The format of an immunochromatographic multiassay is first proposed with native antisera and a universal conjugate of antispecies antibodies with gold nanoparticles. This format allows (1) the exclusion of purification and conjugation stages for specific antibodies and (2) significant reduction of the concentration of specific antibodies in the system. The independent use of specific antibodies and a conjugated marker provided a low detection limit and high signal intensity. The proposed format was implemented for the simultaneous detection of two herbicides. The instrumental limits for the detection of atrazine and chlorsulfuron were 0.1 and 0.7 ng/mL, respectively, and the analysis time was 20 min. The suitability of the test system for monitoring these herbicides in nontreated apple and blackcurrant juices is shown. The assay technique is simple, sensitive, and easily transferrable to any other antigen. Graphical abstract The proposed format of the immunochromatographic multiassay is based on the use of native antisera and a universal conjugate of antispecies antibodies with gold nanoparticles. In this way purification and conjugation stages for specific antibodies are excluded, and the concentrations of specific antibodies and the conjugated marker can be varied independently to obtain a low detection limit.
Keywords: Gold nanoparticles; Herbicides; Immunoassay; Indirect labeling; Lateral flow assay; Test strips.