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SO 2 derivatives, sulfite/bisulfite, are widely employed in both the food processing and drug synthesis industries. Despite their widespread application, excessive levels of sulfite/bisulfite can negatively impact human health. Most probes for detecting sulfite/bisulfite are restricted by their fluorescence within the visible spectrum range and poor solubility in aqueous solution, which limit their use in food testing and biological imaging. Herein, a near-infrared probe comprising of the cyanopyridine cyanine skeleton, 4-((Z)-2-((E)-2-chloro-3-(2-cyano-2-(1-methylpyridine-4(1H)-ylidene)ethylidene)cyclohex-1-en-1-yl)-1-cyanovinyl)-1-methylpyridin-1-ium (abbreviated as CCP), was developed. This probe enables precise quantification of bisulfite (HSO 3 - ) in almost pure buffered solutions, showing a near-infrared fluorescence emission at 784 nm with an impressively low detection limit of 0.32 μM. The probe stands out for its exceptional selectivity, minimal susceptibility to interference, and strong adaptability. The probe CCP utilizes the CC bond to trigger a near-infrared fluorescence quenching reaction with HSO 3 - via nucleophilic addition, which effectively disrupts the large delocalization within the molecule for accurate HSO 3 - identification. Moreover, the probe has been successfully applied in detecting HSO 3 - in various food products and living cells, simplifying the measurement of HSO 3 - content in water samples. This advancement not only enhances the analytical capabilities but also contributes to ensuring food safety and environmental protection. ENVIRONMENTAL IMPLICATION: SO 2 derivatives including sulfite/bisulfite, serving dual roles as preservatives and antioxidants, have widespread application across various sectors including food preservation, water sanitation, and the pharmaceutical industry. Despite their widespread application, excessive levels of sulfite/bisulfite can affect human health. Developing methods for precisely and sensitively detecting sulfite/bisulfite in food products and biological samples is important for ensuring food safety and environmental protection. Here, a sensitive near-infrared and multifunctional fluorescent probe in a 99.9 % buffered solution, along with water gel encapsulation, has been successfully applied for the detection of bisulfite in food, authentic water samples, and biological cells., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a triphenylamine-benzofuran-derived fluorescent probe TBSF was developed for monitoring the sulfite level in Chinese medicinal materials and imaging in living cells. In the testing system, under 445 nm excitation, TBSF responded to sulfite steadily with a 540 nm fluorescence reporting signal. The testing system showed advantages including high sensitivity, rapid response, and high selectivity. In particular, TBSF achieved the sulfite detection in the water decoction of Chinese medicinal materials from both addition and excessive fumigation. It also realized the intracellular imaging of both exogenous and endogenous sulfite in living HepG2 cells. The imaging in water decoction-treated cells inferred the potential for the interdisciplinary detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Bisulfite (HSO 3 - ) serves as a bleaching agent, antioxidant, antimicrobial, and regulator of enzymatic reactions in biosystem. However, abnormal levels of bisulfite can be detrimental to health. Hypochlorous acid (HOCl), which acts as bioactive small molecules, is crucial for maintaining normal biological functions in living organisms. Disruption of its equilibrium can lead to oxidative stress and various diseases. Therefore, it's essential to monitor the fluctuations of HOCl and HSO 3 - at cellular and in vivo levels to study their physiological and pathological functions., Results: This study constructed a novel NIR bifunctional colorimetric fluorescent probe using thienocoumarin-indanedione structures to identify hypochlorite (ClO - ) and bisulfite (HSO 3 - ). By using CSO-IO to recognize HSO 3 - and HOCl, two distinct products were generated, displaying green and blue fluorescence, respectively. This property effectively allows for the simultaneous dual-functional detection of HSO 3 - (LOD: 113 nM) and HOCl (LOD: 43 nM)., Significance: In this work, the biocompatible molecule CSO-IO has been effectively designed to detect HOCl/HSO 3 - in living cells and zebrafish. As a result, the dual-functional fluorescent probe has the potential to be utilized as a molecular tool to detect HSO 3 - derived compounds and HOCl simultaneously within the complex biological system., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Ginseng is a most popular health-promoting food with ginsenosides as its main bioactive ingredients. Illegal sulfur-fumigation causes ginsenosides convert to toxic sulfur-containing derivatives, and reduced the efficacy/safety of ginseng. 24-sulfo-25-ene ginsenoside Rg1 (25-ene SRg1), one of the sulfur-containing derivatives, is a potential quality control marker of fumigated ginseng, but with low accessibility owing to its unknown generation mechanism. In this study, metals/bisulfite system involved generation mechanism was investigated and verified. The generation of 25-ene SRg1 in sulfur-fumigated ginseng is that SO 2 , formed during sulfur-fumigation, reacted with water and ionized into HSO 3 - . On the one hand, under the metals/bisulfite system, HSO 3 - generates HSO 5 - and free radicals which converted ginsenoside Rg1 to 24,25-epoxide Rg1; on the other hand, as a nucleophilic group, HSO 3 - reacted with 24,25-epoxide Rg1 and further dehydrated to 25-ene SRg1. This study provided a technical support for the promotion of 25-ene SRg1 as the characteristic quality control marker of sulfur-fumigated ginseng., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this work, a benzofuranone-derived fluorescent probe BFSF was developed for imaging the sulphite level in living hypoxia pulmonary cells. Under the excitation of 510 nm, BFSF showed a strong fluorescence response at 570 nm when reacted with sulphite. In the solution system, the constructed hypercapnia and serious hypercapnia conditions did not affect the fluorescence response. In comparison with the recently reported probes, BFSF suggested the advantages including rapid response, steady signal reporting, high specificity and low cytotoxicity upon living lung cells. Under a normal incubation atmosphere, BFSF realized the imaging of both exogenous and endogenous sulphite in living pulmonary cells. In particular, BFSF achieved imaging the decrease of the sulphite level under severe hypoxia as well as the recovery of the sulphite level with urgent oxygen supplement. With the imaging capability for the sulphite level in living pulmonary cells under hypoxia conditions, BFSF together with the information herein was meaningful for investigating the anaesthesia-related biological indexes., (© 2024 John Wiley & Sons Ltd.)

