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• The ferrocene-based probe colourimetricaly/electrochemicaly sensed HSO 3 − in a 95 % aqueous solution. • Mechanism of sensing was illustrated by 1H & 13C NMR, HR-MS and DFT/TD-DFT analysis. • The plausible mechanism of sensing is via nucleophilic addition of HSO 3 − ion to olefinic C-atom. • The proposed sensing mechanism was well supported by DFT/TD-DFT calculations. • The probe was utilized to estimate the levels of HSO 3 − ions in natural water and red wine samples. A simple ferrocene-based organic probe (AK5) is described for selective and sensitive colourimetric/electrochemical detection of HSO 3 - ions in a 95 % aqueous solution. Upon adding HSO 3 − ions, the colour of the solution changes from brown to colourless instantaneously. The plausible mechanism of detection of HSO 3 − ions by AK5 was illustrated by 1H NMR, 13C NMR, HR-MS and DFT/TD-DFT analysis, which revealed nucleophilic addition of HSO 3 − ion to olefinic C-atom. The limits of detection (LOD) are determined to be 5.58 and 0.12 µM in colourimetric and electrochemical methods, respectively. The probe is successfully applied to estimate the levels of HSO 3 − ions in natural water and red wine samples. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe TPN-DP was developed for the detection of HSO 3 −. • TPN-DP exhibited high sensitivity, and excellent selectivity for HSO 3 −. • Real-time imaging of HSO 3 − was successfully achieved in plant and zebrafishes. Sulfur dioxide (SO 2) and its derivative bisulfite (SO 3 2−/HSO 3 −) have a serious impact on the human health and environment. Therefore, the development of highly sensitive and specific detection methods for SO 2 and its derivative is of great significance for environmental monitoring, food safety, and related disease research. In this paper, probe TPN-DP based on the triphenylamine fluorophore was developed to enable the imaging and detection of HSO 3 − in plant and zebrafish. In PBS buffer solution, the designed probe TPN-DP can react with HSO 3 − by highly selective nucleophilic addition reaction, leading to a sensitive change in the color of probe TPN-DP solution from pink to colorless. The changes in fluorescence and color can be easily recognized by the naked eye. Moreover, probe TPN-DP exhibited a fast response time of 8 min, high sensitivity of 19.4 nM, and excellent selectivity for sensing HSO 3 −. With the help of probe TPN-DP, the detection of HSO 3 − was successfully achieved in water sample and various biological systems, including onion epidermal cells, tobacco seedling roots, and zebrafish. These findings not only provide valuable insights into the biological role of HSO 3 − but also offer a promising analytical method for efficient HSO 3 − recognition. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, the research on bisulfite (BS) activation by Mn(II) is very limited probably because of the low catalytic efficiency of Mn(II). Adding ligands to Mn(II)/BS system is likely to improve the BS activation, but the relative information is very rare. Therefore, the effect of nitrilotriacetic acid (NTA) on Mn(II)/BS system was investigated in this work using sulfamethoxazole (SMX) as the target contaminant. The results showed that the addition of NTA enhanced SMX removal in Mn(Ⅱ)/BS system through forming Mn(Ⅱ/III)-NTA complexes driving Mn(III)/Mn(II) cycle and stabilizing Mn(III). Alcohol scavenging experiments and competitive kinetic experiments indicated that sulfate radical (SO 4 •−) and hydroxyl radical (HO•) were not the main reactive species in Mn(II)/NTA/BS system. Mn(Ⅲ) was the primary oxidant for SMX elimination in this system and its existence was proved by UV-Vis absorption spectrum of reaction solution. Mn(Ⅱ)/NTA/BS system could greatly degrade SMX in near-neutral conditions, while nearly no SMX removal was observed at pH 3.0. The decrease of dissolved oxygen concentration significantly inhibited BS autocatalytic stage, thus suppressing the removal of SMX. Due to the competitive complexation of HCO 3 − and FA with NTA for Mn(II), their addition in Mn(Ⅱ)/NTA/BS system obviously inhibited SMX degradation. Four intermediates were detected during SMX degradation in Mn(Ⅱ)/NTA/BS system, and the possible SMX transformation pathways were speculated as N-S bond breaking, hydroxylation, amino oxidation and coupling reaction. [Display omitted] • The addition of NTA in Mn(II)/BS system significantly enhanced SMX degradation. • NTA drived Mn(III)/Mn(II) cycle and stabilized Mn(III) by complexing with Mn(II/III). • Mn(Ⅲ) was the primary oxidant for SMX removal in Mn(II)/NTA/BS system. • Near-neutral condition was more beneficial to SMX removal than strongly acidic pH. • DO was essential for Mn(III) formation and BS autocatalysis in Mn(II)/NTA/BS system. [ABSTRACT FROM AUTHOR]

Abstract The genome-wide investigation of DNA methylation levels has been limited to reference transposable element positions. The methylation analysis of non-reference and mobile transposable elements has only recently been performed, but required both genome resequencing and MethylC-seq datasets. We have created epiTEome, a program that detects both new transposable element insertion sites and their methylation states from a single MethylC-seq dataset. EpiTEome outperforms other split-read insertion site detection programs, even while functioning on bisulfite-converted reads. EpiTEome characterizes the previously discarded fraction of DNA methylation at sites of new insertions, enabling future investigation into the epigenetic regulation of non-reference and transposed elements.

