Fungicide effects on ammonium and amino acids of Monastrell grapes

The influence of six fungicides (famoxadone, fenhexamid, fluquinconazole, kresoxim-methyl, quinoxyfen and trifloxystrobin) on the amino acids and ammonium composition of grapes (var. Monastrell) are studied. The treatments were performed under critical agricultural practices (CAP), 6 h before grape collection. The analytical determination of amino acids and ammonium were made using HPLC with a photodiode array detector (DAD), after derivatisation of the sample with diethyl (ethoxymethylene)malonate (DEEMM). The application of fungicides to the vine decreased concentrations of nitrogenous compounds in grapes. Furthermore, the qualitative and quantitative effects on the amino acids in the grapes depended on the type of fungicide used. The fungicides which affected the highest number of amino acids were famoxadone and fenhexamid, while quinoxyfen affected the lowest number of amino acids. Grapes treated with famoxadone contained the lowest concentration of total amino acids.