QuEChERS firstly came out in 2003. The inventors of QuEChERS, Michelangelo Anastasiades and Steve Lehotay, were asked for the three biggest improvements in this method from development to now. They made the following statement.
In the period of conceiving the method QuEChERS, we have conducted many experiments on a wide range of representative pesticides and samples to evaluate each step of the process of extraction and purification.
The earliest version of QuEChERS proposed in 2003 was good for the tested object and its substrates, which is even better than the current version.
When the experimenters test and verify the method with hundreds of pesticides in different samples, they found that the recovery of about 10 pesticides was easily affected by the pH value of solutions. And when the pH value of solutions is five, the results will be accurate than other values. That’s the reason why they pay attention to the used of buffer in the later methods. This is the first improvement of the method, even if the buffer will lead to an increase of some impurities.
When the experimenters test and verify the method with hundreds of pesticides in different samples, they found that the recovery of about 10 pesticides was easily affected by the pH value of solutions. And when the pH value of solutions is five, the results will be accurate than other values. That’s the reason why they pay attention to the used of buffer in the later methods. This is the first improvement of the method, even if the buffer will lead to an increase of some impurities.
Secondly, adding C18 filler together with PSA can significantly improve the purifying effect of some samples, especially those rich in oil, such as olive oil, which does not cause the loss of the tested products. Some chemists use freezing methods to reduce the interference of lipids, which can also remove some impurities from previous extractions.
By contrast, the method of adding C18 is undoubtedly faster and easier, and the effect of decreasing is comparable to that of freezing.
At last, when removing the impurities such as chlorophyll and carotenoids, the experimenters can add a small amount of graphitized carbon black or the adsorbents as described in CEN standard method 156627.
At last, when removing the impurities such as chlorophyll and carotenoids, the experimenters can add a small amount of graphitized carbon black or the adsorbents as described in CEN standard method 156627.
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