Analytical Quantitation and Confirmation of Cyano Metabolite by High-Resolution Mass Spectrometry: Residue Depletion Study in Shrimp Treated with Nitrofurazone

A high-resolution mass spectrometry (HRMS) method was developed and optimized for quantitative and confirmatory analysis of the nitrofurazone (NFZ) cyano metabolite in shrimp. Extraction with 80% acetonitrile: buffer, salting out, and solid phase cartridge cleanup resulted in 87-112% recovery, <10% precision, and good sensitivity with 0.02 ppb limit of quantitation. Current monitoring of unauthorized NFZ use in aquaculture relies upon semicarbazide (SEM) metabolite detection; however, the natural occurrence of SEM in some crustaceans has raised interest for an alternative biomarker. The developed method was used to investigate the suitability of cyano metabolite as an alternate biomarker for unauthorized use of NFZ. In NFZ-incurred shrimp, the cyano metabolite depleted rapidly, with no detection after 6 days, while SEM was detected for at least 20 days. The short-lived stability of cyano metabolite limits its potential for nitrofurazone surveillance in shrimp. However, the method may be adequate for NFZ surveillance in other food animal matrices.