Product Manual for IonPac CS16
Page 53 of 65
6.2.
Preparation of Eluents
A.
Make sure that the eluents and regenerant are made correctly.
B.
Make sure that the eluents are made from chemicals with the recommended purity.
C.
Make sure that the deionized water used to prepare the reagents has a specific resistance of 18.2 megohm-cm.
6.3.
Contamination
6.3.1.
A Contaminated Guard or Analytical/Capillary Column
Determine if the column is contaminated. Column contamination can lead to a loss of column capacity since all of the cation
exchange sites will no longer be available for the sample ions. Polyvalent cations may be concentrating on the column over a
series of runs. Remove the IonPac CG16 Guard and CS16 Analytical or Capillary Columns from the system. If the
background conductivity decreases, the column(s) is (are) the cause of the high background conductivity. Clean or replace the
CG16 at the first sign of column performance degradation (compared to the original test chromatogram) to eliminate
downtime. Clean the column(s) as instructed in, “Column Cleanup” (See, “Column Care”). To make sure that contaminated
hardware is not causing the high background, use deionized water with a specific resistance of 18.2 megohm-cm as eluent.
The background should be less than 1 µS. If it is not, check the detector/conductivity cell calibration by injecting deionized
water directly into it. See the appropriate manual for details.
A.
Check for a contaminated Gradient Mixer.
Gradient Mixers in the Gradient Pump Module should be flushed
thoroughly to remove eluents containing DL-2,3-diaminopropionic acid monohydrochloride (DAP.HCl). Chloride
containing eluents should not be pumped through the CSRS 300.
B.
Use chemicals and deionized water of the proper purity.
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.
C.
The system should be as metal-free as possible.
Gripper tubing fittings used in older systems are a potential source
for metal contamination of the column. The new Dionex ThermoFlare or PEEK ferrule fittings are preferred. Inspect
the eluent pumps periodically for any signs of leakage.
D.
Glass eluent reservoirs can be a source of sodium contamination in the eluent.
Two-liter polyethylene eluent
reservoirs (P/N 039163) are preferred.
E.
For EG operation, use a CR-CTC Trap Column.
Install a CR-CTC Cation Trap Column (P/N 060478) if using an
Eluent Generator with EGC MSA cartridge.
F.
Install an IonPac Cation Trap Column (CTC-1, P/N 040192). It
should be positioned between the pump and the
injection valve. It is highly recommended for all cation gradient applications. The CTC-1 strips the eluent of cation
contaminants that will bind strongly to the analytical column resulting in the loss of column capacity and potentially
interfering with the desired cation analyses. The CTC-1 minimizes baseline changes when performing gradient
analyses. The CTC (2-mm), P/N 043132, should be used in 2-mm and 3-mm systems.
6.3.2.
Sample Loop and/or Tubing Contamination
Eluents made with deionized water that is contaminated with bacteria and samples such as humic acids and soil extracts can
potentially contaminate eluent lines and sample loops. Weak cation exchange sites are created on (or attached to) the tubing.
This can happen to either Tefzel or PEEK tubing. Thus, the sample loop itself can act as a concentrator and depending on the
pH of the sample or the standard and the way these are introduced, inaccurate readings for divalent analytes on weak cation
exchange resins may be observed.
Document No. 031747-05
© 2010 Dionex Corporation
December 2010
