• Features of Packing Material
• Reduced Back pressure
• Scalability
• Linear velocity versus HETP
• Fast LC analysis with conventional LC equipment

When starting to focus on Ultra Fast LC through the use of small particles, very high back pressures have to be considered and a balance sought. The extensive experience in silica production enables YMC to provide small particles with an extremely narrow particle size distribution which results in low back pressures.
YMC’s UltraHT Pro C18 columns offer outstanding effi ciency for Fast LC without exhibiting extremely high back pressure values which can be obtained with sub-2 μm particles from other manufacturers. Therefore YMC’s UltraHT Pro C18 may not require dedicated HPLC equipment for providing outstanding column performances.

Reduced Back pressure

Column: 50 x 2.0 or 2.1 mm i.d. Eluent: acetonitrile / water (60/40) Temperature: 25 °C Sample: butyl benzoate

The introduction of YMC-Pack Pro C18 2 μm allows easy downscaling of existing methods which use YMC-Pack Pro C18 3 μm and 5 μm.

Scalability

Column: 50 x 2.0 or 2.1 mm i.d. Eluent: acetonitrile / water (60/40) Temperature: 25 °C Detection: UV at 270 nm

The graph below shows the dependency of “Height Equivalent of the Theoretical Plate” (HETP) and the linear velocity in the presence of different organic solvents. When methanol is used, the optimum HETP is achieved within a different range of velocity compared to when acetonitrile is used due to their different viscosities. Therefore the optimum range of fl ow rate changes with the organic solvent.
The maximum resolution is obtained by optimising fl ow rate, temperature, and organic solvent in order to achieve the optimum back pressure.

Linear velocity versus HETP*

Column: YMC-UltraHT Pro C18, 2 μm, 50 x 2.0 mm i.d. Temperature: 25 °C Sample: butyl benzoate

Since YMC-UltraHT columns provide substantially lower pressure drop than most competitive 2 μm or sub-2 μm media, high fl ow rates can be achieved without generating excessive back pressure and without the need for specialized equipment. Nevertheless, 3 mm i.d. columns are less affected by the diffusion volume than 2 mm i.d. columns. Therefore, it is neccessary to reduce the system volume in order to obtain outstanding chromatographic performances with 2 mm i.d. columns.

Fast LC analysis with conventional LC equipment

Column: YMC-UltraHT Pro C18   1. Uracil 2. Methyl benzoate 3. Naphthalene 4. Butyl benzoate Eluent: acetonitrile / 20 mM KH2PO4 (10/90)   Temperature: 37 °C   Detection: UV at 260 nm

* Source: Courtesy of YMC Co., Ltd.