Determination of purity and anionic exchange efficiency of amino acid ionic liquids synthesis by multiple-injection capillary zone electrophoresis

Abstract

The purity of ionic liquids (IL) is important for its performance, so the methods able to quantify low concentration impurities are necessaries. Therefore, this paper aims to determine the purity and the anionic exchange efficiency for the preparation of amino acids ionic liquids (AAIL). For this, a Multiple-Injection Capillary Zone Electrophoresis (MICZE) method with direct UV detection was developed and optimized for iodide (I−) determination as impurity of AAIL synthesis, comparing this method with traditional injection modes. Furthermore, this paper aims to demonstrate the use of factorial design methods for the optimization of MICZE method. The method optimization allowed five consecutives I− injections of sample in a single run, with analysis time of less than 3 min, showing a larger analytical frequency, counting with 31 injections per hour. It was possible to determine the high purity of the prepared and analyzed AAIL, ranging from 89% to 95% and its overall ionic exchange yield varying from 55% to 87%.