Determination of elution profile the ¹²⁵I as a tracer for radioimmunoassay (RIA)

The benefits of ¹²⁵I isotope was well known. ¹²⁵I are used as radiotracer in Radioimmunoassay (RIA) technique for early detection of cancer, determine of hormone content which related with fertility of livestock and also for contamination detection of mycotoxins on food by in vitro. ¹²⁵I which is needed in this technique not only must have high radiochemical purity above 95 % but also high radioactivity concentration, so that ¹²⁵I volume which is use must as little as possible. Therefore, ¹²⁵I elution profile for increasing radiochemical purity using a reductor Jones column should be studied. Aim of this study is to determine the optimum volume of eluate which have efficiency and radiochemical purity that can be accepted. The preliminary study was conducted to determine the optimal conditions of reductor Jones column. Reductor Jones column is conditioned on neutral and alkaline pH. At this elution study, the columns conditions selected is alkaline pH. Reductor Jones column which containing ¹²⁵I eluted with NaOH 0,01 N solution by fractionated in 1 mL. The radioactivity of each fraction is measured with dose calibrator. Determination of the radiochemical purity of carried out on the fraction which have the highest radioactivity and the combined fractions using paper chromatography. Highest radioactivity is shown in the second fraction at 16,59 mCi with efficiency 33,95 % and combined fractions at 50,19 mCi with efficiency 92,26 %. The radiochemical purity of ¹²⁵I bulk, second fraction and combined fractions are 41,50 %, 97,5 % dan 98,50 %, respectively. Optimum fraction is 7 mL and pH of ¹²⁵I before and after fractionation are 10 - 11. By studying the elution profile can be known that the optimal volume is the smallest total volume of eluent with efficiency and radiochemical purity level that can be accepted. (author)