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Product Manual for IonPac CS16
C. Column contamination can lead to a loss of column capacity. This is because all of the cation exchange sites will
no longer be available for the sample ions. For example, polyvalent cations from the sample or metals may
concentrate on the column. Refer to, "Column Cleanup" (see, "Column Care"), for recommended column cleanup
procedures.
Possible sources of column contamination are impurities in chemicals and in the deionized water used for eluents or
components of the sample matrix. Be especially careful to make sure that the recommended chemicals are used. The
deionized water should have a specific resistance of 18.2 megohm-cm.
D. Diluting the eluent will improve peak resolution, but will also increase the analytes' retention times. If a 10%
dilution of the eluent is not sufficient to obtain the desired peak resolution, or if the resulting increase in retention
times is unacceptable, clean the column (see, "Column Cleanup" in "Column Care").
After cleaning the column, reinstall it in the system and let it equilibrate with eluent for about 30 minutes. No water
wash is necessary. The column is equilibrated when consecutive injections of the standard give reproducible
retention times. The original column capacity should be restored by this treatment, since the contaminants should be
eluted from the column. If you need assistance in solving resolution problems, contact the Dionex North America
Technical Call Center at 1-800-DIONEX-0 (1-800-346-6390) or the nearest Dionex Office (see, "Dionex
Worldwide Offices").
6.6.3.
Loss of Early Eluting Peak Resolution
Lack of equilibration to the initial eluent or improperly swept out of void volumes are usually the cause of poor resolution or
efficiency of peaks eluting near the system void volume compared to the later eluting peaks.
A. Be sure that the column is equilibrated to the initial eluent. Typically gradient applications require
approximately 10 minutes to equilibrate to the initial eluent. The minimum equilibration time can be determined by
making successive runs with increasing equilibration times. The column is equilibrated to the initial eluent when
additional equilibration time does not increase the runtime of the first eluting peaks.
B. Sluggish operation of the injection valve may be the problem. Check the air pressure and make sure there are no
gas leaks or partially plugged port faces. Refer to the valve manual for instructions.
C. Improperly swept out volumes anywhere in the system prior to the guard and analytical columns may be the
problem. Swap components, one at a time, in the system prior to the analytical column and test for front-end
resolution after every system change.
6.7.
Spurious Peaks
A. Eluents made with chemicals lacking the required purity will contaminate columns rapidly. Remake all stock
solutions and eluents using chemicals that meet the chemical requirements specified in Section 4.3, "Chemical
Purity Requirements." Clean the column as indicated in "Column Cleanup" (see, "Column Care").
B. Spurious peaks may be due to column contamination. If the samples contain an appreciable level of polyvalent
cations, polyvalent cations may contaminate the column. As a result, the retention times for the analytes will
decrease, and spurious, inefficient peaks can show up at unexpected times. This problem may be solved by
increasing the time between analyses or by adding a regeneration step between successive runs to elute polyvalent
cationic contaminants off the column before the next sample injection takes place.
C. An injection valve that needs service may produce baseline upsets. This baseline upset can show up as one or
multiple peaks of varying size(s) and shape(s). Typically this will occur when the particular valve needs to be
cleaned or torqued (see the system manual). Small baseline disturbances at the beginning or at the end of the
chromatogram can be overlooked as long as they do not interfere with the quantification of the peaks of interest
Document No. 031747-05
© 2010 Dionex Corporation
Page 57 of 65
December 2010
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