A 2D tungsten disulphide/diamond nanoparticles hybrid for an electrochemical sensor development towards the simultaneous determination of sunset yellow and quinoline yellow

Abstract We present the development of an electrochemical sensor towards the simultaneous analysis of a mixture of food additives: sunset yellow (SY) and quinoline yellow (QY) dyes. The sensor is based on the synergetic effect observed between diamond nanoparticles (DNPs) and WS2 nanosheets obtained by liquid exfoliation. The prepared TMDs were characterized using Raman spectroscopy, X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM). The AFM characterization showed isolated WS2 flakes with different lateral dimensions scattered over the flat background. The combination of WS2 and DNPs allows resolution of the oxidation signals of the analytes, which overlap working with the bare glassy carbon (GC) electrode. The best electroanalytical response was obtained with a sensor containing both nanomaterials deposited employing the drop-casting method in a sequential manner, a first layer of WS2 and a second layer of DNPs (GC/WS2/DNPs). Electrochemical impedance spectroscopy experiments showed that for the GC/WS2/DNPs system the charge transfer is clearly improved. Under optimized differential pulse voltammetry conditions, the GC/WS2/DNPs sensor allows the determination of SY at +100 mV and QY at +850 mV with detection limits of 0.086 and 3.4 μM respectively, with relative errors ≤ 8.40 % and a relative standard deviation ≤ 12.6 %. The proposed methodology was applied to the determination of SY and QY in commercial throat lozenge samples with very good recoveries on average: 93%, for QY and 106% for SY.