A smart-phone-based electrochemical platform with programmable solid-state-microwave flow digestion for determination of heavy metals in liquid food

Nondestructive detection of cadmium content in oilseed rape leaves under different silicon environments using deep transfer learning and Vis-NIR hyperspectral imaging

In this paper, a transfer stack denoising autoencoder (T-SDAE) algorithm is proposed to implement the migration of cadmium (Cd) prediction depth characteristic model of oilseed rape leaves in different silicon environments. Stacked denoising autoencoder (SDAE) algorithm was used to reduce dimensionality, and the most effective SDAE deep learning network was transferred to create the T-SDAE model. The results showed that SVR model using SDAE to extract depth features had the best prediction effect on Cd content in silicon-free, low-silicon and higher-silicon environments. Moreover, the coefficient of determination of prediction set (Rp2) were 0.9127, 0.9829 and 0.9606, respectively. Specifically, the Rp2 value of the T-SDAE-SVR optimal prediction set under different silicon environments is 0.9273, RMSEP is 0.01465 mg/kg, and RPD is 3.237. By integrating hyperspectral imaging technology with a deep transfer learning algorithm, accurate detection of various Cd contents in oilseed rape leaves is feasible under different silicon environments.

Electrochemical biosensors: The beacon for food safety and quality

Electrochemical biosensors transduce chemical reactions into measurable electrical signals by incorporating recognition components. Although they are capable of detecting a broad range of target molecules, their application in complex matrices, such as food, at minimum or no sample preparation, is challenging and requires the introduction of innovative and effective strategies. This review explores the recent advances in electrochemical biosensors for on-site food safety and quality analysis. We first discuss the presence of chemical contaminants and biohazards in food and the need for robust, rapid, low-cost, and point-of-care (POC) analytical techniques. We then address the critical aspects of sensitivity and selectivity of electrochemical biosensors in detecting chemical and biological contaminants in real food samples. We finally investigate the major drawbacks of these biosensors and provide future perspectives on the field.

Recent advances in photoelectric methods application for cooking oil quality and safety evaluation: a review

Cooking oil is used daily in consumed food and culinary applications; therefore, its safety and quality are very important. Notably, susceptibility to contamination at each processing stage poses threats to living organisms. This review discusses the parameters of oil quality, as well as the role of the various non-destructive photoelectric techniques with respect to its quality and safety, including near-infrared spectroscopy (NIR), mid-infrared spectroscopy, Fourier transform near-infrared spectroscopy, Raman spectroscopy and fluorescence spectroscopy. Data on cooking oil quality, such as values of the following parameters, notably peroxides, thiobarbituric acid, anisidine, iodine, trans-fat and fatty acid profile, carbonyl compounds, adulteration and total polar components, are also demonstrated. Photoelectric methods are rapid and efficient tools for the preliminary screening of cooking oil when aiming to determine its quality before its entry into the food chain. Primarily, NIR has been used to predict most of the cooking oil safety and quality parameters, and thus is considered as the most convenient non-destructive method to be recommended. Accordingly, deep insight into state-of-the-art photoelectric/spectral technologies and the varieties of techniques available provides an opportunity to detect and predict the safety parameters of products prior to their processing and distribution. In this review, we highlight these perspectives with particular emphasis on the cooking oil. © 2025 Society of Chemical Industry.

Research Progress on the Application of Metal Porphyrin Electrochemical Sensors in the Detection of Phenolic Antioxidants in Food

This paper reviews the application of metal porphyrin electrochemical sensors in the detection of phenolic antioxidants in food, focusing on the latest progress and innovative applications in this field. Phenolic antioxidants are widely used in food and can effectively prolong the shelf life of food, but their excessive use may cause potential harm to human health, so the detection of their content is very important. In recent years, electrochemical analysis technology has gradually become an emerging method for quantitative detection of phenolic antioxidants due to its advantages of sensitivity, simplicity and high selectivity. As a new type of sensor, metal porphyrin electrochemical sensors have been widely used in the detection of phenolic antioxidants in food due to their excellent electrochemical performance and high selectivity. By modifying metal nanomaterials, the detection performance of these sensors has been significantly improved. This paper first introduces the basic concepts and physicochemical properties of phenolic antioxidants, analyzes their potential hazards and discusses relevant regulations and limit requirements. Then, the existing analysis methods of phenolic antioxidants are compared, and the development trend of traditional detection methods and new detection technologies is reviewed. Subsequently, the application progress of electrochemical sensors in the detection of phenolic antioxidants is discussed in depth, its working principle is expounded and the research results are summarized. Finally, the innovative applications of metalloporphyrins and their nanocomposites in electrochemical sensors are introduced in detail. The unique advantages of metalloporphyrins in the detection of phenolic antioxidants in food are highlighted, and the future development direction is laid out.

