I had been using tris buffer and sodium phosphate buffers at ph 7.9 on my anion exchange column. I could see few clear peaks in blank runs ie with out any sample injection. I strongly suspect the reagents as we ruled out the chances of involvement of the column or LC system in this problem. Previously I was using reagents sodium phosphate and tris from other brand, I tried your 99.9% trizma. Now the peak area and peak numbers have come down, but still could see clear peaks. Can I ask you if you have come across such a problem asked to you before and if do you have a better grade tris and Nacl (in eluting buffer) with possible little impurities that are not picked up by anion exchangers.