The identification of RNA modifications at single nucleotide resolution has become an emerging area of interest within biology and specifically among virologists seeking to ascertain how this untapped area of RNA regulation may be altered or hijacked upon viral infection. Herein, we describe a straightforward biochemical approach modified from two original published Ψ mapping protocols, BID-seq and PRAISE, to specifically identify pseudouridine modifications on mRNA transcripts from an HIV-1 infected T cell line. This protocol could readily be adapted for other viral infected cell types and additionally for populations of purified virions from infected cells., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Fe 2+ has been commonly selected to activate peroxydisulfate(PDS) for sulfate radical(SO 4 - ·) generation because of its eco-friendly, cost-effective, and high activity characteristics. However, Fe 2+ can be rapidly oxidized to Fe 3+ in the reaction, leading to poor utilization of iron for PDS activation. Further, a fairly high concentration of Fe 2+ -activated PDS system induced by bisulfite(BS) was used to degrade paracetamol(APAP) in water. The results showed that the Fe 2+ -activated PDS system induced by bisulfite(BS) was used to degrade paracetamol(APAP) in water. The results showed that the Fe 2+ -PDS system could be enhanced by the circulation of Fe 2+ -Fe 3+ with the injection of BS and by keeping Fe 2+ at a high concentration. Under the optimal conditions(PDS=0.6 mol·L -1 ; BS=0.4 mol·L -1 ; Fe 2+ =10 μmol·L -1 ; pH=4), 100% APAP(4 μmol·L -1 ) was removed within 180 s. The degradation rate of APAP increased with the increase in BS(0-0.6 mmol·L -1 ) and PDS(0.2-1.5 mmol·L -1 ) concentration, and a modest Fe 2+ concentration could accelerate APAP removal. Co-existing substances inhibited the APAP removal and followed the order of HCO 3 - >HPO 4 2- >Cl - >NO 3 - >humic acid(HA). Based on the quenching experiments and electron paramagnetic resonance spectroscopy test, SO 4 - · was shown to be the primary reactive species for APAP decomposition in the BS-Fe 2+ -PDS process. Three-dimensional fluorescence spectroscopy revealed that APAP intermediates had fluorescence characteristics. Moreover, five intermediates were identified, and the probable APAP degradation pathways were proposed. The removal efficiencies of APAP were lower in real waters than that in ultrapure water. Nevertheless, the removal effect was greatly improved after a prolonged reaction time. All results indicated that the BS-Fe 2+ -PDS system could be a promising method for organic pollutant treatment.

The development of new methods for the detection of redox cycle is important for biological and clinical diagnoses. Here, a new cyclometalated iridium complex, (4-(2-pyridyl) benzaldehyde)2Ir (5-chloro-1,10-phenanthroline) ([(4-pba)2Ir(5-Cl-phen)]PF6, probe 1), has been synthesized and applied to rapid, sensitive, and reversible detection and imaging of redox cycle HSO 3 - /H2O2 in living cells. The probe 1 is synthesized by using 4-(2-pyridyl) benzaldehyde as main ligand and 5-chloro-1,10-phenanthroline as ancillary ligand. Probe 1 exhibited "off–on–off" photoluminescence (PL) signal change in response to HSO 3 - and H2O2 in aqueous solution within 1 min. The change of PL intensity is proportional to HSO 3 - concentration from 40 μM to 300 μM and to H2O2 concentration from 40 μM to 260 μM. The detection limit is 10 μM for HSO 3 - and 20 μM for H2O2. Additionally, probe 1 was applied to detect HSO 3 - in food samples with satisfactory results. More importantly, PL imaging of HeLa cells indicates that probe 1 is able to image redox cycle HSO 3 - /H2O2 in living cells. [ABSTRACT FROM AUTHOR]

• The FRI values of HA decreased obviously after PM/BS pre-oxidation. • The UV-absorbing parts of HA were not impacted significantly by PM/BS process. • PM/BS process reduced the formation of DCAN and 1,1,1-TCAce from all NMW fractions. • With 150 μg/L Br- , PM/BS process reduced the total risk value of DBPs by 14%. • For natural water samples, PM/BS process changed the total ITRVs by <8%. Bisulfite-activated permanganate oxidation (PM/BS) technology is an emerging oxidation process that can rapidly oxidize organic contaminants and degrade some permanganate-resistant organic contaminants. For the first time, the influences of PM/BS technology as a pre-oxidation process on the formation potentials of disinfection by-products (DBPFPs) during chlorination of humic acid (HA) solution and three natural water samples were investigated. The results revealed that PM/BS pre-oxidation only slightly affected the DBPFPs of HA in the absence of Br- although it changed the structure of HA according to the fluorescence characterization result. With the presence of Br-, PM/BS pre-oxidation enhanced the generation of trihalomethanes but inhibited that of nitrogenous DBPs (N-DBPs) during chlorination of HA. The toxic risk analysis showed that the toxicity of the generated DBPs from chlorinating HA solution without Br- only changed slightly after PM/BS pre-oxidation but it was decreased by 14% in the presence of 150 μg/L Br− due to PM/BS pre-oxidation. This should be associated with the inhibiting effect of PM/BS pre-oxidation on the generation of N-DBPs and several haloacetic acids in the presence of Br-. Because of the complex matrix of natural water samples, PM/BS pre-oxidation had minor influence on the amount and the potential toxicity of DBPs generated during chlorination. The above results suggested that PM/BS technology could be an alternative of the drinking water pretreatment. [ABSTRACT FROM AUTHOR]

The homogeneous Fe(VI)/Na 2 SO 3 system has been proposed for highly efficient degradation of recalcitrant contaminants, in which sulfite could significantly enhance the transformation of organic substrate by Fe(VI). Also, the Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH conditions. The degradation rates reached up to 80% within 2 min and 70% within 5 min in strongly acidic and alkaline conditions, respectively. Unexpectedly, a faster removal rate was obtained in Fe(VI)/NaHSO 3 system than that in Fe(VI)/Na 2 SO 3 system for the degradation of methylene blue (MB). A reasonable dye degradation mechanism was proposed and verified by a series of experiments. The high oxidation potential of Fe(VI) and other species such as sulfate and hydroxyl radicals were responsible for the outstanding capabilities of Fe(VI)/NaHSO 3 system, which could significantly improve the treatment of organics in wastewater under a very wide range of pH conditions. Image 1 • Homogeneous Fe(VI)/Na 2 SO 3 system was developed for degradation of contaminants. • Sulfite significantly enhanced the transformation of organic substrate by Fe(VI). • The Fe(VI)/NaHSO 3 system could show high efficiency across a wide range of pH. • Dye degradation rates reached up to 80% within 2 min in strongly acidic conditions. [ABSTRACT FROM AUTHOR]

A new fluorescent probe made from (E)-2-(benzo[d]thiazol-2-yl)-3-(6-hydroxynaphthalen-2-yl) acrylonitrile (Probe 1) was synthesized for the determination of bisulfite concentrations in real food samples (red wine and sugar). Adding bisulfite to a Probe 1 solution caused a marked decrease in fluorescence intensity and a visual color change from yellow to light yellow. This distinct color response indicates that Probe 1 could be used as a visual sensor for bisulfite. Probe 1 can detect bisulfite quantitatively in the range 0–400 μM with a detection limit of 0.10 μM. This makes Probe 1 a convenient signaling instrument for determining bisulfite levels in sugar and red wine samples. [ABSTRACT FROM AUTHOR]

