Corresponds to USP number L01: Octadecyl silane bonded to porous silica or ceramic microparticles, 3 to 10 micrometers in diameter.

Features

1. The effects of metal oxides are suppressed to a minimum due to the use of highly-purified silica gel as a base material in the STR series.
2. STR series columns are durable due to the use of mechanically strong silica gel.
3. STR series columns are highly resistant to acidic and basic mobile phases.
4. STR series columns are easy to operate and display high levels of performance due to low analytical operating pressures.
5. Excellent end capping technology provides sharp peak shapes for basic and acidic compounds, and for samples which form complexes with metals.

Durability with respect to acidic solution

Changes in the capacity factor and theoretical plate number for diphenyl on immersion in 0.1% trifluoroacetic acid (pH 2) at room temperature are shown below.

Durability with respect to basic solution

Changes in the capacity factor and theoretical plate number for diphenyl on immersion in 0.1M Na₂HPO₄(pH9)/Methanol = 60/40 at room temperature are shown below.

Pressure drop

In general, analytical pressures rise in the case of eluents used in water-methanol systems. Higher analytical pressure drops cause reductions in column lifetimes and excessively long analytical times due to the inability to flow large volumes of mobile phase. In comparison with regular ODS columns, STR ODS-II columns have extremely low analytical pressures and are easy to use.
The figure below shows analytical pressures when aqueous solutions of methanol and acetonitrile are used as eluents.