Occurrence and Quantification of Resorcylic Acid Lactones in Porcine Urine Using LC-MS/MS: Evidence from Albania

Abstract

Resorcylic acid lactones (RALs), including zearalenone (ZEN), zearalanone (ZAN), α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), zeranol (α-ZAL) and taleranol (β-ZAL), comprise a group of compounds of considerable importance in veterinary food safety due to their estrogenic activity. Among them, zearalenone is a naturally occurring Fusarium mycotoxin frequently detected in cereal-based animal feed, whereas the administration of zeranol as a growth-promoting agent is prohibited within the European Union. The present study aimed to investigate the occurrence of RAL residues in porcine urine samples collected in Albania using a validated confirmatory liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Sample preparation involved solid-phase extraction (SPE) for purification prior to instrumental analysis. A total of 27 porcine urine samples were collected from different geographical regions of Albania between 2023 and December 2025 in accordance with national sampling procedures. Five samples exceeded the decision limit for confirmation (CCα) and were therefore classified as non-compliant. The detection of non-compliant samples indicates possible exposure of pigs to estrogenic RAL compounds, potentially associated with contaminated feed or the unauthorized use of zeranol. The findings provide valuable baseline data on the occurrence of RALs in porcine urine in Albania and emphasize the importance of routine biomonitoring programs for supporting food safety surveillance and regulatory control.These findings highlight the need for continued monitoring and expanded surveillance to ensure compliance with food safety regulations and to protect animal and public health.