Sunday, 19 June 2016

Breakthrough of our Gas Chromatography

During the last few series of tests for our gas chromtography, our results were quite ambivalently satisfactory and dissatisfactory. On the one hand, there were clearly identifiable peaks that enabled us to recognise the connection between a large surface area for low air humiddity and a small surface area for high humidity. On the other hand, the modulation of our mobile phase (replacing air as the carrier gas by helium) made our base line appear less even. The better the baseline, the easier the following analysis of the peak. Consequently, most of our ambitions were ever since oriented towards a solution to this problem.

Firstly, we identified the cause of our problem itself. In order to plug our helium support into its aspiration port, we use urine bags. Their capacity as well as structure is overall perfectly suitable for our purpose. There is only one thing that we did not consider early on: The tube that we connect to the aspiration port includes a check valve. While this slows down the stream of helium which is good because of our limited supply in Portugal that is much smaller than the one in our huge gas bottle at school, it also makes the stream only a little inconsistent and therefore the baseline uneven.

We then considered possible solutions. While removing the check valve altogether would make our use of helium go beyond the scope of our local supply in Portugal, given also that there is most likely no change of purchasing a sufficient supply, and while replacing the carrier gas or storage again would not certainly lead to an improvement in performance, the only chance was for us to fool the mechanism.

We tried out threading a very tiny tube through the check valve with the idea of keeping the stream of helium constantly up, but at a very low volume-per-time rate. The following experiment delivered the best results that we had ever achieved. Measuring a much higher voltage than before, we were able to change the experiment's zoom view which made most unevennesses disappear. We then created several new series of tests that can now serve as a data basis in the time to come.

At this moment in time, we are finally really satisfied with our gas chromatography and are optimistic to have it work smoothly during our post-flight activities at Santa Cruz.

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