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LC Troubleshooting—Optimizing Your Injection to Improve Peak Shape


Injection volume and solvent choice are among the many factors that contribute to good liquid chromatography. If we inject too much, we can drastically degrade peak shape by causing our peaks to front. At the same time, we want to choose an injection solvent that matches our initial mobile phase conditions. 

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Thanks for joining us today for the latest Restek Tip, where I'll discuss the impact of injection volume and solvent choice on peak shape. We know that, in liquid chromatography, there are a number of factors that can contribute to bad peak shapes. Optimizing injection volume and sample solvent choice are two things that we can look at without really changing many other chromatographic parameters.

When we talk about injection volume, a good rule of thumb is to aim between one and five percent of the total column volume. As we start to exceed that 5%, we'll start to see some peak fronting, which is always a very good indicator that we're reaching capacity and starting to overload our column. Changing our injection volume and reducing that injection volume in that one to five percent range will help mitigate some of that peak shape effect.

Secondly, we can look at changing our sample diluent to match our initial mobile phase conditions. What this does is it avoids that sample and solvent mismatch, and we can start to inject more onto the column without seeing that peak fronting that's indicative of the sample overload.

These are just some things for you to try in your laboratories to help improve peak shape without changing many other chromatographic parameters. Thanks again for joining us for the latest Restek Tip.