Diagnostics (UltiMate 3000 Series)
Dark Current Test (DAD/MWD)

Run this test for a DAD-3000(RS) or MWD-3000(RS) detector to check the detection electronics if you notice an increased signal noise or signal variations of the baseline, and to perform an extended stray light test to detect stray light if you notice a decrease in linearity:

• The standard test evaluates the signal over the full spectrum range without light. You can select if the lamps should be turned off or shaded by an opaque filter. Measured values are represented in a signal plot, and the signal extrema are compared to the allowed limits.

• The extended stray light test compares the signal between turned off and shaded state of the lamps for both lamps separately and examines the influence of the UV lamp to the visible spectrum range and vice versa. This requires that the lamps be turned on and off, such that a longer stabilization phase may be required after the diagnostic test before you can perform an analysis.

If the test is run with a flow cell and the test fails, repeat the test without flow cell. This allows you  to check whether the problem was caused by the cell used in the first place.

 Note: 

The test requires detector firmware version 1.10 or later.

Required materials and preparatory measures

The test can be run with or without a flow cell installed:

• If a flow cell is installed, use an UltiMate 3000 pump and HPLC-grade water as an eluent. Install a restrictor capillary between the pump outlet and the flow cell inlet and check the pump's pressure limits. A flow rate of 1ml/min will be automatically set during the test.

• If you run the test without flow cell, remove the flow cell first, then start the Diagnostics wizard.

 Tip: 

Dionex recommends using the Diagnostics Kit for UltiMate 3000 pumps and detectors (Dionex P/N 6035.3000), which contains all materials required for this test.

How to

This description refers to the test when a flow cell is installed. If you run the test without flow cell, options related to the flow cell and pump flow will appear dimmed.

1. On the first test page, click Next> to proceed with the settings required for the test.

    Tip: 

   If the Next> button is not active on the first test page, the detector is not connected in Chromeleon or is in Standby mode. Connect the detector to Chromeleon before you continue by selecting the Connected check box. If the detector is in Standby mode, clear the Standby check box.

2. Optional: Enter a descriptive text in the Comments field, e.g., the reason why the test is performed.

3. Prepare the detector:

   1. Confirm that a flow cell is installed in the detector by clicking Done.

   2. Choose if you want to perform only the dark current test, or the dark current test with additional stray light test.

   3. If you choose to perform the stray light test, lamps will be turned off for the dark current test. If not, you can select if the lamps should be turned off (None) or shaded by an opaque filter (UV, VIS, or Both). For the stray light test, select if you want to examine the influence of the VIS lamp to the UV range (click UV band), or the influence of the UV lamp to the visible range (click VIS band), or both (click Both).

      Also, select the slit width (narrow or wide).

   4. Confirm installation of the restrictor capillary with Done.

   5. Select the eluent channel for water.

4. Clicking Next> takes you to the next test step(s). Follow the instructions on the panel(s).

5. When the test is finished, remove the restriction capillary and confirm by clicking Done.

6. Clicking Next> takes you to the last wizard page. To view or print the report with details of the analysis, click Finish and Preview Report. Click Finish to quit the test panel without viewing the report. For maintenance and replacement procedures, click Open Troubleshooting Guide.

    Tip: 

   After the test, the flow is set to 0. If you do not plan to continue with further tests, make sure to set a (small) pump flow or turn off the detector lamps to avoid damage to the flow cell. Confirm by clicking Done.

For general information, refer to  Diagnostics (UltiMate 3000 Series).

For more diagnostic tests for UltiMate 3000 Diode Array and Multiple Wavelength Detectors, refer to:

 Holmium Oxide Test

 Intensity Test

Slit Test