Liquid flow in capillary (electro)chromatography: Generation and control of micro‐ and nanoliter volumes

Abstract

We describe and discuss instrumental developments in capillary (electro)chromatography which are of particular relevance for generating (and controlling) required volumetric flow rates in the micro-and nanoliter range through packed capillaries. Both isocratic and gradient elution are considered. For capillary HPLC this practically involves only commercial instrumentation, with systems based on syringe or piston pumps, but it also realizes the innovative concept of a high-pressure electrokinetic pump. The numerous systems that have been used to generate electroosmotic flow through chromatographic beds are classified under the following headings: i) basically commercial capillary electrophoresis instruments (adapted for electrochromatography); ii) home-built configurations; and iii) commercial capillary electrochromatography systems. Concerning the reviewed instrumentation, emphasis is placed on feasibility, automation, as well as system-inherent delay times and dead volumes.

Development and Application of Liquid Chromatography in Life Sciences

“…Special micro-and nano-LC instruments are required to operate these capillary columns which results in generation of flow rates in the range of µl min -1 to nl min -1 [12]. Furthermore, the efficiency for analysis is dramatically improved by capillary columns.…”

Liquid Chromatography—Its Development and Key Role in Life Science Applications

“…The operation of such columns required special micro-and nano-LC instruments, which generated flow rates in the range of ml min À1 to nl min À1 . [22] The capillaries were packed with microparticulate silica and resulted in plate numbers in excess of 100 000 plates m À1 . [23] Fused-silica capillaries were also manufactured as continuous beds with monolithic silica and applied in the gradient-elution reversed-phase mode.…”

Flüssigkeitschromatographie – ihre Entwicklung und Bedeutung für die Lebenswissenschaften

“…[20,21] Der Säu-leninnendurchmesser variierte zwischen 300 und 20 mm, und der Gebrauch dieser Säulen erforderte spezielle Mikro-und Nano-LC-Instrumente, die in der Lage waren, in reproduzierbarer Weise Flüsse im mL-und nL-Bereich zu erzeugen. [22] Die Kapillaren wurden mit mikropartikulären Kieselgelen gepackt und erreichten Bodenzahlen jenseits der 100 000 Böden m À1 . [23] Quarzkapillaren wurden auch mit kontinuierlichen Betten (so genannten monolithischen Säulen) aus Kieselgel und Polymeren hergestellt und bei der Gradientenelution mit RP-Phasen eingesetzt.…”