Quantitative Detection of Nitrite in Food Samples Based on Digital Image Colourimetry by Smartphone

A derivative of 3,3′,5,5′-tetramethylbenzidine for highly robust colorimetric sensing of nitrite in food samples

The accurate determination of nitrite in food samples is of great significance for ensuring people’s health and safety. Herein, a rapid and low-cost detection method was developed for highly sensitive and selective detection of nitrite based on a surface-enhanced Raman scattering (SERS) sensor combined with electrochemical technology and diazo reaction. In this work, a gold nanoparticle (AuNP)/indium tin oxide (ITO) chip as a superior SERS substrate was obtained by electrochemical self-assembled AuNPs on ITO with the advantages of good uniformity, high reproducibility, and long-time stability. The azo compounds generated from the diazotization-coupling reaction between nitrite, 4-aminothiophenol (4-ATP), and N-(1-naphthyl) ethylenediamine dihydrochloride (NED) in acid condition were further assembled on the surface of AuNP/ITO. The detection of nitrite was realized using a portable Raman spectrometer based on the significant SERS enhancement of azo compounds assembled on the AuNP/ITO chip. Many experimental conditions were optimized such as the time of electrochemical self-assembly and the concentration of HAuCl4. Under the optimal conditions, the designed SERS sensor could detect nitride in a large linear range from 1.0 × 10−6 to 1.0 × 10−3 mol L−1 with a low limit of detection of 0.33 μmol L−1. Additionally, nitrite in real samples was further analyzed with a recovery of 95.1−109.7%. Therefore, the proposed SERS method has shown potential application in the detection of nitrite in complex food samples.

Amperometry detection of nitrite in food samples using tetrasulfonated copper phthalocyanine modified glassy carbon electrode

A facile dual-function fluorescent probe for detection of phosgene and nitrite and its applications in portable chemosensor analysis and food analysis

Bimetallic-MOF-derived crystalline–amorphous interfacial sites for highly efficient nitrite sensing

Chitosan-based antibacterial AIE luminogens for bioimaging and dual-mode detecting of nitrite in food samples.

One-pot facile synthesis of green-emitting fluorescent silicon quantum dots for the highly selective and sensitive detection of nitrite in food samples

Nano-palladium-decorated bismuth sulfide microspheres on a disposable electrode integrated with smartphone-based electrochemical detection of nitrite in food samples

In situ preparation of FeSe nanorods-functionalized carbon cloth for efficient and stable electrochemical detection of nitrite

A [5,10,15,20-tetrakis (4-methoxyphenyl) porphyrinato] manganese (III)chloride (TMOPPMn(III)Cl)-modified gold electrode sensor was developed for the determination of nitrite in food samples. The developed sensor showed an excellent catalytic activity and stability for nitrite oxidation. Under optimized conditions, nitrite concentration as low as 2.9 × 10−9 M can be determined in various food samples using the developed sensor. Effect of common interfering ions have been investigated in simulated mixtures containing high levels of interfering ions and the sensor was found to be tolerant against these ions. The determination of nitrite in food samples such as chicken ham, sausage and pickled vegetables with the proposed sensor was in good agreement with those obtained by standard spectrophotometric method.

Nitrite determination in food using electrochemical sensor based on self-assembled MWCNTs/AuNPs/poly-melamine nanocomposite

To create high-performance additive manufactured electrodes that can form the basis of electroanalytical platforms for real-world applications, the development of unique bespoke filament is required. To this end, this study presents the first report of a palladium nanoparticle (PdNP) embedded conductive filament for additive manufacturing electrochemistry, sustainably produced using an environmentally friendly aqueous synthesis, recycled poly(lactic acid) (PLA), bio-based plasticiser castor oil, and solvent-free thermal mixing. Once printed, the additive manufactured electrodes, with palladium nanoparticles supported on acid-activated graphite (PdNPs-AAGr), are applied towards the electrochemical detection of nitrite in food samples. The acid treatment of graphite enhanced PdNP formation, improving electrochemical properties and enabling sensitive nitrite detection via square wave voltammetry, with a linear range of 1 to 120μM and a detection limit of 0.042μM. The electrode exhibited excellent repeatability (RSD 4%) and selectivity, with minimal interference from food matrix components. Real sample analysis in sausage, chicken ham, and pickled vegetables showed recoveries comparable to ion chromatography, confirming analytical accuracy. This work integrates an eco-friendly PdNPs on graphite synthesis method with recycled PLA, carbon black and bio-based castor oil plasticiser, offering a sustainable platform for food monitoring.

Bioinspired iron porphyrin covalent organic framework nanozyme with peroxidase-like activity for ratiometric colorimetric and portable swab-assisted detection of nitrite in food samples.

As a common food additive, nitrites are used in processed meat products, primarily for color enhancement and preservation. Excessive intake of nitrites can lead to high toxicity to pose a significant risk to human health, including potential carcinogenicity and even death. Consequently, developing a rapid and sensitive method for nitrite detection is crucial for food safety monitoring. Herein, this study is developing a nitrite detection system utilizing blue‐fluorescent carbon dots (CDs) derived from carboxylate cellulose. This system operates by detecting the quenching of CDs fluorescence, which is caused by Fe3⁺ ions generated via the oxidation of Fe2⁺ by nitrite under acidic conditions. Within a concentration range of 1–1000 µm, the system demonstrates a strong linear relationship between CDs fluorescence intensity and nitrite concentration, with a detection limit of 0.42 µm. Furthermore, this study is designing a novel CDs‐based fluorescent test strip for rapid and visual nitrite quantification in pakchoi cabbage samples, enabling detection within 30 min. Overall, the CDs‐based fluorescent test strips hold great promise for enhancing food safety monitoring, ensuring effective nitrite control, and protecting public health from the potential risks associated with excessive nitrite consumption.

A simple and sensitive solid‐phase fluorescence quenching method for the determination of trace amounts of nitrite in food samples has been developed. The method is based on that rhodamine B (RhB) which is used as an emission reagent and is included by β‐cyclodextrin polymer(β‐CDP), reacts with nitrite in the presence of iodide to form a nonfluorescence compound in acidic medium. The fluorescence intensity of the RhB‐included β‐CDP was measured in solid phase with excitation and emission wavelengths of 353 and 592 nm, respectively. The fluorescence quenching degree is good linear with the concentration of nitrite over the ranges of 1.0–3.0 µg with a detection limit of 0.04 µg and RSD is 1.2%. The general coexisting ions do not interfere to the reaction of RhB with nitrite. The proposed method has been applied to the determination of trace amount of nitrite in food samples with the recoveries of 102.8% (ham) and 99.0% (sausage), respectively.