The baseline drop in chronoamperometry when using an N2 gas pump for continuous buffer flow in a plastic microfluidics channel could be due to a variety of factors. However, without more information about the specific experimental setup, it is difficult to say for certain. Here are some possible explanations based on the available search results:

• .Air bubbles: Air bubbles can form in the microfluidic channel and interfere with the electrochemical measurements, leading to a baseline drop in the chronoamperogram
• .Electrode fouling: Electrode fouling can occur when the electrode surface becomes coated with reaction products or other contaminants, leading to a decrease in current and a baseline drop in the chronoamperogram
• .Buffer composition: The choice of buffer can affect the electrochemical response, and some buffering systems may be more suitable than others depending on the specific experiment
• .Experimental conditions: Other experimental conditions, such as temperature, pH, and flow rate, can also affect the electrochemical response and should be carefully controlled