Table 6.1 Shelf Lives for Commonly Used Only you can determine how long you can use your radio- isotope after the reference date. The answer depends on the isotope, the compound it's bound to, the experiment, storage, the formulation of the product, and the like. Table 6.1 lists the genera ranges for the most commonly used radioisotopes, which is guideline only. As you carry out your work, you will discover when your material starts to give poorer results Can You Compensate by Adding More Radiochemical If the Reference Date Has Long Pass Sometimes it is not that simple. As an example of the complex- ities involved with radiolytic decomposition, suppose you had a vial of 32P gamma labeled ATP that you routinely use to label the 5 end of dna via T4 Polynucleotide kinase. If one half-life has passed since the reference date(14.28 days), you will have 50% of the stated radioactivity remaining. You might still achieve satisfactory 5" end labeling with T4 Polynucleotide kinase if you double the amount of theP added to the reaction. Often however, you may find that though you have compensated for the adioactive decay by adding more material, you have also intro- duced more of the decomposition products, which will be frag ments of the original labeled compound and free radicals. You also will have added more of the solute that might be present in the stock vial. These contaminants and decomposition products ca significantly interfere with the reaction mechanism and compro mise your results HANDLING RADIOACTIVE SHIPMENTS What should You Do with the Radioactive Shipment When it Ar The radiation safety officer is responsible for ensuring that radioactive materials are received in satisfactory condition, butOnly you can determine how long you can use your radio￾isotope after the reference date. The answer depends on the isotope, the compound it’s bound to, the experiment, storage, the formulation of the product, and the like. Table 6.1 lists the general ranges for the most commonly used radioisotopes, which is a guideline only.As you carry out your work, you will discover when your material starts to give poorer results. Can You Compensate by Adding More Radiochemical If the Reference Date Has Long Passed? Sometimes it is not that simple. As an example of the complex￾ities involved with radiolytic decomposition, suppose you had a vial of 32P gamma labeled ATP that you routinely use to label the 5¢ end of DNA via T4 Polynucleotide kinase. If one half-life has passed since the reference date (14.28 days), you will have 50% of the stated radioactivity remaining. You might still achieve satisfactory 5¢ end labeling with T4 Polynucleotide kinase if you double the amount of the 32P added to the reaction. Often, however, you may find that though you have compensated for the radioactive decay by adding more material, you have also intro￾duced more of the decomposition products, which will be frag￾ments of the original labeled compound and free radicals.You also will have added more of the solute that might be present in the stock vial. These contaminants and decomposition products can significantly interfere with the reaction mechanism and compro￾mise your results. HANDLING RADIOACTIVE SHIPMENTS What Should You Do with the Radioactive Shipment When It Arrives? The radiation safety officer is responsible for ensuring that radioactive materials are received in satisfactory condition, but 150 Volny Jr. Table 6.1 Shelf Lives for Commonly Used Isotopes 32Phosphorous 1–3 weeks 33Phosphorous 4–12 weeks 35Sulfur 2–6 weeks 125Iodine 3–12 weeks 3 Hydrogen 1–12 months 14Carbon 1–2 years