To complete the prototype device a white LED was also controlled by the Raspberry Pi, using PWM (Pulse Width Modulation) to optionally control brightness of the LED, allowing the effect of varying irradiation brightness to be tested. Initial experiments using this prototype device confirmed our hopes. Using the example code provided by Adafruit and pumping test solutions through the flow cell using a hand operated syringe; THF, IPA (isopropyl alcohol) and ethyl acetate showed differences in absorbance, despite all being colourless liquids to the human eye.