Ion Chromatographic Method Research Articles

Insights into interactions of chlorine-based cleaning products with indoor relevant surfaces

Environmental context The chemistry that occurs in indoor environments and the role that indoor surfaces play have recently received increased attention in the scientific community. Here we have investigated the chemistry of chlorine-based cleaning products and their interactions with indoor relevant surfaces and find that these surfaces react with these cleaning products to yield surface adsorbed chlorine oxides and other surface-bound species. Rationale Indoor chemistry has recently received increased attention in the scientific community due to the fact that there is relatively little known given its unique environment including point combustion sources (candles, gas stoves, etc.) resulting in high aerosol concentrations, high surface to volume ratios and the impact of humans on indoor air quality. Recently, surface-initiated reactions during chlorine cleaning events have been proposed. Methodology In this study, we probe the interaction of bleach headspace gas with high surface area silica as a proxy for window glass – an ‘inert’ and impervious surface – using attenuated total reflectance Fourier Transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy photothermal infrared (AFM-PTIR) spectroscopy and transmission electron microscopy (TEM) to observe surface chemical and physical changes. Results The results suggest chemical transformations occur at the silica surface forming surface adsorbed chlorine oxides (ClOx). Conductivity and ion chromatography methods support the presence of adsorbed chloride after surfaces have been exposed to bleach and HOCl. Discussion Interactions between HOCl and indoor surfaces have not been previously studied with molecular based techniques. The possibility of surface-mediated reactions has been relatively unexplored on indoor surfaces and this study shows the chemistry of chlorine-containing cleaning products on indoor relevant surfaces.

Identification and Quantitation of Taste-Active Compounds in Dried Scallops by Combined Application of the Sensomics and a Quantitative NMR Approach.

Application of the sensomics concept on dried scallops, a Japanese specialty produced from the adductor muscle of scallops, revealed after activity-guided fractionation with subsequent (comparative) taste dilution analyses besides nucleotides, amino acids, organic acids, and inorganic ions, the presence of taste-modulating quaternary ammonium compounds and opines in highly taste-active fractions. In order to recreate the taste of dried scallops, two independent quantitation approaches were applied and compared. The first approach used multiple targeted UHPLC-MS/MS and high-performance ion chromatography methods. Besides already established quantitation methods for basic taste compounds, a new HILIC-UHPLC-MS/MSMRM method for the quantitation of chromatographically challenging opines, using synthesized stable isotope-labeled standards, was developed. Furthermore, a qHNMR approach was applied, enabling a direct identification and quantitation of organic taste compounds in a food extract without prior fractionation using a reference 1H NMR database. Both methods yielded similar quantitative results of taste-active compounds in dried scallop extracts and subsequent taste recombination experiments based on these data were able to recreate the taste of dried scallops.

Green Aspects of Ion Chromatography versus Other Methods in the Analysis of Common Inorganic Ions

Due to the increasing environmental awareness of the public, green chemistry has become an important element of environmental protection. In laboratories around the world, millions of analyses of inorganic and organic anions and cations in water and wastewater samples, and solid and gaseous samples are performed daily. Unfortunately, these activities still generate large costs, including environmental costs, which are related to the scale of the studies, the use of toxic chemical reagents, the waste generated, and the energy consumed. The methods used so far for inorganic ion analysis, including classical methods, are increasingly being replaced by instrumental methods, primarily based on ion chromatography. This paper presents the most important advantages and limitations of ion chromatography, and compares them with the costs of classical analyses for the analytes and sample types. Both the financial and environmental costs associated with the determination of common inorganic ions, such as Cl−, NO2−, NO3−, and NH4+, in 1000 environmental samples, were compared using selected reference wet classical methods and ion chromatography. The advantages and limitations of ion chromatography that allow this separation technique to be classified as a green analytical chemistry method have been described herein.

