Development of a γ-γ and X-γ coincidence set-up and feasibility studies for direct determination of selenium in biological samples using neutron activation analysis

A γ-γ and X-γ coincidence set-up has been developed for application in Instrumental Neutron Activation Analysis (INAA). The set-up has been applied for the feasibility studies of direct determination of selenium in blood samples. Synthetic samples representing the blood matrix were prepared and were spiked with neutron activated selenium in the range of ∼40-90 ng. The concentration of Se in these samples was determined using singles counting taking a biological CRM DOLT-1 as a standard. The concentration values were used to obtain the calibration plot for coincidence counting. Using the calibration plot, the concentration of Se in CRM DORM-1 was determined as 1.51±0.15 which was close to the certified value of 1.620±0.120. The γ-γ coincidence counting showed an enhancement in the peak to back ground ratio by about two orders of magnitude and an improvement in detection limit by a factor of about ∼6 if compared for similar order of counting statistics and by a factor of about 1.2 if compared for similar counting time with respect to the singles counting. (author)