Electrochemical detection of heavy metals in rice, milk and tap water using free-standing carbon felt electrodes

In this work, a carbon felt (CF) was utilized to fabricate electrochemical sensors for the simultaneous detection of Cd2+, Pb2+ and Hg2+. The working conditions of CF sensors including thermal activation, electrolytes, and enrichment potentials and times were systematically investigated. Under the optimal detection conditions, the resulting sensors showed good linearity in the concentration ranges of 3-10,000, 2-10,000 and 5-10,000 μg/L for the detection of Cd2+, Pb2+ and Hg2+, corresponding to the detection limits of 1, 0.5, and 1 μg/L, respectively. Meanwhile, the resulting electrochemical sensor demonstrates excellent reproducibility and anti-interference. In addition, the CF electrodes maintain good stability even after 180 days of storage at room temperature. In real water, rice and milk samples, the CF electrodes have been successfully utilized for the detection of Cd2+, Pb2+ and Hg2+ and the results were in agreement with those obtained from the inductively coupled plasma mass spectrometry.

Remediation of heavy metals polluted soil environment: A critical review on biological approaches

Heavy metals (HMs) pollution is a globally emerging concern. It is difficult to cost-effectively combat such HMs polluted soil environments. The efficient remediation of HMs polluted soil is crucial to protect human health and ecological security that could be carried out by several methods. Amidst, biological remediation is the most affordable and ecological. This review focused on the principles, mechanisms, performances, and influential factors in bioremediation of HMs polluted soil. In microbial remediation, microbes can alter metallic compounds in soils. They transform these compounds into their metabolism through biosorption and bioprecipitation. The secreted microbial enzymes act as transformers and assist in HMs immobilization. The synergistic microbial effect can further improve HMs removal. In bioleaching, the microbial activity can simultaneously produce H2SO4 or organic acids and leach HMs. The production of acids and the metabolism of bacteria and fungi transform metallic compounds to soluble and extractable form. The key bioleaching mechanisms are acidolysis, complexolysis, redoxolysis and bioaccumulation. In phytoremediation, hyperaccumulator plants and their rhizospheric microbes absorb HMs by roots through absorption, cation exchange, filtration, and chemical changes. Then they exert different detoxification mechanisms. The detoxified HMs are then transferred and accumulated in their harvestable tissues. Plant growth-promoting bacteria can promote phytoremediation efficiency; however, use of chelants have adverse effects. There are some other biological methods for the remediation of HMs polluted soil environment that are not extensively practiced. Finally, the findings of this review will assist the practitioners and researchers to select the appropriate bioremediation approach for a specific soil environment.

A remote-controlled portable workstation for highly sensitive and real-time chemiluminescent detection of cadmium

The prevention of pollution requires real-time monitoring of cadmium (Cd2+) concentration in the food, as it has a dramatic impact on poultry and can pose a threat to human health. Here, we fabricate a portable workstation integrating a microfluidic chip that facilitates real-time monitoring of Cd2+ levels in real samples by utilizing the Luminol-KMnO4 chemiluminescence (CL) system. Interestingly, Cd2+ can significantly enhance the CL signal, resulting in sensitive detection of Cd2+ in the range of 0-0.18 mg/L with the limit of detection (LOD) of 0.207 μg/L. Furthermore, a remote-controlled unit is integrated into the portable workstation to form a remote-controlled portable workstation (RCPW) performing automated point-of-care testing (POCT) of Cd2+. The as-prepared strategy allows remote control of RCPW to avoid long-distance transportation of samples to achieve real-time target monitoring. Consequently, this system furnishes RCPW for monitoring Cd2+ levels in real samples, thereby holding potential for applications in preventing food pollution.

