Novel ratiometric electrochemical sensing platform with dual-functional poly-dopamine and NiS@HCS signal amplification for sunset yellow detection in foods

In this work, a novel ratiometric electrochemical sensor based on dual-functional poly-dopamine (PDA) and nickel sulfide@hollow carbon spheres (NiS@HCS) was successfully developed for sunset yellow (SY) detection. The NiS@HCS nanocomposite possessing a large specific surface area, good catalytic activity and excellent electrical conductivity was employed for signal amplification. PDA films prepared by electropolymerization acted as an internal reference probe and enhanced the sensitivity of the proposed sensor through electrostatic attraction between SY and PDA. Under optimized conditions, the developed PDA/NiS@HCS/GCE sensor allowed SY quantification over wide linear range (0.01–100 μM), with a low limit of detection of 0.003 μM. SY recovery tests were carried out in rice vinegar and cooking wine with satisfactory recoveries (83.50–112.80 %). Meanwhile, the content of SY in two kinds of carbonated drinks was determined using the constructed sensor and a UV–Vis spectrometry method, with no significant difference found in the results.