Organophosphorus pesticides (OPPs), a kind of effective insecticide, have attracted extensive attention of researchers because of the high toxicity and refractory character of their degradation products. Given the ubiquity of manganese dioxide (MnO 2) and bisulfite (HSO 3 −) in environmental media, the abiotic degradation of several typical OPPs by the MnO 2 -HSO 3 - reaction system was investigated in batch experiments. As a representative OPP, methyl parathion (MP) was chosen to be the focus of the study. The removal rate of MP was remarkably improved by adding bisulfite (HSO 3 −) to the MnO 2 single-reaction system, and the oxidation product methyl paraoxon was below the detection limit. The primary active substances generated from the reaction system were determined to be Mn(III) species by adding excess radical scavengers or complexants (methanol and pyrophosphate) to the reaction system. On the basis of the metabolic products of MP identified by liquid chromatography–high-resolution mass spectrometry (LC/HRMS) and gas chromatography–mass spectrometry (GC/MS), the transformation pathway of MP in the MnO 2 -HSO 3 - reaction system was elicited, which included the predominant processes of hydrolysis and oxidation. Furthermore, the typical OPPs with different structures were also degraded efficiently by the reaction system because of the oxidative degradation of Mn(III). This study offers significative information related to the abiotic oxidation of manganese minerals and the fate and dissipation of OPPs in the actual environment. Image 1 • HSO 3 − significantly enhanced the abiotic degradation of methyl parathion by MnO 2. • The primary active substance was determined to be Mn(III) in the MnO 2 -HSO 3 - reaction system. • Transformation pathway of MP was elicited according to the identified products. • Many OPPs with different structures were also degraded efficiently by the reaction system. [ABSTRACT FROM AUTHOR]

Cyanide and bisulfite are hypertoxic even in low concentration. The development of convenient methods of the detection of analyte is critically important. In this paper, the dual ions fluorescent probe CIM with superior water-solubility has been designed and synthesized with low detection limits of 0.35 μM (for CN− with a linear relationship of 0.996) and 23 nM (for HSO 3 − with a linear relationship of 0.993). Modest pH moderation could be easily used to detect the CN− and HSO 3 − without reciprocal interference. The specific detection is not interfered with other potential coexisted species. The possible recognition mechanism between probe and analytes is illustrated by NMR, HRMS and computational simulation. Both analytes undergo 1, 4-addition reaction on the ethenyl of the probe, which is rare in lots of previous work and results in a fluorescent color change. Image 1 • The dual fluorescent probe CIM has superior water-solubility. • The detection limits of cyanide and bisulfite are separately 3.5 × 10−7 M and 2.3 × 10−8 M. • pH moderation could be used to detect CN− and HSO 3 − without reciprocal interference. • The reaction mechanism is investigated by 1H NMR spectra, HRMS and theoretical calculation. • 1,4-addition on the probe is supported by the simulated absorption spectra and emission spectra. [ABSTRACT FROM AUTHOR]

Abstract To improve the efficiency of traditional advanced oxidation processes (AOPs), a novel photo-assisted heterogeneous Fenton-like process was proposed and verified by experiments. Under visible light, NaHSO 3 and transition metal composite oxide MnO 2 /NiO were tested together for degradation of orange II (OII). MnO 2 /NiO nanocomposites were prepared by a hydrothermal method using different nickel oxide to manganese oxide ratios and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–vis (UV–vis) diffuse reflectance spectroscopy (DRS) and scanning electron microscopy (SEM). The best MnO 2 /NiO nanocomposite (Ni:Mn = 1:2) which was designated as Ni-Mn-3 showed the best OII removal efficiency of about 92.8% among the various MnO 2 /NiO nanocomposites of different Ni:Mn ratios. Moreover, the best catalyst, Ni-Mn-3 also showed good stability and recovery performance for degrading OII. The degradation ability of Ni-Mn-3 decreased no more than 10% after three times of repeated tests, which makes it more competitive in practical industrial applications than other heterogeneous Fenton-like catalysts. Graphical abstract Image 1 Highlights • New photo-assisted heterogeneous Fenton-like process was used with MnO 2 /NiO catalysts. • Key novelty was the use of NaHSO 3 to activate MnO 2 /NiO under visible light. • The MnO 2 /NiO (Ni:Mn = 1:2) showed the best Orange II removal efficiency of about 92.8%. • 1Ni:2Mn oxide showed good stability and recycling performance for degrading Orang II. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Bisulfite drastically enhanced the degradation of bisphenol A in Fe3+-H 2 O 2 system. • Complexing and reducing effects of bisulfite accelerated the Fe3+/Fe2+ cycle. • OH was the major reactive species for BPA degradation in Fe3+-HSO 3 −-H 2 O 2 system. • Fe3+-HSO 3 −-H 2 O 2 system may act as a followed stage of Fe2+-H 2 O 2 system. Abstract The present work aimed at using bisulfites (HSO 3 −) to enhance the oxidative degradation of bisphenol A (BPA) in a Fenton process based on the Fe3+-H 2 O 2 reagents. It was confirmed that both the degradation and mineralization of BPA were drastically enhanced by the addition of HSO 3 −. Typically, the use of 0.1 mmol L−1 Fe3+, 0.3 mmol L−1 HSO 3 − and 10 mmol L−1 H 2 O 2 achieved a complete degradation of BPA (0.05 mmol L−1) in only 2 min. The addition of HSO 3 − increased the BPA degradation rate constant from 0.045 min−1 in the Fe3+-H 2 O 2 system to 2.71 min−1 in the Fe3+-HSO 3 −-H 2 O 2 system by 60 times. This drastic enhancement effect of HSO 3 − was attributed to its complexing and reducing abilities. The formation of FeSO 3 + complex prevented the precipitation of Fe3+ and accelerated the cycling of Fe3+/Fe2+; the reducing ability of HSO 3 − further favored the transformation of Fe3+ to Fe2+. Several reactive species, including OH, SO 3 − and SO 4 − were responsible for the degradation of BPA, among which OH was the dominant one. The proposed Fe3+-HSO 3 −-H 2 O 2 system is suggested be able to act as the followed stage of a traditional Fe2+-H 2 O 2 system in the engineering setting. [ABSTRACT FROM AUTHOR]

