An experimental design study of interferences of clinical relevance of a polytyramine immobilized-enzyme biosensor

The use of a central composite experimental design to determine the extent of interferences of an enzyme biosensor is described. In contrast to method s that change the parameters to be optimized one-at-a-time, simultaneously varying all parameters in a statistical design allows estimation of coeffic ients that describe interaction between the effects of the interferents and analyte. The analysis also gives the sensitivity (i.e., the slope of the c urrent against concentration plot) for the analyte and interferents. The mo del system chosen was a glucose sensor in which glucose oxidase was immobil ized in electrodeposited polytyramine, with interfering compounds of clinic al relevance, uric acid, ascorbic acid and paracetamol. An electrode prepar ed by cyclic voltammetry of tyramine with three to fifteen cycles effective ly reduced the level of interference.