Assessment of the content of biogenic elements in the evaporation pond of the “Caspi Bitum” plant

The article presents the results of environmental monitoring of wastewater generated as a result of the production activities of the» Caspi Bitum « plant. The analysis of the content, distribution, and dynamics of biogenic elements in the evaporation pond belonging to the enterprise is carried out. Today, one of the most pressing problems is the industrial ingress of biogenic elements to water fields, which leads not only to changes in the chemical composition and quality properties of the reservoir, but also to salinization of beaches. Analysis of its composition, tracking the dynamics of biogenic elements in the pond water allows you to describe the overall state of the reservoir. This study was conducted for this purpose. The work is based on materials collected during field research on the evaporation pond of the «Caspi Bitum» plant from autumn 2018 and summer 2019. Samples are collected from the water surface at pre-set coordinates and sent for laboratory analysis. Chemical analyses of water samples were performed for the following parameters: ammonium nitrogen, phosphates, nitrites, nitrates and phenol. Also, the amount of these substances was reviewed and compared with the level of MPC according to regulatory documents. Hydrochemical analysis of samples was performed using photometric and ion chromatography methods. Data on biogenic elements in water allows predicting changes in the quality of water environments and is used in the regulation and control of the overall state and pollution of ecosystems in water.Key words: waste water, biogenic element, purification, evaporation pond, petroleum products.

Association between lithium levels in drinking water and suicide rates: Role of affective disorders

Objective. The study aimed to assess the association between lithium levels in drinking water from public supplies and suicide rates in different municipalities of Lithuania in relation with incidence of affective disorders.Methods. 53 drinking water samples were analysed from the main public drinking water systems of the country's municipalities. Lithium levels were determined using the ion chromatography method. Information on all registered affective disorders across all age groups and gender within the 5-year period was obtained from the Department of Statistics, and was averaged across the investigation time period. For the statistical analysis, lithium levels were averaged per municipality and plotted against suicide standardized mortality rates per 100,000 populations, within the 5-year period.Results. We found that lithium levels in drinking water are positively associated with the incidence of affective disorders. Our findings suggest higher incidence rates of affective disorders in the municipalities with a lithium level in drinking water above median compared to those in the municipalities with a lithium level below median and with the same socio-demographic and psychiatric characteristics. Suicide mortality rates are inversely associated with lithium levels in drinking water only in municipalities with higher lithium levels (above median) and with a high rate of affective disorders.Conclusion. Based on our study results and insights we generate the following hypothesis for the further research, that lithium level in drinking water might have an important protective effect against suicide rates in the population with affective disorders.

Nitrate in groundwater of the west side Magelang Regency, Central Java, Indonesia

Nitrate (NO3-) pollution in groundwater is generally caused by chemical fertilizers from the agricultural sector and wastewater from onsite sanitation. Magelang Regency, Central Java, Indonesia, is a large food estate that has 206 km2 paddy fields. In addition, this area is inhabited by 1.3 million people who produce onsite sanitary waste every day. Due to the concentration and intensity of fertilization and sanitary waste, which are quite high, Magelang Regency is susceptible to groundwater pollution by nitrate. This study aims to determine the characteristics of nitrate in the groundwater of the west side Magelang Regency, Central Java, Indonesia. The research was carried out by testing groundwater samples taken from several springs, dug wells, and drilled wells used by society for their daily needs. Groundwater sampling was carried out in the wet season and tested using the ion chromatography method to determine the level of nitrate in groundwater and know the chemical characteristics to analyze dominant ions in groundwater. The results showed that the average nitrate was 3.9 mg/l; the deviation standard was 5.12; minimum nitrate was 0 mg/l; and maximum nitrat was 20.78 mg/l. The origin of nitrate content may come come from feces but still in small quantities. Facies of groundwater are Ca-HCO3 and Na-Cl. It can be concluded that the groundwater of the west side Magelang Regency is not yet polluted by nitrate. However, there is still a possibility in the future, so that necessary to apply for groundwater protection immediately.

Novel BaSnO3/TiO2@HNTs Heterojunction Composites with Highly Enhanced Photocatalytic Activity and Stability

AbstractThe novel BaSnO3/TiO2@HNTs photocatalysts were successfully synthesized by co‐precipitation peroxide and sol‐gel methods. Microstructures, morphologies, compositions, optical and electrochemical properties of the composites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), fourier‐transform infrared spectroscopy (FT‐IR), UV‐vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), Brunauer‐Emmett‐Teller (BET), electrochemical impedance spectroscopy (EIS) and ion chromatography (IC) methods. The effects of different mass ratios of BaSnO3 and TiO2@HNTs, initial concentration and pH of methylene blue (MB) on the photocatalytic degradation performance of the composites were studied via photodegradation of MB under simulated sunlight irradiation. The characterization results showed that BaSnO3/TiO2 heterojunction and halloysite nanotubes (HNTs) enhanced the electron‐hole pairs separation. The BaSnO3/TiO2@HNTs (BTH‐0.6) composites presented the highest specific surface area (67.957 m2/g), photocatalytic activity (92 %), and MB (Ct=40 mg/L, pH 7) degradation efficiency (2‐4 times that of TiO2, BaSnO3 and BaSnO3/TiO2). Furthermore, the capture experiments verified that ⋅OH, h+ and ⋅O2− were the main active substances during the photo‐catalytic reaction, and a possible degradation mechanism was suggested for their photocatalytic degradation in the presence of BaSnO3/TiO2@HNTs.

