8 • Troubleshooting
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2. Air bubbles may be trapped inside the cell. While wearing gloves and eye
protection, generate a slight temporary backpressure by putting your
finger over the end of the cell outlet tubing for 2 to 3 seconds. Repeat 2 or
3 times. If the baseline does not improve, check the other causes of
baseline instability described in this section.
NOTE To prevent air from becoming trapped in the cell in
the future, increase the backpressure on the cell by
connecting backpressure tubing to the cell outlet.
The backpressure limit for the ED cell is 690 kPa
(100 psi). Do not exceed this limit.
3. The water used to prepare the eluent contains trace contaminants. Remake
the eluent, using ASTM Type I (18 megohm-cm) filtered and deionized
water containing no contaminants.
8.3 Poor Retention Time Reproducibility
• Liquid leaks
1. Check for leaks from the piston seals. Replace the piston seal on any head
with a leak (see Section 9.5
).
2. Check for leaks throughout the remainder of the system, including the
check valves, injection valve, and columns. Tighten or replace fittings as
needed.
• DP/SP not primed
Prime the pump (see Section 9.3
).
• Liquid lines incompletely flushed after an eluent change
Attach a 10 cc syringe (P/N 054578) to the waste port on the priming valve.
Open the priming valve (turn the knob one-half turn counterclockwise). Draw
at least 20 mL of the new eluent through the liquid lines before operation.
Do not block the end of the cell outlet tubing for longer than the
recommended 2 to 3 seconds. Doing so creates high backpressure,
which can break the reference electrode glass membrane.
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