Indirect ELISA analysis of SMCC was performed by coating wells of a 96-well plate with 50 µL per well of different SMCC conjugations diluted in carbonate/bicarbonate buffer, at a concentration of 1 µg/mL overnight at 4℃. Wells of the plate were washed, blocked with 1%BSA blocking buffer for 1 hour at 37℃, and incubated with 50 µL per well of SMCC monoclonal antibody serial diluted starting from a concentration of 1µg/mL for 45 minutes at 37℃. The plate was washed and incubated with 50 µL per well of an HRP-conjugated goat anti-rabbit IgG secondary antibody at a dilution of 1/80,000 for 30 minutes at 37℃. Detection was performed using an Ultra TMB Substrate for 10 minutes at 37℃ in the dark. The reaction was stopped with sulfuric acid and absorbances were read on a spectrophotometer at 450 nm.