DETERMINATION OF ORGANONITRILES USING ENZYME-BASED SELECTIVITY MECHANISMS .1. AN AMMONIA GAS-SENSING ELECTRODE-BASED SENSOR FOR BENZONITRILE

Organonitriles are considered an important class of compounds which co ntribute to environmental pollution. A nitrile sensor was developed to directly and selectively measure nitrile compounds in water. Rhodococ cus sp. nitrilase catalyzes the hydrolysis of ben zonitrile derivative s directly into the corresponding carboxylic acid and ammonia. The enz yme was purified and physically entrapped onto the tip of an ammonia g as sensing electrode using cellulose dialysis membranes. The resulting nitrile sensor was relatively stable for up to 4 days at 4-degrees-C, after daily use at room temperature. It can be reliably used in the p H range of 6-9. The sensor is demonstrated for the detection of benzon itrile in neat water samples at concentration levels as low as 1 X 10( -5) M.