High Background Or Noise; Preparation Of Eluents; A Contaminated Anion Trap Column; A Contaminated Guard Or Analytical Column - Thermo Scientific IONPAC AG2 GUARD COLUMN Product Manual

IonPac AS3, AS4, AS5, CS2
5.2

High Background or Noise

In a properly working system, the background conductivity level for the standard eluent system is shown in Table 1, "Storage
Solutions, Eluents and Regenerants." If the background conductivity is higher than listed in Table 1, "Storage Solutions, Eluents
and Regenerants," check for eluent and system contamination as follows.

5.2.1 Preparation of Eluents

A. Make sure that the eluents and the 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 .

5.2.2 A Contaminated Anion Trap Column

If you are doing gradient analysis, an Anion Trap Column (ATC) should be installed between the pressure transducer on the gradient
pump the injection valve. If it has not been installed, install one and watch the background conductivity. If the background
conductivity decreases, the ATC is trapping contaminants from the eluent. The eluents probably have too many impurities (see
Section 5.2.1, "Preparation of Eluents").
If the ATC is already installed, remove it. If the background conductivity decreases, the ATC is the source of the high background
conductivity.
A. Disconnect the ATC from the injection valve and direct the outlet to waste.
B. Flush the ATC with 200 mL of 70 mM Na
C. Equilibrate the ATC with the strongest eluent used during the gradient run at the flow rate specified in Table 2,
"Standard Flow Rates and Back Pressures."
D. If the problem persists, replace the ATC.

5.2.3 A Contaminated Guard or Analytical Column

Remove the guard and analytical columns from the system. Is the background conductivity still high? If the column is the cause
of the high background conductivity, clean the column as instructed in Section 6.3, "Column Cleanup."

5.2.4 Contaminated Hardware

To eliminate the hardware as the source of the high background conductivity, bypass the suppressor and pump deionized water
with a specific resistance of 18.2 megohm-cm through the system. The background conductivity should be less than 2 µS. If it is
not, check the detector/conductivity cell calibration by injecting deionized water directly into it. See the appropriate manual for
details.
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B O to remove any trapped impurities.
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