On-line capillary electrophoresis enrichment by combining chitosan trapping with surfactant assisted sample stacking for the ultratrace determination of organic acids in Plateau alfalfa roots

In this paper, four organic acids constituents of Plateau alfalfa roots have been identified and detected by a novel capillary electrophoresis (CE) strategy which combined chitosan (CS) trapping and cetyltrimethyl ammonium bromide (CTAB) assisted sample stacking. Under the optimized condition, organic acids, i.e., aconitic acid, gallic acid, citric acid and l-malic acid were concentrated and separated within 3 min. Validation parameters of this method (such as detection limits, linearity and precision) were also investigated and the limit of detection (LOD) was 2.41-53.9 ng mL⁻¹. Linearity was obtained over the magnitude range of 5-4000 ng mL⁻¹ approximately for different organic acids and 3 × 10²-1.5 × 10⁴ folds enrichment was achieved. The method has been applied to the determination of organic acids in roots of normal grown Plateau alfalfa and stressing affected Plateau alfalfa. Satisfactory results and recoveries were obtained in the analysis without costly and complicated sample pretreatment.