Viscosity and sulfur dioxide derivatives were significant indicators for the assessment of health threat and even cancers, therefore, on-site and real time detection of viscosity and sulfur dioxide derivatives has obtained considerable attentions. An FRET-based fluorescence probe JZX was designed and synthesized based on a novel energy donor of N,N-diethyl-4-(1H-phenanthro[9,10-d]imidazol-2-yl)benzamide fluorophore. JZX exhibited a large Stokes shift (230 nm), high energy transfer efficiency, wide emission channel gap (135 nm) and excellent stability and biocompatibility. JZX detected sulfur dioxide with low detection limit (55 nM), fast responding (16 min), high selectivity and sensitivity. Additionally, JZX tend to target endoplasmic reticulum of which normal metabolism will be disturbed by the abnormal levels of viscosity and sulfur dioxide derivatives. Prominently, JZX could concurrently detect viscosity and sulfur dioxide derivatives depending on different fluorescence signals in living cells for the screening of cancer cells. Hence, probe JZX will be a promising candidate for the detection of viscosity and sulfur dioxide derivatives, and even for the diagnosis of liver cancers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

The rapid detection of pyrosulfites in food chemistry is crucial to food safety and health. Here, a coumarin-type ratiometric fluorescent probe was developed based on the Michael addition reaction to detect sodium pyrosulfite (Na 2 S 2 O 5 ). The probe exhibited high selectivity and fast response (t 1/2  = 6 s) to Na 2 S 2 O 5 and a low detection limit (26 nM). Because of its excellent ratiometric response performance, the probe was successfully applied to measure the amount of Na 2 S 2 O 5 in preserved fruits. Colour information analysis and formula calculations were performed to quickly determine the sodium pyrosulfite amount in an actual sample by using a smartphone. Therefore, the intelligent strategy of combining the sensing process and smartphone provides a convenient and efficient method for the fast monitoring of sodium metabisulfite in actual food., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2023. Published by Elsevier Ltd.)

Hydrazine (N 2 H 4 ) and bisulfite (HSO 3 - ) detection methods are urgently needed due to its harmful to the human health and environment safety. Herein, we reported a dual-response fluorescence probe EPC, which is capable of sequential detection of N 2 H 4 and HSO 3 - by two different fluorescence signals. The probe EPC itself showed yellow florescence. In presence of N 2 H 4 , probe EPC exhibited an obviously fluorescence change (from yellow to green). However, a new addition product came into being after probe EPC mixed with HSO 3 - , followed with weak yellow emission. More important, probe EPC exhibited excellent fluorescence response properties for N 2 H 4 and HSO 3 - , such as high sensitivity (0.182 µM for N 2 H 4 , 0.093 µM for HSO 3 - ), rapid response (55 s for N 2 H 4 , 45 s for HSO 3 - ), excellent selectivity and anti-interference performance. The sensing mechanisms for N 2 H 4 and HSO 3 - were proved by 1 H NMR and MS spectra. Practical applications were studied. EPC based test paper can be utilized for quantitative detecting N 2 H 4 in actual water samples. And, probe EPC has been successfully applied to recognize N 2 H 4 contaminant in soil samples. Moreover, EPC has great potential to be used to detect HSO 3 - in real food samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

The emission of venenous sulfur dioxide (SO 2 ) and its derivatives from industrial applications such as coking, transportation and food processing has caused great concern about public health and environmental quality. Probes that enable sensitivity and specificity to detect SO 2 derivatives play a crucial role in its regulations and finally mitigating its environmental and health impacts, but fluorescent probes that can accurately, rapidly and on-site detect SO 2 derivatives in foodstuffs and environmental systems rarely reported. Herein, a near-infrared (NIR) fluorescent probe (ZTX) for the ratiometric response of bisulfite (HSO 3 - ) was designed and synthesized by regulating the structure of high-performance HSO 3 - fluorescent probe SL previously reported by us based on structural analyses, theoretical calculations and related literature reports. The Michael addition reaction between the electronic-deficient C=C bond and HSO 3 - destroys ZTX's π-conjugation system and blocks its intramolecular charge transfer (ICT) process, resulting in a significant fading of the fuchsia solution and the bluish-purple fluorescence turned light blue fluorescence. Fluorescent imaging of HSO 3 - in live animals utilizing ZTX has been demonstrated. The quantitative analysis of HSO 3 - in food samples using ZTXvia a smartphone has been also successfully implemented. Simultaneously, the ZTX-based test strips were utilized to quantificationally determine HSO 3 - in environmental water samples by a smartphone. Consequently, probe ZTX could provide a new method to understand the physiopathological roles of HSO 3 - , evaluate food safety and monitor environment, and is promising for broad applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Intracellular lipid droplets (LDs) are important organelles regulating intracellular redox processes. Endogenous bisulfite/sulfite (HSO 3 - /SO 3 2- ) is one of the metabolites of thiol metabolism. The variation in HSO 3 - /SO 3 2- content around LDs is closely related to cellular homeostasis. However, there is currently no effective method to visualize and quantify the dynamic changes in HSO 3 - /SO 3 2- content around LDs. In this work, a fluorescent probe MC-BEN utilizing a triphenylamine basic framework was developed to selectively recognize HSO 3 - /SO 3 2- via a nucleophilic addition reaction. The probe exhibits excellent anti-interference capability, short response time, outstanding photostability, and a low fluorescence detection limit (6.1 μM) for HSO 3 - /SO 3 2- recognition. More interesting, there is a trend of accelerated contact between LDs and lysosomes after MC-BEN targeting LDs and reacting with endogenous/exogenous HSO 3 - /SO 3 2- , which may provide new ideas for the study of intracellular lysosomal lipophagy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a ratiometric and chromogenic fluorescent probe 1 was synthesized for the detection of SO 3 2- . The probe 1 at PBS (10 mM, pH = 7.4) presented a marked emission band at 661 nm. Upon addition of SO 3 2- ions, a highly emissive adduct with a marked fluorescence at 471 nm were obtained through a Michael addition. The probe 1 displayed a noticeable fluorescence ratiometric response with a large shift (190 nm) in emission wavelength. The probe can quantitatively detect SO 3 2- with high specificity, fast response (within 130 s) as well as low detection limit (13 nM), and a large Stokes shift (139 nm). Fluorescence imaging of HeLa cells indicated that 1 could be used for monitoring the intrinsically generated intracellular SO 3 2- in living cells by ratiometric fluorescence imaging. Furthermore, 1 could be application in real water and sugar samples with high sensitivity and good recoveries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A near-infrared fluorescent "turn on" probe DTMI featuring simple skeleton was constructed easily. It undergoes a structure transformation from an A-π-A to a D-π-A framework towards SO 3 2- . Besides, DTMI is capable of distinctive sensing sulfite with a fast response and a significant Stokes shift as well as with high sensitivity, excellent selectivity, long-term stability of fluorescence signals, and good anti-interference ability. The detection limit (LOD) of DTMI for sulfite within the linear concentration range of 0.5-10 μM is 27.39 nM. More importantly, DTMI has been favorably utilized for detecting sulfite in food samples such as red wine and vermicelli. Based on its low biotoxicity, DTMI has been successfully applied in imaging experiments involving HeLa cells, onion inner epidermal cells, and zebrafish. Therefore, the results show that the presented probe possesses potential sensing activity towards sulfite in complex biological system and food samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Many diseases in the human body are related to the overexpression of viscosity and sulfur dioxide. Therefore, it is essential to develop rapid and sensitive fluorescent probes to detect viscosity and sulfur dioxide. In the present work, we developed a dual-response fluorescent probe (ES) for efficient detection of viscosity and sulfur dioxide while targeting mitochondria well. The probe generates intramolecular charge transfer by pushing and pulling the electron-electron system, and the ICT effect is destroyed and the fluorescence quenched upon reaction with sulfite. The rotation of the molecule is inhibited in the high-viscosity system, producing a bright red light. In addition, the probe has good biocompatibility and can be used to detect sulfite in cells, zebrafish and mice, as well as upregulation of viscosity in LPS-induced inflammation models. We expect that the dual response fluorescent probe ES will be able to detect viscosity and sulfite efficiently, providing an effective means of detecting viscosity and sulfite-related diseases.