Development of smartphone-controlled and machine-learning-powered integrated equipment for automated detection of bioavailable heavy metals in soils

Rapid and accurate on-site detection of crop-absorbable cadmium (Cd) and lead (Pb) in soils is important for food security and human health. The automated soil sample pretreatment method, including the ultrasonic extraction of weakly acid-soluble heavy metals, suction-filtration, and UV photolysis, was proposed to achieve the high-efficiency preparation from soil sample to extract solution. Bismuth-film-modified glass carbon electrode combined with the homemade potentiostat was fabricated to implement the square-wave anodic stripping voltammetry (SWASV) measurements of soil extracts. The peak-information-acquisition algorithm was designed to automatically obtain peak heights and widths of Zn2+, Cd2+, Pb2+, Bi3+, and Cu2+ stripping currents, and then which were used as input variables for establishing machine-learning models to enhance the detection accuracy of SWASV to Cd2+ and Pb2+ under the coexistence of multiple heavy metal ions. Eventually, the smartphone-controlled integrated-automated detection equipment was developed and successfully applied to the automatic pretreatment of soil samples and the determination of weakly acid-soluble Cd2+ and Pb2+ in real soil samples. The detection speed was 75 min/sample, and the detection results were close to the standard method (BCR-ICP-MS). This equipment can provide powerful technical support for on-site rapid and accurate determination of crop-absorbable heavy metals in soils.

A dual-mode green emissive fluorescent probe for real-time detection of doxycycline in milk using a smartphone sensing platform

Real-time quantitative analysis of tetracyclines is urgently needed to provide consumers with early warning of potential risks. Herein, we report a dual-mode green emissive fluorescent probe, which refers to the liquid mode and the solid mode of electrospun films doped with nitride-doped carbon nanosheets (NCNSs) for real-time detection of doxycycline (DOX). Highly fluorescent NCNSs were prepared by low-temperature solid treatment of urea and sodium citrate. With the addition of DOX, the green emission intensity of NCNSs at 475 nm can be obviously reduced. Method validation exhibited a good linear relationship in 0.05-150 μM between the fluorescence quenching of NCNSs and the concentration of DOX with a limit of detection (LOD) of 0.0127 μM. Furthermore, the immobilization of NCNSs in PAN carriers forming electrospun films stabilizes the green fluorescence of NCNSs. Additionally, electrospun films integrated into a smartphone were developed for real-time detection of DOX with LOD of 0.285 μM. Additionally, DOX in milk was monitored with satisfactory recoveries. Therefore, the integration of the smartphone and electrospun film provides a promising and convenient method for real-time identification of DOX in food analysis.

Efficient Adsorption and Electrochemical Detection of Cd2+ with a Ternary MgZnFe-Layered Double Hydroxides Engineered Porous Biochar Composite

Their unique layered structure, large specific surface area, good stability, high negative charge density between layers, and customizable composition give layered double hydroxides (LDHs) excellent adsorption and detection performance for heavy metal ions (HMIs). However, their easy aggregation and low electrical conductivity limit the practical application of untreated LDHs. In this work, a ternary MgZnFe-LDHs engineered porous biochar (MgZnFe-LDHs/PBC) heterojunction was proposed as a sensing and adsorption material for the effective detection and removal of Cd2+ from wastewater. The growth of MgZnFe-LDHs in the PBC pores not only reduces the accumulation of MgZnFe-LDHs, but also improves the electrical conductivity of the composite. The synergistic effect between MgZnFe-LDHs and PBC enables the composite to achieve a maximum adsorption capacity of up to 293.4 mg/g for Cd2+ in wastewater. Meanwhile, the MgZnFe-LDHs/PBC-based electrochemical sensor shows excellent detection performance for Cd2+, presenting a wide linear range (0.01 ng/L-1 mg/L), low detection limit (3.0 pg/L), good selectivity, and stability. The results indicate that MgZnFe-LDHs/PBC would be a potential material for detecting and removing Cd2+ from wastewater.

