Comparison of a Validated LC/MS/MS Method with a Validated GC/MS Method for the Analysis of Zeranol and its Related Mycotoxin Residues in Bovine Urine Samples Collected During Argentina's Residue Monitoring Control Program (2005-2012).

The use of zeranol (ZRL), a resorcylic acid lactone, in food animal production has been banned in Argentina since 2004. To enforce this regulation, a GC/MS method developed by the official laboratory was used to confirm ZRL, taleranol, and α- and β-zearalenol from suspect samples. A few years later, a more sensitive LC/MS/MS method was also developed for testing these four analytes plus zearalenone. Both methods were validated according to local standards that are equivalent to 657/2002/EC, and the GC/MS method was accredited under ISO/International Electrotechnical Commission 17025. This paper describes the analytical methods, compares their performances, and presents conclusions derived from their results. When these methods were used on national control plans in which about 1262 samples were analyzed annually over the 2005-2011 sampling period, the incidence rate for noncompliant samples analyzed by GC/MS ranged from 0.3 to 4%. Of the 1500 samples analyzed in 2012 by both methods, the noncompliance incidence rate was only 0.3%.