Human Pro-Cathepsin B ELISA Kit PicoKine® (96 Tests) . Quantitate Human CTSB in cell culture supernatants, serum, plasma (heparin), saliva and urine. Sensitivity: 20 pg/ml. The brand Picokine indicates this is a premium quality ELISA kit. Each Picokine kit delivers precise quantification, high sensitivity, and excellent reproducibility. Only our most reliable and effective kits qualify as Picokine, guaranteeing top-tier results for your assays.