A new Sorbent for the Simplified Cleanup of Food Extracts Prior to Multiresidue Analysis

Euan Ross, European Headquarters, Waters Corporation, Wilmslow, United Kingdom

Seafood and other tissue samples are typically extracted with an acetonitrile based solvent for LC-MS determination of veterinary drug residues.  Among the most significant co-extractable substances are fats and polar lipids, particularly phospholipids.  For example, a 1 gram sample of  shrimp muscle typically contains about 100 mg of fat and about 5 mg of phospholipids.  Reversed-phase sorbents such as C18 are effective for removal of fat from the acetonitrile based extraction solvent, but are ineffective for removal of phospholipids.  Excessive amounts of phospholipids can shorten LC column life and contribute to ion-suppression and contamination in the mass-spectrometer.  Results indicate that this new sorbent is highly effective for removal of both phospholipids and fats from meat and milk extracts prior to LC-MS analysis.  With the new sorbent, recoveries of veterinary drugs were similar to results obtained using C18 for cleanup, but phospholipid removal was greater than 80% better.