Assessment of Solder Flux Corrosivity and Flux Residue Level in Clip Bonding Assembly

Abstract Most fluxes and their flux residue are corrosive, and their presence on the surface of assemblies may cause reliability concerns due to electrochemical migration. This study firstly refers to the test method IPC-TM-650 2.3.32D and 2.6.15C and the requirements in J-STD-004A to evaluate flux-induced corrosion and the corrosivity of their flux residue. Then thermogravimetric analysis is used to evaluate the flux residue level after soldering under identical conditions. These comparison data can be utilized to compare flux performance of solder pastes. For the cleanliness evaluation after flux cleaning, the qualitative analysis refers to IPC-A-610G and adopts optical inspection to observe the flux cleaning effect. The quantitative analysis refers to IPC-TM-650 2.3.28B ion chromatography test method to analyze the level of ionic species after flux cleaning. In addition to IPC-TM-650 2.3.28B ion chromatography method, the effectiveness of other methods has been well demonstrated to characterize the fluxes and their flux residue in clip bonding assembly.

Generation and immunogenicity evaluation of Senecavirus A virus-like particles

To develop Senecavirus A (SVA) virus-like particles (VLPs), a recombinant prokaryotic expression plasmid pET28a-SVA-VP031 was constructed to co-express SVA structural proteins VP0, VP3 and VP1, according to the genomic sequence of the field isolate CH-FJ-2017 after the recombinant proteins were expressed in E .coli system, and purified by Ni+ ion chromatographic method. The SVA VLPs self-assemble with a high yield in vitro buffer. A typical VLPs with an average diameter of 25-30 nm which is similar to native virions by using TEM detection. Animals immunized by SVA VLPs shown that the VLPs induced high titers neutralizing antibodies in Guinea pigs. This study indicated that the VLPs produced with co-expressing SVA structural proteins VP0, VP3 and VP1 in prokaryotic system is a promising candidate and laid an important foundation for the development of a novel SVA VLPs vaccine.

Розвиток йонної хроматографії в Україні.

The ways of development of ion chromatography in Ukraine from the eighties of the last century to the present time are shown. The achievements of research institutes, in particular, the Dumansky Institute of Colloid Chemistry and Water Chemistry of the National Academy of Sciences of Ukraine, in the development of ion chromatographic methods for the analysis of organic and inorganic anions in various objects, including natural and drinking waters, are highlighted. Scientists of Ukraine (A.T. Pilipenko, O.V. Zuy, A.V. Terletskaya) compared commercially available sorbents for ion chromatography – HIKS-1, ANIEKS-N and KANK ASt for their use in water analysis. The studies were carried out on an ion chromatograph "Tsvet-3006" with a conductometric detector. It has been shown that ANIEKS-N with a borate eluent is the best sorbent for the determination of organic monocarboxylic acid ions, and KANK ASt with a carbonate-hydrocarbonate eluent – for the determination of inorganic anions. Ion chromatography has been used to solve a number of practical problems: for the separation of oxoanions  iodate, chlorate and bromate in waters, to control the results in the development of chemiluminescent methods for the determination of chloride, nitrite and nitrate, to establish the mechanism of destruction of anionic surfactants under the action of vacuum ultraviolet radiation and corona discharge. The method was applied to the analysis of iodine-containing bottled waters for bromide ions due to the absence of the interference from iodides. The accumulated experience has contributed to the adoption in Ukraine of four state standards for water quality, based on the use of the ion chromatographic method. It is shown that the method of ion chromatography at the present stage is widely used in various sectors of the national economy: to determine the traces of anions in steam condensate of power plants, to control the anionic composition of water at nuclear power plants, to correct water treatment processes at waterworks, in particular, when analyzing chlorite ions in tap water obtained with the use of chlorine dioxide as a disinfectant.

