Preconcentration of selenium compounds on a porous graphitic carbon column in view of HPLC-ICP-AES speciation analysis

The retention of organic selenium compounds on a porous graphitic carbon stationary phase was investigated. Different acids were studied as mobile phases to elute selenocystamine, selenoethionine, selenomethionine and selenocystine. Detection was achieved using inductively coupled plasma-atomic emission spectrometry to provide selenium-specific and sensitive detection. The separation of the four species was carried out using methanoic acid. An important on-column preconcentration was obtained when solutes were injected in nitric acid or trifluoroacetic acid (TFA) media. The large injection volume employed (2,500 µL) allowed us to reach low relative detection limits (2–6 µg/L). The method, employing TFA as injection solvent and methanoic acid as the eluent was found to be robust with respect to different matrices spiked with selenocompounds.