FIG. 2.

Electrochemical data collected in vitro showing the response of a platinum electrode, biased at 600 mV, to H₂O₂ added to a PBS solution (mean data are shown in black, error bars shown in gray). After the addition of H₂O₂, there were three doses of aspart insulin that were sequentially added to the solution. There was a large initial rise in current in response to the aspart, but over time, a pattern of electrode poisoning emerged as the current declined below the H₂O₂ response baseline.