So I've got a hot molten salt, hydroxide bath operating at around ~300 to 350 degC. The substrates that I melt have levels of water adsorption that I would like measure. I need to measure the concentration of water in this hot/inorganic/Caustic bath. I'm envisioning some sort of a dip sensor that can detect water concentration. I've looked at FT-IR sensors that can do this but they're expensive. What else do you think will serve my specifications? If you know of anything please provide me a link to that system.