YMC-Pack TMS columns are bonded with trimethylmonochlorosilane to create a phase with intermediate polarity for analysis of extremely hydrophobic compounds using conventional reversed-phase solvents and highly polar compounds using highly aqueous solvents. YMC-Pack TMS is also well-suited for the analysis of multifunctional compounds. Selectivity characteristics of a C1 bonded phase is unique and samples must be tested to determine the applicability.