How does one determine how many HyNic molecules are bound to my biomolecule?

2-Sulfobenzaldehyde is a water-soluble aromatic aldehyde reagent used to quantify the molar substitution ratio (MSR) of HyNic-modified proteins or other biomolecules. This aromatic aldehyde reacts with HyNic-modified biomolecules and forms a quantifiable hydrazone absorbance signature at 390 nm.