Agilent ZORBAX 300Ã… StableBond columns are an ideal choice for the reproducible separations of proteins and peptides for two reasons. Wide-pore, 300Ã… columns are necessary for an efficient separation of proteins and peptides, or other large molecules, in order to allow these analytes to completely access the bonded phase. Second, 300StableBond columns are unmatched in their durability at low pH, such as with TFA-containing mobile phases. For LC/MS separations at low pH, 300StableBond columns can also be used with formic acid and acetic acid mobile phase modifiers.