ELECTROCHEMICAL DETERMINATION OF WATER IN ENVIRONMENTAL HYDRAULIC FLUIDS USING THE FISCHER,KARL REACTION

Different procedures based on the Karl Fischer reaction were investiga ted with respect to their applicability for water determinations in en vironmental hydraulic fluids: (i) continuous coulometry using a recent ly described diaphragm-free cell; (ii) on-line stripping of water at e levated temperature using either continuous coulometry or direct poten tiometry for detection of the liberated water, Except for one of the o ils, Statoil PA, which is a poly(alpha-olefin) with certain polymers a dded, no significant difference was found among coulometry using an op timized imidazole-buffered methanolic reagent containing 75% (v/v) chl oroform, the two different stripping techniques (working in the temper ature interval 100-110 degrees C), and the commercially available Hydr anal Coulomat AG-H. The high stability and sensitivity of the coulomet ric technique described made it possible to work with sample amounts i n the low milligram-range, and this is shown to increase the reliabili ty of the coulometric method as compared to normally used procedures.