Green application of surfactant modified silica as effective sorbent for extraction and preconcentration of sulfonamide residues in environmental water and honey samples.

Micro-solid phase extraction (µ-SPE) using surfactant coated silica for extraction and preconcentration of sulfonamide residues at trace levels in environmental water and honey samples prior their analysis by high performance liquid chronatography coupled with photodiode array detector (HPLC-PDA). The sample solution were dispersed in a small amounts of solid sorbent by vacuum manifold for sample preparation, and extraction occurred by adsorption in a short time. Finally, the analytes were subsequently desorbed using an appropriate solvent. The pure and coated silica were physicochemically and morphologically characterized by nittrogen (N2) sorptions analyses, and transmission electron microscopy (TEM). Parameters influencing extraction efficiency, such as amount of sorbent, kind, concentration and volume of surfactant, and kind and volume of desorption solvent, were investigated. The optimum conditions of the proposed method, were mixed standard/sample solution (10 mL), 0.4 g silica, 0.03 M CTAB (150 µL), and 500 µL methanol (as elution solvent). The proposed method, under optimal conditions, showed excellent linearity in different ranges (9-300 µg L-1, the a coefficient of determination (R2) of greater than 0.99), good repeatability (RSD < 6.72 %), good sensitivity (LODs in the range of 1 to 3 µg L-1), high enrichment factor (5.63-13.33), and acceptable relative recoveries (61.0-121.4 %). The developed µ-SPE method was applied to analyze sulfonamide residues in water and honey samples with relative recoveries of 60.9-119.4 % were obtained. This alternative method is simple and is also environmentally friendly which assessed using Analytical Eco-scale and Analytical GREEnness metric (AGREE).

SERS imaging investigation of the removal efficiency of pesticide on vegetable leaves by using different surfactants.

Pesticide residues on vegetables could be removed by commercial detergents to guarantee food safety, but the removal efficiencies of different formulations of detergents need to be further investigated. In this work, surface enhanced Raman scattering (SERS) imaging method due to its good space resolution as well as high sensitivity is used to track the thiram residue, and evaluate the pesticide removing efficiencies by mixtures of several surfactants at different ratios. Sodium linear alkylbenzene sulphonate-alkyl glycoside (LAS-APG) with the ratio at 5:5 and the concentration at 0.2 % show the best removing effect. In addition, HPLC method is employed to validate the results of SERS imaging. Furthermore, LAS-APG mixture could be efficiently washed out from the leaves through simple household cleaning, meaning no secondary contamination. It is perspective that SERS imaging is an effective technique to explore the effect of fruit and vegetable detergents in removing pesticide residues.

Characterizing Volatile Emissions and Combustion Byproducts from Aqueous Film-Forming Foams Using Online Chemical Ionization Mass Spectrometry.

Aqueous film-forming foams (AFFFs) are used in firefighting applications and often contain per- and polyfluoroalkyl substances (PFAS), which can detrimentally impact environmental and biological health. Incineration is a potential disposal method for AFFFs, which may produce secondary PFAS and other air pollutants. We used online chemical ionization mass spectrometry (CIMS) to measure volatile PFAS emissions from incinerating AFFF concentrate solutions. We quantified perfluorinated carboxylic acids (PFCAs) during the incineration of legacy and contemporary AFFFs. These included trifluoroacetic acid, which reached mg m-3 quantities in the incinerator exhaust. These PFCAs likely arose as products of incomplete combustion of AFFF fluorosurfactants with lower peak furnace temperatures yielding higher PFCA concentrations. We also detected other short-chain PFAS, and other novel chemical products in AFFF combustion emissions. The volatile headspace above AFFF solutions contained larger (C ≥ 8), less oxidized PFAS detected by CIMS. We identified neutral PFAS resembling fluorotelomer surfactants (e.g., fluorotelomer sulfonamide alkylbetaines and fluorotelomer thioether amido sulfonates) and fluorotelomer alcohols in contemporary AFFF headspaces. Directly comparing the distinct chemical spaces of AFFF volatile headspace and combustion byproducts as measured by CIMS provides insight toward the chemistry of PFAS during thermal treatment of AFFFs.

Surfactant-enhanced air-agitation liquid-liquid microextraction of polycyclic aromatic hydrocarbons from edible oil using magnetic deep eutectic solvent prior to HPLC determination.

