A method and apparatus for monitoring fluid in a fluid line are disclosed. The apparatus includes a first capacitor and a processor in communication with the first capacitor. The first capacitor is configured to sense the capacitance of the fluid line at the first capacitor. The processor is configured to compare the sensed capacitance at the first capacitor with a reference capacitance to determine the composition of the fluid in the fluid line at the first capacitor. In some embodiments, the apparatus also includes a second capacitor. The second capacitor is configured to sense the capacitance of the fluid line at the second capacitor. The processor is configured to compare the sensed capacitance at the second capacitor with a reference capacitance to determine the composition of the fluid in the fluid line at the second capacitor.