TPB-DMTP@S-CDs/MnO2 Fluorescence Composite on a Dual-Emission-Capture Sensor Module for Fingerprint Recognition of Organophosphorus Pesticides

Residues of organophosphorus pesticides (OPs) raise considerable concern, while identifying OPs from unknown sources is still a challenge to onsite fluorescence techniques. Herein, a dual-emission-capture sensor module, based on a TPB-DMTP@S-CDs/MnO₂ fluorescence composite, is developed for OP fingerprint recognition. TPB-DMTP@S-CDs/MnO₂, synthesized by a hydrothermal method and self-assembly, is spectrographically validated as a dual-wavelength fluorescence source. OP-sensitive catalysis (acetylcholinesterase on acetylthiocholine chloride) is designed to regulate fluorescence by decomposing quenchable MnO₂. A flexibly fabricated sensor module supports the optimal dual-wavelength fluorescence excitations and captures and converts fluorescence emissions into equivalent photocurrents for feasible access. The most prominent finding is that dual-fluorescence emissions alternatively respond to levels, species, and multi-pH pretreatments of OPs due to varied MnO₂ sizes and distributions. Therefore, OP fingerprint recognition is conducted by refining the multidimensional information from fluorescence-triggered photocurrents and preset hydrolyzation using principal component analysis and the rule of maximum covariance. The recommended method provides a wide dynamic range (1 × 10^-6 ∼ 12 μg mL^-1), a good limit of detection (7.9 × 10^-7 μg mL^-1), 15-day stability, and good selectivity to guarantee fingerprint recognition. For laboratory and natural samples, this method credibly identifies a single kind of OPs from multiple species at trace levels (10^-5 μg mL^-1) and performs well in two-component and multicomponent analyses.

Thermal-controlled active sensor module using enzyme-regulated UiO-66-NH2/MnO2 fluorescence probe for total organophosphorus pesticide determination

An enzyme-regulated UiO-66-NH₂/MnO₂ fluorescence sensor, fully functionalized with spectrometric capacities, is developed for budget-friendly total organophosphorus pesticides (OPs) determination. The fluorescence probe, UiO-66-NH₂/MnO₂, is hydrothermally synthesized and morphologically examined. A specialized enzyme-catalyzed reaction, which can be gradually inhibited by OPs, is designed with participations of alkaline phosphatase (ALP) and sodium L-ascorbyl-2-phosphate (AAP). The reaction product of ascorbic acid (AA) decomposes MnO₂ and restores UiO-66-NH₂ fluorescence, establishing a relationship between OPs level and fluorescence intensity. Interactions among UiO-66-NH₂, MnO₂, OPs, and AA are clarified. Stepwise optimizations are performed to the UiO-66-NH₂/MnO₂ probe, ensuring considerable advantages as OPs affinity and fluorescence quenching behavior over rival nanomaterials. Analytical advances are magnified by fabricating an active sensor module, with self-acting thermal regulation for optimal enzyme activity. Under 4 and 20 °C environment, regulation period is less than 40 and 100 s. In total OPs determination for laboratorial and real-vegetable samples, this method exhibits uniform and log-linear responses to common species of OPs in a range as 1.0 × 10^-7~10 mg L^-1, and limit of detection is established as 8.9 × 10^-8 mg L^-1. Proposed readouts are validated with certified HPLC and recovery test. Relative errors and recovery rates are found as 2.7-6.4% and 95.8-102.6%, respectively.

Ratiometric immunosensor with DNA tetrahedron nanostructure as high-performance carrier of reference signal and its applications in selective phoxim determination for vegetables

A ratiometric electrochemical immunosensor, based on DNA tetrahedron nanostructure (DTNS), is introduced for vegetable phoxim determination. DTNS spontaneously adheres onto gold-nanoparticle-modified electrode and forms stable three-dimensional structure, providing plenty of binding sites to the built-in reference, methylene blue (MB). Monoclonal antibody (m-Ab) is vertically linked onto DTNS vertex, selectively responses antigenic phoxim, and promotes the target signal of I_PHO. Thus, a ratiometric indicator, I_PHO/I_MB, is sensibly established with the target signal (I_PHO) and the reference signal (I_MB). Modifications, mechanisms and advances of the proposed method are subsequently examined with morphological methods and electrochemical experiments. This method brings considerable advances in analytical behaviors. The ratiometric signal presents better performance than solo system in repeatability and long-time stability. As-fabricated sensor presents wide dynamic range as 0.1∼30 μg/L, and limit of detection is well defined as 0.003 μg/L (S/N = 3). Finally, this method is verified with real-vegetable-sample analysis, certified HPLC and recovery test.

