BIOSENSOR FOR THE ENANTIOSELECTIVE ANALYSIS OF THE THYROID HORMONES (+)-3,3′,5-TRIIODO-L-THYRONINE (T3) AND (+)-3,3′,5,5′-TETRAIODO-L-THYRONINE (T4)

ABSTRACT An amperometric biosensor based on L-aminoacid oxidase is proposed for enantioselective assay of (+)-3,3′,5-triiodo-L-thyronine (L-T3) and (+)-3,3′,5,5′-tetraiodo-L-thyronine (L-T4), due to the fact that only the L enantiomer has the hormonal activity. The construction of the amperometric biosensor is simple and reproducible. The analytical information obtained from enantioselective analysis are reliable. The RSD <1% assured by using the amperometric biosensors for L enantiomers assay as raw materials, and from tablets, demonstrated their suitability for the analysis of T3 and T4 at ppb concentration levels.