A monitoring system enables in-situ monitoring of a solution enclosed within a high-pressure, closed loop environment. The monitoring system includes a calcium fluoride disk that is substantially transparent to infrared light. A hole is configured through the disk and a solution passes through the hole. Solution passing through the hole is analyzed by directing infrared light through the disk and the solution currently moving through the hole in the disk. The light exiting the disk is collected and analyzed to determine the composition of the solution through which the light passed.