CarbonX for QuEChERS Greatly Improves Planar Pesticide Recovery
Currently graphitized carbon black (GCB) is generally used for dispersive solid phase extraction (dSPE) cleanup of pigmented QuEChERS samples. While this product does remove the pigments and sterols found in matrices such as spinach, it also drastically affects the recovery of planar pesticides such as Chlorothalonil, Chloropyrifos, Chloropyrifos-methyl, Folpet, and Coumaphos. The manufactured product CarbonX for QuEChERS, on the other hand, also removes the pigments and sterols during dSPE cleanup while retaining high recoveries of planar pesticides. Generally to improve the recoveries of these pesticides when using GCB toluene is added in a separate step. This increases the time necessary to perform the cleanup as well as introducing a toxic solvent to the process. CarbonX for QuEChERS has all the benefits of this process without the need for toluene.
Figure 1. Comparison of recoveries of planar pesticides when spinach matrix is put through dSPE cleanup with GCB (blue) and CarbonX for QuEChERS (red). Spiking levels of pesticides is 50 ng/g.
Figure 2. Comparison of recoveries of planar pesticides when spinach matrix is put through modified dSPE cleanup with GCB and toluene (blue) and original dSPE cleanup with CarbonX for QuEChERS(red). Spiking levels of pesticides is 50 ng/g.
It is clear that without the addition of toluene the recovery of planar pesticides with GCB is quite low, especially for Chlorothalonil and Coumaphos. The recoveries of these same pesticides is excellent with CarbonX for QuEChERS. Even when the modified dSPE method with toluene addition is run with GCB the recoveries of the pesticides are as good or better when run with CarbonX for QuEChERS, without the need for toluene addition. CarbonX for QuEChERS offers a more rapid cleanup process of pigmented samples without the need for toxic solvents.