Abstract An abnormal level of bisulfite can induce toxicological effects associated with lung cancer, cardiovascular and neurological disorders. Therefore, it is of significance to develop an effective fluorescent probe to detect bisulfite in living cells. Herein, a novel fluorescent probe QPCT , based on a 1,4-addition mechanism, was constructed for the colorimetric and ratiometric detection of bisulfite. QPCT displayed high selectivity and anti-interference ability to bisulfite over other anions and biothiols. The probe renders a sensitive ratiometric response to bisulfite with a remarkable fluorescence blue shift from 590 to 537 nm and the fluorescence ratio was linear with bisulfite concentration over the range of 0–120 μM. More importantly, QPCT has been successfully applied to detect bisulfite in sugars and living A549 cells, which indicated that QPCT had a great capability for monitoring bisulfite in complex systems. Graphical abstract A novel fluorescent probe QPCT for the colorimetric and ratiometric detection of HSO 3 − was constructed and successfully applied for sugar analysis as well as imaging in living A549 cells. Image 1 Highlights • QPCT displays a colorimetric and ratiometric response towards HSO 3 −. • QPCT exhibits good selectivity to HSO 3 − among various anions and biothiols. • QPCT has been successfully applied to detect HSO 3 − in real samples and living cells. [ABSTRACT FROM AUTHOR]

The hydrolytic deamination of HOHCytN3+ (paths A and B), and 5-HOHMeCytN3+ (paths C and D) have been explored in the presence of the group. The activation free energy barriers (ΔGs≠) of paths A and C show significant difference, which increases the possibility in differentiating cytosine (Cyt) from 5-methylcytosine (5-MeCyt) under bisulfite conditions. Meanwhile, the calculated rate constants with Wigner tunnelling correction of the rate-limiting step is much lower for path A than for path C, and by extrapolation, the difference between Cyt and 5-MeCyt for both modified pyrimidine base may have a greater chance by bisulfite treatment. [ABSTRACT FROM AUTHOR]

Highlights • Analysis of cytosine-5 methylation in amplicons from bisulfite-treated RNA. • Filtering of bisulfite artifacts in RNA. • Web-based analysis. Abstract RNA cytosine-5 methylation (m5C) has emerged as a key epitranscriptomic mark, which fulfills multiple roles in structural modulation, stress signaling and the regulation of protein translation. Bisulfite sequencing is currently the most accurate and reliable method to detect m5C marks at nucleotide resolution. Targeted bisulfite sequencing allows m5C detection at single base resolution, by combining the use of tailored primers with bisulfite treatment. A number of computational tools currently exist to analyse m5C marks in DNA bisulfite sequencing. However, these methods are not directly applicable to the analysis of RNA m5C marks, because DNA analysis focuses on CpG methylation, and because artifactual unconversion and misamplification in RNA can obscure actual methylation signals. We describe a pipeline designed specifically for RNA cytosine-5 methylation analysis in targeted bisulfite sequencing experiments. The pipeline is directly applicable to Illumina MiSeq (or equivalent) sequencing datasets using a web interface (https://bisamp.dkfz.de), and is defined by optimized mapping parameters and the application of tailored filters for the removal of artifacts. We provide examples for the application of this pipeline in the unambiguous detection of m5C marks in tRNAs from mouse embryonic stem cells and neuron-differentiated stem cells as well as in 28S rRNA from human fibroblasts. Finally, we also discuss the adaptability of BisAMP to the analysis of DNA methylation. Our pipeline provides an accurate, fast and user-friendly framework for the analysis of cytosine-5 methylation in amplicons from bisulfite-treated RNA. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • HSO3- enhanced the oxidation of contaminants by MnO2 significantly. • Mn(III) was the main active species in the MnO2/HSO3- (MO/BS) process. • Proper MnO2/HSO3- molar ratio was critical for efficient removal of contaminants. • Coexisting solutes influence the performance of MO/BS process in different ways. • The oxidation of contaminants by Mn(III) was possibly via electrophilic attack. Abstract Colloidal MnO 2 is the most reactive phase of Mn(IV) while HSO 3 − is a common reductant in water treatment. This study shows that the presence of HSO 3 − resulted in significant increase in the decomposition rate of organic contaminants by colloidal MnO 2. The degradation rate of contaminants in the MnO 2 /HSO 3 − process dropped with elevating pH and a proper MnO 2 /HSO 3 - molar ratio was critical for efficient decomposition of contaminants. The time-resolved spectroscopy of manganese species, the influence of pyrophosphate on UV absorbance spectra, and the relative rate constants of contaminants oxidation in MnO 2 /HSO 3 − process suggested that the synergetic effect of HSO 3 − and colloidal MnO 2 arose from the generation of Mn(III) aq , which could oxidize contaminants rapidly. The presence of pyrophosphate, ethylenediaminetetraacetic acid, and humic acid depressed the degradation of contaminants in MnO 2 /HSO 3 − process by complexing with Mn(III) aq , buffering the solution or competing with contaminants for Mn(III) aq , and/or inhibiting the consumption of bisulfite. However, Ca2+ and Mg2+ accelerated the oxidation of contaminants in MnO 2 /HSO 3 - process by enhancing the reduction of MnO 2 by HSO 3 -. The good negative correlation of the O/N or H Mulliken charges of organic contaminants with their removal in MnO 2 /HSO 3 − process suggested that organic contaminants were oxidized by Mn(III) aq via electrophilic attack. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel Ce(IV)/HSO 3 − process was proposed firstly in this study. • Carbamazepine (CBZ) could be oxidized at pH ini 3.0–7.0 in Ce(IV)/HSO 3 − process. • SO 4 −, HO, and SO 5 − were identified to be reactive species in this process. • SO 4 − played a major role in the degradation of CBZ in Ce(IV)/HSO 3 − system. • Pathways of CBZ degradation in Ce(IV)/HSO 3 − process were proposed. Abstract In this study, the activation of bisulfite by cerium(IV) (Ce(IV)/HSO 3 − process) is proposed for the first time to degrade organic contaminants. Experiments show that carbamazepine (CBZ), a representative recalcitrant contaminant of emerging concern, is oxidized by Ce(IV)/HSO 3 − treatment at pH ini 3.0–7.0 when O 2(aq) is present to promote HSO 3 − autoxidation. SO 4 −, HO, and SO 5 − were identified as active oxidants of CBZ based on the ESR spectra and the results of alcohol quenching experiments. Quantitative analysis indicates that SO 4 − plays a major role, while HO and other species play minor roles in the degradation of CBZ in the Ce(IV)/HSO 3 − process. SO 4 − radicals are derived from the reaction of SO 5 − with HSO 3 − and the activation of hydrogen peroxomonosulfate (HSO 5 −) by Ce(IV). Five degradation pathways of CBZ are proposed based on transformation products identified by UPLC-QToF-MS/MS, and proposed sites for radical attack are supported by the results of frontier electron density calculations. Elevated concentrations of Cl−, Fe(III), and humic acid (HA) inhibit CBZ degradation, while other non-target solutes have minimal effects on CBZ degradation in the Ce(IV)/HSO 3 − process. Finally, experiments demonstrating degradation of a suite of other organic contaminants suggests that the Ce(IV)/HSO 3 − system can be applied as a new advanced oxidation process for wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract A new dual-site fluorescent probe (probe 1) was synthesized for the separate detection of hydrogen sulfide and bisulfite. Probe 1 exhibited a rapid response to H 2 S and HSO 3 − through two emission wavelengths and color changes, and displayed satisfactory sensitivity. Probe 1 changed color in response to various concentrations of H 2 S, while probe 1 test paper changed gradually from colorless to pink. With HSO 3 − addition, there was almost no color change. Furthermore, the presence of HSO 3 − does not affect the detection of H 2 S; however, the presence of H 2 S interferes with the detection of HSO 3 −. Hence, quantitative detection of HSO 3 − must occur in an H 2 S-free environment. The results indicate that probe 1 is suitable for use as a sensor for hydrogen sulfide detection. Graphical abstract A dual-site fluorescent probe was designed and synthesized for separate detection of hydrogen sulfide and bisulfite. Image 1 Highlights • A dual-site fluorescent probe was developed for separate detection of hydrogen sulfide and bisulfite. • The fluorescent probe reacted with various concentrations of H 2 S and produced gradual color changes. • With increasing H 2 S concentration, the color of probe 1 test paper changed gradually from colorless to pink. • The probe was successfully applied to the qualitative and quantitative detection of H 2 S in real water samples. [ABSTRACT FROM AUTHOR]

