QuEChERS Extraction of Seafood -- PAHs, Now PCBs and Organochlorine Pesticides

Previous posts on this subject noted good spike recoveries for PAHs at the 10 and 100 ng/g level from seafood, including scallops, shrimp, and oysters. The beauty of QuEChERS is its multiresidue extraction capability, so it was no trouble to report data for PCBs and organochlorine pesticides, in addition to the previously determined PAHs. That’s what you see in the table. In summary, the results were easily good enough for a quantitative screening method, although I started approaching some limits of detection for certain pesticides at the 5 pg/µL (100% recovery level in QuEChERS extract for 10 ng/g spike).

• Sample preparation on fresh seafood was homogenization with water.
• EN 15662 QuEChERS salts were used with acetonitrile extraction in PTFE centrifuge tubes.
• C18 was used for dispersive SPE cleanup.
• A batch of 10 QuEChERS extracts of seafood can be ready for instrumental analysis in about 1 hour.
• A fast GC-TOFMS method with a 15m x 0.25mm x 0.25µm Rxi-5Sil MS column allowed a 12 min analysis time, or about 5 samples per hour.
• 13 PAHs, 19 PCBs, and 20 organochlorine pesticides were quantified using this approach in scallops, shrimp, and oysters extracts.
• Mean recoveries for all samples and analytes were around 100%, but the range of recoveries was wider for the 10 ng/g samples, mainly an indication of interferences on select analytes, or the approach of limits of detection for others.