>98% [HPLC]. Free 4MU < 200ppm.
Phosphatase substrate: H. Neumann, Experientia, 4, 74 (1984); H.N Fernley and P.G. Walker, Biochem. J., 97, 95 (1965). Differentiation of mycobacterial strains: J.M. Grange, J. Clin. Pathol., 31, 378 (1978).