The use of an inkjet injection technique in immunoassays by quantitative on-line electrophoretically mediated microanalysis

The paper describes a new online quantitative electrophoretically mediated microanalysis (EMMA) for use in immunoassays based on the unique drop-by-drop introduction of a sample by means of an inkjet for capillary electrophoresis (CE). Plugs of a fluorescein-labeled antibody (Anti-humanIgG-DyL550) and human IgG were alternately injected into a capillary using the inkjet, followed by the merging of the plugs and the subsequent immune reaction. The antigen-antibody complex that was formed in the merged zone was then separated by CE. As a proof-of-concept, the method was used to determine human IgG. As a result, both the consumption of the reaction solution and the analysis time were significantly reduced. The method showed a wide linear range (10-2000 ng mL−1, R2 = 0.9912) of calibration and the detection limit (5 ng mL−1) was substantially lower than that by for conventional methods.