Abstract

The performance of a quadrupole-time of flight (Q-TOF) tandem mass spectrometer was evaluated for the identification of low-molecular weight selenocompounds in an aqueous yeast extract. The accuracy of mass measurements, evaluated with selenomethionine, selenoethionine and selenocystine standards was found to be between 0.005 and 0.01% (0.01–0.02 u). The low molecular weight fraction was obtained by collecting selenocompounds eluted in the total volume of a G-15 size-exclusion column. The fraction gave three peaks in anion-exchange HPLC of which the identity was investigated by ES-Q-TOFMS/MS. Altogether, eight clusters with the isotopic pattern corresponding to the presence of Se were observed. They were further investigated by collision induced dissociation TOFMS leading to the demonstration of the presence of a series of new selenocompounds, all characterized by the presence of an adenosyl functional group.