High-performance liquid chromatographic-mass spectrometric analysis of cis-dichlorodiamineplatinum-DNA complexes using an ionspray interface

An efficient RP-HPLC separation technique was used in combination with mass spectrometric detection with an ionspray ionization source to analyse complexes between nucleosides and cis-dichlorodiamineplatinum(II). Conventional detection techniques (UV and atomic absorption spectrometry) were also used as starting points for the setting-up of this HPLC-MS approach. The method was developed using complexes obtained either by reaction of free deoxynucleosides with cis-dichlorodiamineplatinum or by reaction in vitro of DNA samples with the same drug. DNA samples before HPLC-MS were completely depolymerized by digestion with nuclease P1 and alkaline phosphatase, in order easily to separate and determine the complexes formed. The sensitivity obtained makes this technique very suitable for future application in biological studies. The detection level, defined as the detector response with a signal-to-noise ratio of 2, corresponds to 2 pmol injected. In DNA samples treated with cis-dichlorodiamineplatinum, a series of cis-dichlorodiamineplatinum-deoxynucleoside complexes not previously described were also detected.