title: A piezoelectric drop-on-demand generator for accurate samples in capillary electrophoresis.
abstract: In this work, we propose a piezoelectric droplet generator for injection of well-defined amounts of sample in capillary electrophoresis. We demonstrate stable, precise and drop-on-demand droplet formation for various solutions, with precise control of waveform driving piezoelectric crystal inside the ink-jet head. By tuning the waveform, we can also manipulate the droplet size and delivery frequency. This injector was used in sampling for capillary electrophoresis. As a state-of-the-art application, the analysis of theobromine, caffeine and theophiline using micellar electrokinetic chromatography was developed. The volume of sample (single droplet) analyzed in this experiment was 179 pL (RSD=1.2%, n=10). The detection limits for caffeine, theobromine, and theophiline are 0.02, 0.08 and 0.06 mM L(-1), respectively. Compared with conventional methods, the combination of picoliter droplet dispenser with capillary electrophoresis allows precise and accurate sampling, as well as for reduced sample consumption, which will prove to be an efficient tool in quantitative separation and analysis.
authors.affiliation: Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Fengming
authors.initials: F
authors.lastname: Chen
authors.forename: Yandong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yuri
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Hulie
authors.initials: H
authors.lastname: Zeng
authors.forename: Chen
authors.initials: C
authors.lastname: Luo
authors.forename: Hizuru
authors.initials: H
authors.lastname: Nakajima
authors.forename: Katsumi
authors.initials: K
authors.lastname: Uchiyama
authors.forename: Jin-Ming
authors.initials: JM
authors.lastname: Lin
mesh_terms: D001993:Bronchodilator Agents / Q000032:analysis; D002110:Caffeine / Q000032:analysis; D046209:Electrophoresis, Microchip / Q000295:instrumentation*; D004867:Equipment Design; D057230:Limit of Detection; D018401:Sample Size; D013805:Theobromine / Q000032:analysis; D013806:Theophylline / Q000032:analysis
chemical_list: D001993:Bronchodilator Agents; D002110:Caffeine; D013806:Theophylline; D013805:Theobromine