Optimized Extraction and Cleanup Protocols for LC/MS/MS Multi-Residue Determination of Veterinary Drugs in Milk

This application note presents a method for optimized sample preparation and analysis protocols developed for tandem LC/MS/MS determination of a wide variety of veterinary drug residues in milk samples. Samples are initially precipitated and extracted with an equal volume of acetonitrile. The resulting extract is treated with acidified acetonitrile to precipitate remaining proteins, followed by a simple SPE cleanup using Sep-Pak C18 cartridge. After evaporation and reconstitution, the sample is analyzed using tandem LC/MS.