title: Dual-cloud point extraction and tertiary amine labeling for selective and sensitive capillary electrophoresis-electrochemiluminescent detection of auxins.
abstract: The low concentrations of the auxins in samples of plant tissue necessitate the use of selective and sensitive techniques for their quantification. Herein a selective and sensitive method based on dual-cloud point extraction (dCPE) and tertiary amine labeling for the quantification of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) by capillary electrophoresis-electrochemiluminescence (CE-ECL) is proposed. The procedure for dCPE included two cloud point processes with Triton X-114 as the extractant. The two auxins became hydrophobic in an acidic solution and were extracted into surfactant-rich phase after the first cloud point procedure. They were then back-extracted into the alkaline aqueous phase during the second cloud point step. The extracted auxins were reacted with 2-(2-aminoethyl)-1-methylpyrrolidine (AEMP) in acetonitrile that contained N,N'-dicyclohexylcarbodiimide and 3,4-dihydro-3-hydroxy-4-oxo-1,2,3-benzotriazine to produce their AEMP-derivatives. The two auxin-AEMP-derivatives were subjected into CE and detected by Ru(bpy)(3)(2+)-based ECL. The preconcentration factors for IAA and IBA with dCPE were 40.5 and 43.4, respectively. The on-capillary detection limits (S/N=3) were 2.5 and 2.8nM for IAA and IBA. This protocol presents a clear advantage in that it reduces the interference from the matrixes extensively and gives a high sensitivity for the detection of auxins. The proposed method was applied successfully to the detection of the two auxins in acacia tender leaves, buds, and bean sprout.
authors.affiliation: Research Center for Analytical Sciences, College of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, China. xbyin@nankai.edu.cn
authors.forename: Xue-Bo
authors.initials: XB
authors.lastname: Yin
authors.forename: Jun-Min
authors.initials: JM
authors.lastname: Guo
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
mesh_terms: D000045:Acacia / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D007887:Fabaceae / Q000737:chemistry*; D007210:Indoleacetic Acids / Q000032:analysis*; D007211:Indoles / Q000032:analysis; D057230:Limit of Detection; D008163:Luminescent Measurements; D012680:Sensitivity and Specificity
chemical_list: D000588:Amines; D007210:Indoleacetic Acids; D007211:Indoles; C014612:indolebutyric acid; C030737:indoleacetic acid