This lateral flow, chromatographic
assay is reported to produce positive results with hCG
concentrations ≥25 mIU/mL. A urine sample placed on the
membrane reacts with migratory colloidal gold particles
coated with anti-β-hCG antibodies. These antibody-bound
particles then migrate by capillary action to the fixed detection
line coated with either anti-α-hCG or goat-anti-mouse
antibody (control)