How to achieve adequate quenching for DBP analysis in drinking water?

Quenching is an important step to terminate disinfection during preparation of disinfected water samples for the analysis of disinfection byproducts (DBPs). However, an incomplete quenching might result in continued reactions of residual chlorine, whereas an excessive quenching might decompose target DBPs. Therefore, an adequate quenching to achieve simultaneous disinfection termination and DBP preservation is of particular importance. In this study, the two-stage reaction kinetics of chlorine and three commonly used quenching agents (i.e., ascorbic acid, sodium thiosulfate, and sodium sulfite) were determined. Stopping quenching during the first stage prevented interactions of residual chlorine with natural organic matter. Complete quenching was achieved by minimizing the quenching time for ascorbic acid and sodium sulfite, while limiting the quenching time to less than 3 min for sodium thiosulfate. At the optimized quenching times, the molar ratios (MRs) of quenching agent to chlorine were 1.05, 1.10, and 0.75 for ascorbic acid, sodium sulfite, and sodium thiosulfate, respectively. The destructive effects of the three quenching agents on total organic halogen (TOX) followed the rank order of ascorbic acid (33.7-64.8 %) < sodium sulfite (41.6-72.8 %) < sodium thiosulfate (43.3-73.2 %), and the destructive effects on aliphatic DBPs also followed the rank order of ascorbic acid (29.5-44.5 %) < sodium sulfite (34.9-51.9 %) < sodium thiosulfate (46.9-53.2 %). For total organic chlorine (TOCl) and aliphatic DBPs, the quenching behavior itself had more significant destructive effect than the quenching agent type/dose and quenching time, but for total organic bromine (TOBr), the destructive effect caused by quenching agent type/dose and quenching time was more significant. High-dose, long-duration quenching enhanced the reduction of TOX, but had little effect on aliphatic DBPs. Additionally, the three quenching agents reduced the levels of halophenols (except for tribromophenol), while maintained or increased the levels of tribromophenol, halobenzoic/salicylic acids, and halobenzaldehydes/salicylaldehydes. To achieve adequate quenching for overall DBP analysis in chlorinated water samples, it is recommended to use ascorbic acid at a quenching agent-to-chlorine MR of 1.0 for a quenching time of < 0.5 h.

Evolution of chlorinated paraffin and olefin fingerprints in sewage sludge from 1993 to 2020 of a Swiss municipal wastewater treatment plant.

Exposure of humans to chlorinated paraffins (CPs) and chlorinated olefins (COs) can occur via contact with CP-containing plastic materials. Such plastic materials can contain short-chain CPs (SCCPs), which are regulated as persistent organic pollutants (POPs) under the Stockholm Convention since 2017. Municipal wastewater treatment plants (WWTP) collect effluents of thousands of households and their sludge is a marker for CP exposure. We investigated digested sewage sludge collected in the years 1993, 2002, 2007, 2012, and 2020 from a Swiss WWTP serving between 20000 and 23000 inhabitants. A liquid chromatography mass spectrometry (R > 100000) method, in combination with an atmospheric pressure chemical ionization source (LC-APCI-MS), was used to detect mass spectra of CPs and olefinic side products. A R-based automated spectra evaluation routine (RASER) was applied to search for ∼23000 ions whereof ∼6000 ions could be assigned to CPs, chlorinated mono- (COs), di- (CdiOs) and tri-olefins (CtriOs). Up to 230 CP-, 120 CO-, 50 CdiO- and 20 CtriO-homologues could be identified in sludge. Characteristic fingerprints were deduced describing C- and Cl-homologue distributions, chlorine- (nCl) and carbon- (nC) numbers of CPs and COs. In addition, proportions of saturated and unsaturated material were determined together with proportions of different chain length classes including short- (SC), medium- (MC), long- (LC) and very long-chain (vLC) material. A substantial reduction of SCCPs of 84% was observed from 1993 to 2020. Respective levels of MCCPs, LCCPs and vLCCPs decreased by 61, 69 and 58%. These trends confirm that banned SCCPs and non-regulated CPs are present in WWTP sludge and higher-chlorinated SCCPs were replaced by lower chlorinated MCCPs. Combining high-resolution mass spectrometry with a selective and fast data evaluation method can produce characteristic fingerprints of sewage sludge describing the long-term trends in a WWTP catchment area.

