Voltammetric Detection of 3-Nitropropionic Acid in Sugarcane Juices Using a Poly(L-citrulline)/Lanthanide-Containing Cyano-Bridged Heterometallic Coordination Polymer Modified Electrode

Abstract

In this study, a novel poly(L-citrulline)/lanthanide-containing cyano-bridged heterometallic coordination polymer modified glassy carbon electrode, poly(L-Cit)/(Ho(III)-Fe(III)-WO42− CyHMCP/GCE, was constructed as a sensing platform for the electrochemical detection of 3-nitropropionic acid (3-NPA) using the two-step electrosynthesis method. The surface morphology of materials coated on the chemically modified electrode was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the excellent synergistic electrocatalytic performance for electrochemical reduction of 3-NPA, the voltammetric detection of 3-NPA in real sugarcane juice samples was achieved with a facile sample pretreatment process and less matrix interference. Furthermore, by means of water-phase infrared spectra technique, the electrocatalytic reduction pathway of 3-NPA was preliminarily studied. Under the optimized detection conditions, a good linear relationship was obtained between the reduction peak current of 3-NPA and testing concentration in the range of 40.0–4.00 × 103 μM, with a regression equation of Ip (μA) = −3.126 + 0.08804C3-NPA (μM), R2 = 0.9997. The lower detection limit (LOD) of 3-NPA was estimated to be 16.0 μM (S/N = 3). Therefore, the method had been employed to analyze raw sugarcane samples, with the average recovery of 96.8%–104%, and the actual concentration level of free 3-NPA in the raw sugarcane juices was revealed.