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GC Troubleshooting—Split Peaks


Split peaks can show up in gas chromatography when our injection isn’t working right or things aren’t transferring from the inlet to the column correctly. When troubleshooting split peaks, we should pay attention to our inlet configuration and setup, and we should confirm that everything with the injection is working correctly. We also want to make sure we’ve chosen a column stationary phase and solvent that are compatible with one another. 

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Hey, everybody. Welcome to another Restek Tip. We're going to talk about split peaks.

Let's say we're doing some gas chromatography, and we see some split peaks showing up. What might be causing that? If we think about split peaks, in general what's happening there is something is interfering with our sample transfer from the injection port onto the column, in most circumstances. That's not proceeding as a nice, tight band. It's getting spread out over time or separated from one another.

What could cause that? It could be an injection problem. Even something as simple as, our syringe isn't smoothly injecting our sample into the injection port, or it could be that our sample is not making a homogenous vapor cloud inside the inlet before it transfers onto the column.

If aerosol droplets might be making their way onto the column, that could be a contributing factor to split peaks. If we want to manage that a little bit better, we want to have some type of packing in our liner, or a liner with a specific geometry, to help make sure that everything moves into the vapor phase and that no aerosol droplets make their way onto the column.

As for the column itself, we could have some problems there, too, especially a solvent stationary phase polarity mismatch, where the solvent is unable to evenly wet the stationary phase. In order to fix that, what we really want to do is choose a solvent and a stationary phase of more similar polarity, so that they are miscible with one another.

Those are some of the common causes and solutions for split peaks. Thanks a lot for joining us for this Restek Tip.