Interlaboratory trial of short-chain chlorinated paraffin: comparison of mass fractions and homolog profiles in a simulation environmental sample.

Short-chain chlorinated paraffins (SCCPs) are listed in the Stockholm Convention. Therefore, selecting suitable methods for their accurate quantification is essential. Nowadays, the quality of commercial reagents employed as quantification standards is not guaranteed. As a solution, we adopted an SCCP formulation reference material with known homolog composition ratios as the quantification standard to evaluate the appropriateness of the methods. By mixing the SCCP formulation and interferences, an analytical sample was independently prepared and used as the simulation environmental sample. The homolog compositional profiles of the SCCPs resembled those of the quantification standard and the analytical sample. The mass fractions and the homolog profiles, including the carbon chain length and chlorine homolog profiles, of the SCCPs were reported by 14 different laboratories. For the mass fraction, the results reported by participants were consistent, except for the participants that employed low-resolution gas chromatography (GC). The results generated from liquid chromatography (LC) and GC were slightly different, despite of the similar homolog composition ratios between the quantification standard and the analytical sample. Although there were discreet discrepancies in the overall chlorine homolog profiles, the carbon chain length profiles acquired from GC and LC were similar. The differences depended on the method employed. Additionally, compared with the low-resolution data, the high-resolution data displayed less fluctuation since the effect of the interferences on the analytical sample was reduced because of the mass accuracy of high-resolution instruments. Accordingly, the interlaboratory trial employing the similar homolog compositional profiles of the quantification standard and the analytical sample proved valuable in elucidating the differences among methods, considering equipment, resolution specification, and ionization.

Potential and mechanism of disinfection by-products removal in drinking water by bubbling corona discharge.

Disinfection by-products (DBPs) with significant teratogenic and carcinogenic properties have become a growing concern among the public. As an efficient and environmentally friendly technology, non-thermal plasma offers potential for removing emerging micro-pollutants. In this study, the degradation performance of bubbling corona discharge was evaluated on 24 halogenated alicyclic and aliphatic DBPs present in drinking water at concentrations ranging from ng/L to µg/L. The degradation of DBPs followed pseudo-first-order kinetics with rate constants (kobs) in the descending order of halonitromethanes (HNMs), halogenated benzoquinones (HBQs), haloacetonitriles, trihalomethanes (THMs), haloketones, halogenated aldehydes, and haloacetic acids (HAAs). THMs, HNMs, and HBQs were effectively removed within 5 min under a discharge power of 28 W. Degradation rates achieved by plasma treatment surpass those of other conventional treatment technologies. The required energy consumption was in the range of 5-30 kW·h/m3/order. Furthermore, the study investigated the effects of discharge power, initial concentration, and economic analysis on the degradation of four selected DBPs as representatives of mono-, di- and multi-carbon-containing DBPs, namely chloroform (TCM) and bromoform (TBM), tribromoacetic acid (TBAA), and 2,3,5,6-tetrachloro-1,4-benzoquinone (TetraC-BQ). Reactive radicals in the plasma system were investigated using electron paramagnetic resonance, optical emission spectroscopy, fluorimetry, and radical scavengers. Hydrated electrons and hydroxyl radicals played an important role in the removal of DBPs. The intermediates generated during the degradation of TCM, TBM, TBAA, and TetraC-BQ were identified, and the possible degradation pathways for mono- and binary C-DBPs and HBQs were deduced. The breakdown of HBQs did not produce secondary contamination with aliphatic DBPs. The carbon in DBPs was primarily converted to formic acid, acetic acid, and oxalic acid, and the halogens were mainly converted to halogen ions. Additionally, luminescent bacteria toxicity testing confirmed that plasma treatment could reduce the acute toxicity of water samples. These findings demonstrate the potential of plasma treatment as a post-treatment device at the household level.