Highly selective and sensitive fluorescence detection of tetracyclines based on novel tungsten oxide quantum dots

Tetracyclines (TCs) residues in animal products have attracted extensive concern due to their potential toxic to human health. Accordingly, it is urgent to develop an efficient method to determine TCs for providing consumers with risk pre-warning. Herein, a novel tungsten oxide quantum dots (W_xO_y QDs) fluorescence probe for tetracycline (TET) detection was constructed through ethanol-thermal method, which exhibited intense blue fluorescence under 365 nm UV light. Interestingly, blue-emitting W_xO_y QDs could be quenched obviously after the addition of TET, which may be attributed to the synergism of inner filter effect (IFE), fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET). Thereby, the fluorescence method was established for TET detection based on W_xO_y QDs. Additionally, the presented method was demonstrated by monitoring TET in milk and milk powder with satisfactory recoveries. More importantly, this work offered good demonstration for the detection of food hazard factors.

Programmable-Printing Paper-Based Device with a MoS2 NP and Gmp/Eu-Cit Fluorescence Couple for Ratiometric Tetracycline Analysis in Various Natural Samples

Paper-based fluorescence devices, with smartphone aids, bring considerable operation convenience for tetracycline (TC) sensing. Nevertheless, they must meet the challenge in real determination against complicated backgrounds. Considering that, we present a programmable-printing paper-based device and then apply it to TC determination for various natural samples. MoS₂ NPs and Gmp/Eu-Cit are synthetized as composite probes. A static quenching process is found with MoS₂ NP fluorescence at 430 nm, while significant magnification of Gmp/Eu-Cit emission is obtained at 617 nm, establishing a valuable ratiometric indicator. Remarkably, two-stage programmable printing maximizes the proposed sensing capability. A transitive device, containing a gradually changing amount of a certain probe, is prepared to sense TC. With a homemade smartphone application and 3D-printed measurement chamber, the corresponding signals are examined to explore optimal setups. These setups are automatically processed to prepare the final-version device, not requiring manual operations. Benefitting from this interesting feature, the proposed device gains many rewards in performances. It effectively senses TC in a wide range from 12.7 nM to 80 μM and simultaneously provides naked eye-legible signals and smartphone-based readouts with confident selectivity and stability. This device is consequently applied for various samples of soil, river water, milk, and serum and meets well with HPLC-MS and recovery tests.

Label-free Hg(II) electrochemiluminescence sensor based on silica nanoparticles doped with a self-enhanced Ru(bpy)32+-carbon nitride quantum dot luminophore

Herein, a label-free, self-enhanced electrochemiluminescence (ECL) sensing strategy for divalent mercury (Hg(II)) detection was presented. First, a novel self-enhanced ECL luminophore was prepared by combining the ECL reagent tris(2, 2'-bipyridyl) dichlororuthenium(II) hexahydrate (Ru(bpy)₃²⁺) and its co-reactant carbon nitride quantum dots (CNQDs) via electrostatic interactions. In contrast to traditional ECL systems where the emitter and its co-reactant underwent an intermolecular reaction, the self-enhanced ECL system exhibited a shortened electron-transfer distance and enhanced luminous efficiency because the electrons transferred from CNQDs to oxidized Ru(bpy)₃²⁺ via an intramolecular pathway. Furthermore, the as-prepared self-enhanced ECL material was encapsulated in silica (SiO₂) nanoparticles to generate a Ru-QDs@SiO₂ luminophore. Based on the different affinity of Ru-QDs@SiO₂ nanoparticles for single-stranded DNA (ssDNA) and Hg(II)-triggered double-stranded DNA (dsDNA), a label-free ECL biosensor for Hg(II) detection was developed as follows: in the absence of Hg(II), ssDNA was adsorbed on Ru-QDs@SiO₂ surface via hydrogen bond, electrostatic, and hydrophobic interaction. Thus, quenched ECL signal was observed. On the contrary, in the presence of Hg(II), stable dsDNA was formed and carried the ssDNA separating from Ru-QDs@SiO₂ surface, resulting in most of Ru-QDs@SiO₂ existing in their free state. Therefore, a recovered ECL intensity was obtained. On this basis, Hg(II) was measured by the proposed method in the range of 0.1 nM-10 μM, with a detection limit of 33 pM. Finally, Hg(II) spiked in water samples was measured to evaluate the practicality of the fabricated biosensor.

