Potentiometric biosensor for control of biotechnological production of penicillin G

A pa-membrane electrode with tridodecylamine as a hydrogen ion-selective ionophore was used for the construction of a biosensor for the benzylpenicillin determination. The electrode was enzymatically modified by covalent binding of penicillinase directly to the membrane surface. The high sensitivity and short response time of the biosensor allow its application in flow injection analysis (FIA). Up to 30 samples per hour can be analyzed in the flow system. The FIA system with the biosensor was successfully used for the determination of penicillin G in fermentation broth. An optimized analytical procedure results in minimization of interferences from pH and buffer capacity of the real samples. No interferences from inorganic, organic and bioorganic components present in the fermentation medium were observed. An important advantage of the presented analytical system is the long-term stability due to the long lifetime of the biosensor. Consequently fermentation bioprocesses can be controlled using the same biosensor for about two months. Due to the high sensitivity and selectivity, the presented method for the penicillin determination in real biotechnological samples gives analytical results comparable to those obtained using methods recommended by pharmacopoeias. (C) 1998 Elsevier Science B.V. All rights reserved.