HPLC is a mainstay technique in analytical laboratories of chemical industries.Typical application areas are the determination of the molar mass distribution of polymers or the analysis of compositional differences of monomers and oligomers.For RP methods new high-speed columns were developed recently which significantly reduce the analysis time.Columns filled with particles smaller than 2 μm furthermore result in an increase of the chromatographic performance.Besides the improved resolution the advantage of sub-two-micron (STM) material is the almost horizontal h versus u-curve at higher linear eluent velocities [1].Thus an about 30 times reduction of analysis time can be achieved while resolution and sensitivity increase by a factor of 3 to 2.These columns are becoming already an important tool in pharmaceutical and biochemical laboratories [2].