The Influence of Sample pH on the Determination of Selected Carboxylic Acids by Isocratic Ion Chromatography

Validated isocratic ion chromatography method with suppressed conductivity detection has been developed for the simultaneously determination of common inorganic anions (F-, Cl-, NO3-, PO43-, SO42-), as well as formate and acetate. Liquid samples originate from absorption of gaseous by-products from coal combustion with and without the addition of medium-density fireboards. The influence of sample pH changes on carboxylic acids determination has been tested.

Fabrication of Z-scheme ZnO/Bi2O4 heterojunction photocatalyst with superior photocatalytic nitrogen fixation under visible light irradiation

ZnO/Bi2O4 heterojunctions with different ratios were successfully synthesized by one-step hydrothermal method. The photocatalytic activity for nitrogen fixation was investigated by Nessler's reagent spectrophotometry and ion chromatography method for comparison. As a result, the NH4+ concentration over 10%ZnO/Bi2O4 catalyst measured by ion chromatography is 0.22 mmol L−1 h−1·gcat−1 after 150 min visible light irradiation, which is about 1/135 of that obtained by Nessler's reagent method. Furthermore, the photocatalytic activity for degradation of methyl orange and ciprofloxacin was also evaluated. 10%ZnO/Bi2O4 shows optimal photocatalytic degradation efficiency (97.5 % and 95.6 % for methyl orange and ciprofloxacin), which are 40.7 and 28.3 times that of pure ZnO. Various characterization techniques and photoelectrochemical tests have proved that such enhanced photocatalytic activity was due to the heterojunction formation between ZnO and Bi2O4, which possesses a lower charge transfer resistance and efficient electron-hole pairs separation.

Determination of Salt Forms of New Psychoactive Substances by Ion Chromatography

Objective To establish an ion chromatography method for the salt form determination of new psychoactive substances （NPS）. Methods The method of conducting qualitative and quantitative analysis of six types of organic acid ions （acetate ion, tartrate ion, maleate ion, oxalate ion, fumarate ion, citrate ion） and five types of inorganic anions （fluoride ion, chloride ion, nitrate ion, sulfate ion, phosphate ion） in NPS sample by ion chromatography was developed. The salt forms of 222 seized NPS samples （103 samples with synthetic cannabinoids, 81 samples with cathinones, 44 samples with phenylethylamines, 12 samples with tryptamines, 7 samples with phencyclidines, 6 samples with piperazines, 2 samples with aminoindenes, 26 samples with fentanyls and 43 samples with other types of NPS） were analyzed by this method. Results Each anion had good linearity in the corresponding linear range, the correlation coefficients （r） were greater than 0.999, the limits of detection were 0.01-0.05 mg/L, and the limits of quantitative were 0.1-0.5 mg/L. Except that 5F-BEPIRAPIM was hydrochloride, the salt forms of the other 102 synthetic cannabinoids were all base. The salt form of 81 cathinone samples, 44 phenylethylamine samples, 7 phencyclidine samples and 2 aminoindene samples were all hydrochloride. The salt forms of tryptamine samples included base, hydrochloride, fumarate and oxalate. The salt forms of piperazine samples included base and hydrochloride. The salt forms of fentanyl samples and samples of other types included base, hydrochloride and citrate. Conclusion Ion chromatography is a simple, accurate and efficient method for determining the salt form of NPS samples, which makes the qualitative and quantitative conclusions of NPS more scientific and rigorous.

Hazardous inorganic disinfection by-products in Egypt's tap drinking water: Occurrence and human health risks assessment studies

This study is the first that monitored the presence and levels of chlorite, chlorate and bromate in tap drinking water of Egypt. Three hundred and eight samples were collected from 22 governorates across Egypt and were analyzed using a standardized ion chromatography method. Forty-seven samples were contaminated by one or more of the inorganic disinfection by-products (DBPs) and only 12 samples exceeded the admissible maximum contamination levels (MCLs). The ratio of samples detected, and exceeding the MCLs were low relative to the global literature. Chlorate was the most prevalent inorganic DBPs (40 samples; concentration <12–4082 μg/L) followed by bromate (12 samples; concentration <3–626 μg/L) then chlorite (5 samples; concentration <12–123 μg/L). Chlorite was always below the MCL and had no human health risk even for the worst-case scenario. Bromate is a real challenge as it poses a significant cancer risk even for the median concentrations. None of the inorganic DBPs was detected in the tap drinking water of Beheira, Cairo, Gharbia, Giza, Kafr El Sheikh, Luxor, Monufia, and Suez governorates. This study manifested the importance of routine monitoring, and implementing counter measures to control the levels of the hazardous inorganic DBPs in tap drinking water.

