Microemulsion electrokinetic chromatography for separation and analysis of avermectin macrocyclic lactones

Abstract

Microemulsion electrokinetic chromatography (MEEKC) was developed for quantitative analysis of avermectins, such as abamectin, doramectin and ivermectin, in commercial formulations, using the microemulsion buffer containing a 50 mm phosphate buffer at pH 2.5, 1.1 % v/v n-octane as oil droplets, 180 mM sodium dodecyl sulfate as surfactant, 890 mM 1-butanol as co-surfactant and 30 % v/v ethanol as organic co-solvent; applied voltage of -15 kV; and separation temperature at 25 °C. Achieved baseline resolution up to 4.9 was obtained with analysis time within 25 min. High accuracy and precision of the method were obtained. The developed MEEKC method was used for quantitative analysis of avermectins in commercial formulations. The contents of avermectins in commercial formulations determined by MEEKC were found to be insignificantly different with those determined by high performance liquid chromatography (HPLC). Therefore, MEEKC can be used as an alternative method to HPLC for quantitative determination of avermectins with shorter analysis time and lower amount of organic solvent