RESUMEN
Clenbuterol is a steroid-type drug used in respiratory treatments in both humans and animals. However, it has a secondary effect related to the hypertrophy process in muscle and fat reduction. The illegal or bad use of clenbuterol has been reported in several countries, but there is scarce information in South America, where the production and consumption of meat are considerable. In this sense, the present study aimed at evaluating the occurrence of clenbuterol in bovine muscle and liver samples from a high cattle production area of Ecuador in 2015 and 2018. For this purpose, 57-58 samples were evaluated in 2015 and 20 samples in 2018 using the Enzyme-Linked Inmuno Sorbent Assay and ultrahigh-performance liquid chromatography-tandem mass spectrometry. The results showed complained results for clenbuterol in meat samples from both years and 23% (2015) and 85% (2018) of the samples of meat complied the maximum residue level defined by CODEX.