Three-dimensional dual-network magnetic conductive hydrogel for the highly sensitive electrochemical detection of ponceau 4R in foods

Synthetic pigment Ponceau 4 R is a commonly used additive in the process of various foods. Due to its potential toxicity to humans, realizing high sensitivity and rapid detection of Ponceau 4 R is extremely important. In this study, we synthesized a novel dual-network magnetic conductive hydrogel (MCHG) via a simple one-pot low temperature stirring method. In MCHG, cationic guar gum (CGG) and beta-cyclodextrin (beta-CD) formed a primary three-dimensional network cross-linked by N, N-methylene bisacrylamide. A second network was formed in MCHG by CGG, beta-CD and magnetite@carboxylate-terminated carbon nanotubes (Fe3O4@COOH-MWCNTs) through hydrogen bonding and electrostatic interactions. Fe3O4@COOH-MWCNTs enhanced cross-linking in the MCHG hydrogel, whilst also boosting the equilibrium adsorption capacity of Ponceau 4 R (61.8 mg g-1), elec-trical conductivity and electrocatalytic performance. Application of MCHG to a glassy carbon electrode (GCE) created a highly sensitive electrochemical sensor for the detection of Ponceau 4 R. Under optimized testing conditions, the sensor offered a very wide linear range (0.01-200.0 mu M) and a low limit of detection (1.8 nM) for Ponceau 4 R. When the sensor was applied to the detection of Ponceau 4 R in spiked honey and liqueur samples, excellent recoveries were achieved (88.2%-107.0%). Furthermore, analyses of commercial biscuit and candy samples using the MCHG/GCE sensor and a national standard ultraviolet spectrophotometry method afforded identical results. Results demonstrate that multifunctional hydrogels show great promise as signal amplification agents in electrochemical detection of target compounds in foods.

Automated summary

In this study, a novel dual-network magnetic conductive hydrogel was synthesized for the highly sensitive and rapid detection of the synthetic pigment Ponceau 4R in foods. The hydrogel showed improved adsorption capacity and electrical conductivity, and was successfully applied to the creation of an electrochemical sensor for Ponceau 4R detection.