Efficiency of ozonation and sulfate radical - AOP for removal of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates.

This study investigated the elimination of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates during ozonation and UV/persulfate processes. Second-order rate constants for the reactions of candesartan, irbesartan, methyl-benzotriazole, and chloro­benzotriazole with sulfate radical (SO4·-) were determined for the first time. Experiments were conducted in buffered pure water, in buffered water added with the matrix substituents chloride, carbonate, NOM, and reverse osmosis concentrate with spiked micropollutants (MP). UV/persulfate eliminated all MP to a higher extent than ozonation in RO concentrates due to the higher yield of oxidative species and photolytic degradation. Compounds with electron-rich moieties such as carbamazepine, diclofenac, metoprolol, and sulfamethoxazole were completely eliminated with small ozone doses (< 0.5 mg O3 / mg DOC) and with a small fluence (< 5000 J m-2) in UV/persulfate processes. Photosensitive compounds with high reactivity towards hydroxyl radicals (·OH) and SO4·- like the x-ray contrast media Iopamidol, Iohexol, and Amidotrizoic acid were successfully eliminated with a reasonable fluence in UV/persulfate, whereas these compounds persist in ozonation at common ozone dosages. However, much higher fluences and ozone dosages were required for the least reactive compounds like the class of benzotriazoles. Comparing the application of both oxidative processes to the RO concentrate, ozonation has the disadvantage of forming bromate. The energy input of both processes strongly depends on the target compounds to be eliminated. For the elimination of compounds such as sulfamethoxazole, ozonation is a feasible technique, whereas UV/persulfate is better suited for the elimination of recalcitrant compounds such as x-ray contrast media. In general, oxidative process treatment of RO concentrate could be applied to partly abate micropollutants before discharge.

Evaluation of GC-EI&CI-TOFMS for Nontarget Analysis of Industrial Wastewater Using Hydrophilic-Lipophilic-Balanced SPME.

The evaluation of nontarget analysis (NTA) techniques for the monitoring of wastewater is important as wastewater is an anthropogenic pollution source for aquatic ecosystems and a threat to human and environmental health. This study presents the proof-of-concept NTA of industrial wastewater samples. A prototype hydrophilic-lipophilic-balanced (HLB) SPME and gas chromatography interfaced with time-of-flight high-resolution mass spectrometry (GC-TOFMS) with electron ionization (EI) and chemical ionization (CI) in parallel are employed. The HLB-SPME consists of a poly(divinylbenzene-co-N-vinylpyrrolidone) structure, allowing the extraction of hydrophilic as well as lipophilic substances. As the combination of parallel CI and EI data provides a comprehensive data set as a unique feature, this study is strongly focused on the compound identification procedure and confidence reporting of exemplary substances. Furthermore, the use of three different CI reagent ions, including [N2H]+/[N4H]+, [H3O]+, and [NH4]+, enables a broad range of analytes to be ionized in terms of selectivity and softness. The complementary information provided by EI and CI data allows a level 3 identification or higher in 69% of cases. The polarity coverage based on the physicochemical properties of the analytes (such as volatility, water solubility, hydrophilicity, and lipophilicity) was visualized by using Henry's law and octanol-water partitioning constants. In conclusion, the presented approach is shown to be valuable for water analysis and allows enhanced and accelerated compound identification compared to utilizing only one type of ionization.

qPeaks: A Linear Regression-Based Asymmetric Peak Model for Parameter-Free Automatized Detection and Characterization of Chromatographic Peaks in Non-Target Screening Data.