Continuous flow analysis methods for sodium, magnesium and calcium detection in the Skytrain ice core

AbstractDissolved and particulate sodium, magnesium and calcium are analyzed in ice cores to determine past changes in sea ice extent, terrestrial dust variability and atmospheric aerosol transport efficiency. They are also used to date ice cores if annual layers are visible. Multiple methods have been developed to analyze these important compounds in ice cores. Continuous flow analysis (CFA) is implemented with instruments that sample the meltstream continuously. In this study, CFA with ICP-MS (inductively coupled-plasma mass spectrometry) and fast ion chromatography (FIC) methods are compared for analysis of sodium and magnesium. ICP-MS, FIC and fluorescence methods are compared for analysis of calcium. Respective analysis of a 10 m section of the Antarctic WACSWAIN Skytrain Ice Rise ice core shows that all of the methods result in similar levels of the compounds. The ICP-MS method is the most suitable for analysis of the Skytrain ice core due to its superior precision (relative standard deviation: 1.6% for Na, 1.3% for Mg and 1.2% for Ca) and sampling frequency compared to the FIC method. The fluorescence detection method may be preferred for calcium analysis due to its higher depth resolution (1.4 cm) relative to the ICP-MS and FIC methods (~4 cm).

Geochemical Modeling of Scale Formation due to Cooling and CO2-degassing in San Kamphaeng Geothermal Field, Northern Thailand

Scaling in a geothermal piping system can cause serious problems by reducing flow rates and energy efficiency. In this work, scaling potential of San Kamphaeng (SK) geothermal energy, Northern Thailand was assessed based on geochemical model simulation using physical and chemical properties of hot spring water. Water samples from surface seepage and groundwater wells, analyzed by ICP-OES and ion chromatograph methods for chemical constituents, were dominated by Ca-HCO3 facies having partial pressure of carbon dioxide of 10–2.67 to 10–1.75 atm which is higher than ambient atmospheric CO2 content. Surface seepage samples have lower temperature (60.9°C) than deep groundwater (83.1°C) and reservoir (127.1°C, based on silica geothermometry). Geochemical characteristics of the hot spring water indicated significant difference in chemical properties between surface seepage and deep, hot groundwater as a result of mineral precipitation along the flow paths and inside well casing. Scales were mainly composed of carbonates, silica, Fe-Mn oxides. Geochemical simulations based on multiple chemical reaction equilibria in PHREEQC were performed to confirm scale formation from cooling and CO2-degassing processes. Simulation results showed total cumulative scaling potential (maximum possible precipitation) from 267-m deep well was estimated as 582.2 mg/L, but only 50.4% of scaling potential actually took place at SK hot springs. In addition, maximum possible carbon dioxide outflux to atmosphere from degassing process in SK geothermal field, estimated from the degassing process, was 6,960 ton/year indicating a continuous source of greenhouse gas that may contribute to climate change. Keywords: Degassing, Geochemical modeling, PHREEQC, San Kamphaeng Hot Springs, Scaling

An Ion Chromatography Method for Simultaneous Quantification of Chromate, Arsenate, Selenate, Perchlorate, and Other Inorganic Anions in Environmental Media.

Chromium (Cr) (VI) is a toxic, mutagenic, and carcinogenic water pollutant. The standard ion chromatography (IC) method for quantification of Cr (VI) in water samples is Environmental Protection Agency Method 218.7, which requires postcolumn derivatization with 1,5-diphenylcarbazide and UV-Vis spectroscopy detection. Method 218.7 is Cr (VI) specific; thus, it does not allow detection of co-occurring natural and anthropogenic anions in environmental media. In this study, we developed an isocratic IC method with suppressed conductivity detection, a Metrohm Metrosep A Supp 7 column, and sodium carbonate/acetonitrile as mobile phase for simultaneous quantification of Cr (VI), , As (V) as arsenate, Se (VI) as selenate, and the common anions F–, Cl–, , , and . The determination coefficient for every analyte was >0.99 and the method showed good accuracy in quantification. Cr (VI), As (V), Se (VI), and limit of detection and limit of quantification were 0.1–0.6 μg/L and 0.5–2.1 μg/L, respectively. Recovery of Cr (VI) in various aqueous samples (tap water, surface water, groundwater, and wastewater) was between 97.2% and 102.8%. Overall, most analytes showed acceptable recovery (80–120%) in the environmental samples tested. The IC method was applied to track Cr (VI) and other anion concentrations in laboratory batch microcosms experiments with soil, surface water, and anaerobic medium. The IC method developed in this study should prove useful to environmental practitioners, academic and research organizations, and industries for monitoring low concentrations of multiple anions in environmental media, helping to decrease the sample requirement, time, and cost of analysis.

