GC Troubleshooting—High GC Column Bleed

Description 

High bleed is one of the most common issues you’ll encounter when doing gas chromatography. Excessive bleed is often caused by something damaging the stationary phase of the column, things like oxygen from a leak or some aggressive component in the sample. Checking for leaks, installing inline oxygen filters on carrier gas, and taking care to ensure the sample isn’t damaging the column are key steps to eliminating high-bleed problems. 

Additional Resources

• Column Bleed & Septa Bleed—Same Old Thing!
• Ultra–Low Bleed Columns Improve Trace–Level Analysis

Restek Recommended Tools & Parts

• Restek's Inert and Low–Bleed Rxi GC Columns

Transcript

Hi, folks! Welcome to another Restek Tip. We're going to talk about high bleed. In gas chromatography, what is bleed, anyway?

Bleed is the natural degradation process of our stationary phase. It's going to break down a little bit over time, and those components of the stationary phase are going to pass through the column and contribute to some signal. High bleed, though, is when that moves from normal behavior into a problem. The signal's really high, it starts occurring at lower temperatures, unusual circumstances. What can cause that to happen? Something is degrading your stationary phase. Most likely, it's going to be some oxygen. Oxygen is a column killer. It can come into our system from leaks or contaminated carrier gas. Alternatively, we also can damage our stationary phase with aggressive chemicals. Maybe we're injecting some derivatization reagents, or some strong acids, or bases. They also can chew up a column. In that case, likely what we will want to do, take some steps to make our injection a little more mild, so that what we're putting on our column isn't as aggressive. If we get back to the oxygen problem, though, that's something that we want to always keep in our minds. We always want to be leak-checking our GC systems. We always want to be making sure that we are scrubbing oxygen from our carrier gas. Having some type of inline filter to remove that is really important.

Those are the tools and techniques for managing bleed when you're doing your GC work. Thanks for joining us for this Restek Tip.