title: Combining field-amplified sample stacking with moving reaction boundary electrophoresis on a paper chip for the preconcentration and separation of metal ions.
abstract: A common drawback of paper-based separation devices is their poor detection limit. In this study, we combined field-amplified sample stacking with moving reaction boundary electrophoresis on a paper chip with six array channels for the parallel separation and concentration of multiple samples. With a new hyphenated technique, the brown I2from the Fe3+/I-oxidation-reduction reaction emerged near the boundary between the dilute ethylene diamine tetraacetic acid and potassium iodide and highly concentrated KCl solutions. For the separation and concentration of three components, Cr3+, Cu2+, and Fe3+, the Fe3+detection limit was improved at least 266-fold by comparing the hyphenated technique with moving reaction boundary electrophoresis. The detection limit of Fe3+was found to be as low as 0.34 ng (20 μM) on the paper chip. We also demonstrated the analysis of a real sample of four metal ions, with detection limits as follows: 0.16 μg Cr3+, 1.5 μg Ni2+, 0.64 μg Cu2+, and 1.5 μg Co2+. The synergy of field-amplified sample stacking and moving reaction boundary electrophoresis in the micron paper-based array channels dramatically improved the detection limit and throughput of paper-based electrophoresis.
authors.affiliation: Separation Science Institute, the Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, P. R. China.|State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, P. R. China.
authors.forename: Liangfei
authors.initials: L
authors.lastname: Ouyang
authors.affiliation: Separation Science Institute, the Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, P. R. China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Separation Science Institute, the Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, P. R. China.
authors.forename: Heng
authors.initials: H
authors.lastname: Liang
keywords: metal ions; moving reaction boundary; paper chip; sample stacking; sensitivity