Detection of Cisplatin with Boron-Doped Diamond Thin-Film Electrodes Using Flow Injection Analysis and Ion Exclusion Chromatography with Amperometric Detection

Abstract

In this work, we investigated the electrochemical behavior of cisplatin at boron-doped diamond (BDD) thin-film electrodes using cyclic voltammetry. Flow injection analysis with amperometric detection (FIA-EC) was used to determine the detection figures of merit. No electrode surface modification or conventional pretreatment was required to activate the BDD electrodes. Diffusion-limited oxidation of cisplatin, dissolved in 0.1 M HClO₄, occurred at 1.3 V (vs. Ag/AgCl (3M KCl)) in cyclic voltammetric measurements and at 1.5 V in hydrodynamic voltammetric measurements. FIA-EC peak current responses were reproducible over 10 consecutive injections of 100 μM cisplatin (relative standard deviation (RSD) = 2.7%) at 1.5 V. The FIA-EC peak current increased linearly with the cisplatin concentration from 1 to 100 μM (r² = 0.988). The minimum detectable concentration was experimentally determined to be 0.5 μM (S/N = 3). Detection of cisplatin in spiked human urine was also investigated using FIA-EC. Other electrochemically active species present in the urine specimen interfered with cisplatin detection at 1.5 V. These interferents were separated from cisplatin in the spiked urine specimen using solid-phase extraction (SPE) sample pretreatment and ion exclusion chromatography. Both ultraviolet/visible (UV/Vis) and amperometric detection were compared. Cisplatin was detected 8.9 min after injection using a UV/Vis photodiode array (PDA) and 9.3 min after injection using BDD in an amperometric detector placed in series. Overall, BDD electrodes are a good choice for the reproducible and sensitive electrochemical detection of cisplatin using FIA-EC or ion exclusion chromatography prior to amperometric detection. Ion exclusion chromatography (IEC) adds selectivity for the electrochemical detection of cisplatin in urine specimens.