Studies on perchlorate levels in powdered infant formulas available on the Polish market

Abstract Perchlorate has been acknowledged as a health threat due to its ability to interfere with iodine uptake by the thyroid gland. Infants and developing newborns have been considered as the most vulnerable groups to the perchlorate toxicity. A crucial source of perchlorate ingestion are powdered infant formulas. This study was designed to measure perchlorate content in thirty-one powdered infant formulas available on the Polish market. A rapid and sensitive ion chromatography method – conductivity cell detection – was applied to determine ClO 4 − {\rm{ClO}}_4^ - content. Limit of detection (0.150 µg/L) and limit of quantification (0.450 µg/L) were assessed. Collected samples were classified by the age of consumers: first stage, until the baby is six months old and follow-on formula for older children. Geometric mean of perchlorate concentration of 1.041 µg/L and 0.857 µg/L in the groups of the first stage and follow-on formulas were calculated, respectively. A health risk assessment revealed that the Tolerable Daily Intake (TDI) for perchlorate (0.3 µg/kg body weight/day) was exceeded only in a few milk samples. The findings suggest that perchlorate contamination of powdered infant formulas may not to be an immediate health issue, yet testing for ClO 4 − {\rm{ClO}}_4^ - should continuously be conducted. To the best of our knowledge, this is the first study concerning perchlorate content in infant formulas in Poland.

Magnetic Graphene Based Cation Ion Exchange Material for Removal of Heavy Metal Ion (Pb2+) from Water

:In current scenario, water pollution is a major worldwide problem. Many of the toxic heavy metals present in the water affected human body as well as aquatic animal life. Nowadays it has been a great attention to fast removal, cost-effective, sustainable detoxification/elimination of inorganic pollutants from wastewater. In this work, we have synthesized the magnetic Graphene-based hybrid nanocomposites, which is more sensitive and better supporting material for the removal of toxic pollutants from water. The hybrid nanomaterial was prepared by mixing iron (II) and iron (III) salt precursors in the presence of GO dispersion through the co- precipitation method followed by in situ chemical reduction of GO. Further, Magnetic Graphene Oxide (MGO) functionalized with the sulfonic acid group and oxidized by hydrogen peroxide (H2O2). The synthesis of magnetic graphene based nanocomposites was confirmed by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), Raman spectroscopy, Field emission Scanning electron microscopy (FESEM) & EDS and magnetic behavior by vibrating sample magnetometer (VSM). Further, sulfonated magnetic graphene oxide (SMGO) (deposited on glassy carbon electrode) acts as a strong cationic exchanger, in which the negatively charged stationary phase electrostatically binds to the positively charged Pb(II) ions and Pb(II) ion exchange by hydrogen ion. The method exhibited a linear range of Pb(II), 1ppb-10ppm using CV. The CV, EIS and SWASV showed the incorporation of SMGO for electrode improvement with specific surface area, electrocatalytic activity and conductivity supported by GO sheets. This showed that enhanced analytical performance due to higher number of active sites, resulting higher ion exchange capacity and binding affinity of SMGO. It is a simple platform to develop novel electrochemical sensor for detecting heavy metals with high performance. Subsequently, regeneration of eco-friendly SMGO and corresponding reference method for quantitative detection and removal analysis of Pb(II) ions will be tested using ion chromatography method. Figure 1

Atomic-level insights into the activation of nitrogen via hydrogen-bond interaction toward nitrogen photofixation

Summary As the activation of N2 molecules is generally regarded as the bottleneck in N2 reduction, it is of significant importance to develop promising strategies to efficiently activate N2 molecules. Herein, we discovered an innovative approach to activate N2 molecules via hydrogen-bond interaction in N2 photofixation. Porous Cu with surface modification of S atoms (3%-S/Cu) exhibited remarkable catalytic activity and stability in N2 photofixation. Further mechanistic studies revealed that surface S atoms directly participated in the catalytic process by accepting and donating H atoms. In addition, the forming S–H bond significantly promoted the activation of N2 molecules via hydrogen-bond interaction, contributing to the enhanced catalytic activity.