New electrochemical immunoassay using polarographic catalytic current.

A new electrochemical immunoassay that involves combination of the specific immuno-reaction with the electrochemical trace analysis of proteins using polarographic catalytic current has been designed and tested for a system of bovine insulin test solutions containing interfering substances such as bovine serum albumin and cysteine. Bovine insulin was separated from the test solution by adsorption on immunoadsorbents prepared from anti-bovine insulin antiserum-immobilized gel, followed by releasing by urea. The polarographic catalytic current (Brdicka current) of the released-insulin solution was measured by differential pulse polarography. The detection limit of bovine insulin by this method was 40ng. Analytical aspect of the method has been discussed.