Method to Detect Diesel in Fluid Samples

A method includes providing a cuvette containing a fluid sample having a first substance and emitting light from a light source through the cuvette containing the fluid sample for a duration of time. The cuvette is made of a material that at least partially dissolves in the presence of the first substance. Over the duration of time, the cuvette at least partially dissolves and an intensity of light that passes through the cuvette and the fluid sample changes at a rate. The method also includes receiving, by a light detector, the light that passed through the cuvette, measuring a change in intensity of the received light over the duration of time, and determining that the rate of change in intensity of the light over the duration of time is greater than a threshold rate of change.