Luminescent Chemosensor Based on Ru(II) Bipyridine Complex for Detection of Sudan I through Inner Filter Effect

A test strip constructed by molecular imprinting for ratiometric fluorescence with ultra-low limit of detection for selective monitoring of Sudan I in chili powder

An up-conversion molecularly imprinted ratiometric fluorescent probe with a monodisperse nuclear-satellite structure and its test strip are designed which can avoid fluorescent background interference to detect Sudan I in chili powder highly selective and sensitive. The detection mechanism is based on the selective recognition of Sudan I by imprinted cavities on the surface of ratiometric fluorescent probe and the inner filter effect between Sudan I molecules and the emission of up-conversion materials (NaYF₄:Yb,Tm). Under optimized experimental conditions, the response of fluorescent ratio signals (F₄₇₅/F₆₄₅) of this test strip show a good linear relationship in the range 0.02-50 μM Sudan I. The limits of detection and quantitation are as low as 6 nM and 20 nM, respectively. Sudan I is selectively detected in the presence of fivefold higher concentrations of interfering substances (imprinting factor up to 4.4). Detection of Sudan I in chili powder samples show ultra-low LOD (44.7 ng/g), satisfactory recoveries (94.99-105.5%) and low relative standard deviation (≤ 2.0%). This research offers a reliable strategy and promising scheme for highly selective and sensitive detection of illegal additives in complex food matrix via an up-conversion molecularly imprinted ratiometric fluorescent test strip.

Rapid determination of illegally added Sudan I in cake by triphenylamine functionalized polyhedral oligomeric silsesquioxane fluorescence sensor

Triphenylamine functionalized polyhedral oligomeric silsesquioxane (POSS@TPA) was prepared using the Friedel-Crafts reaction with tris(4-bromophenyl)amine (TPA) as the functional monomer and polyhedral oligomeric silsesquioxane (POSS) as the framework. The as-prepared POSS@TPA has a stable structure and accomplished pore performance, allowing for the selective adsorption of Sudan I and result in the fluorescence quenches of POSS@TPA. Thus, the POSS@TPA could be used as sensors to fluorescence detect 0.12-7.4 mg/L Sudan I, with a detection limit of 0.091 mg/L. Moreover, the POSS@TPA have good reuseability can be reused more than 5 cycles after washing. Noteworthily, the response time of POSS@TPA for determination was as short as 1 min. Furthermore, the sensor was effectively used to determine Sudan I in cakes with excellent recoveries (86.4-108.8 %) and relative standard deviations (2.5-4.9 %). The results matched those of high-performance liquid chromatography (HPLC). Our work shows great potential in terms of the rapid detection of food safety.

Multifunctional Carbon Dots-Based Fluorescence Detection for Sudan I, Sudan IV and Tetracycline Hydrochloride in Foods

Sudan dyes are strictly prohibited from being added to edible products as carcinogens and tetracycline hydrochloride (TC) remaining in animal-derived food may cause harm to the human body. Therefore, it is necessary to establish a high-sensitivity, simple and convenient method for the detection of Sudan dyes and TC in foods for safety purposes. In this work, multifunctional blue fluorescent carbon dots (B-CDs) were prepared by a one-step hydrothermal synthesis using glucose as the carbon source. The results show that the fluorescence intensity of B-CDs was significantly affected by the acidity of the solution and can be quenched by Sudan I, IV and TC through selective studies. Interestingly, the fluorescence quenching intensities of B-CDs have a good linear relationship with the concentration of Sudan I and IV at pH = 3-7. The wide range of pH is beneficial to broaden the application of B-CDs in a practical samples analysis. The method has been successfully applied to real food samples of tomato paste, palm oil and honey, and the detection limits are 26.3 nM, 54.2 nM and 31.1 nM for Sudan I, Sudan IV and TC, respectively. This method integrates Sudan dyes and TC into the same multifunctional B-CDs, which shows that the sensor has a great potential in food safety detection.

Electrochemical detection of Sudan red series azo dyes: Bibliometrics based analysis

Sudan red azo dyes are banned from food because of their carcinogenic properties. It is necessary to establish a method for the detection of Sudan azo dyes in food. Among them, electrochemical sensing technology has become a very potential analytical method for food detection because of its fast, sensitive and low price. In this paper, we analyze the electrochemical detection of Sudan red azo dyes by bibliometric method. A total of 161 articles were analyzed from 2007 to 2021. The geographical and institutional distribution of these papers is used to understand the form of collaboration on this topic. Keyword analysis in these papers is used to understand the different directions in which the topic is studied at different stages. The results show that the topic reached its peak in 2015. The development of novel materials with excellent electrochemical activity has promoted the research on this topic. As detection limits continue to be lowered and sensors continue to be optimized, this topic currently does not continue to attract much attention.