Derivative UV/Vis spectroelectrochemistry in a thin-layer regime: deconvolution and simultaneous quantification of ascorbic acid, dopamine and uric acid.

In this work, UV/Vis spectroelectrochemistry (SEC), in a thin-layer regime and parallel configuration, is selected to solve a complex mixture that contains dopamine (DA), ascorbic acid (AA) and uric acid (UA). These molecules, like many other biological compounds, are assuming a highly important place in analytical and biomedical fields due to the fundamental role that they play in human metabolism. In addition, low or high levels of these compounds are associated with diseases such as Parkinson's disease. For this reason, the quantification of these biomolecules is becoming increasingly critical. However, some drawbacks must be overcome, because the three molecules coexist in the human body, and the species are subject to mutual interference. In fact, they are all oxidized at similar potentials, and their UV/Vis absorption bands overlap, greatly complicating their quantification. For this reason, derivative SEC together with suitable chemometric tools such as PARAFAC are proposed to solve this complex matrix. This technique allows us to separate the contribution of each of these molecules present in a sample and to quantify all of them, achieving high resolution and reproducibility. Besides, detection limits at the micromolar level are achieved for DA, AA and UA in mixture solutions. This work thus demonstrates the great potential for derivative potentiodynamic SEC combined with the appropriate chemometric tools in solving complex mixtures, a field where SEC is still taking the first steps. Graphical abstract.