Efficient production and purification of P radioisotope from sulfur by dry distillation: A practical approach with high radiochemical purity.

The P radioisotope, with a half-life of 14.3 days and an energy level of 1.71 MeV, has diverse applications in medicine and research. Consequently, producing a carrier-free P radioisotope characterized by high radiochemical and radionuclide purity is imperative. Two primary methods for generating P radioisotopes exist: irradiating phosphorus through the nuclear reaction (n,γ) or irradiating sulfur through the nuclear reaction (n,p). Using sulfur as a target material provides several advantages. Besides the fact that the chemical element produced after irradiation (P) differs from the irradiated element (S), it also produces aP radioisotope with a higher specific activity than using P as the target. The production of the radioisotope P from sulfur employs the dry distillation method, capitalizing on sulfur's easily sublimated nature. The volatility of sulfur when heated makes it easy to separate the resulting sulfur and radioisotope P without the need for additional reagents. This research aims to establish a practical method for producing the P radioisotope using the dry distillation technique. The dry distillation method utilizes a quartz ampoule containing a mixture of P and S radionuclides, a distillation tube wrapped with heating tape, and a condenser to collect the distilled sulfur. Sulfur, serving as the target material, undergoes irradiation in the reactor at the Central Irradiation Position (CIP) through the S(n,p)P nuclear reaction with a fast neutron flux of 5.380 × 10 n/cm.sec. Separation is achieved through distillation at a temperature of 440 °C. The residual separation products are then dissolved in a 0.1 N HCl solution. The purification process involves using an AG50 WX8 cation exchange resin column, which is pre-conditioned with 0.1 N HCl. The resulting eluate contains the P radioisotope. The radiochemical purity of the P radioisotope is analyzed using thin-layer chromatography (TLC). In this analysis, a PEI Cellulose plate serves as the stationary phase, and a KHPO solution acts as the mobile phase. This vacuum-free distillation method successfully separates the P radioisotope from sulfur, achieving a separation efficiency of 55.1 ± 9.9% (n = 7). The average activity produced after the purification process is 5.690E+10 Bq. Purifying the P radioisotope results in a radiochemical purity of 99.97% at Rf 0.7110, as orthophosphate, the radionuclide purity exceeds 99%.