Preparation of cibacron blue F3G‐A (polyethylene glycol) in large scale for use in affinity partitioning

The reaction parameters for preparation of Cibacron Blue F3G-A polyethylene glycol have been studied, including temperature, concentration of reactants, and addition of neutral salt (Na(2)SO(4)) as well as ethanol. The yield of dypolymer is strongly dependent on temperature and time of reaction. Preparation in large scale has been done under optimal conditions binding more than 30% of the dye to polyethylene glycol in a low-cost procedure. The effectiveness of this dye-polymer for use in liquid-liquid extraction of enzymes is demonstrated by partition of glucose 6-phosphate dehydrogenase and phosphofructokinase when an extract of baker's yeast is included in a dextran-polyethylene glycol-water two-phase system.