Total organic halogen (TOX) in drinking water: Occurrence, correlation analysis, and precursor removal during drinking water treatment.

Total organic halogen (TOX) in drinking water provides a measurement of the overall organic halogenated disinfection by-products (DBPs) formed during disinfection. Yangtze River Delta is one of the regions with the highest population density, the fastest urbanization process, and the most severe water pollution in China. Collecting water samples from full-scale drinking water treatment plants (DWTPs) in this region, this study firstly surveyed TOX occurrence in drinking water. Besides, the correlation of TOX formation potential (TOXFP) and trihalomethane formation potential (THMFP) with general water quality parameters (e.g., dissolved organic carbon [DOC], UV254, and specific ultraviolet absorbance) and the removal efficiencies of TOX precursors by different water treatment processes were also investigated. TOX levels in DWTP effluents (i.e., finished water) ranged from 29 to 165 µg/L (median 67 µg/L), and those in simulated distribution system waters ranged from 101 to 276 µg/L (median 158 µg/L). There were generally higher linear regression coefficient values for raw water (R2 = 0.51-0.88) than for treated water (R2 = 0.33-0.64) in terms of the relationship between DBP formation potentials and general parameters. However, a relatively stronger correlation between THMFP and TOXFP was observed for treated water (R2 = 0.80, p < 0.001) than for raw water (R2 = 0.64, p < 0.001). The overall treatment efficiencies of investigated parameters in DWTPs generally followed the order of UV254 > DOC > TOX precursors > THM precursors. Notably, the overall removal rates of DOC and TOX precursors in summer (averaging 59 % and 54 %, respectively) were obviously higher than those in winter (averaging 39 % and 38 %, respectively), which was assumed to be related to the seasonal variation of bioactivity in sand filter. These results could expand the knowledge of TOX in drinking water, and provide valuable perspectives to water industry and DBP research.

Natural short-lived halogens exert an indirect cooling effect on climate.

Observational evidence shows the ubiquitous presence of ocean-emitted short-lived halogens in the global atmosphere1-3. Natural emissions of these chemical compounds have been anthropogenically amplified since pre-industrial times4-6, while, in addition, anthropogenic short-lived halocarbons are currently being emitted to the atmosphere7,8. Despite their widespread distribution in the atmosphere, the combined impact of these species on Earth's radiative balance remains unknown. Here we show that short-lived halogens exert a substantial indirect cooling effect at present (-0.13 ± 0.03 watts per square metre) that arises from halogen-mediated radiative perturbations of ozone (-0.24 ± 0.02 watts per square metre), compensated by those from methane (+0.09 ± 0.01 watts per square metre), aerosols (+0.03 ± 0.01 watts per square metre) and stratospheric water vapour (+0.011 ± 0.001 watts per square metre). Importantly, this substantial cooling effect has increased since 1750 by -0.05 ± 0.03 watts per square metre (61 per cent), driven by the anthropogenic amplification of natural halogen emissions, and is projected to change further (18-31 per cent by 2100) depending on climate warming projections and socioeconomic development. We conclude that the indirect radiative effect due to short-lived halogens should now be incorporated into climate models to provide a more realistic natural baseline of Earth's climate system.

Optical properties and molecular composition of wintertime atmospheric water-soluble organic carbon in different coastal cities of eastern China.

