Voltammetric determination of platinum from aqueous solutions and from urine

Abstract

I t is shown that platinum can be determlned from aqueous solutions o f clsdiamminedicMotopiatinum( I I ) (cisplatin) or of hexachioropiathic acid by differential pulse voltammetry after deposnbn onto a rotating glassy carbon electrode. For cisplatln, deposltlon Is carried out at -0.5 V In 0.15 M NaCi. For hexachloroplatkdc acld best results are obtalned at -0.2 V In 0.1 Y NaHSO,/O.l M Na$04 buffer. The subsequent analysis step is performed In 0.05 M H,SO, after application of a controlled potentlal program to activate the deposlt. During the analysis, the platinum Is not stripped from the electrode. Measured are the currents In the dmerential pulse mode requlred to oxidize the platlnum deposlt. Between samples, the deposlt Is mechanically removed from the electrode. Analysis of clsplatin In urine involves a chelation procedure wlth sodlum dlethyldlthbcarbamate, extractlon of the platbnm chelate wtth chkrdorm, solvent evaporation, and dlgestlon with aqua regla. The resulting hexachioroplatinlc acld is then analyzed for platlnum as described above. Platlnum levels daennhed In ihk work range from 0.1 to 100 ppm. This is sufficient for the monltorlng of patients under treatment wlth cisplatln, where a peak plasma level of 6 ppm is generally expected.

Electrochemical Fabrication of Amperometric Microenzyme Sensor

“…This may cause loss of activity of some enzymes, which is a disadvantage of the present method. However, some platinum complexes such as cisplatin [cis-diaminedichloroplatinum (II)] have been shown to be platinized at a neutral pH (20). By selecting an appropriate platinum complex, intact immobilization of enzyme molecules may be easily carried out at moderate pH by the present electrochemical microfabrication techniques.…”

Electrochemistry as a Powerful Tool for Investigations of Antineoplastic Agents: A Comprehensive Review

“…[404] DPV 100.0 mM KCl, pH 7.0 LOD ¼ 370.0 pM [405] (continued) PtEs electrolysis in the chlorine ions-containing solution while being placed in the Escherichia coli growing medium. Basic cisplatin redox reactions were also harvested electrochemically during its plating over the GCE followed by its oxidation (analytical step) [395] or direct reduction at the Hg-based electrodes. [396] Indirect sensing of cisplatin was realized on HMDE modified with metallothionein (MT) by monitoring an increase in the reduction peak of Pt 2þ -MT protein complex [397] and on CPE with electrodeposited AgNPs, [398] with the latter procedure providing a lower LOD of 3.2 nM.…”

Platinum antitumour agents: A review of (bio)analysis

“…Electrochemical methods based on accumulation of cisplatin at a glassy carbon [137] and a hanging mercury drop electrode [138] were des-…”

“…Both studies found a good detectability for cisplatin in water, but in urine the detector response disappeared, probably by competition for the active sites on the electrode surface by organic surfactants and by depositing metal ions [138]. Therefore, platinum detection was only possible by indirect assay [138] or by complexation to hexachloroplatinic acid, deposition of this product at -0.2 V (versus satured calomel electrode) and detection at +0.9 V [137].…”

“…Platinum can also be determined by differential pulse voltammetry after deposition of cisplatin at -0.5 V (versus saturated calamel electrode) onto a rotating glassy carbon electrode [137].…”