How much of a pounding can your Gas Chromatograph take?

Robustness is something that needs to be considered when using a Gas Chromatograph (GC) instrument.  You want a system that is rugged and reliable and able to withstand dirty samples and long batch times, so that you don’t have to spend a lot of time troubleshooting, repairing, or cleaning your GC.  After all, you’ve got samples to process and you need results not headaches!

To demonstrate the robustness of the Lucidity GC-FID, I decided to put it through a test of multiple runs of a diesel fuel standard.  I ordered a 5,000 ug/mL diesel standard from Restek (p/n 31093) and injected 99 times with a beginning blank.

The method that I used to test the robustness of the Lucidity GC-FID is as follows in the table below:

Before running, I made sure to use a new septum, liner, O-ring, and a new column.  I used two vials for the diesel fuel and changed out the cap and septum on the vials periodically, to prevent evaporation.  Then, I started the batch of 100 total injections, one blank and 99 diesel fuel injections. 

Due to the Lucidity GC-FID’s smaller oven size, this batch took around 50 hours to complete.  Much faster than I would have though compared to a conventional GC, a smaller oven cools to the starting temperature much faster. In fact the runs themselves were just under 25 minutes, and the cooldown after a run was less than 5 minutes (even though the oven temp at the end of each run was 300℃), so each run including cooldown time was around 30 minutes, allowing me to process more samples in a shorter amount of time.

The batch was also run using the Lucidity GAS system, which means I didn’t need any gasses, only deionized water.  I did have to top off the GAS system with deionized water once during the batch to ensure that enough hydrogen was produced to complete the batch.

Overlay of Diesel run 1 and Diesel run 99

As you can see, the injections suffered no significant change in retention time over the course of the 99 diesel injections.  The retention time of the largest peak in the center was 11 min 40.1 sec for run 1 and 11 min 40.1 sec for run 99, and the overall %RSD for all 99 runs for that one peak was 0.05%.

After the 99 injections, the GC was subjected to a blank run that showed carryover, as expected after 99 injections of a 5,000 ug/mL diesel standard.  

First blank run after 99 injections of Diesel fuel

Due to the carry over, I changed the liner, O-ring, and septum and performed two bake out runs, where I had the oven go to 350C and hold there for 40 minutes.  Then, I did 3 blank runs just to ensure that everything was clean.  After the 3 blank runs the Lucidity GC-FID was ready to run again!

Chromatogram of the 3rd blank after changing out septum, liner, and O-ring

Overall, the Lucidity GC-FID is capable of long-term runs while being left unattended, and it can run dirty samples without contamination of the entire GC-FID system, all while not requiring gas cylinders.  And once the runs are finished it is easy to get the Lucidity GC-FID clean and ready to run another batch.

Now that the GC-FID survived this test, we’re gonna see what else it can handle… stay tuned…