SUPELCOSIL LC-DB phases are specially deactivated for basic compounds. These columns provide shorter retention, better peak shape, and higher efficiency for organic bases than can be obtained on other Type A silica reversed-phase columns.. Surface Coverage: Surface coverage 3.1 µmol/m2. Particle Size: 3 µm. Sold in each. . . Sigma-Aldrich 58978 SUPELCOSIL LC-18-DB HPLC Column, 3 µm Particle Size, 4.6mm ID, 3.3cm Length. Country of Origin : United States. Part Number : 1182K37EA. Pack of : 1.