Speciation analysis of Se-enriched strawberries (Fragaria ananassa Duch) cultivated on hydroponics by HPLC-TR-HG-AFS

•Speciation analysis of Se-enriched strawberries has been performed by HPLC coupled to AFS.•Selenate applied by root irrigation is uptaken, but biotransformation is not observed.•Selenite applied by foliar spray is uptaken and biotranformated mainly to Se–methionine

High-performance liquid chromatography (HPLC) has been coupled to atomic fluorescence spectroscopy (AFS) for speciation of inorganic Se (selenite Se(IV) and selenate Se(VI)) and selenoaminoacids (Se–methionine SeMet, Se–cystine SeCyst and Se–methylselenocisteine SeMeSeCys). A thermoreduction (TR) step is included before hydride generation (HG) to obtain the volatile hydrides of the selenium species before AFS detection. The instrumental coupling HPLC-TR-HG-AFS has been applied for Se speciation in strawberries collected from plants grown on hydroponics and exposed to inorganic Se (Se(IV) and Se(VI)) and one selenoaminoacid (SeMet). Application of Se was performed by foliar spray and root irrigation at concentrations between 0.5–500 mg L− 1. Of the three Se species applied by root irrigation, only Se(VI) was uptaken by the roots, with no significant biotransformation, followed by a sharp disaccumulation after stopping the selenate application. When selenite was applied by foliar spraying at a high concentration, a significant biotransformation was observed, mainly as SeMet. The results indicated that for strawberries, foliar spray is a more suitable route for Se uptake and biotransformation than root irrigation.