Comparison of clonidine and cyproheptadine determination in animal-derived foods by sweeping-micellar electrokinetic chromatography and large volume sample stacking-capillary zone electrophoresis

This study establishes a method for rapid detection of clonidine and cyproheptadine in foods of animal origin. In order to obtain the best detection method, capillary zone electrophoresis (CZE), large volume sample stacking (LVSS), and sweeping-micellar electrokinetic capillary chromatography (sweeping-MEKC) were used respectively. The limits of detection (LODs) of clonidine and cyproheptadine by LVSS-CZE were 0.028 μg mL−1 and 0.034 μg mL−1, and those by sweeping-MEKC were 0.023 μg mL−1 and 0.031 μg mL−1, respectively. Compared with the CZE method, the two online pre-concentration technologies have greatly improved the detection sensitivity and achieved good enrichment results. However, compared with the sweeping-MEKC system, the LVSS system consumed a longer time and was greatly affected by the actual sample matrix. The sweeping-MEKC method was proved to be suitable for real sample analysis. Under the best sweeping-MEKC conditions, clonidine and cyproheptadine could be well separated within 8 min and good linear relationships in the range of 0.1–1.0 μg mL−1 (r 2 > 0.99) were obtained. This method was successfully applied to the determination of clonidine and cyproheptadine in animal-derived foods with the recoveries of 82.3%–90.1% and the relative standard deviations (RSDs) less than 3.11%. The sweeping-MEKC method is simple to operate and has great potential in the rapid detection of clonidine and cyproheptadine in animal-derived foods.

Simultaneous Separation and Analysis of Five Compounds in Cibotium barometz by Micellar Electrokinetic Chromatography with Large-Volume Sample Stacking

A large volume sample stacking (LVSS) method in micellar electrokinetic chromatography (MEKC) with diode array detector was developed for the simultaneous separation and analysis of five compounds: protocatechuic acid, protocatechuic aldehyde, caffeic acid, syringetin and vanillin in Cibotium barometz. The electrophoretic separation was performed in a 10 mM sodium dodecyl sulfate (SDS) and 50 mM sodium borax-sodium dihydrogen phosphate system (pH = 8.5) with 10% methanol at a separation voltage of 30 kV after optimizing the typical parameters. The detection limits were from 32 pg to 65 pg, which were around 12–27 times lower than MEKC, and 500 times less than reported methods. Finally, the established method was validated to be applicable for the determination of protocatechuic acid and caffeic acid in Cibotium barometz. This proposed method is expected to facilitate the quality control of Cibotium barometz.

Determination of rutin, chlorogenic acid and quercetin in solidaginis by large volume sample stacking with polarity switching and acid barrage stacking

The sensitivity of capillary electrophoretic separation of rutin, chlorogenic acid and quercetin was enhanced by combination use of large volume sample stacking with polarity switching (LVSSPS) and acid barrage stacking (ABS). Separating conditions, including the background electrolyte pH and concentration, sample injection and acid barrage were optimized. The optimum conditions were: a background electrolyte of 30 mM Na2B2O7 of pH 9.25, hydrodynamic injection of the sample (60s, 5 psi), then applied voltage of -25 kV, and then hydrodynamic injecting of 0.15 mol/L HAc (18 s, 0.5 psi), and at last separation with 25 kV. Under these conditions, the three analytes could be separated with a sample-to-sample time of 14 min and detection limits from 9.0 to 12.5 ng/mL. When compared to a conventional hydrodynamic injection, the sensitivity was enhanced between 333 to 506 times and the method is 3.6-5.3 times more sensitive than LVSSPS. The applicability of the developed method was demonstrated by the detection of the analytes in aqueous extract of solidaginis.