We present qPeaks (quality peaks), a novel, user-parameter-free algorithm for peak detection and peak characterization applicable to chromatographic data. The algorithm is based on a linearizable regression model that analyzes asymmetric peaks and estimates the specific uncertainties associated with the peak regression parameters. The uncertainties of the parameters are used to derive a data quality score DQSpeak, rendering low reliability results more transparent during processing and allowing for the prioritization of generated features. High DQSpeak chromatographic peaks have a lower chance of being classified as false-positive and show higher repeatability over multiple measurements. The high efficiency of the algorithm makes it particularly useful for application within processing routines of nontarget screening through chromatography coupled with high-resolution mass spectrometry. qPeaks is integrated into the qAlgorithms nontarget screening processing toolbox and appends a parameter-free chromatographic peak detection and characterization step to it. With qAlgorithms, now high-resolution mass spectra are centroided using the qCentroids algorithms, centroids are clustered to form extracted ion chromatograms (EICs) with the qBinning algorithm, and chromatographic peaks are found on the generated EICs with qPeaks. However, all tools from qAlgorithms can also be used independently.

A review of endocrine disrupting chemicals migration from food contact materials into beverages.

A significant and pressing issue revolves around the potential human exposure to endocrine disrupting chemicals (EDCs), which pose a substantial risk primarily through contaminated beverages. However, a comprehensive review for comparison of the migration rates of EDCs into these matrixes is currently lacking. This study reviews the beverages contamination with EDCs, including phthalates (PAEs), bisphenol A (BPA), hormone-like compounds, elements, and other organic EDCs. Also, the EDCs migration into milk and other dairy products, coffee, tea, and cold beverages related to their release from contact materials, preparation components, and storage conditions are briefly summarized. The data illustrates that besides the contamination of raw materials, the presence of EDCs associated with the type of food contact materials (FCMs)and their migration rate is increased with acidity, temperature, and storage time. The highest concentration of PAEs was detected from plastic and synthetic polymer films, while BPA strongly leaches from epoxy resins and canned metal. Furthermore, the presence of elements with endocrine disrupting characteristics was confirmed in cold beverages, soft drinks, hot drink and milk. Moreover, hormone-like compounds have been found to be released from coffee preparation components. Despite the few data about the migration rate of other EDCs including UV-stabilizers, surfactants, and antibacterial compounds into beverages, their presence was reported into milk, coffee, and different beverages, especially in packed samples. Studies on the EDCs leaching have primarily focused on PAEs and BPA, while other compounds require further investigation. Regardless, the possible risk that EDCs pose to humans through beverage consumption cannot be overlooked.

Elucidating the inhibitory effects of natural organic matter on the photodegradation of organic micropollutants: Atrazine as a probe compound.

Natural organic matter (NOM) is a complex mixture of heterogeneous compounds with varying functional groups and molecular sizes. Understanding the impact of NOM on the generation of photochemically produced reactive intermediates (PPRIs) and their potential inhibitory effects on photolysis has remained challenging due to the variations in the reactivities and concentrations of these functional groups. To address this gap, tannic acid (TA), gallic acid (GA), catechin (CAT), and tryptophan (Trp), were chosen as potential substitutes for NOM. Their effects on the photochemical transformation process were evaluated and compared with the widely used Suwannee River NOM (SRNOM). Atrazine (ATZ) was selected as a probe organic micropollutant (OMP). In this investigation, a significantly higher concentration of HO• was observed compared to O21, and the triplet excited state ( NOM*3). The findings suggest that the substituted phenols, particularly those with carboxylate-substitutions, played a substantial role in HO• formation, while electron-rich moieties acted as antioxidants, consuming NOM*3. Hydroxyl, carboxylic, and amino acid were the active groups for O21 formation. However, the inhibitory effects induced by the NOM surrogates were significant and mainly attributed to the direct photolysis inhibition caused by the inner filter effect. The scope of this work was further extended to include SRNOM, where similar trends with less pronounced formation of PPRIs and inner filter effects were observed. Therefore, this study sheds some light on the role of the functional groups in NOM during photochemical transformations of OMPs, thereby deepening our understanding of their fate in aqueous systems.

Non-target screening in water analysis: recent trends of data evaluation, quality assurance, and their future perspectives.