To evaluate the optical properties and molecular composition of water-soluble organic carbon (WSOC) in the atmosphere of coastal cities, particle samples were collected in Tianjin, Qingdao and Shanghai, three coastal cities in eastern China. Subsequent analysis by ultraviolet visible and fluorescence spectrometer and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry were performed. The results showed that the concentration levels and light absorption ability of WSOC decreased from the north to south cities, ranking as Tianjin > Qingdao > Shanghai. Three major fluorescent components including less­oxygenated humic-like substances (52-60 %), highly­oxygenated humic-like substances (15-31 %) and protein-like substances (17-31 %) were identified in WSOC based on the fluorescence spectroscopy and parallel factor analysis, which might be closely related to anthropogenic emissions and continental sources as well as secondary formation processes. Five subgroups of molecular components were further identified in WSOC, including the predominant CHON compounds (35-43 %), sulfur-containing compounds (i.e., CHONS and CHOS compounds, 24-43 %), CHO compounds (20-26 %) and halogen-containing compounds (1-7 %). Compared to marine air masses influenced samples, WSOC affected by continental air masses exhibited higher light absorption coefficients and generally had a higher degree of aromaticity and unsaturation, as well as contained more molecular formulas of WSOC, especially enriched with sulfur-containing compounds. In contrast, relatively more abundant halogen-containing compounds were identified in the marine air masses influenced samples. Overall, this study provided new insights into the light-absorbing and chemical properties of WSOC in coastal cities, especially under the influences of continental and marine air masses.

Comparative cytotoxicity analyses of disinfection byproducts in drinking water using dimensionless parameter scaling method: Effect of halogen substitution type and number.

Up to date, over 700 disinfection byproducts (DBPs) have been detected and identified in drinking water. It has been recognized that cytotoxicity of DBPs varied significantly among groups. Even within the same group, cytotoxicity of different DBP species was also different due to different halogen substitution types and numbers. However, it is still difficult to quantitatively determine the inter-group cytotoxicity relationships of DBPs under the effect of halogen substitution in different cell lines, especially when a large number of DBP groups and multiple cytotoxicity cell lines are involved. In this study, a powerful dimensionless parameter scaling method was adopted to quantitatively determine the relationship of halogen substitution and the cytotoxicity of various DBP groups in three cell lines (i.e., the human breast carcinoma (MVLN), Chinese hamster ovary (CHO), and human hepatoma (Hep G2) cell cytotoxicity) with no need to consider their absolute values and other influences. By introducing the dimensionless parameters Dx-orn-speciescellline and D¯x-orn-speciescellline, as well as their corresponding linear regression equation coefficients ktypeornumbercellline and k¯typeornumbercellline, the strength and trend of halogen substitution influences on the relative cytotoxic potency could be determined. It was found that the effect of halogen substitution type and number on the cytotoxicity of DBPs followed the same patterns in the three cell lines. The CHO cell cytotoxicity was the most sensitive cell line to evaluate the effect of halogen substitution on the aliphatic DBPs, whereas the MVLN cell cytotoxicity was the most sensitive cell line to evaluate the effect of halogen substitution on the cyclic DBPs. Notably, seven quantitative structure activity relationship (QSAR) models were established, which could not only predict the cytotoxicity data of DBPs, but also help to explain and verify the patterns of halogen substitution effect on cytotoxicity of DBPs.

Clues about wood density and trace-element variability of Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby for bioenergy use.

The interest of biofuel producers in Neotropical species that have high growth rates, slight wood density variability, and elemental composition that does not compromise the environment has increased in recent decades. We investigated the density and chemical characteristics of wood of Schizolobium parahyba var. amazonicum (Huber × Ducke) Barneby as a source for the generation of bioenergy. Apparent radial wood density profiles (X-ray densitometry (XRD)) and the elemental distribution (X-ray fluorescence (XRF)) of Cl, S, K, and Ca in the wood of nine S. parahyba var. amazonicum trees, divided into three diameter classes (I = 15.5, II = 19.5, and III = 23.5 cm) were analyzed. The high heating value (HHV) of the wood samples was determined, and the energy density was estimated by the product of the HHV and the apparent density. Trees that grew better (classes II and III) produced wood with higher density. These trees showed higher concentrations of K and S, and lower concentrations of Ca and Cl. The highest Cl concentrations were observed in classes with smaller diameters. The chlorine levels met the standards for use of this wood as fuel, but the sulfur levels were higher than the threshold recommended by the ISO 17225-3:2021 guidelines, which can limit the use of the species for certain energy uses. The wood of S. parahyba var. amazonicum had interesting characteristics for the production of bioenergy due to its low density, so it can be used in the production of solid biofuels such as pellets and briquettes. Monitoring chlorine and sulfur is important, since during the combustion of biomass they are released into the atmosphere and can negatively contribute to the effects of climate change.

