Speciation of Se(IV) in marine sediments using neutron activation analysis after co-precipitation 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°C for 2 weeks and ground to<200 mesh size prior to the analysis. The powdered samples were dissolved by microwave digestion using a MDS-81D Microwave Digestion System. The quantitative determination of Se(IV) was done by co-precipitating the Se(IV) dibenzyldithiocarbamate complex with phenolphthalein (DBDTC-Pp) followed by irradiation of the Se(IV) forms in a neutron flux of 4×1012 neutrons cm−2 s−1 from a TRIGA Mk.II reactor at the Malaysian Institute of Nuclear Technology and Research (MINT). The Se(IV) species concentrations were calculated using the 136.0 keV γ-rays of the 75Se by the comparison method. Standard reference materials, such as SL-7 SRM supplied by IAEA was used to provide good quality assurance control. The results showed that the concentrations of Se(IV) in the sediment samples are 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) concentrations along the South Johore coastal area showed some variations with locations and strata.