Lead Assays with Smartphone Detection Using a Monolithic Rod with 4-(2-Pyridylazo) Resorcinol

A monolithic rod of polyurethane foam-[4-(2-pyridylazo) resorcinol] (PUF-PAR) as a simple chemical sensor for lead assays with smartphone detection and image processing was developed. With readily available simple apparatus such as a plastic cup and a stirrer rod, the monolithic PUF rod was synthesized in a glass tube. The monolithic PUF-PAR rod could be directly loaded by standard/sample solution without sample preparation. A one-shot image in G/B value from a profile plot in ImageJ for a sample with triplicate results via a single standard calibration approach was obtained. A linear single standard calibration was: [G/B value] = -0.038[µg Pb2+] + 2.827, R2 = 0.95 for 10-30 µg Pb2+ with a limit of quantitation (LOQ) of 33 µg L-1. The precision was lower than 15% RSD. The proposed method was tested by an assay for Pb2+ contents in drinking water samples from Bangkok. The results obtained by the proposed method agree with those of ICP-OES and with 100-120% recovery, demonstrating that the method is useful for screening on-site water monitoring.

A smartphone-integrated ratiometric fluorescence sensor for visual detection of cadmium ions

A novel fluorescence sensing platform was fabricated for visual detection of cadmium ions (Cd²⁺) with excellent stability and portability. In this protocol, dual-emission ratiometric fluorescence probe were constructed based on silicon oxide-coated copper nanoclusters (CuNCs@SiO₂) as a signal reference and cadmium telluride quantum dots (CdTe QDs) as signal response, thereby greatly improving the accuracy of test results. The level of Cd²⁺ can be reported within a wide linear range from 0.010 mg·L^-1 to 2.0 mg·L^-1 with a sensitive detection limit of 1.1 μg·L^-1 (2.75 μg·kg^-1) and a quick sample-to-answer monitoring time of 6 min, which was quite qualified for regularly monitoring Cd²⁺. Moreover, aiming to attain portable analysis, the smartphone as colorimetric reader and analyzer were also utilized for rapidly analyzing Cd²⁺ by capturing the change in fluorescence color. Additionally, benefiting from the strong combination of 1, 10-phenanthroline (Phen) and Cd²⁺, the fluorescence probe showed excellent anti-interference activities for Cd²⁺ assay in complex oyster matrix. Overall, the sensing platform had significant stability, specificity and sensitivity, offering a promising potential for conveniently evaluating the quality of marine bivalves polluted with Cd²⁺.

Rapid detection of cadmium ions in meat by a multi-walled carbon nanotubes enhanced metal-organic framework modified electrochemical sensor

This work presents an electrochemical device based on a composite modification of amine functionalized Zr(IV) metal-organic framework (UiO-66-NH2) and multi-walled carbon nanotubes (MWCNTs) for voltammetry determination of cadmium ions (Cd2+). The UiO-66-NH2@MWCNTs composites were prepared by one-pot hydrothermal reaction. The prepared sensor performs excellent performance, which was attributed to the synergism between UiO-66-NH2 with a special octahedral structure and enlarged surface area and MWCNTs with outstanding conductivity. Under optimal experiment condition, the fabricated sensor showed good linear relationship from 0.5 to 170 μg/L, with a detection limit of 0.2 μg/L. Finally, the sensor was successfully applied to detect Cd2+ in meat samples (N = 21) with relative standard deviation (RSD) lower than 4.5% and recovery of 95.1-107.5%, and the results were compared with certified method, there was no statistical significance difference between the developed sensor and certified method at a 95% confidence level.