Herein, an air-agitation liquid-liquid microextraction procedure was developed for the extraction of several polycyclic aromatic hydrocarbons from edible oil samples. In this study, the extraction procedure was achieved using a new magnetic deep eutectic solvent as the extraction solvent, in which there was no need for centrifugation. To enhance the rate of extraction of the analytes from the samples, the method was promoted by the use of surfactant addition. The extracted analytes were determined by high-performance liquid chromatography with a diode array detector. The influence of various parameters on the extraction efficiency was studied by response surface methodology using a central composite design. Under optimal conditions, linear calibration curves for the target analytes were achieved in the range of 0.43-250 ng g-1. The limits of detection and quantification were in the ranges of 0.04-0.13 and 0.13-0.43 ng g-1, respectively. The repeatability of the method in terms of intra- and inter-day precision was ≤4.7% and ≤6.7%, respectively. The extraction recovery of the method ranged from 75 to 88%. The obtained results show that the proposed method is efficient for the analysis of the target analytes in various oil samples without obvious matrix effects. Pyrene was found in olive oil at a concentration of 42 ng g-1.

Unveiling the origin, fate, and remedial approaches for surfactants in sewage-fed foaming urban (Bellandur) Lake.

Foam formation in surface water bodies has become a global phenomenon, but the solutions to this crisis are often insufficient. Foam formation in water bodies is attributed to surfactants and requires a comprehensive assessment of various sources of surfactants to evolve mitigation strategies. The study is focused on thoroughly analyzing surfactants in the water and foam fractions of a large waterbody in Bangalore (India) spanning around 1000 acres (400 ha), which has been foaming for two decades. Results revealed that the key surfactants originate predominantly from anthropogenic sources with a small component emerging from naturogenic sources. Anthropogenic surfactants were found to be predominant (96.5%), with linear alkylbenzene sulphonates (LAS) of various C-chain lengths 12-20 being the most prevalent. Naturogenic surfactants derived from bacterial genera Pseudomonas exhibited significant microbial diversity, accounting for over 19% of total bacterial population in both the water and organic sediments of the lake. Modelling studies and field validation efforts were carried out to understand the fate of LAS in the foaming lake. The results indicated that these surfactants donot degrade under the prevailing conditions and timeframe as wastewater traverses through the lake, and their presence was also observed in the organic sludge sediment. Modeling the underlying processes revealed that a minimum dissolved oxygen (DO) concentration of 3.5 mg/l enables the degradation of over 90% of surfactants within the residence time of 8-10 days in Lake. Additionally, the process of desludging could contribute to an additional increase to the overall efficiency of surfactant removal, simultaneously removing legacy sorbed surfactants to sediments.

Effects of solvent extracted organic matter from outdoor air pollution on human type II pneumocytes: Molecular and proteomic analysis.

Outdoor air pollution is responsible for the exacerbation of respiratory diseases in humans. Particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5) is one of the main components of outdoor air pollution, and solvent extracted organic matter (SEOM) is adsorbed to the main PM2.5 core. Some of the biological effects of black carbon and polycyclic aromatic hydrocarbons, which are components of PM2.5, are known, but the response of respiratory cell lineages to SEOM exposure has not been described until now. The aim of this study was to obtain SEOM from PM2.5 and analyze the molecular and proteomic effects on human type II pneumocytes. PM2.5 was collected from Mexico City in the wildfire season and the SEOM was characterized to be exposed on human type II pneumocytes. The effects were compared with benzo [a] pyrene (B[a]P) and hydrogen peroxide (H2O2). The results showed that SEOM induced a decrease in surfactant and deregulation in the molecular protein and lipid pattern analyzed by reflection-Fourier transform infrared (ATR-FTIR) spectroscopy on human type II pneumocytes after 24 h. The molecular alterations induced by SEOM were not shared by those induced by B[a]P nor H2O2, which highlights specific SEOM effects. In addition, proteomic patterns by quantitative MS analysis revealed a downregulation of 171 proteins and upregulation of 134 proteins analyzed in the STRING database. The deregulation was associated with positive regulation of apoptotic clearance, removal of superoxide radicals, and positive regulation of heterotypic cell-cell adhesion processes, while ATP metabolism, nucleotide process, and cellular metabolism were also affected. Through this study, we conclude that SEOM extracted from PM2.5 exerts alterations in molecular patterns of protein and lipids, surfactant expression, and deregulation of metabolic pathways of type II pneumocytes after 24 h of exposure in absence of cytotoxicity, which warns about apparent SEOM silent effects.

Tween 80 assisted washing ciprofloxacin-contaminated soil, and recycled it using active chlorines.