Associations between serum polychlorinated biphenyls, halogen flame retardants, and renal function indexes in residents of an e-waste recycling area.

E-waste handling activities release large quantities of polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) into the surrounding area, creating a high exposure risk for local residents. However, the possibility of PCBs and HFRs exposure contributing to renal injury has not been extensively studied. To fill this knowledge gap, we conducted an epidemiological analysis of adolescents and adults recruited from an e-waste recycling area and a control area. Some PCBs and HFRs compounds were statistically significantly associated with the levels of ß2-microglobulin (ß2-MG), blood urea nitrogen (BUN), serum creatinine (SCr), and uric acid, with thyroid hormone-related genes found to partly mediate these associations. The interactions of PCBs and HFRs with metals also influenced renal function indexes. Exposure to high concentrations of PCBs and HFRs resulted in higher levels of ß2-MG and lower levels of BUN and SCr in the exposed group. As indicated by the elevated ß2-MG levels, high exposure to PCBs and HFRs may increase the risk of early renal injury for adolescents. These findings help to clarify the impacts of PCBs and HFRs on renal function and highlight the need to protect the health of residents in regions impacted by e-waste handling activities.

Hexagonal boron nitride nanosheets based magnetic solid phase extraction for the extraction of phenoxy carboxylic acid herbicides from water samples followed by high-performance liquid chromatography-tandem mass spectrometry.

High-efficiency caption of pesticide residue is of vital significance for environmental safety monitoring. Herein, a hexagonal boron nitride nanosheets-based magnetic composite (Fe3O4@h-BNNSs) was synthesized and applied for the magnetic solid phase extraction (MSPE) of five phenoxy carboxylic acid (PCA) herbicides from water samples. Based on the π-π interaction, hydrogen bond and halogen bond, the Fe3O4@h-BNNSs composite showed excellent adsorption ability towards PCA herbicides. Several main variables that influenced the extraction efficiencies of PCA herbicides were investigated and optimized via single-factor experiment. Combining this Fe3O4@h-BNNSs composite-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of PCA herbicides was developed. Under the most favorable conditions, the proposed method displayed good linear ranges (20.0-10000.0 ng L-1), low limits of detection (5.6-10.3 ng L-1), satisfactory precisions (1.1-6.8%) and recoveries (76.6-107.2%). Overall, the present work can be a versatile and worthy utility for the determination of PCA herbicides from different water samples.

Revisiting the effect of boiling on halogenated disinfection byproducts, total organic halogen, and cytotoxicity in simulated tap water.

Boiling is a widely adopted household tap water treatment method because of its ability to inactivate chlorine-resistant pathogenic bacteria, and to reduce certain groups of disinfection byproducts (DBPs). From a more comprehensive point of view, this study revisited the effect of boiling on four groups of 17 aliphatic DBPs and six groups of 44 aromatic DBPs in both simulated chlorinated and chloraminated tap water samples, with a special focus on the changes of total organic halogen (TOX) and cytotoxicity. Results showed that the concentrations of aliphatic DBPs substantially decreased during boiling via volatilization (trihalomethanes and chloral hydrate) and hydrolysis (haloacetamides) in chlorinated and chloraminated tap water samples. The concentrations of aromatic DBPs during boiling generally followed an increasing trend due to decarboxylation of polycarboxylic precursors in chlorinated tap water samples, and showed a first increasing and then decreasing trend in chloraminated tap water samples. A sharp decreasing of TOX occurred in the heating process of tap water samples from room temperature to 100 °C, and a relatively gentle decreasing was kept in the prolonged boiling process till 5 min. The most abundant DBP group in the tap water samples without boiling was trihalomethanes, and was replaced by haloacetic acids with boiling for 5 min. Continuous boiling for 5 min substantially reduced the cytotoxicity of chlorinated and chloraminated water samples by 52.6% and 21.3%, respectively. Reduction of cytotoxicity matched well with the reduction of TOCl (r = 0.907, P < 0.01), TOBr (r = 0.885, P < 0.01) and TOX (r = 0.905, P < 0.01), suggesting that the cytotoxicity reduction during boiling was mainly ascribed to the reduction of halogenated DBPs. Therefore, boiling of tap water to 100 °C was strongly recommended to reduce the potential health risks induced by tap water ingestion.

