Veterinary Drug Residues

The use of veterinary drugs may be integral to the process of raising food producing animals and fish. These compound types include:
  • Antibiotics (aminoglycosides, chloramphenicol, fluoroquinolones, malachite green dye, etc.) used to inhibit microbial growth
  • Feed additives (hormones and steroids) used to increase yield

It is possible that residues may remain in the final food or beverage product, even after processing steps. Because elevated amounts of some of these drugs may cause detrimental health effects to humans (including being carcinogens and allergy-triggers), it is important to monitor their levels. Several techniques are commonly used:
  • Extraction/Cleanup using QuEChERS (pronounced ′catchers′): The Quick, Easy, Cheap, Effective, Rugged, Safe sample preparation approach developed by Anastassiades and Lehotay simplifies the sample preparation of pesticides from foods of plant origin. This dispersive SPE method uses bulk materials instead of traditional tube-based hardware. Extraction is done using a solvent (such as acetonitrile) and pre-weighed extraction/buffer salts. After a centrifugation step, the extract is cleaned with bulk sorbents. Several materials are available as QuEChERS cleanup sorbents, each effective for the removal of specific interferences, and can be used individually or in combinations best suited to the sample matrix.
  • Extraction/Cleanup using Mixed Mode SPE: One difficulty in the analysis of drugs in complex matrices is that the sample preparation process tends to capture many non-target compounds along with the target analytes. The presence of these interferences may lead to ion-suppression effects when LC-MS is used as the analytical technique. It is necessary to select cleanup steps that remove the interferences from extracts, without also removing target analytes. One approach is to use a mixed mode SPE material, such as Discovery DSC-MCAX. The two ligands blended in this mixed mode hydrophobic-cation exchange material are C8 (provides reversed-phase interaction) and benzene sulfonic acid (provides strong cation exchange interaction). This unique combination of ligands allows aggressive washing steps to remove interferences without loss of target analytes.
  • Extraction/Cleanup using Traditional SPE: Traditional SPE can also be employed for the cleanup of samples prior to analysis. Our Supelclean offering includes tubes with a single sorbent, and also tubes with multiple sorbents. An SPE tube with a multi-layer design allows all cleanups to be accomplished in a single step.
  • Extraction/Cleanup using Molecular Imprinted Polymers: Another approach for the removal of interferences without the loss of target analytes is through the use of molecular imprinted polymer (MIP) materials. MIPs are highly cross-linked polymer-based molecular recognition elements. Their primary feature is that they can be engineered to be highly selective to compounds that are structurally similar. The benefit is increased affinity for the specific compound structure they are engineered for, and decreased affinity for other structures.
  • HPLC Analysis: LC-MS/MS is able to quickly achieve proper identification and low detection limits for large analyte lists. It is critical to use high quality columns, solvents, and mobile phase buffers to minimize artifacts which will interfere with the sensitivity of the instrumentation.
  • GC Analysis: GC-MS is also used as an analytical technique, requiring columns with low bleed and high inertness characteristics.