Core-shell column：get high efficiency at low pressure

Superior core-shell column

There are mainly two kinds of chromatographic packing materials: silica gel and polymer. Their structural difference makes maintenance and separation results different. Silica based packing materials contain fully porous silica, ethyl bridged hybrid silica, monolithic silica and core-shell silica. Ultra-efficient analytical results of UHPLC can be obtained on a HPLC instrument with a core-shell silica column. Of course, it will be awesome if core-shell column is used on UHPLC instruments.

The core-shell silica consists of a hard core and a porous shell. During the analysis, the sample only needs to pass through a thin porous layer surrounding the surface of the particle, so the diffusion is faster than that of the fully porous column, and the equilibrium time and analysis time are greatly reduced.

Advantages of the Welch core-shell column:

● Provide sub-2μm column efficiency (~200000 p/m) and ultra-high resolution at 50% of sub-2μm column pressure

● Super-fast separation to reduce analysis time and improve efficiency

● Compatible with both HPLC and UHPLC system

● Narrow size distribution

● A standard 2μm frit is used to resist plugging, avoid the high column pressure easily caused by sub-2μm column, provide high performance and long lifetime for complex samples

● Multiple bonding phases provide different selectivities, excellent peak shape and lot-to-lot reproducibility

● Maximun pressure: 600 bar

As figure 1 shows, the same project was analysed with different columns, the peak width of the 2.7 μm core-shell silica column is the smallest of all columns. And it has high column efficiency and fast separation.

Here is a same project analysed by conventional analytical column, UHPLC, and core-shell column. The results showed as following:

It can be seen from the results that the core-shell column maintains ultra-high efficiency, while the core-shell column pressure is much lower than that of UHPLC. Also, its rapid separation performance greatly improves the analysis efficiency.

Separation of flavonoid glycosides from Ginkgo

A: Ultisil XB-C18，4.6x250mm，5um

B: Ultisil UHPLC XB-C18,3.0x100mm，1.8um

C: Boltimate-C18，3.0x100mm，2.7um

From the results, while using the Welch core-shell column for the separation of flavonoid glycosides, the retention time is only about 1/5 of the conventional column’ retention time, and the pressure is only about 1/2 of the UHPLC column’s pressure.

Different projects need different column selectivity, Welch core-shell provides multiple bonding phases for selection, which can meet analysis requirements of complex samples:

The core-shell column not only combines high column efficiency with low column, but also decrease the analysis time greatly. And its pollution resistance is better than that of UHPLC. It is the trend of column development in the future.