I have 2 columns:
1. Waters IC-Pak A HC 4.6 x 150mm, 10um. capacity: 30 +/-3ueq/mL
2. Alltech Allsep Anion column 4.6 x 50mm, 7um.

Both are methacrylate based with quaternary ammonium functional group.

Is the Alltech column with smaller particle size a better one?
For separation of common anions such as nitrate and nitrite, which IC column in the market is the best in terms of peak shape and lowest detection limit?

Thank you very much.