Abstract A new colorimetric fluorescent probe 1 contained a C˭C double bond for the detection of bisulfite (HSO 3 -) via Michael-Addition was developed. Significantly, probe 1 can detect HSO 3 - with excellent selectivity, high sensitivity, fast response (< 10 min) and low detection limit (21 nM). Furthermore, the live cell imaging results provided a powerful method to study HSO 3 - chemistry in biological systems. [ABSTRACT FROM AUTHOR]

Abstract A series of compound oxides of Fe-MnX (Fe-Mn1, Fe-Mn2, Fe-Mn3, Fe-Mn4) were synthesized and tested in the activation of bisulfite for methylene blue (MB) degradation in aqueous solution under dark condition. X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area were used to characterize the Fe-MnX oxides. Fe-Mn2 could remove about 92% of MB from solution in 70 min, which was much more than the amounts removed by either Fe 2 O 3 or MnO 2. Mechanism analysis of synergistic effects was validated by simple detection of ionic species such as, Fe (III), Fe (II) and Mn (III) and controlling different variables. After thermal treatment, the current catalysts could be regenerated and recycled for at least three times. [ABSTRACT FROM AUTHOR]

A fluorescent probe is constructed to quickly and accurately detect bisulfite. The detection mechanism was considered to operate via the bisulfite, causing deprotonation of amido bond of 8-aminoquinoline derivative leading to fluorescence enhancement. The probe has a good selectivity for bisulfite over the other competitive substances such as F − , Cl − , Br − , I − , C 2 O 4 2− , NO 2 − , ClO 4 − , OAc − , PO 4 3− , CO 3 2− , HCO 3 − , HS − , HSO 4 − , SCN − , SO 4 2− , S 2 O 3 2− , Cys, Hcy and GSH. There is a good linear relationship between fluorescence intensity and the concentration of bisulfite in the range of 0–200 μM. The limit of detection was calculated to be 0.61 μM. Furthermore, the probe has also been successfully used for imaging bisulfite in living cells. [ABSTRACT FROM AUTHOR]

Background: Trinucleotide repeat (TNR) expansion is a kind of mutation with instability in the number of microsatellite repeats. This nature of mutation leads to the different kinds of neurological and neuromuscular disorders; among them, fragile-X syndrome is the main cause of intellectual disability in which the increasing number of CGG TNR in 5' untranslated region is the main reason for epigenetic silencing of Fragile X mental retardation 1 gene. The aim of this study is to decrease the CG content of the candidate region to facilitate amplification by conventional polymerase chain reaction (PCR). Bisulfite treatment of the genomic DNA results in conversion of unmethylated cytosine to uridine and may overcome the diagnostic pitfalls. Materials and Methods: The whole blood DNA was extracted and bisulfite treated. Then any simplification in PCR process of desire sequence were assayed through following conventional PCR using specifically designed primers for converted sequence. Bisulfite-treated PCR product of a nearby sequence confirmed our results as a conversion control. Results: Both the control and the candidate sequences undergoing bisulfite treatment were successfully amplified by PCR. Conclusions: Decreasing the GC content of the sequence by bisulfite treating could be a new approach to overcome difficulties in amplifying GC-rich sequences.

We report the development of a bifunctional near-infrared fluorescent probe (QZB) for selective sensing of bisulfite (HSO 3 −) and hypochlorous acid (HOCl). The synergistic detection of HSO 3 − and HOCl was achieved via a C=C bond recognition site. In comparison with the red-fluorescence QZB , two different products with non-fluorescence and paleturquoise fluorescence were produced by the recognition of QZB towards HSO 3 − and HOCl respectively, which can realize effectively the dual-functional detection of HSO 3 − and HOCl. QZB features prominent preponderances of dual-function response, near-infrared emission, reliability at physiological pH, low cytotoxicity and high sensitivity to HSO 3 − and HOCl. The detection of HSO 3 − in actual food samples has been successfully achieved using QZB. Utilization of QZB -based test strip to semi-quantitatively detect HSO 3 − and HOCl in real-world water samples by the "naked-eye" colorimetry are then demonstrated. Simultaneously, the determination of HSO 3 − and HOCl in real-world water sample has been achieved by smartphone-based standard curves. Additionally, the applications of QZB for imaging HSO 3 − and HOCl in vivo are successfully demonstrated. Consequently, the successful development of QZB could be promising as an efficient tool for researching the role of HSO 3 −/HOCl in the regulation of redox homeostasis regulation in vivo and complex signal transduction and for future food safety evaluation. A bifunctional near-infrared fluorescent probe (QZB) was developed for selective sensing of HSO 3 − and HOCl by two different fluorescence signals. QZB features near-infrared emission, low cytotoxicity and high sensitivity. The detection of HSO 3 − in actual food samples has been successfully achieved using QZB. Utilization of QZB -based test strip to semi-quantitatively detect HSO 3 − and HOCl in real-world water samples by the "naked-eye" colorimetry are then demonstrated. Simultaneously, the determination of HSO 3 − and HOCl in real-world water sample has been achieved by smartphone-based standard curves. Additionally, the applications of QZB for imaging HSO 3 − and HOCl in vivo are successfully demonstrated. [Display omitted] • A bifunctional probe (QZB) has been successfully developed for the detection of HSO 3 − and HOCl. • QZB features advantages of near-infrared emission, reliability at physiological pH, low cytotoxicity and high sensitivity. • The quantitative determination the levels of HSO 3 − and HOCl in real-world water samples has been achieved under the assistance of smartphone. • The imaging HSO 3 − and HOCl in vivo using QZB are successfully demonstrated. [ABSTRACT FROM AUTHOR]