Employing CuInS2 quantum dots modified with vancomycin for detecting Staphylococcus aureus and iron(iii)

This paper describes a near-infrared quantum dot (CuInS₂ QD)/antibiotic (vancomycin) nanoparticle-based assay for the Staphylococcus aureus and iron(iii) detection. CuInS₂ QDs with good biological tissue permeability and biocompatibility are combined with vancomycin through covalent interaction to form a detection system for two harmful factors. The detection principle of Staphylococcus aureus is mainly the fluorescence quenching caused by the accumulation of CuInS₂@Van QDs on the surface of Staphylococcus aureus. The detection principles of the iron(iii) ion are mainly ascribed to the aggregation of quantum dots and the transfer of charges, which cause the fluorescence signal to change. The linear range of S. aureus and the Fe³⁺ ion is 10³ to 10⁸ CFU mL^-1 and 10-90 μM, respectively. Their detection limits are 665 CFU mL^-1 and 3.5 μM, respectively. The procedure was validated by the quantitation of Staphylococcus aureus and iron(iii) in spiked samples, and was found to demonstrate the feasibility of this method.

Direct detection of Pb2+ and Cd2+ in juice and beverage samples using PDMS modified nanochannels electrochemical sensors

Direct electrochemical detection in real food samples remains challenging due to the fouling and interference by abundant interference components. Herein, we report an electrochemical sensing platform based on binary assembly of silica nanochannels and polydimethylsiloxane that is able to detect Pb²⁺ and Cd²⁺ in real food samples without complex pretreatments. Using differential pulse anodic stripping voltammetry, the electrochemical detection consists of electro-deposition of metal species and subsequent anodic stripping in the modified silica-nanochannels. Under the optimized conditions, the linear ranges were obtained from 4 to 1500 μg L^-1 for Pb²⁺ and 30 to 900 μg L^-1 for Cd²⁺. The relative standard deviations were 2.9% and 3.6% for Pb²⁺ and Cd²⁺ of 300 μg L^-1. Without tedious pretreatments, the quantitative detection of Pb²⁺ and Cd²⁺ in real juice and beverage samples was successfully performed, revealing that the developed sensor possesses excellent anti-interference and practicability properties for unprocessed food.

A portable test strip based on fluorescent europium-based metal-organic framework for rapid and visual detection of tetracycline in food samples

Residual tetracycline (TC) in animal food caused by abuse of antibiotics leads to many chronic diseases in the human body. The development of a simple and on-site visualization method for TC detection is need of the hour. Herein, a fluorescent europium-based metal-organic framework (Eu-MOF) sensor for visual and rapid detection of TC was developed. Eu-MOF displays a red emission being excited at 260 nm. Upon exposure to TC, significant fluorescence quenching was observed due to the inner filter effect and photoinduced electron transfer. Moreover, the developed sensor was applied for the detection of TC in milk and beef samples with recoveries of 96.1% to 106.3%, respectively. More importantly, a portable test strip based on Eu-MOF was manufactured. It is a highly selective and sensitive portable device for TC detection. The results can be distinguished immediately by naked eyes, making it become an excellent choice to detect TC in real-time application.

The Role of Suspension Array Technology in Rapid Detection of Foodborne Pollutants: Applications and Future Challenges

Food safety is an important livelihood issue, which has always been focused attention by countries and governments all over the world. As food supply chains are becoming global, food quality control is essential for consumer protection as well as for the food industry. In recent years, a great part of food analysis is carried out using new techniques for rapid detection. As the first biochip technology that has been approved by the Food and Drug Administration (FDA), there is an increasing interest in suspension array technology (SAT) for food and environmental analysis with advantages of rapidity, high accuracy, sensitivity, and throughput. Therefore, it is important for researchers to understand the development and application of this technology in food industry. Herein, we summarized the principle and composition of SAT and its application in food safety monitoring. The utility of SAT in detection of foodborne microorganisms, residues of agricultural and veterinary drugs, genetically modified food and allergens in recent years is elaborated, and the further development direction of SAT is envisaged.

Development and perspectives of rapid detection technology in food and environment

Food safety become a hot issue currently with globalization of food trade and food supply chains. Chemical pollution, microbial contamination and adulteration in food have attracted more attention worldwide. Contamination with antibiotics, estrogens and heavy metals in water environment and soil environment have also turn into an enormous threat to food safety. Traditional small-scale, long-term detection technologies have been unable to meet the current needs. In the monitoring process, rapid, convenient, accurate analysis and detection technologies have become the future development trend. We critically synthesizing the current knowledge of various rapid detection technology, and briefly touched upon the problem which still exist in research process. The review showed that the application of novel materials promotes the development of rapid detection technology, high-throughput and portability would be popular study directions in the future. Of course, the ultimate aim of the research is how to industrialization these technologies and apply to the market.