This trend article provides an overview of recent advancements in Non-Target Screening (NTS) for water quality assessment, focusing on new methods in data evaluation, qualification, quantification, and quality assurance (QA/QC). It highlights the evolution in NTS data processing, where open-source platforms address challenges in result comparability and data complexity. Advanced chemometrics and machine learning (ML) are pivotal for trend identification and correlation analysis, with a growing emphasis on automated workflows and robust classification models. The article also discusses the rigorous QA/QC measures essential in NTS, such as internal standards, batch effect monitoring, and matrix effect assessment. It examines the progress in quantitative NTS (qNTS), noting advancements in ionization efficiency-based quantification and predictive modeling despite challenges in sample variability and analytical standards. Selected studies illustrate NTS's role in water analysis, combining high-resolution mass spectrometry with chromatographic techniques for enhanced chemical exposure assessment. The article addresses chemical identification and prioritization challenges, highlighting the integration of database searches and computational tools for efficiency. Finally, the article outlines the future research needs in NTS, including establishing comprehensive guidelines, improving QA/QC measures, and reporting results. It underscores the potential to integrate multivariate chemometrics, AI/ML tools, and multi-way methods into NTS workflows and combine various data sources to understand ecosystem health and protection comprehensively.

Analysis of aromatic amines in human urine using comprehensive multi-dimensional gas chromatography-mass spectrometry (GCxGC-MS).

Several aromatic amines (AA) are classified as human carcinogens, and tobacco smoke is one of the main sources of exposure. Once in the human body, they undergo different metabolic pathways which lead to either their excretion or ultimately to the formation of DNA and protein adducts. The aim of this study was to investigate AA in 68 urine samples (aged 29-79, 47% female), including 10 smokers (S), 28 past-smokers (PS) and 30 never-smokers (NS), and to study if there was a relation between the smoking status and the amount of the AA present. GCxGC-MS was used to analyze AA in complex urine samples due to its high peak capacity and the fact that it provides two sets of retention times and structural information, which facilitates the separation and identification of the target analytes. First, a qualitative comparison of an example set of a NS, PS and S sample was carried out, in which 38, 45 and 46 AA, respectively, could be tentatively identified. Afterwards, seven AA were successfully quantified in the samples. Of these, 4-ethylaniline (4EA, p = 0.015), 2,4,6-trimethylaniline (2,4,6TMA, p = 0.030), 2-naphthylamine (2NA, p = 0.014) and the sum of 2,4- and 2,6-dimethylaniline (DMA, p = 0.017) were found in significantly different (α = 0.05) concentrations for the S, 29 ± 14, 87 ± 49, 41 ± 26, and 105 ± 57 ng/L respectively, compared to the NS, 15 ± 6, 42 ± 30, 16 ± 6, and 48 ± 28 ng/L. And 2,4,6TMA (39 ± 26, p = 0.022), 2NA (18 ± 9, p = 0.025) and DMA (53 ± 46, p = 0.030), were also found at significantly higher concentrations in samples from S when compared to PS. However, some samples had AA concentrations outside the calibration curve and could not be taken into account, especially for 2-methylaniline (2MA). Therefore, all the samples were evaluated using a quantitative screening approach, by which the intensities of 4EA (p = 0.019), 2,4,6TMA (p = 0.048), 2NA (p = 0.016), DMA (p = 0.019) and 2MA (p = 0.006) in S were found to be significantly (α = 0.05) higher than in the NS, and 2MA (p = 0.019) and 4EA (p = 0.023) in S were found to be significantly higher than in the PS. An association between the smoking status and the amount of certain AA present could therefore be found. This information could be used to study the relation between the smoking status, the amount of AA present, and smoking related diseases like bladder cancer.

Enhanced efficiency of MS/MS all-ion fragmentation for non-targeted analysis of trace contaminants in surface water using multivariate curve resolution and data fusion.

