5
– Troubleshooting Guide
Thermo Scientific
Product Manual for CarboPac PA200 Columns
Page 28 of 37
065734-01
For Research Use Only. Not for use in diagnostic procedures.
5.2
High Background
While it may be possible to obtain reasonable performance even with elevated levels of detection
background according to some requirements, high background frequently brings about an
increased size of gradient artifacts and can be accompanied by a presence of ghost peaks.
Detection sensitivity may also change suddenly when the detection background is too high. A
background >50 nC with 8 mM KMSA/150 mM KOH at 0.0.063 mL/min for the 1-mm system
and 0.010 mL/min for 0.4-mm system and 30°C using the quadruple waveform indicates one of
the following possibilities:
A.
Incorrect detection parameters.
Verify that Ag/AgCl is specified as a reference electrode. Check all values of
waveform in program against those in the Disposable Electrode Manual.
B.
Compromised working electrode surface.
Briefly install a new working electrode and check the background as above. If the
reading remains > 50 nC, remove the new electrode within 30 minutes and continue
testing for column or system contamination. Otherwise continue with your work with
the new electrode installed.
C.
Insufficient degassing vacuum.
Verify that the vacuum applied to both the Dionex RFIC EGC 400 MSA degasser
(Item # 22181-60210) and the Dionex RFIC EGC 400 KOH degasser (Item # 22181-
60201) are above 27 inch Hg for 1-mm system (the Dionex RFIC Capillary EGC MSA
Degasser (Item # 22181-60211) and the Dionex RFIC Capillary Eluent Degasser (Item
# 22181-60202) for the 0.4-mm system).
D.
Column contamination: Remove the column set from the system first and replace it
with a length of 0.001” i.d. PEEK tubing, generating a pressure drop over 2000 psi. If
the background reading improves after the column is removed from the system, go to
Appendix A, “CarboPac PA200 Column Care”.
E.
Water contamination: Prepare eluents using a fresh ultra-pure water from another
source. If the background is reduced, investigate the source of contamination in the
original source of water.
F.
System Contamination: If the background remains high even with fresh water and
without the column, carry out the 2 M sodium hydroxide rinse. In a properly working
system, the electrochemical detection (ED) background for the Dionex CarboPac
PA200 QAR eluent is 25-40nC. If the background is much higher, determine the cause
of high background.
G.
Minor leak at the ED cell. Due to the low flow rate, the minor leak at the ED cell might
not set off the leak alarm. The minor leak can cause increased background and noise.
Verify that there is no leak at the ED cell. If leaking around the 1mil gasket is
observed, remove the gasket, carefully dry with lint free cloth the wet ED surface and
replace with new 1mil gasket.
5.2.1
Preparation of Eluents
A.
The Dionex CarboPac PA200 1 mm and 0.4 mm columns are not compatible with
manually prepared eluents. The use of a Dionex EGC 400 MSA cartridge and a Dionex
EGC 400 KOH cartridge is required.
B.
Make sure that the deionized water used has a specific resistance of 18.2 megohm-cm or
greater.
