Background: This paper is focused on application of a recently developed disposable array
of carbon composite electrodes and carbon paste electrode for the determination of indoxyl sulphate.
Results: Measurement of basic electrochemical behaviour of indoxyl sulphate on working electrode
resulted in the selection of BR buffer pH 2.0 and pH 3.0 as the optimum medium for carbon composite
film electrode and carbon paste electrode, respectively. In this medium, concentration dependences of
indoxyl sulphate were measured; calculated quantification limits were 0.72 µmol L-1 for the carbon
composite film electrode and 1.7 µmol L-1 for the carbon paste electrode. Pasivation of the electrodes
during repeated measurements and negligible indoxyl sulphate accumulation was observed. Applicability
of the method for the indoxyl sulphate determination in spiked urine samples was tested in combination
with the solid phase extraction, where methanol, BR buffer, deionised water and their combination
were used as elution reagents.
Conclusion: Selected graphite-based working electrodes were successfully applied for the development
of suitable voltammetric method for the determination of indoxyl sulphate in BR buffer. Both electrodes
showed similar behaviour and sufficient sensitivity and accuracy was reached; however, solid phase
extraction was not successful due to ineffectual removal of interferents from human urine.