Bio-Rad Fluorescent Assay Kits - Manual (Page 8)

5.3 Regenerating a Plugged Capillary
If the capillary becomes plugged (as evidenced by zero cur-
rent, or failure of the liquid to appear at the capillary outlet during
manual purging), there are two ways to unplug the capillary.
On-line method
Leave the capillary cartridge installed in the BioFocus
system. Place vials containing 100 µl deionized water in the inlet
and outlet carousel. Select Pressure Diagnostics from the toolbar.
In the Pressure Diagnostics window, select High Pressure Mode,
select the carousel positions containing the water vials, enter
180 seconds for the Maximum Limit for Testing, then press
Start. After the 3 minute purge period, exit from Pressure
Diagnostics and visually check the liquid level in the inlet water
vial. If the vial is empty, the capillary has been unplugged.
Off-line method
Remove the capillary cartridge from the instrument and
immerse the capillary ends in hot (70 °C, not boiling) deionized
water for 10–15 minutes and check by manually purging with
water. Alternatively, immerse the capillary ends in a sonic bath
filled with deionized water and sonicate for about 5–10 minute
before purging with water.
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Section 5
Optimization of Nucleic Acid
Separations
5.1 Shortening Analysis Time
The time of analysis can be shortened by increasing the run
voltage, although this can result in some loss in performance. For
example, running at 4.0 kV on a 24 cm capillary can shorten the
analysis time of the CE-LIF dsDNA 100 bp ladder to about
12 minutes.
5.2 Increasing Resolution
Resolution can be improved by increasing the length of the
capillary, but this will also result in longer analysis times. To main-
tain the same field strength, the operating voltage should be
increased proportionately to the increase in capillary length.
Resolution also depends upon the width of the sample zone
loaded into the capillary; narrow zones improve resolution. Narrow
sample zones can be obtained by reducing the injection time and/or
the injection voltage for electrophoretic injection, or the psi*second
value for pressure injection.
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