Sprouts of black beans ( Phaseolus vulgaris L.), soybeans ( Glycine max L.) and mung beans ( Vigna radiata L.) are widely consumed foods containing abundant nutrients with biological activities. They are commonly treated with sulphites for the preservation and extension of shelf-life. However, our previous investigation found that immersing the bean sprouts in sulphite might convert the active components into sulphur-containing derivatives, which can affect both the quality and safety of the sprouts. This study explores the use of FTIR in conjunction with chemometric techniques to differentiate between non-immersed (NI) and sodium sulphite immersed (SI) black bean, soybean and mung bean sprouts. A total of 168 batches of raw spectra were obtained from NI and SI-bean sprouts using FTIR spectroscopy. Four pre-processing techniques, three modelling assessment techniques and four model evaluation indices were examined for differences in performance. The results show that the multiplicative scatter correction is the most effective pre-processing method. Among the models, the accuracy rate of the three models was as follows: radial basis function neural network (95%) > convolutional neural network (91%) > random forest (82%). The overall findings indicate that FTIR spectroscopy, in conjunction with appropriate chemometric approaches, has a high potential for rapidly determining the difference between NI and SI-bean sprouts.

Background: Sulfur dioxide (SO 2 ) is a significant gas signaling molecule in organisms, and viscosity is a crucial parameter of the cellular microenvironment. They are both involved in regulating many physiological processes in the human body. However, abnormalities in SO 2 and viscosity levels are associated with various diseases, such as cardiovascular disease, lung cancer, respiratory diseases, neurological disorders, diabetes and Alzheimer's disease. Hence, it is essential to explore novel and efficient fluorescent probes for simultaneously monitoring SO 2 and viscosity in organisms., Results: We selected quinolinium salt with good stability, high fluorescence intensity, good solubility and low cytotoxicity as the fluorophore and developed a highly sensitive ratiometric probe QQD to identify SO 2 and viscosity changes based on Förster resonance energy transfer/twisted intramolecular charge transfer (FRET/TICT) mechanism. Excitingly, compared with other probes for SO 2 detection, QQD not only identified HSO 3 - /SO 3 2- with a large Stokes shift (218 nm), low detection limit (1.87 μM), good selectivity, high energy transfer efficiency (92 %) and wide recognition range (1.87-200 μM), but also identified viscosity with a 26-fold fluorescence enhancement and good linearity. Crucially, QQD was applied to detect HSO 3 - /SO 3 2- and viscosity in actual water and food samples. In addition, QQD had low toxicity and good photostability for imaging HSO 3 - /SO 3 2- and viscosity in cells. These results confirmed the feasibility and reliability of QQD for HSO 3 - /SO 3 2- and viscosity imaging and environmental detection., Significance: We reported a unique ratiometric probe QQD for detecting HSO 3 - /SO 3 2- and viscosity based on the quinolinium skeleton. In addition to detecting HSO 3 - /SO 3 2- and viscosity change in actual water and food samples, QQD could also monitor the variations of HSO 3 - /SO 3 2- and viscosity in cells, which provided an experimental basis for further exploration of the role of SO 2 derivatives and viscosity in biological systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Sulfite, a widely used food additive, is subject to regulated labeling. The extraction of sulfite as the stable hydroxymethylsulfonate (HMS) form and its quantitative analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been recognized for their good sensitivity, selectivity, and versatility across various food materials. This study aimed to develop a cost-effective and simpler method for sulfite quantitation, while maintaining the superior sensitivity and selectivity of mass spectrometry (MS). To achieve this, we introduced paper spray ionization (PSI), an ambient desorption ionization technique that could achieve the direct measurement of analytes without employing separation. We also employed a novel internal standard (IS) structurally similar to the analyte, replacing the more expensive isotopically labeled IS. Although the PSI-MS/MS method developed in this study exhibited slightly lower analytical performance compared to the conventional LC-MS/MS, it remained effective for sulfite analysis in dried fruits.

The development of reliable probe technology for the detection of bisulfite (HSO 3 - ) in situ in food and biological samples is contributing significantly to food quality and safety assurance as well as community health. In this work, a responsive probe, EHDI, is developed for ratiometric fluorescence detection of HSO 3 - in aqueous solution, meat samples, and living cells. The probe is designed based on the HSO 3 - triggered 1,4-addition of electron deficit C = C bond of EHDI. As a result of this specific 1,4-addition, the π-conjugation system was destructed, resulting in blue shifts of the emission from 687 to 440 nm and absorption from 577 to 355 nm. The probe has good water solubility, high sensitivity and selectivity, allowing it to be used for imaging of HSO 3 - internalization and production endogenously. The capability of probe EHDI for HSO 3 - was then validated by traditional HPLC technology, enabling accurately detect HSO 3 - in beef samples. The successful development of this probe thus offers a new tool for investigating HSO 3 - in situ in food and biological conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

With the booming development of food manufacturing, developing ideal analytical tools to precisely quantify food additives is highly sought after in the food science field. Herein, a new series of quinoline-derived multifunctional fluorescent probes has been synthesized. Bearing double reactive sites, these compounds display fluorescence response toward both bisulfite (HSO 3 - ) and hypochlorous acid (HClO). Among these compact structures, compound ethyl-2-cyano-3-(6-(methylthio)quinolin-2-yl)acrylate ( QTE ) was screened out. Probe QTE not only shows ratiometric variation toward HSO 3 - with little cross talk but also performs turn-off signal toward HClO. In addition, probe QTE has been utilized for bioimaging of HClO in living cells. Furthermore, the HSO 3 - content in dried food samples has been appraised by QTE with satisfactory results. Meanwhile, relying on the apparent chromaticity change, a flexible dark-box device has been elaborated for chromatic analysis, promoting visualization of HSO 3 - in the field.

