Free 4MU < 100ppm.
Free 4-methylumbelliferyl N-acetyl-β-D-glucosamine, product code 44007 (Non-sulfated product) < 0.1%.
Sensitive fluorogenic substrate for Hex A in Tay-Sachs disease: J. Bayleran et al., Clin. Chim. Acta, 143, 73 (1984); G.T.N. Besley et al., NATO ASI Ser., Ser. A,150, 247 (1988).