Behaviour of selenium compounds in FI-HG-AAS
The borohydride active volatile compound formation potential of twelve selenium compounds [selenous acid, selenic acid, selenocystine (Secys), selenohomocystine (Sehcys), selenomethionine (Semet), selenoethionine (Seet), trimethylselenonium iodide (TmSe), selenocystathionine (Secystha), selenocystamine (Secysta), selenourea (Seur), selenocholine (Sech), and dimethyl(3-amino-3- carboxy-1-propyl)selenonium iodide (DmpSe)] were investigated in a FI-HG system with different sodium borohydride concentrations (0.3% in 0.1% sodium hydroxide, and 0.5, 0.7, and 1.0% in 0.2% sodium hydroxide) in the presence of 3 M hydrochloric acid using an atomic absorption spectrometer as selenium-specific detector. Percentage recoveries with respect to selenous acid of selenic acid, Secys, Sehcys, Semet, Seet, TmSe, Secystha; Secysta, Seur, Sech, and DmpSe were 0, 10.3, 19.7, 23.5, 32.4, 13.7, 16.5, 16.5, 11.3, 5.6 and 7.7%, respectively in the presence of 0.3% borohydride stabilized with 0.1% sodium hydroxide. By multiplying the borohydride concentrations, percentage recoveries of TmSe, DmpSe, Sech, Sehcys and Secysta were elevated, whereas those of Semet, Seet and Seur were reduced. However, percentage recoveries of Secys and Secystha remained almost uniform within the entire borohydride range. TmSe exhibited a 105% recovery with respect to selenous acid at 1.0% borohydride concentration, whereas selenic acid was inert to borohydride active volatile compound formation.