardiovascular events with cholesterol metabolism as well as the drug efficacy of statins.

• YAKHAK HOEJI
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• v.42 no.5
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• pp.473-479
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• 1998

Lovastatin (LOVA), a fungal metabolite isolated from cultures of Aspergillus terreus, is a competitive HMG-CoA reductase inhibitor used for the treatment of primary hyper cholesterolemia, and has also been shown to suppress growth in a variety of non-glioma tumor cell lines. A sensitive reversed-phase high-perfonnance liquid chromatographic method with ultraviolet (UV) absorbance detection has been developed to quantitate LOVA in human plasma and urine samples using liquid-liquid extraction procedure. Baseline separation of LOVA and internal standard, simvastatin was achieved on a Novapak $C_{18}$ analytical column with a mobile phase containing 0.025M $NaH_2PO_4$: CAN (35:65, v/v%), adjusted pH to 4.5. The flow rate was set at 1.5ml/min, and the column effluent was monitored by a UV detection at 238nm. The limit of quantification was determined to be 0.5${\mu}$g/ml while extraction efficiency of LOVA ranged from 73.4-82.9% at LOVA concentrations of 0.5 to 10${\mu}$g/ml. Good linearity with correlation coefficients greater than 0.999 was obtained in the range of LOVA concentrations from 0.5 to 10${\mu}$g/ml. The accuracy and the precision were proven excellent with relative standard deviation (RSD, %) and relative error (RE, %) of less than 4.2 and 4.0, respectively. Intraday precision, evaluated at five LOVA concentrations (0.5, 1, 2, 5, 10${\mu}$g/ml) and expressed as RSD ranged from 0-1.82% while the interday precision at the same concentrations ranged from 0.7-10.5%. The analytical method described was then successfully employed for the determination of LOVA concentrations in plasma samples obtained during a phase II clinical trial using high doses of LOVA (30-40mg/kg/day). This method could be further utilized for the ongoing pharmacolkinetic studies and therapeutic drug monitoring of the high-dose LOVA therapy in adenocarcinoma patients.