Analysis of veterinary drug residues in food: The nitrofuran issue

摘要

For many years, nitrofurans were detected using analytical methods that detect the parent drugs. However, it has been known for some time, that these methods are ineffective, since mtrofurans are excreted very rapidly from treated animals and are highly unstable in vitro. Work carried out during the 1980s and early 1990s showed that measuring tissue concentrations of a moiety (AOZ), released from tissue bound nitrofuran residues, could more effectively monitor furazolidone use. An EU funded research project "FoodBRAND", set out to develop screening and confirmatory methods for tissue bound residues of all four of the nitrofuran drugs, resulted in the launch of two commercial immunoassay kits. The demands of the consumer, industry, and the European Union (EU) for increased testing for nitrofurans is now leading to the development of in-house biosensor tests for these compounds. Traditionally, confirmation of veterinary drug residues by single quadrupole MS required the monitoring of at least four diagnostic ions and three ion ratios. In practice, this is impossible to achieve for the nitrofuran metabolites. However, the increasing availability of LC-MS/MS in residues laboratories; coupled with the inclusion of MS/MS in the recently revised EU criteria for the confirmation of drug residues (at least two transition products and one ratio) has greatly increased the applicability of this technique in routine control. This technique can readily meet EU identification criteria and enable the confirmation of tissue bound metabolites of the nitrofuran drugs at sub-ppb levels. The recently developed LC-MS/MS methods are now finding an application in residues laboratories worldwide to control the widespread misuse of these drugs in global food production systems.