Flowcell.

The Next step was to measure ultraviolet light absorption. I found a ready-to-use UV-measuring cell on eBay, which had a UV-lamp (uses a 12V battery) and an UV-sensor, which was able to work at 3,3V- voltage, that Arduino can provide- and measures at 280nm. Sadly enough, I did not had enough time to build a measuring cell by myself- however, it is possible to assemble one with a simple UV disinfection lamp and UV sensors (these can be found on the internet). 

Together with Sebastian we have built a device that creates flow through the cell and is able to inject samples through the septum. I have run many tests with different substances that are UV-active in different concentrations and mixtures.

Here is an example of the separation of Furfural, Triphenylphosphine and Acetonaphthone (I injected 200μl of 1% mixture): The y-axis represents the signal intensity and the x- the number of measurements. Arduino sent measurements every 500 milliseconds, so the whole separation lasted almost 30 minutes and you can see all 3 peaks:

Those tests have shown that it is possible to detect different substances and it is possible to separate them but it had some issues. In order to move solvent through the system we used a vacuum pump, which worked fine until we connected the device to a separating column (stuffed with silica gel). The vacuum was so high, that the gas bubbles developed inside the column and went through the measuring cell. Moreover, the cables and Arduino were not shielded.  As a result the signal had a strong noise and the measurements were not very reliable.