Platinum determination in cis-dichlorodiammineplatinum(II)--DNA complexes by differential pulse polarography

A simple polarographic assay for platinum determination in cis-dichlorodiammineplatinum(II)-DNA complexes is described. The method makes it possible to determine the free (unbound) drug in the presence of DNA or platinum-DNA complex, i.e., without a separation of free drug and macromolecular components of the solution to be analyzed. This method is based on the polarographic activity of intact cis-dichlorodiammineplatinum(II) at -1.5 V, which can be measured by differential pulse polarography even in the presence of DNA or platinum-DNA complex. The lower level of analytical utility of this method is ca. 1 X 10(-6) M (195 ng of platinum/ml).