Data-independent acquisition-all-ion fragmentation (DIA-AIF) mode of mass spectrometry can facilitate wide-scope non-target analysis of contaminants in surface water due to comprehensive spectral identification. However, because of the complexity of the resulting MS2 AIF spectra, identifying unknown pollutants remains a significant challenge, with a significant bottleneck in translating non-targeted chemical signatures into environmental impacts. The present study proposes to process fused MS1 and MS2 data sets obtained from LC-HRMS/MS measurements in non-targeted AIF workflows on surface water samples using multivariate curve resolution-alternating least squares (MCR-ALS). This enables straightforward assignment between precursor ions obtained from resolved MS1 spectra and their corresponding MS2 spectra. The method was evaluated for two sets of tap water and surface water contaminated with 14 target chemicals as a proof of concept. The data set of surface water samples consisting of 3506 MS1 and 2170 MS2 AIF mass spectral features was reduced to 81 components via a fused MS1-MS2 MCR model that describes at least 98.8% of the data. Each component summarizes the distinct chromatographic elution of components together with their corresponding MS1 and MS2 spectra. MS2 spectral similarity of more than 82% was obtained for most target chemicals. This highlights the potential of this method for unraveling the composition of MS/MS complex data in a water environment. Ultimately, the developed approach was applied to the retrospective non-target analysis of an independent set of surface water samples.

Development of a column switching for direct online enrichment and separation of polar and nonpolar analytes from aqueous matrices.

Trace substances in surface waters may threaten health and pose a risk for the aquatic environment. Moreover, separation and detection by instrumental analysis is challenging due to the low concentration and the wide range of polarities. Separation of polar and nonpolar analytes can be achieved by using stationary phases with different selectivity. Lower limits of detection of trace substances can be obtained by offline enrichment on solid phase materials. However, these practices require substantial effort and are time consuming and costly. Therefore, in this study, a column switching was developed to enrich and separate both polar and nonpolar analytes by an on-column large volume injection of aqueous samples. The column switching can significantly reduce the effort and time for analyzing trace substances without compromising on separation and detection. A reversed phase (RP) column is used to trap the nonpolar analytes. The polar analytes are enriched on a porous graphitized carbon column (PGC) coupled serially behind the RP column. A novel valve switching system is implemented to enable elution of the nonpolar analytes from the RP column and, subsequently, elution of polar analytes from the PGC column and separation on a hydrophilic interaction liquid chromatography (HILIC) column. To enable separation of polar analytes dissolved in an aqueous matrix by HILIC, the water plug that is flushed from the PGC column is diluted by dosing organic solvent directly upstream of the HILIC column. The developed method was tested by applying target analysis and non-target screening, highlighting the advantage to effectively separate and detect both polar and nonpolar compounds in a single chromatographic run. In the target analysis, the analytes, with a logD at pH 3 ranging from -2.8 to + 4.5, could be enriched and separated. Besides the 965 features in the RP phase, 572 features from real wastewater were observed in the HILIC phase which would otherwise elute in the void time in conventional one-dimensional RP methods.

Ozonation products of purine derivatives, the basic structures of antiviral micropollutants.

Purine and its nucleobases adenine and guanine are the basic structures of a large group of antiviral agents such as acyclovir and penciclovir. Hence, their ozonation is of interest with regard to wastewater treatment due to the formation of products that could affect the aquatic environment. In this study, the transformation products of the mentioned substances are investigated under different defined reaction conditions in order to gain insight into the ozonation characteristics of this compound class. Results show that examining related molecules significantly improves product screening by compiling known products and analogues leading to comprehensive candidate lists, for the purines with a total number of >120 candidates (including possible duplicates for several purines) of which 49 were detected for the derivatives studied. One product, cyanuric acid, which was previously postulated for adenine, was tentatively confirmed and quantified for the first time for the reaction of purine and adenine with ozone. In addition, two prioritisation approaches are presented to identify the major products that are either formed under specific reaction conditions or are potentially relevant for structurally related pollutants. First, principal component analysis allowed the prioritisation of the products formed according to reaction conditions. In the analysis of guanine and the two antivirals, this approach showed that at neutral and basic pH the 2-imino-5-oxoimidazoline products dominated while at acidic pH either analogues of 5-amino-2,4-imidazolidinedione or 2,4-diamino-1,3-oxazol-5-(2H)-one were abundant. A second approach prioritising common products in the ozonation of all three basic structures revealed the formation of two products that had not been reported before: C4H8O3 and C3H2N2O3, presumably oxalylurea. Both molecules or their analogues may also be formed from related micropollutants. Overall, examining basic structures and exemplary micropollutants in combination was shown to be a worthwhile approach to gain knowledge on the ozonation of a whole range of compounds.

