-- A standard curve was first constructed from the standards in the kit at concentrations of 0,1,2,4,8,16 pg/ml and added to a 96-well plate according to the instructions.

-- The OD value corresponding to each concentration was determined by microplate reader at the end of incubation in 96-well plates.

-- The software Origin was used to draw the function curve of OD and concentration, and the standard curve was obtained.