Electrokinetic Sample Injection

Pumera et al. [34] used gold nanoparticle enhanced open channel NCEC for the separation of p-aminophenol, o-aminophenol, and m-aminophenol in a bare glass channel and polydiallyl dimethyl ammonium chloride (PDADMAC) gold coated channel. The mobile phase used was acetate buffer (20 mM, pH 5.0) with electrokinetic sample injection at 1.5kV/cm for 3 seconds and 2.0kV/cm as separation voltage (Fig. 7.15). Broyles... 

Application of a potential between reservoirs 1 (sample) and 4 (injection waste) electrokinetically pumps sample solution as indicated in Fig. 3. In this way, a geometrically defined 150 pm (90 pi) section of the separation channel can be filled [19]. If the injection potential is applied long enough to ensure that even the slowest sample component has completely filled the injection volume, a representative aliquot of sample can be analyzed (so-called volume defined injection). This is in contrast to electrokinetic sample injection in conventional capillaries, which is known to bias the sample according to the respective ionic mobilities [61]. These characteristic differences are shown schematically in Fig. 4. It should be noted that this picoliter sample injector is exclusively controlled by the application of electric fields and does not require any active elements with moving parts such as valves and external pumps. The reproducibility of the peak height of the injected sample plugs has been reported to be within 2 % RSD (relative standard deviation) and less [19,23]. 

Fig. 4. Schematic representation of electrokinetic sample injection in a a volume defined injection scheme (unbiased loading) and b conventional CE (biased sample loading). The sample migrates through the injection volume in a way resembling a frontal electropherogram...

Huang Z, Gordon MJ, Zare RN (1988) Bias in quantitative capillary zone electrophoresis caused by electrokinetic sample injection. Anal Chem 60 375-377. 

Electrokinetic Sample Injection, Fig. 1 Cross-fonn injection method, (a) schematic diagram of injection system, (b) injection step, (c) separation step... 

Reproducible sample introduction is a crucial factor in p-chip-based electrophoretic separations. Various p-chip sample introduction schemes are illustrated in Fig. 2. Of the many proposed injection methods, electrokinetic injection based on electro-osmotic flow (EOF) is most commonly encountered on chips, because electrically driven fluid flow is easier to generate and control than pressure-driven flow. Electrokinetic sample injection is generally... 

Electrokinetic Motion of Polarizable Particles Electrokinetic Sample Injection Electrokinetic Transport in Nanofluidic Sensing Devices... 

Electrokinetic Sample Injection, Figure 4 Double-L injection mettiod in... 

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