Differential pulse voltammetric determination of homovanillic acid as a tumor biomarker in human urine after hollow fiber-based liquid-phase microextraction
Abstract
Novel method for the determination of a tumor marker homovanillic acid (HVA) in human urine was developed. Combination of hollow fiber - based liquid-phase microextraction (HF-LPME) and differential pulse voltammetry (DPV) at a cathodically pre-treated boron doped diamond electrode (BDDE) was applied for these purposes.
Optimum conditions were: butyl benzoate as supported liquid membrane (SLM) formed on polypropylene HF, 0.1 mol L(-1) HCl as donor phase, 0.1 mol L(-1) sodium phosphate buffer of pH 6 as acceptor phase, and 30 min extraction time. HF-LPME-DPV concentration dependence was linear in the range from 1.2 to 100 μmol L(-1).
Limits of quantification (LOQ) and detection (LOD) were 1.2 and 0.4 μmol L(-1), respectively. The applicability of the developed method was verified by analysis of human urine.
Standard addition method was used, found HVA concentration was 13.5 +/- 1.3 μmol L(-1), RSD = 9.3% (n=5).