Elucidating nicotine transfer into water environments via cigarette butt remaining parts.

Nicotine, the main alkaloid in tobacco, enters water environments through discarded cigarette butts (CBs), possibly causing detrimental effects. However, there is no comprehensive investigation on the long-term leaching of nicotine from the different CBs parts. Therefore, in the present study, the ecological risk and the leachate levels of nicotine from different CBs parts were investigated. Freshly smoked CBs, aged CBs collected from streets, remaining tobacco and ash of freshly smoked CBs, and filter plus paper of freshly smoked CBs were evaluated for the leachate experiments. The order of nicotine leachate from different types of CBs and parts investigated were as remaining tobacco plus ash of freshly smoked CBs > freshly smoked CBs > aged CBs > filter plus paper of freshly smoked CBs with the ranges of 5.73-17.34, 0.36-8.6, 0.31-4.12, and 0.17-2.79 mg of nicotine per g of CB or remaining parts (mg g-1), respectively. The ecological risk assessment revealed that nicotine leachates from all the CBs types or their remaining parts could be highly hazardous to fish, cladocerans, algae, and Daphnia magna. Based on the mean leachate levels of nicotine via freshly smoked CBs at exposure times of 1 min to 1 month and the estimated number of littered CBs every year on a worldwide scale, freshly smoked CBs may release 380-7065 tons of nicotine into water environments.

First report on BTEX leaching from waterpipe tobacco wastes (WTWs) into aquatic environment.

Waterpipe tobacco wastes (WTWs) may contain considerable levels of hazardous contaminants such as BTEX (benzene, toluene, ethylbenzene, o-xylene, and m/p-xylene). However, no research has been carried out on BTEX levels in WTWs and the release of these pollutants into the water environment. This research examined the levels of BTEX in WTWs of flavored/local tobacco and also the release rate of these toxins into three kinds of water, including seawater (SW), tap water (TW), and distilled water (DW) with different leaching times (15, 30 min, 1.2, 4, 8 h, and 1, 2, and 4 days). The mean contents of BTEX in WTW samples of Al-Mahmoud, Al-Fakher, Mazaya, Al-Ayan brands, and local tobacco samples were 17.0 ± 4.14, 19.1 ± 4.65, 19.6 ± 4.19, 18.8 ± 4.14, and 3.16 ± 0.63 µg/kg, respectively. The mean BTEX levels in flavored tobacco samples were considerably greater than that of local tobacco (p < 0.05). The WTWs leaching experiments showed that the levels of BTEX ranged from 5.26 to 6.12, 5.02-5.60, and 3.83-5.46 µg/L in DW, TW, and SW, respectively. All target compounds were found for all exposure times in DW, TW, and SW samples. After adding sodium azide as an antibacterial agent to water samples (simulating biodegradation processes), higher levels of BTEX compounds were detected in SW. Further research is needed to address the potential environmental hazards due to WTWs leaching into aquatic environments.

Isotope-labeling in situ derivatization and HS-SPME arrow GC-MS/MS for simultaneous determination of fatty acids and fatty acid methyl esters in aqueous matrices.

