Simultaneous detection of dopamine and ascorbic acid by using a thread-based microfluidic device and multiple pulse amperometry

Abstract

This study presents a novel approach for the simultaneous detection of ascorbic acid (AA) and dopamine (DA) using an affordable and user-friendly microfluidic device. Microfluidic devices, when combined with electrochemical detectors like screen-printed electrodes (SPEs), offer numerous advantages such as portability, high sample throughput, and low reagent consumption. In this study, a 3D-printed microfluidic device called a μTED was developed, utilizing textile threads as microfluidic channels and an unmodified SPE as the amperometric detector. The method employed multiple pulse amperometry (MPA) with carefully selected potential values (+0.65 V and −0.10 V). The reduction current signals generated by dopamine o-quinone were used to calculate a correction factor for the oxidation signals of ascorbic acid, enabling simultaneous quantification. The developed microfluidic device ensured a stable flow rate of the carrier solution at 1.19 μL s⁻¹, minimizing the consumption of samples and reagents (injection volume of 2.0 μL). Under the optimized experimental conditions, a linear range from 50 to 900 μmol L⁻¹ was achieved for both DA and AA. The obtained sensitivities were 2.24 μA L mmol⁻¹ for AA and 5.09 μA L mmol⁻¹ for DA, with corresponding limits of detection (LOD) of 2.60 μmol L⁻¹ and 1.54 μmol L⁻¹, respectively. To confirm the effectiveness of the proposed method, it was successfully applied to analyze AA and DA in a commercial blood serum sample spiked at three different concentration levels, with a medium recovery rate of 70%. Furthermore, the MPA technique demonstrated its simplicity by enabling the simultaneous determination of AA and DA without the need for prior separation steps or the use of chemically modified electrodes.