Penentuan Profil Elusi Iodium-125 Sebagai Perunut Untuk Tujuan Radioimmuniassay (Ria)

Abstract

Manfaat iodium-125 (125-I) sudah banyak diketahui. 125-I dapat digunakan antara lain sebagai perunut dalam teknik Radioimmunoassay (RIA) untuk deteksi dini berbagai penyakit kanker, menentukan kesuburan hewan ternak serta cemaran mikotoksin di dalam pangan secara invitro. 125-I yang dibutuhkan dalam teknik ini disamping harus mempunyai kemurnian radiokimia > 95%, konsentrasi radioaktifitas juga tinggi, sehingga volume 125-I haruslah sekecil mungkin. Dengan demikian perlu dipelajari profil elusi 125-I dari kolom reduktor Jones saat proses peningkatan kemurnian radiokimia. Penelitian ini bertujuan untuk menentukan volume optimal eluat dengan efisiensi dan kemurnian radiokimia yang dapat diterima. Pada penelitian ini kondisi kolom yang dipilih adalah kolom dengan pH basa. Kolom reduktor Jones yang mengandung 125-I dielusi dengan larutan NaOH 0,01N secara fraksinasi volume 1 ml. Radioaktifitas masing-masing fraksi diukur menggunakan dose calibrator. Penentuan kemurnian radiokimia dilakukan pada fraksi yang memiliki radioaktifitas tertinggi dan fraksi gabungan dengan metode kromatografi kertas. Radioaktifitas tertinggi ditunjukkan pada fraksi kedua yaitu 16,59 mCi dengan efisiensi 33,95% dan fraksi gabungan yaitu 50,19 mCi dengan efisiensi 92,26%. Kemurnian radiokimia 125-I bulk, fraksi kedua dan fraksi gabungan berturut-turut adalah 41,50, 97,5 dan 98,50%. Volume optimal eluat adalah 7 ml serta pH 125-I sebelum dan sesudah fraksinasi adalah 10 -11. Determination of Elution Profile the Iodine-125 as a tracer for Radioimmunoassay (RIA). The benefits of the Iodine-125 (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 1mL. 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 125-I bulk, second fraction and combined fractions are 41,50%, 97,5 % dan 98,50%, respectively. Optimum fraction is 7 mL and pH of 125-I before and after fractination 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.

A Modified Method for Increasing Radiochemical Purity of I-125 for Radiopharmaceuticals

“…There has been an increasing demand for 125 I radioisotope on the world market for research, diagnosis, and therapy [1][2][3]. However, there has been limited availability of 125 I products worldwide.…”

“…In the US alone, there were around 36 000 procedures which required radioisotopes, including 125 I [3]. In Indonesia, 125 I has been widely used in the field of health, agriculture, and energy [2]. In the medical field, 125 I is employed as a tracer in radioimmunoassay (RIA) and immunoradiometric assay (IRMA) kits such as PSA, CA-125, and CA 15-3 kits for early detection of various cancer in-vitro [4].…”

“…A radiopharmaceutical is a radioactive-labeled compound that meets the requirements for pharmaceutical products, used for diagnosis or treatment of various diseases [12]. Iodine-125 as a radioisotope marker generally has several advantages, including easy binding to organic molecules especially those containing tyrosyl groups such as proteins or smaller molecules such as thyroxine in peptides, and the resultant marking obtained can have high purity and specific activity [2]. Besides, 125 I is a gamma-ray emitter with low energy (35 keV) that can be detected with most gamma counters with a high efficiency, and its halflife is relatively long at 60 days [13].…”

“…Radiochemical purity is the ratio between radioactivity in the desired chemical form and total radioactivity [19,20]. A radiochemical purity that does not meet the requirements (< 95 %) will cause the compound to be distributed to other organs, causing undesired radiation exposure and making image quality poor [2,12,21].…”

“…However, in recent years, the resulting 125 I quality has decreased due to the low purity of its radiochemicals; therefore, its use is limited to certain fields. As a result, the 125 I cannot be used optimally [2]. Various attempts have been made to improve the quality of the 125 I but have not yet achieved the results expected for use in the field of radiopharmaceuticals, either for research, diagnostic, or therapeutic purposes [1,2].…”