Column efficiency measurement

Bidlingmeyer, Brian A.; Warren, F. Vincent

doi:10.1021/ac00278a002

Cited by 145 publications

(52 citation statements)

References 13 publications

(8 reference statements)

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“…The peak asymmetry of the probe, measured at 10% of peak height [27], was used to assess its ability to interact electrostatically with the fused-silica surface [19,20]. Unless stated otherwise, a 50 mM Ru(bpy) 3 Cl 2 solution in BGE was used.…”

Section: And the Conditioned Silica Surfacementioning

confidence: 99%

The effect of conditioning of fused‐silica capillaries on their electrophoretic performance

Gómez

Sandoval

2008

Electrophoresis

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In CE practice, conditioning of the capillary tube with strong base, acid, or both in sequence, has been recognized as essential to obtain reasonable precision in electroosmotic mobility (EOM), and consequently, in the migration times of analytes. This report focuses on the comparative study of three different approaches for capillary conditioning: etching with HF, etching with NaOH, and leaching with HCl after NaOH treatment. EOM-based measurements, including the hysteresis effect that characterizes the dependence of EOM with pH, were used to evaluate the conditioned silica surface. Additionally, indirect inspection of the conditioned surface was carried out by examining the electrophoretic profile of the cationic probe Ru(bpy)(3) (2+), known to strongly interact with the ionized silica surface while displaying no significant acid-base activity. It was shown that, once conditioned and prior to any CE measurement, extensive rinse of the capillary with the running electrolyte at high flow rate was essential to attain relatively rapid re-equilibration of the tube with the fluid. Insufficient rinse with the running electrolyte would result in negatively biased EOM measurements and significant drift in migration times. It was also established that relatively high flow rates of 1 M NaOH conditioning solution (4-5 column volumes per minute) was required to attain capillaries with reproducible electrophoretic performance within a reasonable conditioning time (typically, 1 h). In addition to relatively more extensive rehydroxylation of the silica surface, evidenced by the highest EOM values obtained, the sequential use of NaOH-etching and HCl-leaching provided better precision than HF-etching or NaOH-etching alone.

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Section: And the Conditioned Silica Surfacementioning

confidence: 99%

The effect of conditioning of fused‐silica capillaries on their electrophoretic performance

Gómez

Sandoval

2008

Electrophoresis

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“…Separation efficiency and resolution are two terms that have been extensively used for characterizing separation in HPLC [24,25] and electrophoresis [26]. However, Giddings and Dahlgren [27] pointed out that separation efficiency, expressed in theoretical plate number, should not be used for IEF because a steady state is reached at the end of the focusing process and the peak variance is not proportional to the position in the IEF.…”

Section: Theoretical Considerationmentioning

confidence: 99%

Effects of separation length and voltage on isoelectric focusing in a plastic microfluidic device

Das

Fan

2006

Electrophoresis

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This paper describes the investigation on the effects of separation length and voltage on IEF in a plastic microfluidic device. A LIF, whole-channel imaging detection (WCID) system was developed to monitor proteins while they were moving under an electric field. IEF was carried out in a separation medium consisting of carrier ampholytes and a mixture of linear polymers (hydroxyethylcellulose and hydroxypropylcellulose). We found that the IEF separation resolution is essentially independent of separation length when the same voltage is applied, which agrees with the theory. This result supports the notion that IEF in a microfabricated device leads to more rapid analysis without sacrificing the resolving power. A higher separation voltage also brought about more rapid analysis and superior separation resolution. IEF of two proteins (green fluorescence protein and R-phycoerythrin) was achieved in 1.5 min when 500 V was applied across a 1.9-cm channel. We found that a linear relationship exists between the focusing time and the inverse of the electrical field strength. In addition, we confirmed the phenomenon in which the pH gradient was compressed to the middle of a channel, and we found that the relative amount of the gradient compression decreased with the channel length.

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“…The reduced velocities for nonaphenone are given for comparison. All plate counts reported were calculated by the statistical moments method and are generally somewhat lower than those calculated by other means, i.e., equations based on Gaussian peak shapes [45,49].…”

Section: Resultsmentioning

confidence: 95%