Low-Cost Potentiometric Sensor for Chloride Measurement in Continuous Industrial Process Control.

Recently, the new updates in legislation about drinking water control and human health have increased the demand for novel electrochemical low-cost sensors, such as potentiometric ones. Nowadays, the determination of chloride ion in aqueous solutions has attracted great attention in several fields, from industrial processes to drinking water control. Indeed, chloride plays a crucial role in corrosion, also influencing the final taste of beverages, especially coffee. The main goal is to obtain devices suitable for continuous and real-time analysis. For these reasons, we investigated the possibility to develop an easy, low-cost potentiometric chloride sensor, able to perform analysis in aqueous mediums for long immersion time and reducing the need of periodic calibration. We realized a chloride ion selective electrode made of Ag/AgCl sintered pellet and we tested its response in model solutions compatible with drinking water. The sensor was able to produce a stable, reproducible, and accurate quantification of chloride in 900 s, without the need for a preliminary calibration test. This opens the route to potential applications of this sensor in continuous, in situ, and real time measurement of chloride ions in industrial processes, with a reduced need for periodic maintenance.

Occurrence and fate of Adsorbable Organic Halogens (AOX) in two WWTPs from Romania.

Absorbable organic halogens (AOX) are a global parameter which refers to a group of chemical compounds that contain one or more chlorine, bromine or iodine atoms in their molecule and can easily adsorb on activated carbon. The global concern related to the occurrence of the AOX compounds in the environment is due to their toxic and mutagenic effects on aquatic organisms and their potential role as inhibitors of microorganism growth, even at AOX low concentrations. The purpose of this study was to analyze the presence, occurrence and composition of absorbable organic halogens in wastewater and sewage sludge. In addition, their genotoxicity effect on the environment was tested on a bacterial biological model. Daily mass loading, mass emission and fate of AOX parameter were investigated in two wastewater treatment plants (wastewater and sewage sludge samples) from Romania, Galati and Iasi. Their AOX daily mass loadings (151 and 55.4 g/day/1000people) and mass emissions into the environment (47.8 and 23.5 g/day/1000 people) for both locations were correlated with the concentration level of volatile organic compounds, chlorophenols, organochlorine pesticides and polychlorinated biphenyls from both wastewater and sewage sludge, respectively. Concentration levels of detected halogenated organic compounds (regulated by current standards) accounted only for a small percentage (3.70-14.5%) from the total AOX amount. An exception was observed in the case of dehydrated sludge samples where the identified compounds accounted for 80% of the AOX content from Iasi WWTP and 53% for Galati. Evaluating the genotoxic activity of AOX in sludge samples showed that genotoxicity was not induced up to 100 µg/mL dehydrated sludge.

Vortex-assisted matrix solid-phase dispersion: An eco-friendly alternative for the determination of halogens in edible seaweed.

