Determination of platinum levels in serum and urine samples from pediatric cancer patients by TXRF

Abstract

A simple total reflection x-ray fluorescence (TXRF) procedure was developed to monitor plasma drug levels and urine elimination in pediatric cancer patients undergoing chemotherapy with platinum-containing drugs. Serum and urine specimens were irradiated with cut-off filtered or monochromatized x-rays using an easy procedure that avoids sample digestion. Specimens from normal patients were standardized by adding known trace amounts of elements absent in these matrices and diluting to 1 : 1 in water. These were used to derive TXRF spectrometer sensitivity curves relative to cobalt as internal element standard and to the incoherently scattered Compton peak as internal standard. Accuracy, precision and detection limits attained in the analysis of minute amounts of unknown serum and urine, treated in the same manner as the standardized samples, are shown to be appropriate for routine monitoring of platinum in cancer patients. Copyright © 2000 John Wiley & Sons, Ltd.