• 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.284.2-284.2
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• 2003

Using a column-switching technique. highly sensitive and selective semi-micro high-performance liquid chromatographic (HPLC) method has been developed for the determination of baclofen in human plasma. Following precipitation of plasma sample containing baclofen with zinc sulfate-acetonitrile, samples were directly injected on to the system. (omitted)

• 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.

• Archives of Pharmacal Research
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• 제17권5호
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• pp.360-363
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• 1994

Column--swtiching technique with a reversed-phase high performance liquid chromatographic method has been developed for the routine analysis of radioiodinated insulin and its degadation products in biological fluids. The diluted biological samples were loaded onto a precolumn packed with LiChrosorb RP-8 $(25-40{\;}{\mu}m)$ using 0.1% trifuoroacetic acid (TFA) in water as a washing solvent. After valve switching, the concentrated insulins were eluted in the back-flush mode and separated by a W-Porex $C_{18}$ column with a gradient of 0.1% TFA in water and 0.1% TFA in acetonitrile as the mobile phase. The method showed good precision, accuracy and speed with the detection limit of 20 pg/ml. Total analysis time per sample was about 40 min and the coefficients of variation were less than 8, 2%.

• Archives of Pharmacal Research
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• 제21권2호
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• pp.212-216
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• 1998

A coupled achiral-chiral high-performance liquid chromatographic system has been developed for the determination of the enantiomers of salmeterol, S-(+)-salmeterol and R-(-)-salmeterol in urine. THe salmeterol was separated from the interfering components in urine and quantified on the silica column, and the enantiomeric composition was determined on a Sumichiral OA-4700 chiral stationary phase. The two columns were connected by a switching valve equipped with a silica precolumn. The two columns wer connected by a switching valve equipped with a silica precolumn. The precolumn was used to concentrate the salmeterol in the eluent from the achiral column before backflushing onto the chiral phase. The coupled system was validated.

• Bulletin of the Korean Chemical Society
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• 제34권12호
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• pp.3629-3634
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• 2013

In this study, an improved method for the quantitative analysis of ginkgolic acids (GAs) in Ginkgo biloba leaf extract was developed. The samples were extracted with a mixture of chloroform and 50 % ethanol, after which the chloroform extract was dried and reconstituted in methanol. GAs with 13:0, 15:1, and 17:1 in the extract were successfully separated within 40 min and determined with high throughput performance using an online column-switching HPLC method using an SP column C8 SG80 ($4.6{\times}150mm$, $5{\mu}m$) and a Cadenza 5CD C18 column ($4.6{\times}150mm$, $3{\mu}m$). The developed HPLC method was validated for Ginkgo biloba leaf extract. The validation parameters were specificity, linearity, precision, accuracy, and limits of detection and quantitation (LODs and LOQs, respectively). It was found that all of the calibration curves showed good linearity ($r^2$ > 0.9993) within the tested ranges. The LODs and LOQs were all lower than $0.04{\mu}g/mL$. The established method was found to be simple, rapid, and high throughput for the quantitative analysis of GAs in ten commercial Ginkgo biloba leaf extract and dietary supplements. The samples were also analyzed in LC-electrospray ionization (ESI) tandem mass spectrometry (MS/MS) - multiple-ion reaction monitoring (MRM) mode to confirm the identification results that were obtained by the column switching HPLC-DAD method. The developed method is considered to be suitable for the routine quality control and safety assurance of Ginkgo biloba leaf extract.

• 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/$m\ell$ .

• 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.281.1-281.1
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• 2003

Purpose. The purpose of this study was to develop and validate sensitive and specific analytical method for determinination of simvastatin in human plasma by the column-switching high-performance liquid chromatography (HPLC) system with UV detection. Methods. Simvastatin and internal standard were extracted into diethyl ether from plasma. (omitted)

• 대한화학회지
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• 제39권4호
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• pp.257-265
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• 1995

시중에 시판되고 있는 우유를 전처리하여 이 우유에 포함된 유리 아미노산을 dansyl-chloride로 유도체화시켜 C-18 컬럼을 이용한 역상 LC법으로 분리한 다음 표준물 첨가법으로 정량했다. 미량의 D-아미노산의 분리에서는 LC의 Column-Switching System을 이용하였으며 비키랄 컬럼을 통과한 단실 D/L-아미노산에 $Cu(N-benzyl-L-proline)_2$를 이동상에 첨가한 키랄 분리를 수행하여 L-아미노산에서 D-아미노산을 분리 정량했다. 이 방법은 우유시료 중에 존재하는 16가지 아미노산의 정량이 가능하며 이중에 12가지의 D-아미노산이 column switching 방법을 통한 키랄 분리로 정량이 가능하다. 우유 100 mL에 총 유리 아미노선이 41.00 mg 포함되어 있음을 확인했으며, D-아미노산은 D-glutamic acid가 2.05%, D-alanine 2.93%만이 포함되어 있음을 확인했다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2002년도 창립10주년기념 및 국립독성연구원 의약품동등성평가부서 신설기념 국재학술대회:생물학적 동등성과 의약품 개발 전략을 위한 국제심포지움
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• pp.216-216
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• 2002

• 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.