Solution color Brownish yellow to brownish red Enzymatic Specific Activity >100,000 units/ml Aryl Sulfatase Activity <20,000 units/ml β-Glucuronidase Activity Unit Definition: One unit will liberate 1.0 microgram of phenolphthalein from phenolphthalein glucuronide per hour at pH 3.8 at 37 deg C. (30 minute assay) Sulfatase Activity Unit Definition:Enzyme specific activity is defined as one unit causes the formation of one micromole of p-Nitrophenylglucuronide per minute at 37 C and a pH of 6.8.