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Choosing the Right QuEChERS Extraction Salt


QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) sample preparation has grown rapidly in popularity. Originally used for pesticide residue analysis in food commodities, this technique has expanded in to many other matrices. But, that can lead to tough questions, such as how to select the right salt mixture for an extraction. Here we share some information on how to make the best choice.

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Hi, and welcome to this Restek Tip, where we’ll be talking about QuEChERS extraction salt selection. So, you’ve decided to try QuEChERS, awesome. You go, and you look for the products that you’re going to need, and you’re going to find that the extraction salts come in three basic varieties. There is the original method. And then there are two methods which represent revisions on the original method, named, the EN method and the AOAC. And they’re just named after the bodies that published the specific methods. 

So, which one are you going to pick? To understand which of these two options, the revised methods or the original methods, you need to understand the distinction between the two. The original method is also sometimes referred to as the unbuffered method. So, what does that mean? Being unbuffered, it means that the final sample pH is going to be determined pretty much solely by the commodity. It will be what it will be. 

In contrast to that, the two revisions, the EN and the AOAC, are both buffered methods, which means they have salts that are intended to specifically land at a range of pH that is going to be very stable for most pesticides. And that is a little bit below 5 for the AOAC method or around 5-5½ pH for the EN method. 

So, which one still do you pick? If you have pesticides that are rock solid and will be stable regardless of the final sample pH, the original method will work great for you. And that’s a lot of pesticides and a lot of matrices. However, if you have concerns about the stability of your sample due to the pH of the actual sample, then one of the buffered methods, and either will be a great place to start for your application, would be what you’d want to choose. 

So, good luck with your next QuEChERS extraction, and thanks for joining us for this Restek Tip.