The exhaustive control required for the correct wine production needs of many chemical analysis throughout the process. The most extended investigations for wine production control are focused on the quantification of total and free SO 2 . Most methods described in the literature have an adequate detection limit, but they usually lack reproducibility and require a previous sample treatment for the extraction of the SO 2 from the wine-matrix. In this context, Surface-Enhanced Raman Spectroscopy (SERS) can be a promising technique for free SO 2 determination without the need for any sample pre-processing. This work describes a proof of concept of a new methodology based on SERS and supported by Density Functional Theory (DFT) calculations to identify the active vibrational modes of the key molecules that contribute to the concentration of free SO 2 in solution. Theoretical predictions and experimental outcomes are brought together to chemometrics to get a simple and real-time free SO 2 monitoring. This general procedure could pave the way towards an implementation of a portable SERS detection module for in-field measurements., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Alberto Villar Verguizas reports financial support was provided by European Commission. Alberto Villar Verguizas reports financial support was provided by Basque Government., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In this study, we have described a miniaturized, simple, and low-cost device for sulfite determination in beverages by coupling Gas Diffusion Microextraction to paper-based analytical devices. The color change of an acid-base indicator - promoted by the generated gaseous SO 2 - impregnated onto the paper surface was monitored in the function of time by video recording using a smartphone. The analytical information was related to the Hue, Saturation, Value (HSV) color space extracted from the video file. The complete analytical platform was built using a 3D printer, allowing the easy fabrication of a low-cost tailored device. Under optimized conditions, a linear relation from 5 to 90 mg L -1 was obtained using 30 µL of the reagent, 1 mL of sample, and 10 min of analysis. The relative standard deviation and the limit of detection were 2.2 % and 1.6 mg L -1 , respectively. The method was successfully employed in several beverages, such as juices, soda, and coconut water., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This work describes the analysis of formaldehyde using a 96-well microplate as multiple headspaces for the separation of sulfur dioxide gas generated from the sulfite remaining after its reaction with the formaldehyde in the sample. The quantitation of the gas is by colorimetric detection of an indicator paper placed over the microplate. The samples are aqueous extracts of various foods that are possibly adulterated with formaldehyde. A known excess amount of sulfite is added to the extract solution aliquoted in the well. The remaining sulfite is acidified with hydrochloric acid to generate sulfur dioxide gas which diffuses through the headspace above the solution to be absorbed at the moist strip of the indicator paper placed over the mouth of the wells. Anthocyanins extracted from the butterfly pea flower is used as the pH indicator giving a color change from the increase of hydrogen ions by hydrolysis of the absorbed sulfur dioxide gas. The exposed paper strip is scanned, and the digital images of the colored region analyzed using ImageJ software. The optimized method has a linear range of 200-1000 mg L -1 formaldehyde with limit of detection ((2.57*SD of intercept)/(slope of calibration line)) of the aqueous extract of 40 mg L -1 and coefficient of determination (r 2 ) > 0.9979. Samples of fresh produce, such as seafood, meat, and vegetables, and various processed food were analyzed for their possible formaldehyde content. The results obtained from the headspace paper-based colorimetric detection are not statistically different from the values obtained from the titration method by paired t-tests., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The increasing consumption of processed foods demands the usage of chemical preservatives to ensure freshness and extended shelf life. For this purpose, sodium sulfite and its derivatives have been widely used in a variety of food products to inhibit microbial spoilage and for mitigating oxidative decay. However, the excessive consumption of sulfite may cause health problems, thus requiring rapid and accurate analytical methods for the rapid identification of threshold levels. Conventionally, sulfite is volatilized from food samples by acidification followed by trapping of the gaseous SO 2 and determination using a suitable analytical technique. Herein, we propose a yet unprecedented reagent-less approach via direct absorbance measurements of gaseous SO 2 at 280 nm after sample acidification. The detection system combines a deep-UV LED and a SiC photodiode with a substrate-integrated hollow waveguide (iHWG) gas cell. Absorbance measurements were performed using a log-ratio amplifier circuitry, resulting in noise levels <0.7 mAU. This innovative concept enabled the determination of sulfite in beverages in the range of 25-1000 mg L -1 with suitable linearity (r 2  > 0.99) and an analysis time <30 s. The limit of detection (LOD) was calculated at 14.3 mg L -1 (3σ) with an iHWG providing an optical path length of 75 mm. As a proof of concept, this innovative analytical platform was employed for sulfite quantification in concentrated grape juice, coconut water and beer, with suitable accuracy in terms of recovery (83-117%) and favorable comparison with the official Monier-Williams method. Given the inherent modularity and adaptability of the device concept, we anticipate the application of the proposed analytical platform for the in-situ studies addressing sulfite and other volatilized preservatives in a wide variety of food products with tailorable detectability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The milk quality and characteristics of the local Gharbi sheep and autochthonous goat population were studied and compared to those of the local Maghrebi camel. Milk samples from 378 lactating animals raised in the Tunisian oasis region were obtained and processed for various physicochemical compositions (pH, density, acidity, dry matter, fat, protein, lactose, casein, ash, and casein-protein ratio), mineral concentrations (Ca, P, Na, and K), and bacteriological properties (total mesophilic aerobic bacteria (TMAB), total coliform count (TCC), lactic acid bacteria (LAB), sulfite-reducing Clostridium (CSR), yeast and molds (Y/M), Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Salmonella) using standard methods. Milk from sheep breeds had a higher average of all physical parameters (pH, density, and dornic acidity) than milk from goat species. The sheep population produced milk with a similar pH to the camel population, but with a higher density and acidity content. The pH and acidity were higher in Neggas than in goat species, while density was similar in both. For chemical composition, the results showed significant heterogeneity in milk content across all species. Except for the casein-protein ratio, which favors goat species, the analysis indicates that sheep species were superior to populations of goats and camels in all chemical compositions. The present results showed considerable variation in the mineral content of milk from different species. The levels of calcium and phosphorus are higher in sheep than in goat and camel milk. Compared to small ruminants, milk from camels is the richest in Na and K. Additionally, more calcium is present in the milk of camels than that of goats. Goat milk, the lowest in Ca and Na, contains more P than camel milk and more K than sheep's milk on average. The poorest microbial quality was that of camel milk for all bacterial counts. Based on TMAB, TCC, and E. coli counts, the microbiological quality of goat milk was higher than that of ovine milk, while ovine milk had better quality based on LAB, Y/M, and S. aureus values. For Escherichia coli and Staphylococcus aureus, there were no significant variations between the species studied. Results showed that all milk samples studied were completely free of two dangerous pathogens, Salmonella and sulfite-reducing Clostridium. The bacteriological quality of small ruminant's milk was acceptable and met the regulatory limits set by Tunisian dairy legislation. Regarding camel milk, the microbial analysis revealed poor quality that exceeds standard criteria., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Sulfur dioxide, an essential gas signaling molecule mainly produced in mitochondria, plays important roles in many physiological and pathological processes. Herein, a near-infrared fluorescent probe, A1, with good mitochondria targeting ability was developed for colorimetric and fluorescence detection of HSO 3 - . Probe A1 has a conjugated cyanine structure that can selectively react with HSO 3 - through the nucleophilic addition. The reaction with HSO 3 - destroys the conjugated structure of probe A1, resulting in fluorescence quenching, and accompaniedby color change of probe A1 solution from purple-red to colorless. Probe A1 showed high selectivity and good sensitivity to HSO 3 - in PBS. And the limit of detection was calculated to be 1.28 and 0.037 μM for colorimetry and fluorescence spectrophotometry respectively. In addition, probe A1 mainly entered the mitochondria in living cells, and was successfully used for imaging the exogenous/endogenous HSO 3 - in cells. These results suggest the potential applications of probe A1 in biological systems., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Red wines produced without the addition of any SO 2 are currently the source of a new consumer trend. The first characterization approaches regarding these specific wines were devoted to sensory studies that highlighted differences according to the use of SO 2 during winemaking. The goal of this paper is to extend our knowledge of such aromatic specificities. Examining experimental wines produced with and without the addition of SO 2 , aroma fractionation, gas chromatography coupled with olfactometry, and mass spectrometry were applied to identify compounds at the origin of the specificities of these wines. Thus, we identified methyl salicylate as being impacted by the use of SO 2 during the winemaking process. Studying a large number of commercial Bordeaux red wines, methyl salicylate was significantly quantified at a higher content in wines without added SO 2 . A sensory approach revealed a significant impact of methyl salicylate on wines without the sulfite aroma, particularly concerning fruity aromas and wine freshness.

