Hi I'm Gerard Sharp. Welcome to the March 2011 issue of the monthly newsletter. This month the Tech Tip is on priming your HPLC Pump.

Ardent Scientific has just launched a new Chromatography eLearning site full of interactive multi media training modules with voice overs explaining the content as you go along. There's lots of free content and if you want to follow on from this month's Tech Tip and see an animation of pump priming, click here to view. Enjoy!

Tech Tip - Priming Your HPLC Pump

At the start of every day before using your HPLC, you will need to prime the pump.

First of all make sure the purge valve is directing the flow to waste and then ensure there is enough solvent in the solvent bottle and the solvent filter is immersed in the solvent.
Turn the pump on and then as the solvent flows through the plastic lines into the pump, look for air bubbles.
Keep the pump on and in purge mode until all the air has been flushed from the system. This could take several minutes.
When the lines are clear, turn the pump off, close the purge valve and turn the pump back on. I always do this in this order so as to not pressure shock the column. HPLC pumps will have a soft start up function so the pump gradually increases the flow to the required set point. The back pressure will also slowly build up to a maximum pressure. If you close the purge valve while the pump is running the will cause the pressure to change from ambient pressure to possibly several hundred bars instantly and could damage the column by causing column voiding.
Let the pump run to completely flush the system before beginning your first run. A rule of thumb is 10-20 system volumes worth of solvent. In a conventional HPLC system, the system volume will be of the order of 1-2 mls so leave the pump running for 10-20 minutes.

Column Voiding

Column voiding can cause split and / or broad peaks. One of the causes of column voiding is pressure shocking the column. This can be due to the column experiencing a sudden high pressure. When you are priming the system, be sure to turn the pump off before closing the purge valve.

If you happen to close the purge valve while the pump is running, then the sudden extra resistance will lead to a high back pressure. By turning the pump off before closing the valve, when the pump re-starts, it will go through a soft start-up whereby the flow will slowly be increased leading to a gradual build-up of the back pressure.

Pressure shocking the column can also be caused through dropping the column.

eLearning

Chromatography eLearning is yet another way to enhance your chromatography knowledge. While not ever being able to replace a classroom course, eLearning does offer advantages on cost and rich interactive content.

Also, unlike a classrom course you can learn at your own pace and return to the content time after time.

Ardent Scientific offers varying levels of membership for viewing eLearning content. The Single Membership starts at $300 / year and corporate memberships are also available. View here for full details.