A needle is used to break the barrier between the TLC chamber and the mobile phase chamber. The rubber septum maintains the hermetic seal before and after breaking the barrier. 4. The cartridge is rotated to allow the mobile phase to flow through the opened barrier and contact the TLC plate. 5. The TLC plate is kept in this upright orientation to allow the TLC plate to fully develop in 13 min. 6. The cartridge is rotated back down to allow the mobile phase to drain out of the TLC chamber stopping the development of the TLC plate. 7. The TLC plate can now be imaged to quantify band intensity.