The last six years have seen the introduction of a new generation of core-shell particles, all around 2.6 μm in particle size. A distinguishing characteristic of these particles is that they provide efficiencies on par with or better than most sub-2 μm fully porous media on the market. Due in part to the particle size and narrow particle size distribution, the back-pressure of columns made with such particles is about 30 % higher than what you would get on 3 μm fully porous particle columns. Using these columns it is possible to get UHPLC performance on more traditional instrumentation, assuming it is 400 bar-capable. However, the column dimensions compatible with a 400 bar-capable HPLC system are somewhat limited, and even further limited if a 200 bar max system is used. It would therefore be interesting to evaluate larger core-shell particles and the resulting trade-off between efficiency and back-pressure. In this paper we investigated a new 5 μm core-shell material that gives nearly twice the efficiency of traditional 5 μm materials with no increase in back-pressure.

We compare the performance of the new material to traditional fully porous materials in different applications. We will also show that, because this material has the same surface area and surface chemistry to a 2.6 μm core-shell material, scaling between HPLC and UHPLC is possible.