Does anyone have experience comparing X-5ms (such VF-5ms, DB-5ms, BPX-5) columns? We would like to use the same column in different instrument for analyses such as pesticides, TPH & BTEX, PCB. We currently use a VF-5ms column from Varian (now Agilent). Do some have lower bleeds than others (although if you read each manufacturer's literature they all claim to be best).