• Journal of Pharmaceutical Investigation
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• 제30권1호
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• pp.51-54
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• 2000

A column-switching high performance liquid chromatographic method has been developed for the determination of a fluconazole in human plasma. Each plasma sample was centrifuged for 10 min at 5000 g. After an aliqout of the supernatant was taken to nylon microcentrifuge filter, these samples were centrifuged for 10 min at 5000 g. An aliqout of the supernatant was injected directly onto the HPLC column. Deionized water was run for 2 min at a flow rate of 1.0 ml/min to retain fluconazole in an extration column, while proteins and endogenous interferences were eluted to the waste. The analyte was then back-flushed onto an analytical column, $C_{18}$ reversed-phase column. The mobile phase for analytical column, 0.01 M sodium acetate (pH 5.0)-methanol (65:35, v/v), was run at a flow rate of 1.0 ml/min. The column effluent was monitored by ultraviolet detection at 261 nm. The retention time for fluconazole was 11.76 min in human plasma. The detection limit for fluconazole in human plasma was $0.2\;{\mu}g/ml$. No interference from endogenous substances was observed.

• 분석과학
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• 제28권2호
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• pp.125-131
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• 2015

사람혈장 중 베타투 수용체 작용약 테르부탈린의 정량법을 개발하고 밸리데이션을 실시하였다. 혈장시료를 Sep-pak 실리카를 이용하여 고상추출한 후 HPLC로 측정하였다. C18 칼럼을 사용하여 혈장 중의 방해물질로부터 테르부탈린 분획을 분리하여 실리카칼럼으로 보내어 테르부탈린과 내부표준물질을 분리 정량하였다. 두 칼럼은 짧은 실리카 전칼럼이 달린 절환밸부로 연결하여 사용하였다. C18 칼럼의 이동상에 녹아있는 테르부탈린의 분획은 전칼럼에서 농축되어 실리카칼럼으로 보내지고 형광 여기파장 276 nm와 들뜸파장 306 nm로 측정하였다. 이 분석법은 여섯 명의 혈장에서 특이성이 있음을 확인하였다. 혈장 중 테르부탈린 0.4-20.0 ng/mL 농도범위에서 상관계수 0.9999로 양호한 직선성을 나타내었다. 정량한계농도는 0.4 ng/mL 농도로 정밀도가 10.1% 를 나타내었다.

• Archives of Pharmacal Research
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• 제23권5호
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• pp.441-445
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• 2000

Achiral-chiral column switching HPLC assay was developed to allow the separation and quantification of the enantiomers of terbutaline in human plasma by means of fluorescence detection. Plasma samples were prepared by solid-phase extraction with sep-pak silica, followed by HPLC assay. The enantiomers of terbutaline and the internal standard were separated from the biological matrix on a silica column, and the two enantiomers were resolved and quantified on a Sumichiral OA-4900 column. The two columns were connected by a switching valve equipped with silica trap column, The trap column was used to concentrate the terbutaline in the eluent from the achiral column before back flushing onto the chiral phase. For each enantiomers, the assay was linear between 2.5-125 ng/$m\ell$ (r=0.9999) and detection limit was 1.0 ng/$m\ell$ .

• 한국진공학회지
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• 제21권6호
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• pp.312-321
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• 2012

한 쌍의 대기압 플라즈마 제트 장치의 전극에 인가하는 교류 전압의 극성에 따라서 발생되는 플라즈마 칼럼의 전위를 고전압 프로브를 사용하여 계측하였다. 고전압이 인가되는 플라즈마 제트 장치에서 발생되는 플라즈마 칼럼은 고전압 인가측의 전위는 높고 플라즈마 칼럼을 따라서 선형적으로 전위가 감소한다. 이러한 플라즈마 칼럼은 단위 길이당 저항이 수 $M{\Omega}/m$에서 수십 $M{\Omega}/m$의 저항체이다. 한 쌍의 플라즈마 제트 장치의 전극에 극성이 다른 전압으로 발생되는 플라즈마 전위의 극성은 인가전압의 극성과 동일하다. 따라서 서로 다른 극성의 전압을 인가한 한 쌍의 플라즈마 제트 장치에서 방출되는 플라즈마의 대기 중의 병합점에서 상호 인력이 작용하며, 병합점의 전위는 수십 V로 낮다. 동일한 극성의 전압을 인가하여 방출되는 한 쌍의 플라즈마 제트는 상호 동일한 극성의 전위에 의하여 상호 척력이 작용하며, 병합점에서의 전위는 수백 V로 높다. 이러한 한 쌍의 플라즈마 제트에서 방출되는 플라즈마를 인체에 조사하는 경우는 전기적인 충격이나 열적인 손상은 플라즈마의 전위와 전류의 곱인 플라즈마 전력의 크기에 비례한다.

