• Bulletin of the Korean Chemical Society
• /
• 제19권5호
• /
• pp.524-526
• /
• 1998

A sensitive and specific method is described for the determination of midazolam in human plasma. The drug was extracted from 1 mL of carbonate buffered plasma (pH 9.6) with 8 mL of diethyl ether. Famprofazone was used as internal standard. The organic phase was evaporated to dryness. The residue was dissolved in methanol for the direct analysis by gas chromatograph-nitrogen phosphorus detector system. In the concentration range of 1-5000 ng/mL, the calibration curve was linear. The coefficients of variation from the precision test were <6% at the range of the concentration of 0.10-2.00 μg/mL and the detection limit for midazolam in 1 mL of plasma was o.5 ng. This assay is more sensitive, selective, simple and rapid than earlier methods. Plasma midazolam concentrations were determined by this method after administration of midazolam.

• Journal of Pharmaceutical Investigation
• /
• 제35권1호
• /
• pp.51-55
• /
• 2005

A high-performance liquid chromatographic method was employed for the determination of bumetanide in human plasma. After addition of internal standard (IS, naproxen) and acidification of the plasma with 1 M hydrochloric acid, the drug and IS were extracted into dichloromethane. The organic phase was back-extracted into 1 M sodium bicarbonate solution and 50 ${\mu}l$ of the aqueous phase was injected onto a reversed-phase C18 column with a mobile phase consisting of methanol: water: glacial acetic acid = 65 : 35 : 1. The samples were detected utilizing a fluorescence detector (excitation wavelength 235 nm, emission wavelength 405 nm). The method was specific and validated with a lower limit of 5 ng/mL. Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification. The applicability of the method was demonstrated by analysis of plasma after oral administration of a single 2 mg dose to 24 healthy subjects. From the plasma bumetanide concentration vs. time curves, the mean AUC was $246.5{\pm}73.8\;ng{\cdot}hr/mL$ and $C_{max}$ of $132.1{\pm}40.9$ ng/mL reached 1.2 hr after administration. The mean biological half-life of burnet ani de was $1.1{\pm}0.2$hr. Based on the results, this simple and validated assay method could readily be used in any pharmacokinetic or bioequivalence studies using humans.

• 한국임상약학회지
• /
• 제5권2호
• /
• pp.71-74
• /
• 1995

A high performance liquid chromatographic method has been developed for the simultaneous analysis of non-steroidal anti-inflammatory drugs in plasma. The simultaneous determination of ibuprofen, fenoprofen and ketoprofen is performed by RP-HPLC with UV detection. The chromatographic system consisted of Spherisorb octyl column$(5{\mu}m)$ ; the mobile phase was $acetonitrile\;-\;0.5\%$ phosphoric acid(55 : 45, v/v) and the detection wavelength was 230nm. Tolmetin was employed as an internal standard. The method described is rapid and simple with sensitivity limits of $2.0{\mu}g/ml$ ibuprofen, $0.5{\mu}g/ml$ fenoprofen and $0.3{\mu}g/ml$ ketoprofen and is suitable for routine clinical and pharmacokinetic studies.

• 한국분말재료학회지
• /
• 제14권6호
• /
• pp.405-409
• /
• 2007

The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

• Journal of Pharmaceutical Investigation
• /
• 제41권5호
• /
• pp.289-294
• /
• 2011

A rapid and specific high performance liquid chromatography-tandem mass (LC/MS/MS) method for the analysis of montelukast in human plasma has been developed and validated. After cold acetonitrile-induced precipitation of the plasma samples, montelukast and glipizide (internal standard, IS) were eluted on a reverse-phase $C_{18}$ column by isocratic mobile phase consisted of 10 mM ammonium formate buffer (adjusted to pH 3.5 with formic acid) and acetonitrile (3:97, v/v). Acquisition was performed with multiple reaction monitoring (MRM) mode by monitoring the transitions: m/z 587.2${\rightarrow}$ 423.2 for montelukast and m/z 446.0${\rightarrow}$321.2 for IS. Ranges of concentration for calibration curves (10-1000 ng/mL) showed correlation coefficients ($r^2$) were better than 0.9948. Precision of intra- and inter-day ranged from 3.70 to 11.68% and from 3.04 to 12.95%, accuracy of intra-day and inter-day ranged from 93.34 to 102.75% and from 100.79 to 107.63%, respectively. The described method provides a fast and sensitive analytical tool for determining montelukast levels in plasma, and was successfully applied to a pharmacokinetic study in 16 healthy human subjects after oral administration of 10mg tablet formulation of montelukast sodium under fasting conditions.

