The disclosure provides a method for determining a composition of a fluid. The method comprises diverting a sample of a portion of the fluid to a test chamber. The method further comprises actuating a heat source disposed around the test chamber to increase the temperature within the test chamber to produce vapors from the sample of the portion of the fluid and directing the vapors from the sample of the portion of the fluid to a chemical sensor array comprising one or more chemical sensors. The method further comprises determining a composition of the vapors from the sample of portion of the fluid, wherein the composition of the vapors is associated with the composition of the fluid.