A near-infrared fluorescent probe LJ was rationally constructed for sensing HSO 3 −. The fluorescence quenching recognition mechanism was realized by the addition reaction of electron-deficient C C bond in probe LJ and HSO 3 −. Probe LJ revealed multifarious preponderances such as longer wavelength emission (710 nm), low cytotoxicity, larger Stokes shift (215 nm), better selectivity, higher sensitivity (72 nM) and short response time (50 s). Encouragingly, probe LJ can detect HSO 3 − in living zebrafish and mice in vivo by fluorescence imaging techniques. Probe LJ was also successfully employed to semi-quantitatively detect HSO 3 − in real foodstuff samples by "naked-eye" colorimetriy. More importantly, quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. [Display omitted] • Probe LJ has many advantages such as near-infrared emission, short response time and reliability in a wide range of pH. • Probe LJ was successfully employed for the fluorescence imaging of HSO 3 − in live zebrafish and mice in vivo. • Semi-quantitative analysis of HSO 3 − in food and water samples has been realized by "naked-eye" colorimetry using probe LJ. • Quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. Bisulfite (HSO 3 −) has been widely used as an antioxidant, enzyme inhibitor and antimicrobial agent in foodstuffs, pharmaceutical and beverages industries. It is also a signaling molecular in the cardiovascular and cerebrovascular systems. Nevertheless, a high level of HSO 3 − can cause allergic reactions and asthmatic attacks. Accordingly, the monitoring of HSO 3 − levels possesses momentous significance from the perspectives of biological technology and food security supervision. Herein, a near-infrared fluorescent probe LJ is rationally constructed for sensing HSO 3 −. The fluorescence quenching recognition mechanism was realized by the addition reaction of electron-deficient C C bond in probe LJ and HSO 3 −. Probe LJ revealed multifarious preponderances such as longer wavelength emission (710 nm), low cytotoxicity, larger Stokes shift (215 nm), better selectivity, higher sensitivity (72 nM) and short response time (50 s). Encouragingly, probe LJ can detect HSO 3 − in living zebrafish and mice in vivo by fluorescence imaging techniques. In the meantime, probe LJ was also successfully employed to semi-quantitatively detect HSO 3 − in real foodstuff samples and water samples by the "naked-eye" colorimetry without the help of any special instruments. More importantly, quantitative detection of HSO 3 − in practical food samples was achieved through a smartphone application software. Consequently, probe LJ is expected to provide an effective and convenient way for the detection and monitoring of HSO 3 − in organisms and for food safety detection, which has tremendous application potential. [ABSTRACT FROM AUTHOR]

Bifunctional fluorescent probes for recognizing different substances have important research significance due to the wide variety of analytes. Here, a triphenylamine structural fluorescent probe (TPA-CHO) for the recognition of hydrazine (N 2 H 4) and bisulfite (HSO 3 -) in environment and lipid droplets based on aldehyde group sensing site was developed. The probe can detect those analytes with low detection limits and distinguishable color change (0.24 µM, red to green for N 2 H 4 ; 1.71 µM, red to blue for HSO 3 -). The reaction mechanism indicates that after reacting with N 2 H 4 and HSO 3 -, the production of hydrazone or hydroxy methanesulfonate group leads to a different molecular length and intramolecular charge transfer degree and then induces color-differentiated fluorescence emission. This structural design strategy for bifunctional fluorescent probes provides essential ideas for the design of single-molecule dual-analyte target probes. [Display omitted] • A triphenylamine fluorescent probe for N 2 H 4 /HSO 3 - was developed. • The probe can detect N 2 H 4 /HSO 3 - with distinguishable color change. • Aldehyde reacts with N 2 H 4 /HSO 3 - producing hydrazone or methanesulfonate group. • The probe can distinctively recognize N 2 H 4 /HSO 3 - in lipid droplets. [ABSTRACT FROM AUTHOR]

Bisulfite-activated permanganate (S(IV)/Mn(VII)) process has proven to be a promising method for rapidly degrading micropollutants. Previous studies have shown that the treatment efficiency of the S(IV)/Mn(VII) process suffer from significant water matrix effects while the mechanism still remains unclear. This study systematically investigates the influence of chloride, which is a common water constituent, on the S(IV)/Mn(VII) process. Addition of chloride decreased the removal of methyl phenyl sulfoxide, phenol, benzoic acid and carbamazepine by the S(IV)/Mn(VII) process but increased dimethoxybenzene removal. The distribution of reactive species in the S(IV)/Mn(VII) process in the absence and presence of chloride was determined with relative rate method. The S(IV)/Mn(VII) process primarily relies on SO 4 •− and reactive manganese species (RMnS) for pollutant abatement while dosing chloride decreased the concentration of these reactive species. Reactive chlorine species (RCS), such as Cl 2 •– and ClO•, are formed through the reaction of SO 4 •– with chloride, and become more important at high concentrations of chloride. RMnS includes Mn(VI), Mn(V) and Mn(III), but none of these species are capable of oxidizing chloride. However, chloride retarded the consumption of bisulfite which reduced RMnS and RCS in turn. DOM inhibited pollutant removal by the S(IV)/Mn(VII) process while the impact mechanism was significantly altered by chloride. Additionally, the study observed a synergistic inhibition of DOM and chloride on the degradation of pollutants that are highly reactive towards Cl 2 •– and ClO•. [Display omitted] • Cl− altered the treatment efficiency of pollutants by the S(IV)/Mn(VII) process. • Cl− changed the distribution of reactive species in the S(IV)/Mn(VII) process. • Cl− retarded HSO3 − consumption, resulting in the decrease of RMnS concentration. • The impact mechanism of DOM on S(IV)/Mn(VII) process was markedly changed by Cl−. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A dual responsive ratiometric fluorescent probe for N 2 H 4 and HSO 3 − was developed. • Different color changes based on different sensing mechanisms for N 2 H 4 and HSO 3 −. • It has high selectivity and low detection limit for N 2 H 4 and HSO 3 −. • Good recovery was achieved in industrial water for detecting N 2 H 4 and HSO 3 −. • It has good biocompatibility. Abstract Hydrazine and bisulfite are poisonous to the environment and human health, hence it is necessary to monitor hydrazine and bisulfite in the environment and living cells. In this study, we reported a smart fluorescent probe (CMCA) for discriminative detection of hydrazine and bisulfite. The single fluorescent probe can respond to hydrazine and bisulfite with two different sets of colorimetric and ratiometric fluorescence signals together with high selectivity, fast response and low detection limit. The discriminative sensing behaviors of the probe for hydrazine and bisulfite were ascribed to different reaction mechanisms, which were confirmed by 1H NMR and HR-MS spectra. The probe has been successfully used to discriminatively determine hydrazine and bisulfite in industrial wastewater with good recoveries. Furthermore, the probe was employed to visualize hydrazine and bisulfite in live cells from different fluorescence channels with good performance. Therefore, this probe has great potential applications for discriminative detection of hydrazine and bisulfite in the environment and living cells. [ABSTRACT FROM AUTHOR]

