Apparatus and process for reducing peristaltic pump noise in a high impedance electrochemical measuring system

An improved high impedance electrochemical measruing system having reduced peristaltic pump noise, said system including a high impedance measuring electrode for analyzing a fluid sample, a peristaltic pump having an elastomeric tubing streteched over rollers, and a fluid conduit extending from a first end of said elastomeric tubing to said measuring electrode, said rollers being movable over said elastomeric tubing for moving said fluid sample through said fluid conduit between said pump and said measuring electrode, said improvement comprising:

• a nonconductive fluid segment having a first impedance, said fluid segment being disposed in said fluid conduit for electrically isolating said pump and said measuring electrode;
• and
• an AC capacitive ground having a second impedance less than said first impedance, said AC capacitive ground being electrically connected to said fluid sample adjacent said first end of said peristaltic tubing for damping the peristaltic pump noise generated by said pump without significantly affecting the response time or precision of said measuring electrode.