Edible seaweed has been widely consumed around the world through oriental cuisine and it is important to monitor the levels of some elements, especially halogens. This study proposes, for the first time, the development of an analytical method using the vortex-assisted matrix solid-phase dispersion (VA-MSPD) combined with alkaline extraction of halogens (F, Cl, Br, and I) in edible seaweed for further determination by ion chromatography. The proposed method was evaluated using edible seaweed of the Nori (Porphyra spp.) type and applied to samples of the Wakame (Undaria pinnatifida), Kombu (Laminaria ochroleuca), and Hijiki (Hizikia fusiformis) types. Important VA-MSPD parameters were investigated and using 0.1 g sample, 1 g sea sand as solid support, 50 mmol L-1 (NH4)2CO3 as extraction solution, and 5 min of maceration, higher extraction efficiencies were obtained. The method was linear within the evaluated range (R2 > 0.99) for all elements and no matrix effect was observed. The detection limits of the method were 27, 26, 19, and 28 µg g-1 for F, Cl, Br, and I, respectively. The accuracy was evaluated by a recovery test (ranging from 92 to 108%) and analysis of certified reference materials for apple leaves (NIST 1515) and peach leaves (NIST 1547), which had a good agreement (ranging from 97 to 101%) with the certified values. Comparing the results with those obtained by inductively coupled plasma-mass spectrometry after microwave-induced combustion, no significant difference was found between the results, and the relative standard deviations were lower than 12%. The proposed method proved to be efficient for the determination of halogens in different algae species, showing advantages such as simplicity and low cost, combined to the use of a material from renewable sources (sea sand) as a solid support, contributing to the principles of Green Analytical Chemistry.

Impact of abiotic and biogeochemical processes on halogen concentrations (Cl, Br, F, I) in mineral soil along a climatic gradient.

In contrast to earlier ideas that halogens behave inertly in soil, extensive biogeochemical cycling of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I) has been shown for temperate forests. To further advance our understanding of halogen behaviour in soil beyond humid temperate forests, we sampled soil profiles in protected areas along the Chilean Coastal Cordillera, representing a pronounced climatic gradient spanning from arid to humid. Halogen concentrations in soil were analysed by combustion ion chromatography. Highest average total halogen concentrations occurred at the arid site (Cl, F: 4270 and 897 mg kg-1) as well as the humid end of the climatic gradient (Br, I: 42.6 and 9.8 mg kg-1). Vertical distribution patterns of halogens were most pronounced at the humid end of the gradient and became less distinct under drier climate. The climatic gradient demonstrates the important role of biotic processes (e.g. the halogenation of organic matter) on the retention of halogens in the soil. However, this climate-specific role may be overridden by mainly abiotic processes within a given climate zone (e.g. weathering, leaching, sorption to secondary soil minerals, evaporative enrichment), resulting in vertical relocation of halogens in the soil. Since some of these processes oppose each other, complex interactions and depth distributions of F, Cl, Br and I occur in the soil. In summary, our findings provide new insights into the fate of halogens in mineral soil of different climatic zones, which is important, for example, when radiohalogens are deposited on a large scale after nuclear accidents.

Microwave-induced self-ignition: An efficient approach for high purity graphite digestion and multitechnique halogen determination.

In this work, high purity graphite, a high chemically stable material, was effectively digested using a single method allowing compatible solutions for the further multitechnique determination of halogens by: ion chromatography (F and Cl), inductively coupled plasma mass spectrometry (Cl, Br and I) and by ion selective electrode (only for F). The recent system using microwave-induced self-ignition (MISI) is based on the strong interaction between microwave radiation and graphite in a closed system pressurized with oxygen (Maxwell-Wagner effect). Carbon-based materials present intense and specific interfacial polarization when exposed to microwave electromagnetic field resulting in a fast heating rate. This effect associated to a pressurized oxygen system, provides a quick self-ignition of carbon-based materials and consequent combustion/digestion of organic matrices. Under optimized conditions, sample masses up to 600 mg were fully digested in a quartz vessel under 20 bar of oxygen pressure and using just a diluted solution (100 mmol L-1 NH4OH) for the quantitative absorption of all the analytes. MISI method was validated, and the accuracy (better than 94%) was evaluated by comparison of results obtained by pyrohydrolysis for two coal certified reference materials as well as with subsequent analytes determination by the three techniques: IC, ICP-MS and ISE. It is important to point out that no filter paper disks, electrical connections or other ignition aids are required as in the case of previous or classical combustion methods. Moreover, just a diluted absorbing solution was used resulting in negligible blanks and relatively low limits of detection. The digestion efficiency was higher than 99%, making the proposed method a suitable and powerful alternative for the quasi complete digestion of graphite and determination of halogens virtually free of interferences.

