The present invention relates to immobilized procainamide analogs, as well as to a method of making immobilized procainamide analogs. These immobilized analogs are prepared by activating the carboxyl group on a substituted p-benzoic acid derivative toward nucleophilic attack; reacting the activated benzoic acid derivative with a polyamine to produce the benzoic acid derivative of Formula 3: and binding the benzoic acid derivative of Formula 3 to a latex polymer having functional groups that react with aliphatic amino groups. A method of conducting an immunoassay using the immobilized procainamide analog Formula 3 is described, comprising the steps of preparing a solution comprising said immobilized procainamide analog; adding a sample suspected of containing procainamide to said solution; adding an anti-procainamide antibody to said solution and observing the rate of increase in solution turbidity following antibody addition.