The use of tritium (3H) as a radio-label for tracking metabolites is a powerful tool in analytic chemistry. In fact, it is the isotope of choice for thousands of different reactions. Depending on the precursor, tritiation can be accomplished in several ways. Tritium is incorporated as radiolabel into organic molecules through a number of methods.

Exchange Reactions

In the simplest process, the labeling of such compounds as nucleotides, pyrimidines and alkaloids is easily, if somewhat inefficiently, accomplished by exposure to the appropriate amount of tritiated water. Any labile tritium is then removed and the product assayed for total activity.

For carbohydrates, nucleosides, amino acids and compounds containing benzylic protons, it is necessary to use a hydrogen transfer catalyst to obtain a satisfactory level of total activity in the tritiation. Similar to the above process, the labile tritium gas must also be evacuated at the end of the procedure but usually results in far higher total activity.

Known more familiarly as the Wilzbach method, this procedure simply involves the exposure of the substrate to isotopically pure tritium in a sealed, non-reactive container for several weeks. Since the reaction is promoted by the radioactive decay of the tritium, it is extremely destructive to the precursors and is rarely used.

Direct Synthesis

Molecule synthesis can be completed using tritium gas as a reducing or dehalogenating agent or reduction with borohydride.

Recent developments using activated spillover tritium in conjunction with a high-temperature, solid-state catalytic isotopic exchange procedure have shown remarkable – read, very pure – results with aliphatic compounds, steroids, and peptides.

The replacement of a halide, most usually of bromine and chlorine,with tritium in this process is preferred for use on heterocyclic aromatic especially purines and pyrimidines. It is quite efficient and easily achieves total activities equal or greater than standard solvent technique. Borohydride reduction is particularly well-suited for the labeling of carbohydrates and usually uses tritiated sodium borohydride, although it often results in relatively low levels of total activity.

Our experienced analytical group is able to use these methods coupled with orthogonal analytical methodologies and specific activity determinations in order to provide accurate and conclusive evidence to supportive final product delivery.

Our team is ready to discuss your needs and reliably deliver your compound with time and cost efficiency. Please contact the radiolabeling group at 610-337-3762 or Email .