Scaling SFC: Column Chemistry for a New Generation of Complex Molecules

In an interview with LCGC International, Jeff Caldwell, owner and president of Princeton Chromatography—a longtime supercritical fluid chromatography (SFC) instrumentation partner to JASCO—discusses nearly three decades developing packed column technology for SFC. As pharmaceutical pipelines increasingly include complex chiral active pharmaceutical ingredients (APIs), peptides, and novel modalities, chromatographers are looking to SFC to keep pace. Caldwell says that shift has already reshaped his customer base, with packed column SFC now supporting small peptides, monoclonal antibodies (mAbs), oligonucleotides, and natural product analysis in the hemp and cannabis space.

What first drew you to supercritical fluid chromatography (SFC), and how has the technology evolved since you started working with it?

We initially started with packed column SFC in the late 1990s. We worked closely with Terry Berger and several industry colleagues on the development of the first suite of SFC specific achiral columns available from a column manufacturer. Following that came the invention and commercialization of the 2-ethylpyridine stationary phase, which is still considered the gold standard for achiral SFC applications. I am so very proud of the ground we broke at Princeton Chromatography in SFC packed column technology, and that work continues to this day. We are continually developing new stationary phases for use in SFC and expanding our range of products.

What trends are you seeing in the types of molecules customers are asking you to help separate—more complex chiral APIs, larger biomolecules, novel modalities?

We’ve seen a migration from small molecule pharma compounds to a more diverse workflow for our customers. There is interest in packed column SFC for small peptides, monoclonal antibodies (mAbs), and even oligonucleotides. Additionally, there is a growing sector for SFC analysis and purification of natural products, especially in the hemp and cannabis space. We’ve developed some unique and powerful column technologies for those applications in the last five years.

Where do you see SFC column and instrument technology heading over the next five years, and what would you like to see instrument makers prioritize next?

It’s our job as a column manufacturer to listen to our customers and do our best to meet their needs. The same holds true for instrument manufacturers. SFC instruments have come a long way in the last 25 years, but there is still more to be done. Providing users with a truly robust instrument and software that is easy to understand and manipulate is key. The barrier to SFC entry is already high vs. high performance liquid chromatography (HPLC), so anything that can be done to make things easier for a more “casual” user could really help push adoption forward.

The push toward greener chromatography has been building across the industry for years now. As that shift plays out—with instrument makers advancing SFC hardware alongside it—how do you see the roles of column chemistry vs. instrumentation in delivering on that sustainability promise?

It’s pretty simple in theory. Column chemistries need to evolve with the expansion of SFC into new areas of research and production. The more efficient and reproducible we can make the chromatography at lab scale, the better the chances of seeing some larger pilot or production level instruments in the field. The benefits of SFC are obvious in terms of sustainability, the mountain to climb is finding the right applications and scaling them. We are already working on some interesting projects that have potential, so these advances are not far off.

High-throughput experimentation and automated screening are changing how labs approach method development generally. How is that shift toward faster, more automated screening changing what customers expect from a supplier?

We see more and more requests for sub-2-µm columns in very narrow i.d. and short length, so there is a shift to faster screening for sure. SFC is unique in the sense that we can flow 2,3,4,5x, or even faster than HPLC. Some analyses are being done in 10–15 s per run. The limitation is how fast the instrument can inject samples!

As drug pipelines increasingly include complex chiral APIs, peptides, and novel modalities, the whole SFC ecosystem—instrument makers, column suppliers, and the end users—has to keep pace together. Where do you see the biggest strain in that ecosystem right now, and who needs to move fastest to relieve it?

The hardest part for us as a column manufacturer is staying up on what the needs of the community are. Things do move quickly, so we’re constantly engaging with our core customer group and colleagues to provide the best solutions for what they are working on now, and where they are going. It’s not always possible to solve every problem quickly, so that is often the challenge.

There's been an industry-wide effort to make SFC less intimidating for labs that have historically lived in HPLC. Thinking about that broader accessibility push—including the training and application support instrument vendors provide—what more do you think the industry needs to do to bring more labs into SFC?

I think having an instrument that’s truly robust with intuitive software control would be the best pathway forward. SFC really isn’t theoretically different than HPLC, there are just more variables and levers we can manipulate to get a separation. Training new users is key and getting them excited about the power of SFC is certainly helpful. SFC will never take the place of HPLC, but it is an incredibly powerful complementary technique that can be leveraged much more that it currently is.

For a lab that's new to SFC and intimidated by achiral method development, what's the single piece of advice you'd give them to get started on the right foot?

Purchase an instrument that you are comfortable with and that has excellent field support. Find a great partner for columns (I can think of one!) and work with that supplier to build a library of stationary phases that meets your needs. Once you have the initial foundation, there is endless opportunity to grow with the technology. Pick industry partners that will support your growth and success long term. There’s a lot of untapped potential for SFC and we’re just getting started!