Ultra C18 is an endcapped, monomeric C18 (USP L1) suitable for the analysis of a wide range of compounds from acidic through slightly basic. Pore size: 100A, surface area: 300 m2/gram, carbon load: 20%, pH range: 2.5-8.0. Method development on an analytical Ultra C18 column is highly recommended before purchasing a prep column. Prep columns cannot be returned or exchanged once used.