Karl Fischer Reagent Method - method for determining water content of liquid petroleum products (ASTM D 1744) and crude oil (ASTM D 4377 and D 4928), using the Karl Fischer reagent ethylene glycol monomethyl ether solution. Depending on the test, either the standard reagent containing pyridine or pyridine-free Karl Fischer diluted with xylene is used. A current is applied to electrodes immersed in the titration mixture. The material to be analyzed is titrated with the reagent to an electrometric end point, i.e., when the potentiometer needle remains deflected from the reference point. The water content in parts per million can be calculated from the milliliters of reagent used in the titration. See crackle test.