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Wednesday, September 20, 2017

Method Validation Tip: Do Robustness Studies First

After method development, I find that a lot of chemists will delve into method validation studies like accuracy, precision, etc. but leave robustness for the end. However, I think it is better to do robustness first. The reason for this is that the results can help you further refine the method in ways that you may not have considered during the method development stage.
                Let’s say for example that you do your method development have a perfectly satisfactory separation where your critical peak pair is baseline-resolved. You move on to validation and go through all the necessary studies (e.g. accuracy, linearity, repeatability, intermediate precision, LOD, LOQ, etc.). Then in the robustness studies you find that alteration of one of the method variables actually leads to a superior separation. This was what I found when I varied the TFA concentration. I chose a 0.1% concentration originally during the method development stage but hadn’t given much thought to it at the time. Then in robustness studies, I found that the critical peak pair, which had been just baseline-resolved with 0.1% TFA, became vastly better separated upon a decrease to 0.05%. Before proceeding with the rest of the validation, I could use the 0.05% concentration in my method.
                I hope this information helps you as much as it helped me. I am always learning new tips and tricks to make chromatographic analytical techniques more streamlined and efficient.

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