Determination of drugs in pharmaceuticals and pesticides by micellar liquid chromatography

Abstract

1973-1982Micellar liquid chromatography (MLC) is a reversed-phase liquid chromatography technique that uses surfactants as components in the mobile phase at a concentration higher than the critical micellar concentration. Chromatographic procedures using micellar mobile phases have been reported for the analysis of pharmaceutical formulations commercialised as tablets, pills, capsules, drops, solutions, syrups, gels, suspension s, enemas, sprays, oily injections, ointment and creams. The compounds studied in this work include benzodiazepines, phenethylamines, antihistamines, vitamins, and corticosteroids formulations, and carbamates pesticides. These compounds are usually determined by reversed-phase liquid chromatography (RPLC) with aqueous-organic mobile phases. MLC has the advantages of avoiding sample pretreatment, analysis time, accuracy, reproducibility, toxicity, environmental impact and low cost of the procedures respect to the classical RPLC. Some features of the analytical procedures arc examined including modelling of the retention behaviour of solutes, selection of column, surfactant and alcohol, study of hydrophobicity, and screening analysis. Usually, optimum pH is fixed at 7, but pH 3 is used in the case of the most hydrophilic analytes. C18 columns are often used, but C8 columns allow the obtention of rapid procedures with the lowest analysis time. Pentanol, butanol or propanol are used in function of the hydrophobicity of the substrate. Finally, optimised procedures have been applied for the determination of the substances in pharmaceuticals and in biological samples, including serum and urine