Platinum speciation in clinical and environmental samples: Scrutiny of data obtained by using electrophoresis techniques (flatbed and capillary)

The commercially available and widely used flatbed electrophoresis apparatus Phast-System and MultiPhor II (Amersham Pharmacia Biotech, Uppsala, Sweden) were checked for the possible release of significant amounts of platinum from the electrodes during isoelectric focusing (IEF) and native polyacrylamide gel electrophoresis (PAGE). Capillary electrophoresis (CE; Biofocus 3000; Bio-Rad, Munich, Germany) in zone electrophoresis (CZE) mode was investigated for the same purpose. Platinum analysis was done by inductively coupled plasma mass spectrometry (quadrupole and magnetic sector field) either "off-line" for all flatbed gels or "on-line" for the CE measurements. The buffers and process chemicals did not significantly leach platinum from the electrodes. During flatbed electrophoresis, application of the electrical field, however, released high platinum amounts exceeding by far the amount of platinum originally present in the sample. For CE, no platinum was released from the electrodes. The results are strongly dependent on the system and conditions used. The results presented in this paper underline the necessity to replace the platinum electrodes with ultrapure gold electrodes whenever investigating platinum species. Previous literature data, in which electrophoresis was used for platinum speciation without mentioning the platinum recoveries, becomes questionable.