Novel variable volume injector for performing sample introduction in a miniaturised isotachophoresis device

• Published in: Journal of Chromatography A Vol. 1042; no. 1; pp. 181 - 188
• Main Authors: Baldock, S.J, Fielden, P.R, Goddard, N.J, Kretschmer, H.R, Prest, J.E, Treves Brown, B.J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 09-07-2004; Elsevier
• Subjects: Analysis; Analytical biochemistry: general aspects, technics, instrumentation; Analytical chemistry; Analytical, structural and metabolic biochemistry; Anions; Biological and medical sciences; Cations; Chemistry; Chip technology; Chromatographic methods and physical methods associated with chromatography; Electrolytes; Electrophoresis - instrumentation; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; General pharmacology; Injection methods; Instrumentation; Isotachophoresis; Medical sciences; Metals; Microcomputers; Miniaturization; Nanotechnology; Pharmacology. Drug treatments; Polymethyl Methacrylate; Injection methods; Instrumentation; Chip technology; Isotachophoresis; Miniaturization; Injector; Microequipment; System on a chip; Injection; Microfluidics
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2004.05.062

A microdevice design furnished with a novel sample injector, capable of delivering variable volume samples, for miniaturised isotachophoretic separations is presented. Micromachining by direct milling was used to realise two flow channel network designs on poly(methyl methacrylate) chips. Both designs comprised a wide bore sample channel interfaced, via a short connection channel, to a narrow bore separation channel. Superior injection performance was observed with a connection channel angled at 45° to the separation channel compared to a device using a channel angled at 90°. Automated delivery of electrolytes to the microdevice was demonstrated with both hydrostatic pumping and syringe pumps; both gave reproducible sample injection. A range of different sampling strategies were investigated. Isotachophoretic separations of model analytes (metal ions and an anionic dye) demonstrated the potential of the device. Separations of ten metal cations were achieved in under 475
s.