Method to detect diesel in fluid samples using partially dissolvable cuvettes

A method for detecting a level of a substance in a fluid sample, the method comprising:

• providing a cuvette containing a fluid sample having a first substance, the cuvette comprising a material that is configured to at least partially dissolve in the presence of the first substance;
• emitting light from a light source through the cuvette containing the fluid sample for a duration of time, wherein the cuvette at least partially dissolves over the duration of time such that an intensity of light that passes through the cuvette and the fluid sample changes at a rate over the duration of time;
• receiving, by a light detector of the system, the light that passed through the cuvette and the fluid sample;
• measuring a change in intensity of the received light over the duration of time;
• determining if the rate of change in intensity of the light over the duration of time is greater than a threshold rate of change;
• and
• outputting, in response to the determination, a signal indicating that the fluid sample includes the first substance.