The retention time of 22 barbituric acid derivatives was measured on a narrow-bore porous graphitized carbon (PGC) column using water-dioxane mixtures as mobile phases. The capacity factor (k), theoretical plate number (N), and asymmetry factor (AF) were calculated for each solute in each mobile phase. The relationships between chromatographic characteristics and physicochemical parameters of s...

Quantitative analysis of triacylglycerols (TGs) in plant oils and animal fats by normalization of peak areas can lead to erroneous results due to the large response differences with common HPLC detectors between the various TGs. The charged aerosol detector (CAD), that generates an almost universal response for non-volatile compounds, was combined with non-aqueous reversed-phase HPLC (NARP-HPLC...

A preliminary gradient separation in reversed-phase liquid chromatography of a mixture of 25 solutes (diuretics, probenecide, and atenolol) is carried out using several C18 columns and an aqueous phosphoric acid solution (pH 3.2)-acetonitrile mobile phase as a control. Using this separation, the chromatographic behavior of these solutes is studied using 11 water-soluble primary, secondary, and ...

A continuous flow liquid membrane extraction (CFLME)–C18 precolumn-liquid chromatography system was developed for preconcentration and determination of chlorinated phenols (CPs). After preconcentration by CFLME, which is based on the combination of continuous flow liquid–liquid extraction and supported liquid membrane, CPs were enriched in 960 l of 0.5 mol l−1 NaOH used as acceptor. This accept...

Capillary electrochromatographic (CEC) separations of plant sterols and related esters were evaluated under various conditions. Stationary phases included octadecylsilica (C18) and triacontylsilica (C30). Mobile phases comprised acetonitrile, tetrahydrofuran, and tris(hydroxymethyl) aminomethane buffers in aqueous or non-aqueous systems. Apart from notable differences in component resolution, b...

The retention time of 23 barbituric acid derivatives was determined on an narrow-bore porous graphitized carbon (PGC) column employing water-dioxane mixtures as mobile phases. The retention factor (k), theoretical plate number (N), and asymmetry factor (AF) were computed for each analyte in each mobile phase. Quantitative structure-retention relationship (QSRR) calculations using stepwise regre...

A simple, selective, accurate high performance liquid chromatographic method was developed and validated for an analysis of Halobetasol Propionate and p-Chlorocresol in pharmaceutical formulations. Chromatographic separation achieved by gradient programme on a C18 column (Waters Novapak C-18, 250 x 4.6mm, 4μm column) utilizing a mobile phases of A (pH 2.5 phosphate buffer) and B (mixture of buf...

A new ZORBAX stationary phase, Agilent ZORBAX Eclipse Plus Phenyl-Hexyl, separated five estrogen type steroids better than a C18 and better than three other phenyl columns under identical conditions, due to its unique selectivity for analytes containing phenyl groups. The comparisons support selectivity as the most important factor to optimize resolution, to separate peaks completely. Selectivi...

We describe a simple, reproducible liquid-chromatographic method for determination of esmolol (a short-acting beta blocker) and its major metabolite in human urine. Esmolol is extracted from urine at a pH of 8.4 into methylene chloride; the more polar metabolite remains in the aqueous phase. We then measure esmolol with a muBondapak C18 column and measure ultraviolet absorbance at 229 nm; the m...