To investigate the selectivity of the sensor for insulin, the
interference of some coexisting physiological substances in the
amperometric response of the sensor for 15 nM insulinwas studied.
It was found that the interfering effects of glucose at 2000-fold,
ascorbic acid at 700-fold, dopamine at 400-fold, uric acid at 500-
fold, and acetaminophen at 400-fold of insulin concentration are
negligible to the insulin signal. It must be noted that an additional
coating of modified electrode surface with a Nafion film can eliminate
the interfering effects of these compounds at higher concentrations
of the mentioned ones.