4-Hydroxy-3-Nitrophenyl Acetate-OVAL (Ovalbumin) is a hapten-carrier protein conjugate formed by coupling 4-Hydroxy-3-Nitrophenyl Acetate (NP) to chicken ovalbumin (OVA). As a hapten, 4-Hydroxy-3-Nitrophenyl Acetate alone cannot induce an immune response and must be conjugated to a large molecular protein to become a complete antigen with immunogenicity. 4-Hydroxy-3-Nitrophenyl Acetate-OVAL (Ovalbumin) may be supplied as a lyophilized powder or as a solution. The solution is prepared in 0.01 M PBS (pH 7.4) buffer at a typical concentration of 1 mg/mL.