BIOSENSORS BASED ON CRYOSCOPIC OSMOMETRY - A PRELIMINARY INVESTIGATION

Cryoscopic osmometry, the determination of total molality (moles/kg so lvent) by the depression of the freezing point of the solvent through the presence of osmotically active species, has been tested for its ap plicability to biosensor-type concentration determinations in aqueous solution. Sucrose hydrolysis by invertase to yield glucose and fructos e (one osmotically active species converted to two osmotically active species) in the presence of acetic acid buffer pH 4.6 served as the mo del system. Data illustrate the method is applicable to sucrose determ inations in the concentration range 5 mM to 100 mM with an accuracy of better than 1.5% of the total (equivalent to about 2 mM with 100 mM s ucrose under the conditions employed). Advantages and disadvantages of the methodology are discussed.