• Bulletin of the Korean Chemical Society
• /
• 제34권8호
• /
• pp.2425-2430
• /
• 2013

A simple, fast and robust analytical method was developed to determine imatinib in human plasma using liquid chromatography-tandem mass spectrometry with electrospray ionization in the positive ion mode. Imatinib and labeled internal standard were extracted from plasma with a simple protein precipitation. The chromatographic separation was performed using an isocratic elution of mobile phase involving 5.0 mM ammonium formate in water-5.0 mM ammonium formate in methanol (30:70, v/v) over 3.0 min on reversed-stationary phase. The detection was performed using a triple-quadrupole tandem mass spectrometer in multiple-reaction monitoring mode. The developed method was validated with lower limit of quantification of 10 ng/mL. The calibration curve was linear over 10-2000 ng/mL ($R^2$ > 0.99). The method validation parameters met the acceptance criteria. The spiked samples and standard solutions were stable under conditions for storage and handling. The reliable method was successfully applied to real sample analyses and thus a pharmacokinetic study in 27 healthy Korean male volunteers.

• Mass Spectrometry Letters
• /
• 제8권4호
• /
• pp.109-113
• /
• 2017

Single analytical procedure including extraction, liquid chromatography, and mass spectrometric analysis was evaluated for the simultaneous measurement of lysophospholipids (LPLs). LPLs, particularly, lysophosphatidic acids (LPA) and sphingosine 1-phosphate (S1P) are lipid messengers ubiquitously found in various biological matrix. The molecular species mediate important physiological roles in association with many diseases (e.g. cancer, inflammation, and neurodegenerative disease), which emphasize the significance of the simple and reliable analytical method for biomarker discovery and molecular mechanistic understanding. Thus, we developed analytical method mainly focusing on, but not limited by those lipid species S1P and LPA using reverse phase liquid chromatography-tandem mass spectrometry (RPLC-ESI-MS-MS). Extraction method was modified based on Folch method with optimally minimal level of ionization additive (ammonium formate 10 mM and formic acid). Reverse-phase liquid-chromatography was applied for chromatographical separation in combination with negative ionization mode electrospray-coupled Orbitrap mass spectrometry. The method validation was performed on human blood plasma in a non-targeted lipid profiling manner with full-scan MS mode and data-dependent MS/MS. The proposed method presented good inter-assay precision for primary targets, S1P and LPA. Subsequent analysis of other types of LPLs identified a broad range of lysophosphatidylcholines (LPCs) and lysophosphatidyl-ethanolamines (LPEs).

• Bulletin of the Korean Chemical Society
• /
• 제33권7호
• /
• pp.2163-2167
• /
• 2012

A rapid, specific, and reliable LC-MS/MS-based bioanalytical method was developed and validated in rat plasma for the simultaneous quantitation of amitriptyline and its metabolite nortriptyline. Chromatographic separation of these analytes was achieved on a Gemini C18 column ($50{\times}4.60mm$, $5{\mu}m$) using reversed-phase chromatography. The mobile phase was an isocratic solvent system consisting of 1% formic acid in water and methanol (10:90, v/v), at a flow rate of 0.2 mL/min. The analytical range was set as 0.1-500 ng/mL for amitriptyline and 0.08-500 ng/mL for nortriptyline using a $200{\mu}L$ plasma sample. The accuracy and precision of the assay were in accordance with FDA regulations for the validation of bioanalytical methods. The validated method was successfully applied to a pharmacokinetic study in six rats after oral administration of amitriptyline (15 mg/kg). This method allows laboratory scientists to rapidly determine amitriptyline and nortriptyline concentrations in plasma.

• Journal of Pharmaceutical Investigation
• /
• 제30권4호
• /
• pp.279-282
• /
• 2000

Simple and precise high-performance liquid chromatographic (HPLC) assay was developed and validated for the determination of a HMG-CoA reductase inhibitor, $lovastatin^{TM}$ and its active metabolite (mevinolinic acid) in human plasma. The method involved solid phase extraction of mevinolinic acid and internal standard using Sep-Pak Cartridge. Samples were analyzed by reversed-phase HPLC using $Capcell-Pak\;C_{18}$ column with ultraviolet detection at 238 nm. The quantitation limit of mevinolinic acid was 2 ng/ml and the calibration curve was linear over the range of 2-50 ng/ml $(r^2>0.999)$ with human plasma. The analyses of quality control samples indicated that the normal values could be predicted with an accuracy >97%. The intra- and inter-day coefficients of variation for the analyses were <10%. The average recoveries were similar (79%) for mevinolinic acid and methylmevinolinic acid. The method described has been successfully applied to the quantification of mevinolinic acid in about 1,000 human plasma samples over six-month period.

• 한국가스학회지
• /
• 제18권1호
• /
• pp.1-7
• /
• 2014

본 연구에서는 LPG자동차용 LPG 액상분사 인젝터의 분사구 앞에 장착할 수 있는 플라즈마 개질기의 개발을 진행하였다. 이 개질기는 플라즈마 방전이 발생하는 영역에 공기와 LPG 연료를 분사시켜 고분자 탄소연료를 열해리시키고 추가로 수소를 발생시키기 위한 목적으로 개발되었다. 인젝터와 플라즈마 발생부와의 거리와 기하학적인 방전길을 최적화하여 개질 반응이 일어나는 인젝터 개질기를 완성하였으며, 개질 결과 공급 전력 70~100W 일 때 HC은 전체 개질가스의 약 0.7% 이며, 수소는 1.2~1.5% 발생하였다.