Microfluidic heavy metal immunoassay based on absorbance measurement

► A rapid, sensitive, and cost-effective microfluidic heavy metal immunoassay system based on absorbance measurements using gold nanoparticle-labeled antibodies. ► Using monoclonal antibodies specific for cadmium, chromium, or lead, the theoretical (antibody Kd-limited) levels of detection were achieved. ► The dynamic ranges of these assays satisfied the Japanese environmental standard for cadmium, chromium, and lead in waste elution. ► Multiplexed cadmium immunoassay was also successfully developed using integrated microchannel device.