How Much of the Total Organic Halogen and Developmental Toxicity of Chlorinated Drinking Water Might Be Attributed to Aromatic Halogenated DBPs?

Although >700 disinfection byproducts (DBPs) have been identified, >50% of the total organic halogen (TOX) in drinking water chlorination is unknown, and the DBPs responsible for the chlorination-associated health risks remain largely unclear. Recent studies have revealed numerous aromatic halo-DBPs, which generally present substantially higher developmental toxicity than aliphatic halo-DBPs. This raises a fascinating and important question: how much of the TOX and developmental toxicity of chlorinated drinking water can be attributed to aromatic halo-DBPs? In this study, an effective approach with ultraperformance liquid chromatography was developed to separate the DBP mixture (from chlorination of bromide-rich raw water) into aliphatic and aromatic fractions, which were then characterized for their TOX and developmental toxicity. For chlorine contact times of 0.25-72 h, aromatic fractions accounted for 49-67% of the TOX in the obtained aliphatic and aromatic fractions, which were equivalent to 26-36% of the TOX in the original chlorinated water samples. Aromatic halo-DBP fractions were more developmentally toxic than the corresponding aliphatic fractions, and the overall developmental toxicity of chlorinated water samples was dominated by aromatic halo-DBP fractions. This might be explained by the considerably higher potentials of aromatic halo-DBPs to bioconcentrate and then generate reactive oxygen species in the organism.

Determination of Cl, Br and I in granola: Development of an accurate analytical method using ICP-MS.

Microwave-induced combustion (MIC) system for further Cl, Br, and I determination in granola by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. A high sample mass of granola was pressed as pellets and inserted into the proposed MIC system. Water and NH4OH were evaluated as absorbing solutions. The accuracy was estimated by the analysis of two certified reference materials and also by spike recoveries. Using the optimized conditions (zirconium ball milling, 1 g of granola and 6 mL of 50 mmol L-1NH4OH), the agreement with the certified values ranged from 94 to 98% and recoveries higher than 95% were obtained. Low carbon concentration in digests (<25 mg L-1) was achieved, minimizing interferences by ICP-MS. Blanks were negligible and only diluted solutions were required. The concentration in samples ranged from 322 to 896, 0.618 to 0.980 and < 0.002 to 0.181 µg g-1 for Cl, Br and I, respectively.

Determination of halogens and sulfur in honey: a green analytical method using a single analysis.

The halogen determination is important in view of their biological and environmental roles, but their determination has still been considered a challenge, especially at low concentrations. Therefore, a method for honey decomposition using microwave-induced combustion (MIC) combined with ion chromatography and conductimetric detection (for Cl, F, and S determination) or mass detection (for Br and I determination) (IC-CD-MS) is proposed. Trueness was evaluated by adding reference materials (RMs) or a standard solution in the sample. By using 50 mmol L-1 NH4OH as the absorbing solution, recoveries for all analytes were between 94 and 103%, in both tests. Moreover, no statistical difference (t test, confidence level of 95%) was observed for the results obtained by IC in comparison with those obtained by inductively coupled plasma optical emission spectroscopy (Cl and S) and by inductively coupled plasma mass spectrometry (Br and I). Finally, the proposed method was applied to 19 honey samples from different origins. The concentrations ranged from < 0.45 to 2.39 mg kg-1 (Br), 21.8 to 671 mg kg-1 (Cl), and 11 to 154 mg kg-1 (S), while the F and I concentrations were below that their quantification limits (LOQs) in all analyzed samples. The LOQs for Br, Cl, F, I, and S were 0.45, 21, 3.7, 0.077, and 8.7 mg kg-1, respectively. The MIC method provided a compatible solution to IC for the halogen and S determination in honey by a single analysis. Graphical abstract.