A novel sulfate-reducing bacterium, strain PPLL T , was isolated from marsh soil. Cells of strain PPLL T were rod-shaped with length of 1.5 μm and width of 0.7 μm. Growth was observed at 22-37 °C (optimum 35 °C) and pH 6.8-8.4 (optimum 7.3). Lactate, succinate, fumarate, formate and malate were utilized as electron donors for sulfate reduction. Fermentative growth was not observed on tested organic acids. Besides sulfate, sulfite, thiosulfate and elemental sulfur were utilized as electron acceptors. Hydrogen is used only in the presence acetate or yeast extract. The major fatty acid was C 16:0 . The complete genome of strain PPLL T was composed of a circular chromosome with length of 4.2 Mbp and G + C content of 57.7 mol%. Sequence analysis of the 16S rRNA gene showed that strain PPLL T was affiliated with the genus Desulfofustis in the family Desulfocapsaceae. On the basis of differences in the phylogenetic and phenotypic properties between the strain and the type strain of the genus Desulfofustis, strain PPLL T (DSM 110475 T  = JCM 39161 T ) is proposed as the type strain of a new species, with name of Desulfofustis limnaeus sp. nov., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A novel sulfate-reducing bacterium, strain ASN36 T , was isolated from sediment of a brackish lake in Japan. Cells of strain ASN36 T were not motile and rod-shaped, with length of 2.0-4.9 μm and width of 0.6-0.9 μm. Growth was observed at 5-35 °C with an optimum growth temperature of 25-30 °C. The pH range for growth was 6.6-8.8 with an optimum pH of 7.3. Major fatty acids were C 16:1 ω7c and C 16:0 . Under sulfate-reducing conditions, strain ASN36 T utilized lactate, malate, pyruvate, butyrate, ethanol, butanol, glycerol, yeast extract and H 2 /CO 2 as growth substrate. Fermentative growth occurred on malate and pyruvate. The novel isolate used sulfate, sulfite and thiosulfate as electron acceptors. The genome of strain ASN36 T is composed of a chromosome with length of 6.3 Mbp and G + C content of 55.1 mol%. Analyses of the 16S rRNA gene indicated that strain ASN36 T is related to Desulfoluna species. Overall genome relatedness indices indicated that strain ASN36 T does not belong to any existing species. In contrast to the closest relatives, strain ASN36 T lacks genes for reductive dehalogenase required for organohalide respiration and does not use halogenated aromatics as electron acceptors. On the basis of its genomic and phenotypic properties, strain ASN36 T (= DSM 111985  T  = JCM 39257  T ) is proposed as the type strain of a new species, Desulfoluna limicola sp. nov., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Accurate and rapid on-site analysis of free SO 2 content is crucial in the process of winemaking from a producer and consumer perspective. Herein, we present an amperometric sensor based on commercially available screen-printed electrodes coupled with an electrochemical oxygen filter. The developed amperometric method gave a linear response in a concentration range up to 200 mg L -1 with a limit of quantification of 7.5 mg L -1 . The applicability of the developed sensor was successfully tested on 27 white and red wine samples and compared to the Ripper method (iodometry) that is a standard procedure for free SO 2 determination. The sensor exhibits similar precision and accuracy but shows no interference from oxidizable species such as ascorbic acid, which is a major advantage over iodometric titration. The performance of the sensor was in addition positively evaluated during on-site analysis in a winery.

Sulfites are used widely in food and beverage production to prevent browning or oxidation. However, the overingestion of sulfites is harmful to human health and may cause medical complications. Chinese herbal teas have been widely consumed for centuries. However, sulfite levels in Chinese herbal teas are rarely investigated and reported. Here, we present a simple, sensitive, and quantitative method to determine sulfites in Chinese herbal teas using ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) coupled with dispersive solid phase extraction. The method utilized a SeQuant ZIC-HILIC column for separation, and the optimal gradient eluents consisted of acetonitrile and aqueous solution with 0.1% acetic acid and 10 mM ammonium acetate. Porous chitosan/partially reduced graphene oxide/diatomite (CS/prGO/DM) composites were used as efficient dispersive solid phase extraction adsorbents for sample preparation. Several parameters were investigated during the extraction process, including sample-to-extraction solvent volume ratios, the extraction procedure and dosage of the adsorbent. Under the optimum conditions, the developed method gave a good determination coefficient ( r 2 > 0.99), low detection limits (0.51-12.1 μg kg -1 ) and high recoveries in the range of 83.8-102.7% at different spiked levels. The method has the great advantages of being time saving, good reproducibility and much lower detection limits when compared to titration methods. The method was further applied to analyze real herbal tea samples collected from the local market, demonstrating that our developed method is robust and useful for determining sulfites in practical application.

A lysosome-targeting ratiometric fluorescent probe was synthesized for detecting sulfite based on sulfite-triggered nucleophilic addition reaction. Due to the specific reaction, the fluorescence intensity ratio (I 530 /I 390 ) of the probe in an almost aqueous solution (0.5% DMSO) changed significantly after the addition of HSO 3 - , corresponding to the change in the fluorescence color of the solution from green to blue. The recognition was conducted using high-resolution mass spectrometry, proton nuclear magnetic resonance, and density functional theory calculations. The fluorescent probe could be utilized to quantitatively monitor HSO 3 - in lysosomes of living C6 glioma cells and real-water samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This work presents a fully disposable microchamber for gas generation of a sample solution. The microchamber consists of a cylindrical well-reactor and a paper-based microfluidic lid (μFluidic lid), which also serves as the reagent loading and dispensing unit. The base of the reactor consists of a hydrophobic membrane covering an in-house graphene electrochemical gas sensor. Fabrication of the gas sensor and the three-layer μFluidic lid is described. The μFluidic lid is designed to provide a steady addition of the acid reagent into the sample solution instead of liquid drops from a disposable syringe. There are three steps in the procedure: (i) acidification of the sample in the reactor to generate SO 2 gas by the slow dispensing of the acid reagent from the μFluidic lid, (ii) diffusion of the liberated SO 2 gas through the hydrophobic membrane at the base of the reactor, and (iii) in situ detection of SO 2 by cathodic reduction at the graphene electrode. The device was demonstrated for quantitation of the sulfite preservative in wine without heating or stirring. The selectivity of the analysis is ensured by the combination of the gas-diffusion membrane and the selectivity of the electrochemical sensor. The linear working range is 2-60 mg L -1 SO 2 , with a limit of detection (3SD of intercept/slope) of 1.5 mg L -1 SO 2 . This in situ method has the shortest analysis time (8 min per sample) among all voltammetric methods that detect SO 2(g) via membrane gas diffusion.

