John working in a biopharmaceutical company and is in charge of purifying insulin (mw 6,000 da, pl =7.3). in the recent experiment, the insulin was contaminated by a glycoprotein (mw-48,000 da, pl= 6.9) and protein a (mw=5,500 da, pl 10.2). john to design a process based on chromatography methods to purify his product