LC Troubleshooting—Retention Time Shift

Description

What can cause my retention times to change when I am doing liquid chromatography? There are lots of potential causes and temperature fluctuations, leaks, and particulate contamination are a few of them. If we want to maintain stable, reproducible retention times, there are a few things that we should monitor and maintain, and when we do that, they should be rock solid. 

Additional Resources

• LC Column Cleaning Recommendations
• Shifting Analyte Retention Times or Matrix Interferences?

Restek Recommended Tools & Parts

• LC Columns

Transcript

Hey everyone, welcome to another Restek tip. Today we are going to talk about troubleshooting LC retention time shift. Retention times must be reproducible from run to run. When problems occur, late, early, or variable retention times may be observed. Let’s say we are doing some liquid chromatography and we start seeing retention time shifts over subsequent runs. One possible reason for this could be a leak in the system. If there is no leak, then check the flow rate manually. Sometimes inadequate degassing, faulty check valves, and pump seal failure may also cause flow instability. Temperature fluctuations can also cause shifts in retention time; therefore, it is important to use a thermostatted column compartment to maintain the column temperature throughout the day. You should always strive to match the aqueous to organic ratio as well as the buffer strength of the sample diluent to the start of the gradient. If we do not, it can affect analyte retention time and peak shape.

Another reason could be sample overloading—injecting more sample than the column can hold often results in broader peaks with tailing from diffusion. Lastly, column fouling due to the buildup of particulates from the sample matrix can cause changes in retention times and increased back pressure. Column flushing or simply changing the column can solve the problem. Check with the column manufacturer to find the suitable wash solvent for your column. So those are some of the common causes and solutions for retention time shifts.

I hope these tips make it easier for you to troubleshoot the next time you observe variable retention times. If you enjoy these videos, please like, share, and subscribe. You can share your own ideas for a future tip in the comments below. Thank you so much for joining us for this Restek Tip.