A new fluorescent probe tetrahydro[5]helicene-malononitrile derivative was designed and synthesized for selective detection of bisulfite. This fluorescent probe exhibites high response speed and selectivity toward HSO 3 − in PBS solution over other coexisting species accompanied by a distinct fluorescence color change from yellow to blue, which can be visually identified. The probe shows excellent sensitivity to HSO 3 − and the detection limit is as low as 0.27 μM. Once reacted with HSO 3 − , the signal-to-background ratio of fluorescence intensity can reach a 45-folds enhancement and the quantum yield dramatically increases from 1.9% to 52.3%. The response mechanism proved to be a nucleophilic addition reaction of probe with HSO 3 − , which was confirmed by 1 H NMR, Mass titration and theory calculation. Additionally, the preliminary cell imaging experiments demonstrated that the probe could be used for intracellular bisulfite detection. [ABSTRACT FROM AUTHOR]

A novel ratiometric fluorescent probe was designed and synthesized for detection of bisulfite, via pyrene as an electron donor (D) and 4, 5-dibromothiophene as an electron acceptor (A). It had good selectivity, sensitivity and short response time. The fluorescence intensity ratio at 420 nm and 530 nm (I 420 /I 530 ) displayed a good linear relationship with the concentration of HSO 3 − in the range of 0–35 μM, and the detection limit was 0.77 μM. The possible recognition mechanism of probe and HSO 3 − was illustrated by NMR, HRMS and computational analysis. Notably, the probe was successfully applied for imaging HSO 3 − in A549 cells, Caenorhabditis elegans and zebrafish, which indicated that this probe had great potential for HSO 3 − detection in vivo. [ABSTRACT FROM AUTHOR]

Abstract A spinel-type Co-Mn oxide was designed and synthesized through a two-step oxidation-precipitation method at modest temperatures. The Co-Mn oxide was applied as the catalyst in the presence of NaHSO 3 under visible light irradiation in order to establish the superiority of heterogeneous photo-chemical catalysis system. In the above system, the Co-Mn catalyst exhibited much better catalytic capability than that in either single photocatalysis or chemocatalysis system, implying that the Co-Mn catalyst could well combine photocatalysis and chemocatalysis to obtain the highest degradation efficiency of up to 94% within 40 min when using Orange II as the target pollutant. Recycling experiments results showed that the as-obtained catalyst has excellent stability and recyclability. Powder X-ray diffraction (XRD) analysis showed that the as-obtained Co-Mn catalyst had a cubic MnCo 2 O 4.5 spinel structure. Because of relatively low temperature (180 ℃) synthesis, the catalyst was formed with nanoparticles (25–65 nm) and high specific surface area as confirmed by SEM and BET analyses. XPS indicated the presence of both manganese and cobalt species that serve as reactive sites for the catalytic oxidation reactions. Rational degradation mechanisms responsible for superior catalytic activity and durability were proposed based on a series of experimental results. The active species such as Mn(III), holes and sulfate and hydroxyl radicals were proposed to be responsible for the outstanding degradation results. [ABSTRACT FROM AUTHOR]

A new benzo[ e ]indolium derivative 1 including pyridyl and thienyl groups was synthesized and characterized, which failed to response to Hg 2+ or Cu 2+ in aqueous system. However, it is interesting that when it reacted with bisulfite in HEPES buffer, the in situ generated ensemble as 1 -SO 3 H displayed dramatic absorption and fluorescence changes after adding Cu 2+ or Hg 2+ , which were contrary to the changes of 1 upon the addition of bisulfite ions. By contrast, the other two derivatives 2 and 3 showed the almost similar trends of spectral changes, which were short of ligating atoms N or S. The further investigation of 1 HNMR spectra changes of 1 showed that C−SO 3 H bond may be interrupted because the good binding capacity of Hg 2+ and Cu 2+ with O of C−SO 3 H weaken the binding force of C−SO 3 H, which resulted in the recovery of ethylene with benzo[ e ]indolium block. The DFT calculations results further confirmed it. [ABSTRACT FROM AUTHOR]

A new cycloruthenated 2-(2-thienyl)pyridine complex ( 1 ) with a benzo[ e ]indolium block was successfully synthesized and characterized, which has good water-solubility and displays a maximum absorption band centered at 730 nm (ε = 6.3 × 10 3  M −1  cm −1 ) in water. Moreover, its absorption edge can extend to 1000 nm. When either HSO 3 – or SO 3 2– ions were added to the buffer solutions of 1 , obvious color changes from dark-red to purplish-red were observed. However, it is noticeable that the addition of HSO 3 – ions resulted in the solution color of this complex changing from dark-red to colorless other than purplish-red. The different solution color changes displayed that 1 can be used as an optical chemo-sensor to distinguish HSO 3 – from SO 3 2– in pure water. [ABSTRACT FROM AUTHOR]

