Separation and Purification of ε-Poly-L-lysine with Its Colorimetric Determination Using Dipicrylamine.

A separation method for a biopolymer, ε-poly-L-lysine (εPL), with its colorimetric determination using a yellow anionic dye, dipicrylamine anion (DPA(-)), is presented. The εPL-producing culture broth was mixed with a NaDPA solution to precipitate the εPL in polycationic form with the DPA(-) anion. The precipitate was dissolved into acetonitrile (AN).