A formazin suspension was prepared by mixing 7.5 mL of hydrazine
sulfate solution (10 mg/mL) and 7.5 mL of hexamethylenetetramine solution
(100 mg/mL) in a final volume of 100 mL to yield a reference
standard of 600 Formazin Turbidity Units (FTU). The turbidity of MP
(2 mg/mL) was monitored at room temperature by determining absorbance
at 600 nm with standards from 0 to 600 FTU. The turbidity of MP
was expressed as FTU per mg protein.