Dionex ICS-3000, Руководство оператора

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ICS-3000 Ion Chromatography System
180
Doc. 065031-04 1/08
Noisy Baseline: ED Only
•
(DC Amperometry and Integrated Amperometry modes) Air bubbles
trapped inside cell
While wearing gloves and eye protection and with the pump running and all
plumbing connected, 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.
•
(DC Amperometry and Integrated Amperometry modes) Frequent,
random spikes in the baseline
The reference electrode diaphragm is plugged. First, try regenerating the
reference electrode frit by soaking the electrode in a solution of 1 M KCl plus
1 M HCl. If this does not eliminate the spiking, replace the electrode
(P/N 061879).
•
(DC Amperometry and Integrated Amperometry modes) Regular
baseline oscillation on high-sensitivity ranges
Reconnect the short length of titanium tubing to the cell inlet (see
Figure 2-22 ).
•
(DC Amperometry and Integrated Amperometry modes) Dirty or pitted
conventional (nondisposable) working electrode
Polish the working electrode (see Section 9.24.3 ). If you are using a
disposable electrode, replace it.
•
(Integrated Amperometry mode) Regular baseline oscillations
1. Check the pump pressure plot to verify that the pump is working properly.
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.