Background: The commercial preservation of table grapes largely depends on the application of sulfur dioxide (SO 2 ). However, little is known about whether SO 2 participates in sulfur metabolism to improve the postharvest quality of table grapes. In this study, the contents of sulfur-containing compounds, activities of enzymes, and expression of genes involved in sulfur metabolism in table grapes (Vitis vinifera cv. Thompson Seedless) were evaluated., Results: The results indicated that SO 2 treatment maintained the postharvest quality of table grapes. The sulfite content in rachises and berries, but not the sulfate content, increased in response to SO 2 treatment. SO 2 caused high activities of sulfite reductase, O-acetylserine (thiol)-lyase, and γ-glutamylcysteine synthetase, thereby increasing the contents of cysteine, hydrogen sulfide, and glutathione in the rachises and berries. The expression of VvSURTL, VvATPS1, VvATPS2, and VvAPR3 decreased in response to SO 2 treatment; however, the transcript levels of VvSiR1 and VvOASTL exhibited the opposite tendency., Conclusion: These findings indicated that the sulfite converted from SO 2 participated in sulfur metabolism and maintained the postharvest quality of table grapes by modulating the contents of metabolites, activities of enzymes, and expression of genes related to sulfur metabolism. © 2021 Society of Chemical Industry., (© 2021 Society of Chemical Industry.)

Sulfite (SO 3 2- ) and thiosulfate (S 2 O 3 2- ) ions are used as food preservative and antichlor agent respectively. To detect low levels of such anions we used Cu(II) complex of the Tris-Methyl Pyridine Amine (TMPA) ligand, denoted L. Formation of [LCu(SO 3 )] (1) and [LCu(S 2 O 3 )] (2) in solution were monitored using UV-Vis, EPR and cyclic voltammetry, while the solid-state X-ray structures of both complexes were solved. In addition, we also evaluated the pH range in which the complexes are stable, and the anions binding affinity values for the [LCu(solvent)] 2+ (3) parent complex. As a matter of illustration, we determined the sulfite content in a commercial crystal sugar., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The detection of changes in the reactive oxygen species (ROS)/reactive sulfur species (RSS) couple is important for studying the cellular redox state. Herein, we developed a 1,8-naphthalimide-based fluorescence probe (NI) for the reversible detection of bisulfite (HSO 3 - ) and hydrogen peroxide (H 2 O 2 ) in vitro and in vivo. NI has been designed with a reactive ethylene unit which specifically reacts with HSO 3 - by a Michael addition reaction mechanism, resulting in the quenching of yellow fluorescence at 580 nm and the appearing of green fluorescence at 510 nm upon excitation at 500 nm and 430 nm, respectively. The addition product (NI-HSO 3 ) could be specifically oxidized to form the original C=C bond of NI, recovering the fluorescence emission and color. The detection limits of NI for HSO 3 - and NI-HSO 3 for H 2 O 2 were calculated to be 2.05 μM and 4.23 μM, respectively. The reversible fluorescence response of NI towards HSO 3 - /H 2 O 2 couple can be repeated for at least five times. NI is reliable at a broad pH range (pH 3.0-11.5) and features outstanding selectivity, which enabled its practical applications in biological and food samples. Monitoring the reversible and dynamic inter-conversion between HSO 3 - and H 2 O 2 in vitro and in vivo has been verified by fluorescence imaging in live HeLa cells, adult zebrafish and nude mice. Moreover, NI has been successfully applied to detect of HSO 3 - levels in food samples., (© 2021 Wiley-VCH GmbH.)

Hydrogen sulfide is a common wine fault, with a rotten-egg odour, which is directly related to yeast metabolism in response to nitrogen and sulfur availability. In grape juice, sulfate is the most abundant inorganic sulfur compound, which is taken up by yeast through two high-affinity sulfate transporters, Sul1p and Sul2p, and a low affinity transporter, Soa1p. Sulfate contributes to H 2 S production under nitrogen limitation, by being reduced via the Sulfur Assimilation Pathway (SAP). Therefore, yeast strains with limited H 2 S are highly desirable. We report on the use of toxic analogues of sulfate following ethyl methane sulfate treatment, to isolate six wine yeast mutants that produce no or reduced H 2 S and SO 2 during fermentation in synthetic and natural juice. Four amino acid substitutions (A99V, G380R, N588K and E856K) in Sul1p were found in all strains except D25-1 which had heterozygous alleles. Two changes were also identified in Sul2p (L268S and A470T). The Sul1p (G380R) and Sul2p (A470T) mutations were chosen for further investigation as these residues are conserved amongst SLC26 membrane proteins (including sulfate permeases). The mutations were introduced into EC1118 using Crispr cas9 technology and shown to reduce accumulation of H 2 S and do not result in increased SO 2 production during fermentation of model medium (chemically defined grape juice) or Riesling juice. The Sul1p (G380R) and Sul2p (A470T) mutations are newly reported as causal mutations. Our findings contribute to knowledge of the genetic basis of H 2 S production as well as the potential use of these strains for winemaking and in yeast breeding programmes., (© 2021 John Wiley & Sons, Ltd.)

It is well known that sulfite (SO 3 2- ) plays an indispensable role in various physiological processes. Abnormal levels of SO 3 2- can trigger a wide variety of diseases involving respiratory, nervous and cardiovascular systems. Hence, it is necessary to find an efficient approach for detection of SO 3 2- . In this study, a pyrene derivative, (E)-4-(3-oxo-3-(pyren-1-yl)prop-1-en-1-yl)phenyl acrylate (PPA), was designed and synthesized for monitoring SO 3 2- . The probe possessed simple synthetic steps, excellent anti-interference ability and specific response to SO 3 2- in the presence of other substances. The reaction between PPA and SO 3 2- was ascribed to Michael addition and the detection mechanism was confirmed by HRMS spectra analysis and FTIR analysis. Additionally, PPA responded linearly to detect SO 3 2- within the rang of 0-100 μM. The limit of detection was calculated as low as 0.17 μM in accordance with the recommendation of IUPAC (CDL =3sb/m). Notably, PPA was further applied in biological imaging in HepG2 cells, which provided a possibility to monitor SO 3 2- in vivo.

