Method for non-intrusive measurement of low water content in oil

A method for determining trace amounts of water in oil, the method comprising the steps of:

• obtaining a blended sample of a low water content fluid, wherein the low water content fluid comprises an amount of water and an amount of oil, and wherein the amount of water in the blended sample is distributed as water droplets, the water droplets having an average diameter in a range between 30 μm and 70 μm such that the blended sample is a stable emulsion;
• transferring a portion of the blended sample to a cuvette to create a measurement sample, the cuvette having a laser-receptive surface adjacent to a viewing surface, the viewing surface of the cuvette having an opaque sheet applied thereto to form a covered side, wherein the opaque sheet contains a slit such that the position of the slit is fixed for all measurements, wherein the slit if 0.5 mm wide;
• transmitting a pulsed laser beam from a laser source through the laser-receptive surface of the cuvette;
• inducing fluorescence in a fluorescence spectrum of the measurement sample, wherein the pulsed laser beam induces fluorescence, and wherein the fluorescence emits from the slit in the opaque sheet on the covered side of the cuvette;
• focusing the fluorescence through a collecting lens and transmitting the fluorescence to a spectrometer, wherein the collecting lens is located between the cuvette and the spectrometer, wherein the spectrometer comprises a spectrograph coupled with an intensified charge coupled device;
• and
• measuring the fluorescence with the spectrometer, comprising the steps of:
• dispersing the fluorescence with the spectrograph;
• and
• intensifying the fluorescence with the intensified charge coupled device.