Analysis of antitumour [1,1-bis(aminomethyl)cyclohexane]platinum(II) complexes derived from spiroplatin by high-performance liquid chromatography with differential pulse amperometric detection

A reversed-phase high-performance liquid chromatographic analysis was developed for aqua[1,1-bis(aminomethyl)cyclohexane]sulphatoplatinum(II) (spiroplatin) and its hydrolysis and oligomerization products. The platinum complexes were detected by differential pulse amperometry at a hanging mercury drop electrode, at -540 mV vs. Ag/AgCl. The limit of detection was 0.05 μM. Aqueous solutions of spiroplatin appeared to contain the diaqua, monoaquamonosulphato, monoaquamonochloro, dichloro and hydroxo-bridged dimer complexes of [ 1,1 -bis(aminomethyl)cyclohexane]platinum(II) in mutual equilibrium. The equilibrium shifts after dilution in infusion fluids were studied. Detection of these platinum(II) complexes in untreated human plasma ultrafiltrate and urine demonstrated the selectivity of the described analysis.