By connecting 1,8-naphthalimide and indole sulfonate, a ratio fluorescent probe capable of differential detection of hydrogen sulfite and hypochlorite was synthesized for the first time. It was able to achieve the qualitative detection of HSO 3 - and ClO - with high sensitivity and selectivity, respectively. It provides a multi-purpose probe and is based on different emission channels without mutual interference. The probe has the advantages of larger Stokes shift (ClO - : 115 nm, HSO 3 - : 88 nm), longer λ em (ClO - : 515 nm, HSO 3 - : 548 nm) and better water solubility (DMF/PBS = 1:99, v/v). In addition, the probe is a ratio fluorescence probe, which can detect fluorescence intensity with two different emission waves. It provides internal self-calibration, reduces interference from the background and increases detection accuracy. In vitro cytotoxicity and imaging experiments show that the probe can effectively perform the detection of exogenous HSO 3 - and ClO - in cells. It can also achieve the detection of HSO 3 - and ClO - in the plasma environment. Because the probe can detect endogenous ClO - , it also has a good prospect for biological application in identifying tumor cells. Graphical abstract.

In this work, a reaction-based ratiometric and colorimetric sensor was designed and synthesized for probing bisulfite (HSO 3 - ) by coupling coumarin ( CM ) with barbituric ( BA ) moiety. Further tests have shown that CM-BA has high selectivity and sensitivity for the recognition of HSO 3 - , which can be applied for the detection of HSO 3 - in environmental and biological systems very effectively. The fluorescence intensity ratios ( F 462 / F 568 ) exhibited an outstanding HSO 3 - -dependent response with ultrafast response time (within 20 s) and a lower detection limit (105 nM). Meanwhile, the color of the CM-BA solution changed from green to colorless during the recognition process, and its fluorescence changed from green to blue. The mechanism of response is confirmed by the density functional theory (DFT) model. In summary, CM-BA has demonstrated low toxicity and good permeability, which can be applied for imaging HSO 3 - in cells and zebrafish safely and effectively. Besides, this novel sensor CM-BA successfully realized the quantification of the concentration of HSO 3 - in paper strips and food samples.

Epilepsy is the fourth most common neurological disorder, and aberrantly elevated sulfur dioxide derivatives (SO 3 2- /HSO 3 - ) are thought to underlie the hippocampal neuronal apoptosis in epilepsy. We have designed and synthesized a mitochondria-targeted polydopamine nanoprobe for visualizing endogenous SO 3 2- /HSO 3 - by the nucleophilic addition reaction. The nanoprobe was used for imaging SO 2 derivatives both in the mitochondria of cultured cells and zebrafish, and successfully applied in the hippocampus of a rat model of epilepsy. The PDAD nanoprobe could be of great value for the elucidation of mechanisms of abnormal SO 3 2- /HSO 3 - involved in diseases such as epilepsy.

A reaction-based luminescence chemosensor was synthesized for sulfite detection based on a fluorescein derivative with thermally activated delayed fluorescence (TADF). The chemosensor exhibited a fluorescence turn-on effect on sulfite with good sensitivity and selectivity. Importantly, utilizing the long luminescence lifetime of the TADF compound, the chemosensor realized photoluminescence lifetime imaging for sulfite in living cells with the luminescence lifetime distribution mainly around 14 μs.

A reaction-based sensor (NAS-1) showed a high affinity and sensitivity to HSO3- via a nucleophilic addition reaction in the aqueous media, giving dual signals from absorption and emission spectra. NAS-1 was successfully applied in RK13 epithelial cells to detect HSO3- in a cellular environment.

Sulfites are a class of chemical compounds, SO 2 releasers, widely used as additives in food industry, due to their antimicrobial, color stabilizing, antibrowning, and antioxidant properties. As the results of these pleiotropic functions they can be added to a broad range of products including dried fruits and vegetables, seafood, juices, alcoholic and nonalcoholic beverage, and in few meat products. Sulfites ingestion has been correlated with several adverse and toxic reactions, such as hypersensitivity, allergic diseases, vitamin deficiency, and may lead to dysbiotic events of gut and oral microbiota. In many countries, these additives are closely regulated and in meat products the legislation restricts their usage. Several studies have been conducted to investigate the sulfites contents in meat and meat products, and many of them have revealed that some meat preparations represent one of the main sources of SO 2 exposure, especially in adults and young people. This review discusses properties, technological functions, regulation, and health implications of sulfites in meat-based foods, and lays a special emphasis on the chemical mechanisms involved in their interactions with organic and inorganic meat components., (© 2020 Institute of Food Technologists®.)

Since seafood is susceptible to decomposition, additives may be used to maintain its quality. However, some additives may be improperly used to disguise spoilage, thus resulting in food fraud. Market growth demands faster and more reliable quality control tools that incorporate the most common additives in a single analysis. This study developed a rapid analytical method for the determination of citrate, phosphate and sulfite in seafood by capillary zone electrophoresis with indirect UV-Vis detection. Electrophoretic separation was achieved in less than 3.5 min. The background electrolyte consisted of 20 mmol L -1 of benzenesulfonic acid and 45 mmol L -1 of aminocaproic acid. After validation, the method was applied for 24 seafood real samples. Citrate was found in five samples. Four samples presented higher phosphate and sulfite concentrations than those permitted by Brazilian legislation. Good analytical performance indicates that the method is a viable alternative for food control in routine analysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Overdoses of SO 2 and its derivatives (SO 3 2- /HSO 3 - ) in food or organisms are harmful to health. To detect SO 3 2- /HSO 3 - , a novel NIR fluorescent probe 1, based upon the intramolecular charge transfer (ICT) mechanism, was developed. This probe was easily synthesized, and gave noticeable colorimetric and linear fluorescence changes at 690 nm after reaction with sulfite from 3.13 to 200 µM. Moreover, probe 1 displayed high sensitivity (LOD = 0.46 µM), excellent selectivity (among 13 kinds of anions and 3 kinds of biothiols) and quick response (within 30 min) towards SO 3 2- /HSO 3 - . The SO 3 2- /HSO 3 - sensing mechanism was confirmed as the Michael addition reaction. Furthermore, the probe showed wide applications for measuring SO 3 2- /HSO 3 - in real samples, including sugar, tap water, wine and traditional Chinese medicine. The probe could also be used to detect SO 3 2- /HSO 3 - in mitochondria of HepG2 cells and zebrafish, which suggested potential application for monitoring SO 2 derivatives in clinical diagnostics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier Ltd.)