• Archives of Pharmacal Research
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• 제17권6호
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• pp.458-461
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• 1994

A new high-performance liquid chromatographic method with column switching has been onto a Bondapak phenyl/corsil $(37-50{\;}{\mu}m)$ precolumn and polar plasma components were washed with 0.06 M borate burffer. After valve switching, the concentrated drug were eluted in the back-flush mode and separated on a ${\mu}-Bondapak$ C18 column with acetonitrilke-phosphate buffer as the mobile phae. The method showed excellent precision, accuracy and speed with detection limit of $0.01{\;}{\mug}/ml^{-1}$. Total analysis time per smaple was less than 20 min and the coefficients of variation for intra and inter-assay were less than 5.635. This method has been successfully applied to plasma smaples from eats after oral administration of omeprazole.

• Archives of Pharmacal Research
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• 제24권3호
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• pp.207-210
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• 2001

A fully automated high performance liquid chromatography with column-switching was developed for the simultaneous determination of KR60436, a new reversible proton pump inhibitor, and its active metabolite O-Demethyl-KR60436 from rat plasma samples. Plasma sample (50$\mu$l) was directly introduced onto a Capcell Pak MF Ph-1 column ($10{\times}4$ mm I.D.) where primary separation was occurred to remove proteins and concentrate target Substances Using acetonitrile-Potassium Phosphate (PH 7, 0.1 M) (2 : 8, v/v). The drug molecules eluted from MF Ph-1 column were focused in an intermediate column ($10{\times}2$ I.D.) by the valve switching step. The substances enriched in intermediate column were eluted and separated on a Vydac 218MR53 column ($250{\times}3.2$ I.D.) using acetonitrilepotassium phosphate (pH 7, 0.02 M) (47:53, v/v) at a flow rate of 0.5 ml/min when the valve status was switched back to A position. The method showed excellent sensitivity (detection limit of 2 ng/ml) with small volume of samples ($50{\mu}$l), good precision and accuracy, and speed (total analysis time 24 min) without any loss in chromatographic efficiency. The response was linear ($r^2{\geq}0.797$) over the concentration range of 5-500 ng/ml.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.398.2-398.2
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• 2002

A column switching HPLC assay was developed to allow the separation and quantitation of cetirizine in human plasma by ultraviolet (UV) detection. Plasma samples were prepared by liquid-liquid extraction. After drying, the residue was reconstituted in 20 mM phosphate buffer (pH 2.8) containing 15% acetonitrile. The samples were initially injected onto a clean-up Capcell Pak MF C18 column. (50 mm $\times$ 4.6 mm I.D.), and the chromatographic region containing the peaks of interest was followed in an analytical C18 microcolumn (250 mm$\times$1.5 mm I. D.) via column switching device. (omitted)

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.59-63
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• 2003

Modal properties of guided waves along circular dispersive double negative (DNG) index metamaterial rod waveguides are numerically investigated. Identical forms of dispersive dielectric and magnetic material constants are used for simplicity. For degenerated azimuthally symmetric mode, a multimode region, a single mode region, a band gap region and a forbidden region are found which cannot be observed in the case of the conventional dielectric rod waveguide. As the normalized frequency goes down, discrete guided modes are continuously generated, which is a reverse property of conventional dielectric rod waveguide. Also, there are high-frequency cutoffs, which have been generally examined in dispersive circular geometries such as a plasma column or a plasma Goubau line. In the single mode region, both the low- and high-frequency cutoffs are existed where the propagation constants are continued between the guided oscillating and surface modes.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.278.2-278.2
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• 2003

A column-switching semi-micro HPLC method with fluorescence detection was developed for the direct analysis of rebamipide in human plasma. Plasma was filtered through a 0.45 $\mu\textrm{m}$ membrane filter and 5 ${\mu}\ell$ of the filtrate was directly injected onto the pre-column. After elution of the plasma proteins to waste, the retained rebamipide and internal standard(ofloxacin) were transferred to a C18 semi-microcolumn (5$\mu\textrm{m}$, 150 ${\times}$2.0mm) where they were separated using acetonitrile-1.4％ acetic acid (40:60, v/v) as mobile phase. (omitted)

• 분석과학
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• 제37권2호
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• pp.123-129
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• 2024

We present a rapid method for the determination of Cs, Sr, and Ba, heat generators found in highly active liquid wastes, by gas-pressurized extraction chromatography (GPEC) using a column containing a cation-exchange resin. GPEC is a microscale column chromatographic technique that uses a constant flow rate of solvent (0.07 mL/min) with pressurized nitrogen gas supplied through a valve. In particular, because this method uses a small sample volume (a few hundred microliters), it produces less chemical waste and allows for faster separation compared to traditional column chromatography. In this study, we evaluated the separation of Cs, Sr, and Ba using GPEC. The eluate from the column (GPEC or conventional column chromatography) was quantitatively analyzed using inductively coupled plasma-mass spectrometry to measure the column recovery and precision. The column reproducibility of the proposed GPEC system (RSDs of recoveries) ranged from 2.7 to 4.1 %, and the column recoveries for the three elements ranged from 72 to 98% when aqueous HCl was used as the eluent. The GPEC results are slightly different in efficiency and separation resolution compared to those of conventional column chromatography because of the differences in the eluent flow rate as well as the internal diameter and length of the column. However, the two methods had similar recoveries for Cs and Sr, and the precision of GPEC was improved by two-fold. Remarkably, the solvent volume required for GPEC analysis was five times lower than that of the conventional method, and the total analysis time was 11 times shorter.