Platinum Determination in Plasma and Urine by Flameless Atomic Absorption Spectrophotometry

A method is described for the measurement of total platinum in plasma and urine, using flameless atomic absorption spectrophotometry, which is sensitive and reproducible enough to permit pharmacokinetic studies on cis-dichlorodiammineplatinum(II). The plasma platinum concentrations are determined after ten-fold dilution in 0.5% nitric acid, and urine is analysed after twenty-fold dilution in distilled water. The use of tantalized-treated graphite furnaces prior to each dosing series allows one to increase the sensitivity and reproducibility of measurements. A comparative study made on the classic method, which consists of introducing samples manually, and an original automatic one, confirms the latter's superiority. By taking ten measurements, the reproducibility of the injections is 1.89% for calibration points containing 100 ng ml(-1) of platinum and is 2.47% for those containing 35 ng ml(-1) of platinum. The reproducibility of the method was determined on plasma samples to which cis-DPP had been added, using an automatic sample injection system. It varies between 4.73% and 2.93% for platinum concentrations between 0.32 mu g ml(-1) and 2.61 mu g ml(-1). This represents the range of the concentrations observed in the kinetic studies. The absolute detection limit of platinum is 10 ng ml(-1).