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 apparatu s Phast-System and MultiPhor II (Amersham Pharmacia Biotech, Uppsala, Swede n) were checked for the possible release of significant amounts of platinum from the electrodes during isoelectric focusing (IEF) and native polyacryl amide gel electrophoresis (PAGE). Capillary electrophoresis (CE; Biofocus 3 000; Bio-Rad, Munich, Germany) in zone electrophoresis (CZE) mode was inves tigated for the same purpose. Platinum analysis was done by inductively cou pled 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 relea sed from the electrodes. The results are strongly dependent on the system a nd conditions used. The results presented in this paper underline the neces sity to replace the platinum electrodes with ultrapure gold electrodes when ever investigating platinum species. Previous literature data, in which ele ctrophoresis was used for platinum speciation without mentioning the platin um recoveries, becomes questionable.