Fatty acids (FAs) and fatty acid methyl esters (FAMEs) co-occur in many samples, and analysis of both substance classes is frequently of high interest. To this end, this study introduces the first method for simultaneous determination of FAs and FAMEs including fully automated solvent-free solid-phase microextraction (SPME) arrow headspace extraction combined with isotope-labeling in situ FA derivatization with deuterated methanol (CD3OD). By using the chromatographic isotope effect (ΔRt = 0.03 min) and the + 3 m/z mass shift, FAs can be selectively differentiated from the FAMEs during gas chromatography tandem-mass spectrometry (GC-MS/MS) operated in the multiple reaction monitoring (MRM) aquisition mode. Additionally, an approach is presented to predict the retention times of deuterated compounds. Optimization of the derivatization conditions was accomplished by design of experiments and found to be 20 min, 50 °C, 4 v/v% CD3OD, and pH 2.1. During method validation, FAs and FAMEs were calibrated in different concentration ranges by standard addition in five real matrices and ultrapure water leading to good linearities and method detection limits for FAs ranging from 1-30 µg L-1 and for FAMEs from 0.003-0.72 µg L-1. FAs and FAMEs were detected in real samples from surface water, wastewater treatment plant effluent, and three different bioreactor samples and could be quantified in concentrations ranging from 2-1056 µg L-1 for FAs and 0.01-14 µg L-1 for FAMEs.

Exploring the efficacy of metabarcoding and non-target screening for detecting treated wastewater.

Wastewater treatment processes can eliminate many pollutants, yet remainder pollutants contain organic compounds and microorganisms released into ecosystems. These remainder pollutants have the potential to adversely impact downstream ecosystem processes, but their presence is currently not being monitored. This study was set out with the aim of investigating the effectiveness and sensitivity of non-target screening of chemical compounds, 18S V9 rRNA gene, and full-length 16S rRNA gene metabarcoding techniques for detecting treated wastewater in receiving waters. We aimed at assessing the impact of introducing 33 % treated wastewater into a triplicated large-scale mesocosm setup during a 10-day exposure period. Discharge of treated wastewater significantly altered the chemical signature as well as the microeukaryotic and prokaryotic diversity of the mesocosms. Non-target screening, 18S V9 rRNA gene, and full-length 16S rRNA gene metabarcoding detected these changes with significant covariation of the detected pattern between methods. The 18S V9 rRNA gene metabarcoding exhibited superior sensitivity immediately following the introduction of treated wastewater and remained one of the top-performing methods throughout the study. Full-length 16S rRNA gene metabarcoding demonstrated sensitivity only in the initial hour, but became insignificant thereafter. The non-target screening approach was effective throughout the experiment and in contrast to the metabarcoding methods the signal to noise ratio remained similar during the experiment resulting in an increasing relative strength of this method. Based on our findings, we conclude that all methods employed for monitoring environmental disturbances from various sources are suitable. The distinguishing factor of these methods is their ability to detect unknown pollutants and organisms, which sets them apart from previously utilized approaches and allows for a more comprehensive perspective. Given their diverse strengths, particularly in terms of temporal resolution, these methods are best suited as complementary approaches.

qBinning: Data Quality-Based Algorithm for Automized Ion Chromatogram Extraction from High-Resolution Mass Spectrometry.

Due to the complexity and volume of data generated through non-target screening (NTS) using chromatographic couplings with high-resolution mass spectrometry, automized processing routines are necessary. The processing routines usually consist of many individual steps that are user-parameter-dependent and, thus, require labor-intensive optimization. Additionally, the effect of variations in raw data quality on the processing results is unclear and not fully understood. Within this work, we present qBinning, a novel algorithm for constructing extracted ion chromatograms (EICs) based on statistical principles and, thus, without the need to set user parameters. Furthermore, we give the user feedback on the specific qualities of the generated EICs using a scoring system (DQSbin). The DQSbin measures reliability as it correlates with the probability of correct classification of masses into EICs and the degree of overlap between different EIC construction algorithms. This work is a big step forward in understanding the behavior of NTS data and increasing the overall transparency in the results of NTS.

