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A fast and gradient ion-pair chromatographic method was developed for determination of five homologue imidazolium ionic liquid cations using a silica-based monolithic column and ultraviolet detection. Chromatographic separations were performed on a Chromolith Speed ROD RP-18e column with 1-heptanesulfonic acid sodium aqueous solution (pH adjusted by citric acid)–acetonitrile as the mobile phase. The effects of chromatographic column, mobile phase, flow rate, and column temperature on retention and separation of the cations were investigated. The retention rules of homologue imidazolium cations were discussed. The results showed that the analysis time could be significantly reduced owing to the application of monolithic column. Simultaneous and fast separation of five imidazolium cations was achieved under the optimum chromatographic conditions. Detection limits (S/N = 3) for the cations were 0.26–1.61 mg/L. Relative standard deviations (n = 5) for peak areas and retention times were less than 0.8%. The method has been successfully applied to the determination of two ionic liquids synthesized by chemistry lab. Recoveries of the cations after spiking were 96.8–101.9%. [ABSTRACT FROM AUTHOR]

A high-throughput, high performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed phase monolithic silica column Chromolith Performance 18e (100 mm×4.6 mm I.D.). The mobile phase consisted of acetonitrile:phosphate buffer (50:50 v/v , pH 3.0) at a flow rate of 4.0 mL/min. The photodiode array detector was set at 235 nm. The developed method showed a good linear relationship in the concentration range from 1.0 to 40.0 µg/mL with a correlation coefficient of 0.999. The limit of detection and limit of quantification were 0.97 µg/mL and 3.52 µg/mL, respectively. [ABSTRACT FROM AUTHOR]