A biosensor based on catalase for determination of highly toxic chemical azide in fruit juices

In this work, an amperometric biosensor based on catalase enzyme was developed for the determination of azide. The principle of the measurements was based on the determination of the decrease in the differentiation of oxygen level which had been caused by the inhibition of catalase in the bioactive layer of the biosensor by azide. Firstly, the optimum conditions for the inhibitor biosensor were established. In the optimization studies of the biosensor, the most suitable catalase and gelatin amounts and glutaraldehyde ratio were determined. Optimum catalase activity, optimum gelatin amount and glutaraldehyde percentage were 5000 U cm(-2), 5.94 mg cm(-2) and 2.5% respectively. Characterization studies of the biosensor such as optimum pH and optimum temperature were carried out. The repeatability experiments were done and the average value (x), standard deviation (S.D.) and variation coefficient (C.V.) were calculated as 98.6 mu M, +/- 4.16 mu M and 4.23%, respectively. A good linear relationship with a correlation coefficient of 0.9902 was obtained over the concentration range of 25 mu M to 300 mu M azide. After the optimization and characterization studies the proposed biosensor was applied to the determination of azide in certain fruit juices. (c) 2005 Elsevier B.V. All rights reserved.