A general purpose hydrophobic alkyl phase that is very retentive and gives good peak shape for a wide variety of compounds.. Parameter: =70 °C temp. limit. Application(s): HPLC: suitable. Sold in each. . . Sigma-Aldrich 58230-U SUPELCOSIL LC-18 HPLC Column, 5 µm Particle Size, 4.6mm ID, 15cm Length. Country of Origin : United States. Part Number : 1180Q77EA. Pack of : 1.