Ion Chromatograph: Cation Startup

Be sure the eluant bottle is full of DI water. It’s easiest to refill it using the liter bottle that is either here or on top of the anion chromatograph.

Turn on the cation system box and (if you will be using it) the autosampler. Switches are low in the back.

The system takes a minute or two to boot up.

Regardless, you can turn on the cation computer now.

Double-click on the Chromeleon 7 icon to start the software. It might take a few minutes, especially if the system box isn’t ready to communicate. If you get bored, double click it again. You won’t get two instances of the running program.

Be sure the window being shown is Instruments. If not, click on the Instruments button.

Also be sure the tab being shown is Pump_ECD. If not, click on the Pump_ECD tab.

Check that the Connected light is green, that the Connect button is gray and the Disconnect button is black. If not, press the Connect button.

Open the pump purge valve by turning counterclockwise about half a turn.

Press the pump Prime button, and then the Execute despite warnings in the warning window.

The warning is to remind you to open the pump purge valve.

The pump will run at high-speed. DI water will come into the pump from the eluant bottle, and go our via the larger, transparent purge tube. A few small bubbles can usually be seen scooting out from the pump. That takes less than a minute.

Once the bubbles are through, turn off the pump.

Close the purge valve on the pump by turning it counterclockwise. It should just be somewhat tight. The threads are plastic, so don’t overtighten. If you later notice that the pump pressure is low or unstable, you can tighten this a bit more.

Check that the pump is set to 1 ml per minute. If not, change the value to 1.0 ml per minute.

Press all the On buttons in sequence to turn everything on.

There is a bug in the program that resets the eluant concentration to zero. Change the eluant concentration to 15 mM.

Here it is, changed to 15 mM (milliMolar).

Eluant coming out of the column goes into the suppressor. You should see a steady stream of bubbles coming out of the suppressor, going to the drain. These bubbles are hydrogen and oxygen, electrolized in the suppressor.

To monitor the electrical conductivity baseline, click the little TV icon, be sure CD is selected (conductivity detector), and then press the OK button.

The conductivity baseline graph starts being drawn. Normally there are two peaks that come out in the first few minutes. I think the first one if from ions coming off ion exchange resin in the suppressor, and the second is ions that leak out of the eluant generator cartridge into the eluant stream.

If you are just running this chromatograph to keep the suppressor membranes from drying out, you can stop here and just shut the instrument down.

At this point it’s usually a good idea to make sure the instrument is working well. Pump pressure may go over 2500 psi, but after a while should stabilize near 2000 psi. The conductivity signal should usually stabilize somewhere below 0.5 μS. This is a good time to load your samples.

You can load the autosampler, starting in position 1.

If you have more than 50 vials, you can put those in as earlier ones have been run through the machine. Just take the empties out, and put the new ones in to replace them, in proper sequence, of course.

Each sample takes about half an hour, so the rack of 50 will take more than a day. You don’t have to hang around, just come in the next morning and load in the new ones.

To get the auosampler rack to move, to load in your first sample set, Push the button to release the carosel.

Don’t push this button if samples are running.