What is SPP and when should I use a Raptor column?

While this sounds like a very broad question, I’m sure it is crossing some of your minds. To start out, SPP stands for superficially porous particles. It has also been called “core-shell”.   If you are a veteran in the world of HPLC, this term is old hat for you. If you are new to the game, some explanation might be helpful. Here are a couple of links to articles you could read to brush up on the topic:

Characteristics of Superficially-Porous Silica Particles for Fast HPLC: Some Performance Comparisons with Sub-2-µm Particles

The Increasing Role of Superficially Porous Particles in HPLC

SPP particles are silica based, but they have a solid core with an outside porous layer. In our case, for Raptor columns, we have columns with diameter of 2.7 µm, composed of a 1.7 µm non-porous core and a 0.5 µm porous outer layer. We also have 5 um diameter particles, composed of a 3.3 µm core and 0.6 µm outer shell.

 

The greatest benefit of using a column with SPP particles is increased efficiency without an increase in backpressure. Particularly for the 2.7 µm particles, you can obtain separation that resembles that of a UHPLC column (1.9 µm fully porous particle), at a pressure that is closer to that of traditional HPLC. This is because pressure is mostly a function of outer diameter, regardless of porosity. The consequence of this is that you don’t need an expensive UHPLC instrument to use our Raptor columns.

You might ask, “Why the increase in efficiency?”. Hopefully you can take time to read up on this if you’re interested, but in summary, the transfer time of molecules through the porous layer is greatly reduced. This, in turn, reduces the diffusion terms in the Van Deemter Equation, which automatically increases efficiency. More discussion of this phenomenon can be found in the FAQ section of our website. Other advantages of our Raptor columns are described in our product brochure, “Dissecting Raptor LC Columns”.