A simple potentiometric sensor is described for accurate, precise, and rapid determination of sulfite additives in beverages. The sensor is based on the use of cobalt phthalocyanine as a recognition material, dispersed in a plasticized poly(vinyl chloride) matrix membrane. o -Nitrophenyl octyl ether ( o -NPOE) as a membrane solvent and tri-dodecylmethyl- ammonium chloride (TDMAC) as ion discriminators are used as membrane additives. Under the optimized conditions, sulfite ion is accurately and precisely measured under batch and flow injection modes of analysis. The sensor exhibits fast and linear response for 1.0 × 10 -2 -1.0 × 10 -6 M (800-0.08 µg/mL) and 1.0 × 10 -1 -5.0 × 10 -5 M (8000-4 µg/mL) sulfite with Nernstian slopes of -27.4 ± 0.3 and -23.7 ± 0.6 mV/concentration decade under static and hydrodynamic modes of operation, respectively. Results in good agreement with the standard iodometric method are obtained.Validation of the assay method is examined in details including precision, accuracy, bias, trueness, repeatability, reproducibility, and uncertainty and good performance characteristics of the method are obtained. The sensor response is stable over the pH range of 5 to 7 without any significant interference from most common anions. The advantages offered by the proposed sensor (i.e., wide range of assay, high accuracy and precision, low detection limit, reasonable selectivity, long term response stability, fast response, and long life span and absence of any sample pretreatment steps) suggest its use in the quality control/quality assurance routine tests in beverages industries, toxicological laboratories and by inspection authorities.

In the US, sulphites must be declared on the label if they are present in concentrations greater than 10 mg/kg (determined as) SO 2 because an allergic-like response has been reported in a small subset of the population upon consumption of sulphite-containing products. The most widely used method for sulphite determination, the optimised Monier-Williams (OMW), produces false positive results with vegetables from the Allium (garlic) and Brassica (cabbage) genera due to extraction conditions that are thought to cause endogenous sulphur compounds to release SO 2 . Recently, an LC-MS/MS method was developed for sulphites but has only been tested with samples that are 100% Allium or Brassica . Since regulatory samples may contain these vegetables as ingredients, additional investigations were necessary to determine the potential extent of false positives. Four blank matrices, chips, phyllo shells, hummus, and quinoa were spiked with various concentrations of onion and garlic powders. The sulphite concentrations were determined using an LC-MS/MS method. The matrix is extracted with a buffered formaldehyde solution, converting free and reversibly bound sulphite to the stable formaldehyde adduct, hydroxymethylsulfonate (HMS). It was determined that even at concentrations up to 8% garlic powder or 2% onion powder, the measured sulphite concentration was below the 10 mg/kg SO 2 labelling threshold. Commercial dried garlic powders were evaluated to determine the variation in responses that might be encountered in future regulatory samples. Recovery studies were conducted to determine if these methods would detect added sulphite. The ability to eliminate false positives due to these ingredients will result in a greater reliability in the accurate determination of added sulphite to ensure compliance with labelling requirements.

RSSs (reactive sulfur species) and their metabolites, such as H 2 S, S n 2- , SO 3 2- /HSO 3 - , S 2 O 4 2- and S 2 O 5 2- (Reactive Inorganic Sulfur Species, RISSs), play a crucial role in the cushion against oxidative stress and the other physiological events. The molecular mechanisms how they affect cellular signaling and other physiological events remain largely unknown. To address their physiological functions, the techniques that can track their levels should be invaluable. Herein, six coumarin hemicyanine scaffolds (CH-RISSs) were synthesized and their fast and strong responses upon H 2 S, S n 2- , SO 3 2- , HSO 3 - , S 2 O 4 2- and S 2 O 5 2- (Reactive Inorganic Sulfur Species, RISSs) were clarified in the absorption (colorimetric) and fluorescence (ratiometric) spectra, which showed good stability in the physiological pH (7.4). Upon the analytes, the maxima absorption of CH-RISSs switched from ~580 nm to ~400 nm in the absorption spectra. The fluorescence of CH-RISSs depleted at 650-660 nm and increased at 480-505 nm upon the RISSs. Both of coumarin hemicyanine structures with C12 alkyl chain (CH-RISS-3 and CH-RISS-6) showed quick and robust ratiometric fluorescence switch in the living cell imaging. Access to the fluorescent probes for RISSs sets the stage for applying the developing technologies to probe reactive sulfur biology in living systems., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2020. Published by Elsevier B.V.)

A unique fluorescent probe (ZACA) for the monitoring of SO2 derivatives was developed from coumarin and benzoindoles based on FRET and ICT. ZACA exhibited an active emission signal, large Stokes shift, wide emission window distance, and high photostability. It also possessed many advantages in the ratiometric detection of HSO3-/SO32- including low detection limit and high selectivity and sensitivity. Importantly, ZACA was successfully applied in the ratiometric detection of endogenous HSO3-/SO32- in living cells with excellent cellular imaging capability (1 μM) and mitochondria-targeting ability (co-localization coefficient: 0.91).

Sodium pyrosulfite is a browning inhibitor used for the storage of fresh-cut potato slices. Excessive use of sodium pyrosulfite can lead to sulfur dioxide residue, which is harmful for the human body. The sulfur dioxide residue on the surface of fresh-cut potato slices immersed in different concentrations of sodium pyrosulfite solution was classified by near-infrared hyperspectral imaging (NIR-HSI) system and portable near-infrared (NIR) spectrometer. Principal component analysis was used to analyze the object-wise spectra, and support vector machine (SVM) model was established. The classification accuracy of calibration set and prediction set were 98.75% and 95%, respectively. Savitzky-Golay algorithm was used to recognize the important wavelengths, and SVM model was established based on the recognized important wavelengths. The final classification accuracy was slightly less than that based on the full spectra. In addition, the pixel-wise spectra extracted from NIR-HSI system could realize the visualization of different samples, and intuitively reflect the differences among the samples. The results showed that it was feasible to classify the sulfur dioxide residue on the surface of fresh-cut potato slices immersed in different concentration of sodium pyrosulfite solution by NIR spectra. It provided an alternative method for the detection of sulfur dioxide residue on the surface of fresh-cut potato slices.

Development of a novel colorimetric and turn-on fluorescent sensor for potassium metabisulphite (KMS) using graphene oxide stabilized gold nanoparticles (GO-AuNPs) was described. The red color GO-AuNPs was changed to violet while adding 250 × 10 -5  M KMS whereas the absorbance band at 523 nm was decreased. The observed changes were ascribed to the leaching of AuNPs from GO. The emission maximum was observed at 448 nm for GO while exciting at 335 nm. However, the GO emission was "turn-off" after the formation of AuNPs on GO surface due to masking of oxygen functional groups responsible for emission. Interestingly, the emission of GO-AuNPs becomes "turn-on" after the addition of 75 × 10 -6  M KMS. Further addition of KMS from 150 to 1125 × 10 -6  M, the emission intensity of GO-AuNPs linearly increases with the correlation coefficient of 0.9980 and the limit of detection was found to be 9.4 µM L -1 /1.2 mg L -1 (S/N = 3)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)