Simultaneous separation of neutral and cationic analytes by one dimensional open tubular capillary electrochromatography using zeolitic imidazolate framework-8 as stationary phase

Developing simple methods for separation of analytes that belong to different classes is of great importance. Herein, we developed a simple one-dimensional (1-D) capillary electrochromatography method to demonstrate the simultaneous separation of target fractions that belong to two different classes (i.e., cationic and neutral analytes) without switching buffer solution by a zeolitic imidazolate framework ZIF-8 coated capillary column. Owing to the difference of charge-to-mass ratio of the cationic analytes, the interaction of the cationic analytes and coating material ZIF-8 and the hydrophobic interactions between the neutral analytes and the microporous framework of ZIF-8, six cationic analytes and four neutral analytes were simultaneously separated in a single run by 1-D capillary electrochromatography. The relative standard deviations (RSDs) of the analytes migration time for intra-day, inter-day and column-to-column were in the range of 0.11–0.87%, 0.54–2.04% and 2.00–6.89% and the RSDs of the analytes peak area for intra-day, inter-day and column-to-column were in the range of 0.70–4.45%, 1.33–6.20% and 2.27–11.88%. Additionally, the developed method was employed in the analysis of urine samples with satisfactory recoveries.