Oxidation of the N-containing phosphonate antiscalants NTMP and DTPMP in reverse osmosis concentrates: Reaction kinetics and degradation rate.

N-containing organophosphonate antiscalants such as Aminotris (methylene phosphonic acid) (NTMP/ATMP) and Diethylenetriamine penta(methylene phosphonic acid) (DTPMP) are commonly used in reverse osmosis (RO) to prevent scaling, as well as to increase permeate yields. However, the concentrate in RO still contains antiscalants which can cause adverse effects in the environment such as mobilization of heavy metals. The abatement of antiscalants from RO concentrate can promote the precipitation of oversaturated scale-forming substances and reduce the risk of adverse environmental effects. In the present study, the degradation of NTMP and DTPMP as representatives for N-containing organophosphonate by ozone, hydroxyl radicals (•OH), and sulfate radicals (SO4•-) are studied regarding reaction kinetics and degradation in different matrices. The results show that NTMP and DTPMP react fast with ozone and sulfate radicals (formed in UV/persulfate). Reaction rate constants of ozone showed a strong pH dependency due to the dissociation of the amine. The apparent reaction rates for pH 7 have been determined to be kapp(NTMP + ozone) = 1.44 × 105 M-1 s-1 and kapp(DTPMP + ozone) = 1.16 × 106 M-1 s-1. Reaction kinetics of •OH and SO4•- did not play a distinctive pH dependency (k(•OH) = 109-1010 M-1 s-1 and k(SO4•-) = 107-108 M-1 s-1). Furthermore, real water experiments have shown that ozonation and UV/persulfate are effective tools to abate organophosphonates in RO concentrates. The formation of carcinogenic bromate in ozonation is minimized by the presence of N-containing organophosphonates presumably due to enhanced ozone consumption and scavenging of free bromine.

Effects of organic matter and alkalinity on the ozonation of antiviral purine derivatives as exemplary micropollutant motif.

Ozonation of micropollutants strongly depends on the water matrix. Natural organic matter is known to highly affect the hydroxyl radical exposure due to radical promoting and inhibiting effects. Other important matrix components in ozonation are carbonate species which scavenge hydroxyl radicals. However, additional factors such as the formation of other radicals might also play a role but are generally not covered in research or considered in modelling of micropollutant degradation. Hence, the ozonation of purine derivatives, the basic structure of various antiviral micropollutants, in different artificial water matrices is investigated in this study with focus on the impact of natural organic matter and increasing alkalinity on the degradation and product formation. The degradation of purine and adenine is inhibited by bicarbonate in the water matrix due to the anion's scavenging of hydroxyl radicals. This effect is already observed for low bicarbonate concentrations of 0.3 mM. However, formed carbonate radicals contribute to the compounds' degradation and also affect the stability of transformation products. This effect gains in relevance with increasing alkalinity and needs consideration in evaluating ozonation of very hard waters. Three ozonation products are evaluated in detail, which are affected by the matrix due to impacts on ozone stability, hydroxyl radical yield and carbonate radical formation. One product of adenine with the mass 147 was reported for the first time and only occurs in presence of matrix components. Under typical water treatment conditions rough predictions of pollutants' degradation are possible by the Rct concept using ozone and hydroxyl radical exposures. However, other reactive species such as carbonate radicals are not considered leading to deviations between modelled and experimental data at extreme conditions such as industrial wastewater. A general correlation between the Rct and the fraction f of hydroxyl radicals scavenged by bicarbonate (ln(Rct) = - 5.9  ×  f - 16.3) calculated from the concentration of organic matter and alkalinity was observed for various water samples allowing the estimation of micropollutant degradation during ozone treatment at moderate conditions by simple organic and inorganic carbon measurements.

Determination of anti-SARS-CoV-2 virustatic pharmaceuticals in the aquatic environment using high-performance liquid chromatography high-resolution mass spectrometry.