Organic contaminants can be oxidized rapidly in permanganate/bisulfite (PM/BS) process due to generation of Mn(III) aq . However, the influence of O 2 and its role in contaminants degradation in PM/BS process are poorly understood. Thus, the influence of O 2 concentration on phenol removal was quantified and isotopic oxygen tracers ( 18 O-labeled water and 18 O 2 ) were employed to further unravel the mechanisms of PM/BS process. The introduction of O 2 to PM/BS process appreciably improved phenol oxidation. Under oxic conditions the oxidation products of bisulfite included SO 4 2− and HSO 5 − while SO 4 2− was the single stable oxidation product under anaerobic conditions. The oxygen isotope labeling experiments confirmed that HSO 5 − originated from the oxidation of SO 3 − by O 2 to SO 5 − and the following reduction of SO 5 − by HSO 3 − . Incorporation of oxygen isotope from H 2 18 O to MnO 2 due to the disproportionation of Mn(III) aq was observed, which verified the generation of Mn(III) aq in PM/BS process. The critical influence of O 2 on PM/BS process was mainly associated with rapid oxidation of SO 3 − by O 2 to SO 5 − , which otherwise competed with target contaminants for Mn(III) aq . Oxygen from H 2 O and/or O 2 can also be incorporated in the degradation products of organics in PM/BS process. [ABSTRACT FROM AUTHOR]

Electrochemical oxidation of sulfite at a platinum electrode was investigated, in which changing the pH of supporting electrolytes caused qualitative changes in the oxidation behavior. In an acidic environment, oscillations in current were found to occur; however, only transient behavior was observed without the incorporation of an external resistor. Electrochemical impedance spectroscopic measurements indicate that the system possesses a region of negative differential resistance (NDR) at acidic conditions. To gain insights into the influence of pH, electrochemical oxidation of bisulfite was also studied, in which NDR was found, suggesting that changes in the dominant species induced by pH is responsible for the observed phenomena. Perturbation experiments illustrate the presence of bistability under galvanostatic conditions, lending support that the observed instabilities belong to the N-NDR class of electrochemical oscillators. Mass spectroscopic analysis and precipitation with barium ion suggest that SO 4 2− is a major product of the electro-oxidation of sulfite. [ABSTRACT FROM AUTHOR]

Two unprecedented solid phases involving the 3,7-bis­(di­methyl­amino)­pheno­thia­zin-5-ium cation, i.e. methyl­ene blue (MB+), have been obtained and structurally characterized. In the crystals of 3,7-bis­(di­methyl­amino)­pheno­thia­zin-5-ium chloride dihydrate, C16H18N3S+·Cl−·2H2O (I) and 3,7-bis­(di­methyl­amino)­pheno­thia­zinium bis­ulfite, C16H18N3S+·HSO4− (II), the cationic dye mol­ecules are planar and disposed in an anti­parallel mode, showing π–π stacking inter­actions, with mean inter­planar distances of 3.326 (4) and 3.550 (3) Å in (I) and (II), respectively. In compound (I), whose phase was found affected by merohedral twinning [BASF = 0.185 (3)], the presence of water mol­ecules allows a network of hydrogen bonds involving MB+ as both a donor and an acceptor, whereas in compound (II), the homo-inter­action of the anions causes an effective absence of classical hydrogen-bond donors. This substantial difference has important consequences for the stacking geometry and supra­molecular inter­actions of the MB+ cations, which are analysed by Hirshfeld fingerprint plots and subsequently discussed. [ABSTRACT FROM AUTHOR]

Bisulfite (HSO 3 − ) and sulfite (SO 3 2− ) compounds play key roles in numerous geochemical and biochemical processes extending from the atmosphere to the subseafloor biosphere. Despite decades of spectroscopic investigations, the molecular composition of HSO 3 − in solution remains uncertain and, thus, the role of bisulfite in (bio)chemical and isotope fractionation processes is unclear. We report new experimental estimates for the bisulfite isomer quotient ( Q i  = [(HO)SO 2 − ]/[(HS)O 3 − ]; [] = concentration) as a function of temperature from the interpretation of Raman spectra collected from aqueous NaHSO 3 solutions contained in fused silica capsules. In pure NaHSO 3 solutions (1Na + :1HSO 3 − , stoichiometric) over [NaHSO 3 ] = 0.2–0.4 m (moles/kg H 2 O), the following relationship is obtained: ln ( Q i ) = 878.59 ( ± 32.98 ) T - 1.9642 ( ± 0.1081 ) , where T = 278–358 K (5–85 °C) (based on 50 determinations; additional significant figures are provided to avoid rounding errors). This relationship suggests that the minor isomer, (HS)O 3 − , may comprise 23–38% (±3%) of the mole fraction of HSO 3 − over 5–85 °C, respectively, which is higher in relative abundance than has generally been understood previously. We additionally provide estimates for Q i in NaHSO 3 solutions containing a total ionic strength of µ  = 1.0 m (0.2 m NaHSO 3  + 0.8 m NaCl) and different pH (3.3–4.5), but do not appear to resolve any significant differences in Q i as a function of these additional variables. These new values of Q i are employed to re-assess the bulk sulfur isotope fractionations among bisulfite and other S(IV) compounds as a function of temperature, which appear to be highly dependent on the amount of (HS)O 3 − present. Our new constraints on the bisulfite isomer quotient may allow for a detailed assessment of the molecular composition and isotope mass balance of S(IV) solutions containing HSO 3 − , and may be useful in the further investigation of the mechanisms and isotope fractionations associated with a number of processes that involve bisulfite compounds. These may include the intracellular enzymatic transformations of sulfite and bisulfite compounds that occur as part of dissimilatory sulfate reduction, which is a major and geologically important form of anaerobic respiration. [ABSTRACT FROM AUTHOR]

A novel and powerful chemiluminescence (CL) system was developed based on the promoting effect of graphene quantum dots (GQDs)/bisulfite on rhodamine B (RB)-H 2 O 2 CL reaction. GQDs were synthesized by a simple, green and affordable approach and characterized using their distinctive absorption and emission patterns. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) transmission and transmission electron microscopy (TEM) analysis were implemented for complementary studies on the structural and morphological characteristics of GQDs. The simultaneous enhancing effect of the synthesized GQDs and bisulfite on the CL emission of RB-H 2 O 2 reaction provided a more strong and efficient CL system. The mechanism of CL emission was described. Furthermore, HCHO as a well-known pollutant, could selectively diminish the developed CL system. This effect was linearly proportional to HCHO concentration which turned the introduced CL system to a susceptible chemosensor for HCHO. Under the optimized operational condition, the linear changing of CL response was obtained in HCHO concentration ranges of 0.02–5 μg L −1 and 5–11 μg L −1 , with limit of detection (LOD) and quantification (LOQ) of 6 ng L −1 and 20 ng L −1 , respectively. Ultimately, presented CL chemosensor was served as an accurate tool for determination of formaldehyde concentration in water and wastewater samples. [ABSTRACT FROM AUTHOR]