Reliable Reversed-phase High-performance Liquid Chromatography Research Articles

Standardisation of Artemisia annua using Reversed Phase High Performance Liquid Chromatography (RP-HPLC).

Artemisia annua L is a traditional Chinese medicine for the treatment of many disorders including drug resistant malaria. The active constituent against malaria, artemisinin, has been isolated and characterized by Chinese scientists. Artemisia annua is now being grown in malaria endemic countries like Nigeria. The aim of the present study was to quantify artemisinin content of Nigerian Grown Artemisia annua using a fast and reliable Reversed Phase-High Performance Liquid Chromatography (RP-HPLC) analytical technique since artemisinin content is affected by geographical and seasonal variations. HPLC conditions used for determination of the artemisinin content were established as follows; phenomenex luna column (5 μm; 250 mm × 4.6 mm) was employed with the mobile phase of acetic acid (% 0.1 v/v): acetonitrile: H2O (70:30) mixture at the flow rate of 1 ml/min. The good linearity of artemisinin was observed with y = 11714 × (r2 = 0.9989). Artemisinin was detected in our sample and was calculated to be 1.0975%.

A high-performance liquid chromatographic method for determination of the niguldipine analogue DHP-014

A simple and reliable reversed-phase high-performance liquid chromatography method was developed and validated for the determination of DHP-014, a niguldipine analogue with potent P-glycoprotein inhibitory and negligible calcium channel blocking properties, in rat plasma. DHP-014 and niguldipine hydrochloride (the internal standard) were extracted from rat plasma by liquid extraction using hexane. DHP-014 was then separated by HPLC on a C18 column and quantified by ultraviolet detection at 238 nm. The mobile phase consisted of acetonitrile-aqueous 5 mM phosphate buffer (65:35, v/v) containing 0.4% (v/v) triethylamine adjusted to pH 7.0. The mean extraction efficiency of DHP-014 was 109.0 +/- 12.9, 97.7 +/- 8.0 and 102.9 +/- 7.5% for DHP-014 concentrations of 10, 50 and 100 nM, respectively (n = 5). The method was linear over the concentration range 2.5-200 nM with a regression coefficient of 0.998. The limit of detection of DHP-014 in rat plasma was 1.0 nM. The intra- and inter-day coefficients of variation for DHP-014 in rat plasma were 4.7-7.9 and 6.9-9.9%, respectively. The intra- and inter-day accuracy was 98.2-99.5 and 97.9-103%, respectively. The bioanalytical technique was used to determine DHP-014 in plasma samples in a pharmacokinetic study of DHP-014 administered to female Sprague-Dawley rats.

Analysis of biogenic thiols in natural water samples by high-performance liquid chromatographic separation and fluorescence detection with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F)

A sensitive and reliable reversed-phase high-performance liquid chromatography (HPLC) method has been developed to analyze naturally occurring low-molecular weight thiols using pre-column derivatization with ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F) and fluorescence detection in a gradient elution. The derivatization procedure and separation conditions were optimized by careful control of the reaction conditions in terms of time, temperature, pH and reducing agent. A linear calibration in the nM range was obtained for all the standard compounds, allowing measurement of thiols in natural water samples. Results show that the reducing agent tri- n-butylphosphine (TBP) not only acts as an anti-oxidant/disulfide cleaving agent, but also enables the SBD-F to react with thiols complexed by soft metals. This is the first study reported using the SBD-F labeling technique to measure phytochelatin concentrations. The methodology has been successfully applied to estuarine water samples from Galveston Bay.

Quantitative determination of maitenin and 22β-hydroxymaitenin in callus ofMaytenus aquifolium (celastraceae) by reverse phase high performance liquid chromatography

Explants of Maytenus aquifolium were induced to form callus and, subsequently, suspension cultures. The isolation of natural products from callus led to the identification of the cytotoxic triterpene quinonemethides, maitenin (1) and 22β-hydroxymaitenin (2). A rapid, sensitive and reliable reversed-phase high-performance liquid chromatography method was developed using a C18 column and isocratic elution for the determination of 1 and 2. The elaborated method gave well-resolved peaks for these compounds with good detection response and linearity in the range of 0.08–72.0 μg. The quantification of 1 and 2 was performed by an external standard method. © 1998 John Wiley & Sons, Ltd.