The Covid-19 pandemic has affected the global population since 2019. The rapid development and approval of vaccines has brought relief. Yet, effective cures are still being researched. Even if the pandemic situation may end, SARS-CoV-2 will remain and, thus, continued application of the drugs will lead to emissions of the active ingredients into the aquatic environment, as with other anthropogenic micropollutants. However, a general method for trace analysis of antiviral drugs is still missing. To this purpose, favipiravir, remdesivir, its active metabolite GS-441524, molnupiravir and its active metabolite EIDD-1931 were selected as representative analytes. A method was developed based on solid phase extraction and high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight high-resolution mass spectrometry. Optimization comprised the choice of chromatographic columns, elution gradient, mass spectrometry and tandem mass spectrometry parameters. Solid phase extraction proved suitable for increase in limits of detection and quantitation. amelioration of the limits of detection and quantitation. Matrix effects were investigated applying the optimized method to a wastewater sample with added virustatics. All five compounds could be separated with reversed phase chromatography, whereas EIDD-1931 profited from hydrophilic interaction liquid chromatography. The optimized method yielded limits of detection and quantification of 2.1·10-1, 6.9·10-1 µg·L-1 for favipiravir, 1.8·10-3, 5.5·10-3 µg·L-1 for remdesivir, 1.9·10-3, 7.6·10-3 µg·L-1 for GS-441524, 2.9·10-3, 8.7·10-3 µg·L-1 for molnupiravir, and 1.3·10-1, 3.8·10-1 µg·L-1 for EIDD 1931. The method was first applied to compound stability testing at pH 2.8 and 9.7. At pH 2.8, remdesivir, GS-441524 and molnupiravir proved stable, whereas about 14% of EIDD-1931 and favipiravir were degraded. All five antiviral compounds were almost completely decomposed at pH 9.7. The application of the method was further demonstrated for potential transformation product detection on favipiravir ozonation monitoring.

Enrichment and quantification of 18 polycyclic aromatic hydrocarbons from intermediates for plastics production by a generic liquid chromatography column switching.

The polycyclic aromatic hydrocarbon concentration in plastic products is regulated in (European Union) No. 1272/2013. However, this only covers the end products and not intermediate substances. Therefore, a generic method was developed to analyze the polycyclic aromatic hydrocarbons listed by the Environmental Protection Agency and the European Union. This method is based on direct large volume injection from solutions of plastic additives followed by liquid chromatography coupled to fluorescence detection. The additives Irganox 1010, ureido methacrylate, and cetyl methacrylate 1618F were used as examples for method development. Two serially coupled columns allowed the matrix to be removed on the first column and the analytes to be separated on the second column. The columns were connected by an intermediate valve. The valve allowed the matrix to be diverted after the first column and water to be dosed upstream of the second column via an additional pump. This allowed samples in aqueous or organic media to be focused at the column head. An injection volume of 100 µl and online aqueous dilution of 1:3 led to a limit of detection below 1 ng/ml for 15 polycyclic aromatic hydrocarbons. Moreover, concentrations between 1.6 and 10.3 ng/ml were found in the three plastic additives.

Improving greenness and sustainability of standard analytical methods by microextraction techniques: A critical review.

Since environmental awareness has increased in analytical chemistry, the demand for green sample preparation methods continues to grow. Microextractions such as solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) miniaturize the pre-concentration step and are a more sustainable alternative to conventional large-scale extractions. However, the integration of microextractions in standard and routine analysis methods is rare, although these applications are used most frequently and have a role model function. Therefore, it is important to highlight that microextractions are capable to replace large-scale extractions in standard and routine methods. This review discusses the greenness, benefits, and drawbacks of the most common LPME and SPME variants compatible with gas chromatography based on the following key evaluation principles: Automation, solvent consumption, hazards, reusability, energy consumption, time efficiency, and handling. Furthermore, the need to integrate microextractions into standard and routine analytical methods is presented by using method greenness evaluation metrics AGREE, AGREEprep, and GAPI applied to USEPA methods and their replacements.