title: Sensitive analysis of amino acids and vitamin B3 in functional drinks via field-amplified stacking with reversed-field stacking in microchip electrophoresis.
abstract: An on-line preconcentration strategy combining field-amplified stacking and reversed-field stacking was developed for efficient and sensitive analysis of amino acids and vitamin B3 including lysine (Lys), taurine (Tau), and niacinamide (NA) by microchip electrophoresis with LIF detection. In this technique, the addition of a reversed-polarity step termed reversed-field stacking could enhance the preconcentration effect of field-amplified stacking and push most of the sample matrix out of the separation channel, thus greatly improving the sensitivity enhancement by 1-2 orders of magnitude over the classical MCE-LIF methods. The related mechanism as well as important parameters governing preconcentration and separation have been investigated in order to obtain strongest sensitivity amplification and maximum resolution. Under optimal conditions, all analytes were successfully focused and completely separated within 4 min. The limits of detection for Lys, Tau, and NA were 0.25, 0.50, and 0.20 nM (S/N=3), respectively, and enhancement factors of 165-, 285-, and 236-fold were obtained for Lys, Tau, and NA as compared to using the no concentration step. Other validation parameters such as linearity and precision were considered as satisfactory. The proposed method also gave accurate and reliable results in the analysis of these functional ingredients in eight functional drink samples.
authors.affiliation: Department of Chemistry, East China Normal University, 500 Dongchuan Road, Shanghai 200241, PR China.
authors.forename: Minglei
authors.initials: M
authors.lastname: Wu
authors.affiliation: Department of Chemistry, East China Normal University, 500 Dongchuan Road, Shanghai 200241, PR China.
authors.forename: Fan
authors.initials: F
authors.lastname: Gao
authors.affiliation: Department of Chemistry, East China Normal University, 500 Dongchuan Road, Shanghai 200241, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, East China Normal University, 500 Dongchuan Road, Shanghai 200241, PR China. Electronic address: qjwang@chem.ecnu.edu.cn.
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: College of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, PR China. Electronic address: chemlihui@sjtu.ecnu.edu.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D046209:Electrophoresis, Microchip / Q000379:methods*; D055951:Functional Food / Q000032:analysis*; D057230:Limit of Detection; D009536:Niacinamide / Q000032:analysis*
chemical_list: D000596:Amino Acids; D009536:Niacinamide
keywords: Amino acids; Field-amplified stacking; Functional drinks; Reversed-field stacking; Vitamin B(3)