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 methods that change the parameters to be optimized one-at-a-time, simultaneously varying all parameters in a statistical design allows estimation of coefficients that describe interaction between the effects of the interferents and analyte. The analysis also gives the sensitivity (i.e., the slope of the current against concentration plot) for the analyte and interferents. The model system chosen was a glucose sensor in which glucose oxidase was immobilized in electrodeposited polytyramine, with interfering compounds of clinical relevance, uric acid, ascorbic acid and paracetamol. An electrode prepared by cyclic voltammetry of tyramine with three to fifteen cycles effectively reduced the level of interference.