A new approach for measuring water concentration in oil using copper sulfate powder and infrared spectroscopy.

An approach for measuring water concentration in oil, based on the use of CuSO particles and infrared spectroscopy, is described. The particles interact with both dissolved water and water droplets to form the monohydrate, CuSO·HO. These particles are collected on an infrared transparent membrane and then an infrared spectrum in transmission mode is recorded. Strong interaction of the water with the CuSO shifts and intensifies the water bending mode to produce a unique band at 1743 cm. The method provided values which are equivalent to those measured by Karl Fischer titration over the range of 10 to 3500 mg L with a linearity R value of > 0.99 and an average %RSD for all measurements was 6%. No matrix specific calibrations are required.