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We have recently reported the new concept of temperature-responsive capillary electrochromatography (CEC) using a poly( N-isopropylacrylamide)-grafted capillary column. In this study, temperature-responsive CEC separation of six clinical drugs including thymopentin and octreotide acetate (two peptides), homatropinum and oxazepam, benazepril hydrochloridec and amlodipine acetate was conducted to evaluate the separation efficiency of the CEC column. For comparison purposes, a bare capillary column was used for the control experiments. It was found that the resolutions and migration times of thymopentin and octreotide acetate, homatropinum and oxazepam on the modified column were much larger than those on the bare column. Enhanced resolving power mainly resulted from the interactions between analytes and PNIPAAm-grafted capillary surfaces. Therefore, the modification with temperature-responsive PNIPAAm was evaluated to achieve a better separation of the four analytes. The resolutions of benazepril hydrochloridec and amlodipine acetate on the modified column were smaller than those on the bare column because peak broadening and tailing were also obtained, although the differences in migration time between them were much larger. Furthermore, significant changes in the resolution and migration time were only observed on the modified column around the lower critical solution temperature of PNIPAAm, demonstrating its temperature-responsive property. [ABSTRACT FROM AUTHOR]

A novel and simple coating method was developed by coating bovine serum albumin (BSA) onto the inner surface of a fused-silica capillary, to avoid the adsorption of analytes during CE. The advantage presented here was that the coating process is more simple, fast, stable, and reproducible. The coated capillary avoided the adsorption of analytes onto the inner surface of a fused-silica capillary and might be a promising candidate for separation of complex biological samples with further development. Meanwhile, the efficiencies of the coated capillary were evaluated by EOF, chromatographic peak shape, and theoretical plate number (N m) of RNase A. The optimal coating conditions were obtained from the results. The pH value of coating buffer PB was 4.2, the standing time was 12 h at 4 °C, and the coating concentration of BSA was 1.5 mg mL. The stability of the coating on the inner wall of the capillary and the reproducibility of the coated capillaries were good. The theoretical plate number values of RNase A were over 1.3 × 10 (N m) in the coated capillary. After successive electrophoresis for 48 h using the coated capillary, the RSD values of EOF and the theoretical plate number were 4.14 % and 9.14 %, respectively. In addition, the RSD values of EOF and the theoretical plate number (N m) in the coated capillaries were 13.19 % and 8.96 %, respectively. Finally, the coated capillary was successfully applied to separate the mixture of four basic proteins (RNase A, lysozyme, trypsin and myoglobin). [ABSTRACT FROM AUTHOR]