Superficially porous columns (SPCs), which consist of a non-porous core fused with a porous outer layer, has been around for nearly as long as other analytical HPLC column-packing technologies. However, in the past several years, the superficially porous column technology has reinvented itself for the ultra-performance HPLC (UHPLC) era. SPCs are used for smaller particles, typically ranging from 2 µm to 3 µm, and enables UHPLC-like separations without the drawbacks of the increased backpressures of a sub-2 µm particle column. As a result, SPCs can be used with conventional HPLC systems.

One of the biggest advantages of the SPC technology is that it provides comparable separation speeds and efficiencies to sub-2 µm UHPLC columns, but without the need to purchase expensive hardware. In fact, SPCs can also be used on most UHPLC systems, which enhance their performance since they experience backpressure that is two or three times less than sub-2 µm columns.

A drawback of SPCs are their lack of scalability to semi-preparative and preparative LC systems. Because the technology is still somewhat novel, many end-users are quite skeptical of SPCs’ performance. For other end-users, switching to SPCs would require regulatory changes, new protocols and other hurdles, all of which take time and can be expensive, making SPCs difficult to implement.

There are only a handful of vendors currently manufacturing SPCs. Phenomenex introduced its first Kinetex Core-Shell columns in 2009 and quickly became the leading supplier of the technology. The particle size of the company’s Kinetex Core-Shell columns measures 2.6 µm, with a 1.9 µm non-porous core and a 0.35 µm semi-porous shell. Sigma-Aldrich Supelco’s Ascentis Express Fused-Core columns are based on Advanced Materials Technology’s (AMT) HALO Fused-Core technology. In fact, AMT was among the first innovators of the technology. AMT’s technology was the focus of a lawsuit brought by Agilent (see IBO 3/15/10). The Ascentis Express Fused-Core columns feature a 1.7 µm solid core with a 0.5 µm porous shell for a 2.7 µm particle size.

Agilent’s Poroshell 120 HPLC columns are based on the company’s superficially porous particle technology. The Poroshell 120 columns feature similar particle sizes to those of the Ascentis Express. Smaller vendors manufacturing SPCs include Michrom Biosciences and Mac-Mod. Both companies manufacture their lines of SPCs based on AMT’s HALO packing material.

The market for SPCs is small compared to the total HPLC column market. However, SPC the market is expected to show double-digit growth as more end-users realize the benefits of the technology. Furthermore, it’s only a matter of time until manufacturers introduce new chemistries, phases and different particle sizes, all of which will affect the market’s growth.

SPC at a Glance:

Leading Suppliers

• Phenomenex

• Agilent Technologies

• Supelco (Sigma-Aldrich)

Largest Markets

• Pharmaceutical

• Biotechnology

• CROs

Instrument Cost

• $300–$1,500