Application of smartphone in detection of thin-layer chromatography: Case of salvia miltiorrhiza

In this work, a smartphone-based device was constructed for thin-layer chromatography (TLC) detection and semi-quantitative analysis of the components of Salvia miltiorrhiza. The key construction and shooting parameters were investigated by the relative peak area and signal-to-noise ratio. The best conditions were as follows: shooting height, 17 cm; angle between the UV lamp and TLC plate, 58°; exposure compensation, 0~0.2 EV; and shutter speed under daylight and UV 365 nm, 1/50 s and 1/5 s, respectively. These ideal conditions could be replicated by smartphones from different brands with different versions of software. With good precision, repeatability and stability, the developed device was used for the semi-quantitative analysis of salvianolic acid B, rosmarinic acid, cryptotanshinone, tanshinone I, tanshinone IIA, and miltirone in the TLC analysis of 10 batches of S. miltiorrhiza. The results were compared with those obtained by a TLC densitometric scanner and two common types of image processing software, i.e., Gelanalyzer and ImageJ. Except for salvianolic acid B in the TLC densitometric scanner, all results were not significantly different among these methods, which suggested that smartphones might be a useful tool for the quality control of traditional Chinese medicines.

Cloud-point extraction associated with voltammetry: preconcentration and elimination of the sample matrix for trace determination of methyl parathion in honey

This work presents the association of cloud point extraction (CPE) and electroanalysis for the selective and sensitive determination of methyl parathion (MP) in honey. The CPE step provided the pre-concentration of MP from a complex sample, in which the optimized extraction parameters (Triton X-100 concentration of 0.75% w/v, NaCl concentration of 1.0% w/v and heating time of 30 min) were investigated using a factorial design (23). The detection of MP was performed using a cathodically pre-treated boron-doped diamond (BDD) working electrode and square wave voltammetry (SWV), after a suitable dilution of the CPE extract in Britton-Robinson buffer pH 6.0 as the supporting electrolyte. MP presented three electrochemical processes over the BDD surface, but only the reduction peak at around -0.7 V was monitored for the MP determination (higher detectability). Improved reproducibility was reached by applying an in situ cleaning step (+2.0 V for 15 s) followed by a re-activation process (-2.0 V for 15 s) between measurements. Using the optimized variables, a linear range between 0.1 and 2.0 μmol L-1 was obtained for MP with a limit of detection of 0.006 μmol L-1, a 6-fold lower value when compared with the value attained without the CPE step. The experimental enrichment factor of MP was 6.1. Also, the optimized CPE allowed the determination of MP in honey samples with good accuracy (recovery between 94 and 106%), which was not possible using direct detection (without CPE) due to the matrix interference. This is the first paper that demonstrates the combination of CPE and electroanalysis for the determination of an organic compound.

Flow Chemistry in Contemporary Chemical Sciences: A Real Variety of Its Applications

Flow chemistry is an area of contemporary chemistry exploiting the hydrodynamic conditions of flowing liquids to provide particular environments for chemical reactions. These particular conditions of enhanced and strictly regulated transport of reagents, improved interface contacts, intensification of heat transfer, and safe operation with hazardous chemicals can be utilized in chemical synthesis, both for mechanization and automation of analytical procedures, and for the investigation of the kinetics of ultrafast reactions. Such methods are developed for more than half a century. In the field of chemical synthesis, they are used mostly in pharmaceutical chemistry for efficient syntheses of small amounts of active substances. In analytical chemistry, flow measuring systems are designed for environmental applications and industrial monitoring, as well as medical and pharmaceutical analysis, providing essential enhancement of the yield of analyses and precision of analytical determinations. The main concept of this review is to show the overlapping of development trends in the design of instrumentation and various ways of the utilization of specificity of chemical operations under flow conditions, especially for synthetic and analytical purposes, with a simultaneous presentation of the still rather limited correspondence between these two main areas of flow chemistry.