Cisplatin, mono- and diaquacisplatin were measured in aquatic samples and in diluted urine of a cancer patient by HPLC-ICP-MS. On-line IDMS was applied for accurate, species unspecific quantification. Limits of detection of 0.74, 0.69 and 0.65 μg L-1 (3 s criterion) were calculated for cisplatin, monoaqua- and diaquacisplatin, respectively. Degradation kinetics of 6 × 10-6 M cisplatin were determined over a period of 48 h in solutions containing 100, 50 and 0 mg L-1 chloride, showing the suitability of the HPLC-ICP-MS method for kinetic model studies. The first order rate constants k1 of cisplatin aquation for the three chloride concentrations were 1.79 × 10-5, 1.68 × 10-5 and 2.06 × 10-5 s-1. For cisplatin anatation (second order reverse reaction), rate constants of k-1 = 6.5 × 10 -3, 5.8 × 10-3 and 4.1 × 10-3 M-1 s-1 could be assessed. At low chloride levels, no equilibrium was established between cisplatin and its degradation products. It was found that the intermediately formed mono- and diaquacisplatin-products started to decay after several hours. Diluted urine of a cancer patient contained the parent drug cisplatin and a considerable fraction of highly active monoaquacisplatin, as well as several unknown platinum species.
ASJC Scopus subject areas
- Analytical Chemistry