Expert Insight: How to overcome challenges and improve your semivolatile organic compound analysis

Semivolatile organic compound (SVOC) analysis can be tough. When analyzing acidic, basic, or neutral compounds, you need a column with a balanced, highly inert deactivation that is also rugged enough to withstand repeated injections of challenging matrices, such as wastewater and hazardous waste extracts.

In this free on-demand SelectScience^® webinar, discover how the Rxi-SVOCms columns were designed and built from the silica surface up to perform reliably and consistently under the harshest testing conditions. Whether it is PAH analysis in under 10minutes or a wide calibration range for routine 8270 analysis, there is an Rxi-SVOCms column to meet all needs.

Key learning objectives

• Learn how the specific challenges of SVOC analysis were used to guide development of the Rxi-SVOCms
• Examine how the inertness of the column impacts sensitive analytes
• See how the column performs over time and how routine maintenance restores performance

Read on for highlights from the live Q&A session, or watch the webinar on-demand, at a time that suits you. 

Do you recommend using a guard column when running dirty samples?

Restek: We've found during testing and development that the performance holds up fairly well with a large amount of the column cut away eventually. When you're using a guard column, you run the risk of leaks damaging the stationary phase with whatever union you're using to couple the guard to the analytical column. I suppose the only times when I would recommend it would be for large volume injection to improve the peak shape, so you don't have solvent flooding the analytical column.

If you don't like your retention times moving around from trimming, you can use a sacrificial piece of the analytical column from another column and replace, I suppose the head of the column in 2-m or 3-m segments, so that your peaks all stay in the same place most of the time.

Are any of the Rxi-SVOCms columns manufactured with an integrated guard?

Restek: They are not. It's possible that we will release something in the future, as the technology behind the column doesn't prevent it. However, with an integrated guard, there's some migration of non-volatile or really low-volatility material from the head of the column down through the deactivated tubing or the retention gap to the head of the analytical column. As a result, you end up having to remove the integrated guard, and trimming the head of the column, and then reattaching the guard. That's one of the reasons why we opted not to go forward with the integrated guard for this application.

Is the column good for benzoic acid and Kepone^® analysis?

Restek: The column works very well for a large group of pesticides that are generally considered troublesome by GC because they're rather reactive. Kepone is one where it shows a very good response with minimal degradation. Benzoic acid isn't really soluble in any GC phase. That's why it shows up more as that smear than a peak. But yes, the column is inert enough that you can get a linear calibration with benzoic acid. It's just not going to look very good.

Can I run this column with hydrogen as the carrier gas?

Restek: Yes. The hydrogen limitation more comes from the instrument manufacturer or the instrument’s capabilities. I'm only familiar with Agilent's mass spec when it comes to hydrogen. Your source assembly should have a serial number on the magnet or the serial number has to be beyond a certain number. I would suggest checking with the manufacturer before running hydrogen, but the column itself is compatible with hydrogen and nitrogen as carrier gases.

If you are trying ultra-low-level PAHs by SPME Arrow techniques with both immersion and headspace methods, will the new column phase help in achieving recoveries above 80% for analytes such as indeno, dibenzo, and benzo GHI anthracene?

Restek: I suspect that the poor recovery has more to do with the desorb settings for the injection using the arrow. The column shouldn't really have anything to do with that. I would play around more with the preheating before doing the desorb, possibly even incorporating some labeled deuterated PAHs to use as isotope dilution standards to correct for the loss. I would check more into the sample preparation and the injection for that type of issue.