The production of S-35 is similar to the production of carrier-free P-32; it is pro­duced in the 35Cl(n, p)35S nuclear reaction by irradiating the KCl target. The irradi­ated KCl is dissolved in water, while sulfur is dissolved as sulfate. Chloride and sulfate are separated by anion exchange. The half-life of 35S isotope is 87.9 days, and it emits weak beta particles, similar to C-14. As a by-product, a weak beta emitter 36Cl isotope is formed by the 35Cl(n, Y)36Cl nuclear reaction, the half-life of which is 301,000 years. In addition, the 41K isotope of KCl is activated in the 41K (n, Y)42K nuclear reaction. The half-life of the beta and gamma emitter 42K, how­ever, is short enough (12.6 hours) so its disintegration can be waited. For additional information, see Section 8.7.1.2.