SPECIATION OF SE(IV) IN MARINE-SEDIMENTS USING NEUTRON-ACTIVATION ANALYSIS AFTER COPRECIPITATION WITH DIBENZYLDITHIOCARBAMATE (DBDTC) WITH PHENOLPHTHALEIN

The determination of Se(IV) forms in marine sediments was performed on core samples taken from a fairly polluted environment. Sediment core samples were sliced into strata of between 2 and 3 cm thickness, dried at 60 degrees C for 2 weeks and ground to < 200 mesh size prior to th e analysis. The powdered samples were dissolved by microwave digestion using a MDS-81D Microwave Digestion System. The quantitative determin ation of Se(IV) was done by co-precipitating the Se(IV) dibenzyldithio carbamate complex with phenolphthalein (DBDTC-Pp) followed by irradiat ion of the Se(IV) forms in a neutron flux of 4 x 10(12) neutrons cm(-2 ) s(-1) from a TRIGA Mk.II reactor at the Malaysian Institute of Nucle ar Technology and Research (MINT). The Se(IV) species concentrations w ere calculated using the 136.0 keV gamma-rays of the Se-75 by the comp arison method. Standard reference materials, such as SL-7 SRM supplied by IAEA was used to provide good quality assurance control. The resul ts showed that the concentrations of Se(IV) in the sediment samples ar e between 3.93 +/- 0.05 ng g(-1) and approximately 50.17 +/- 0.08 ng g (-1). In general it was found that the distribution of Se(IV) concentr ations along the South Johore coastal area showed some variations with locations and strata. (C) 1998 Elsevier Science B.V.