Active chlorines (ACs) can selectively oxidize contaminants with benzene rings to recycle surfactants, which greatly facilitates the resource cycle. This paper firstly utilized Tween 80 to assist in ex-situ washing the ciprofloxacin (CI) contaminated soil, including the solubilization experiment, shake washing and soil column washing, all of which showed that 2 g/L of Tween 80 (TW 80) was the most effective in removing CI. Then electrochemically treated the collected soil washing effluent (SWE) at 10 V with an electrolyte of 20 mM NaCl + 10 mM Na2SO4; Pre-experiments screened the range of electrode spacing, pH and temperature, based on which an orthogonal design Table L9 (34) was designed. Visual analysis and ANOVA were performed on the ciprofloxacin removal efficiency and Tween 80 retention efficiency during the orthogonal experiments in 9 groups, and the results showed that CI was usually degraded within 30 min, and 50% of TW 80 was still present at the end of the experiment, and there was no significant effect of all three factors. LC-MS demonstrated that CI was mainly degraded synergistically by ·OH and ACs, and ·OH effectively reduced the biotoxicity of the SWE, so the mixed electrolyte may be more suitable for the electrochemical recycling system of ACs. This paper conducted the washing remediation study of CI-contaminated soil for the first time, and applied the theory of selective oxidation by ACs on benzene ring to treat the SWE, which provides a new treatment idea for antibiotic-contaminated soil.

Unravelling the reason for seasonality of foaming in sewage-fed urban lakes.

Foaming surface waters are a global phenomenon but are understudied. Bellandur lake in India has gained international attention due to its foaming events, which occur seasonally after rainfall. This study investigates the seasonality of foaming and the sorption/desorption of surfactants onto sediment and suspended solids (SS). Results show that foaming lake sediment can contain as much as 3.4 g of anionic surfactant/ kg of dry sediment, and its concentration was proportional to the organic matter (OM) content and surface area of the sediment sample. This is the first study to demonstrate the sorption capacity of SS in wastewater, which was found to be 53.5 ± 4 mg surfactant/g SS. In contrast, only a maximum of 5.3 mg surfactant was sorbed/g of sediment. The lake model analysis revealed that sorption is a first-order process and that surfactant sorption on SS and sediment is reversible. SS was found to desorb ∼73 % of sorbed surfactant back to the bulk water, while sediment desorbed 33-61 % of sorbed surfactants proportional to their OM. Contrary to the common assumption, rain does not dilute the surfactant concentration but instead increases the foaming potential of lake water through desorption from SS.

Ultimate and Primary Biodegradation of a Range of Nonpolymeric and Polymeric Surfactants in Seawater.

Surfactants are chemicals commonly used in a wide range of domestic and industrial products. In the present study, ultimate biodegradation of 18 surfactants representing different classes (including several polymeric alcohol ethoxylates [AEs]) was determined in seawater at 20 °C by a Closed Bottle test method. After 28 days of incubation, 12 surfactants reached 60% biodegradation and were considered to be readily biodegradable in seawater. The results for the six additional surfactants indicated that the 60% pass level may be reached by extended incubation time, or that reduced biodegradation could be associated with toxicity of the chemicals. All these six surfactants were biodegraded >20% after 28 days, indicative of primary biodegradation in seawater. Polymeric ethoxylates with high numbers of ethylene oxide (EO) groups (40-50 EO groups) were more slowly biodegraded than polyethoxylates with 4 to 23 EO groups. Biodegradation experiments of the AE C12 EO9 (3 to 18 EO groups) in a carousel system at 20 °C with natural seawater and a surfactant concentration of 500 µg/L showed rapid primary biodegradation by targeted analyses of the AE, with >99% primary biodegradation after 2 days of incubation. The surfactant depletion coincided with temporary formation of polyethylene glycols, suggesting that central fission is an important degradation step in seawater. A primary biodegradation experiment in the carousel system with C12 EO9 was conducted in the presence of suspended particulate materials (SPMs; marine phytoplankton and clay particles), showing that the presence of SPMs did not hamper the primary biodegradation of the surfactant. Separation of fractions in 20-µm steel filters indicated some particle association of the surfactant. Environ Toxicol Chem 2023;42:1472-1484. © 2023 SETAC.

Rapid, sensitive detection of PFOA with smartphone-based flow rate analysis utilizing competitive molecular interactions during capillary action.

Perfluorinated-alkyl substances (PFAS) pose an unmet threat to the public because they are not strictly monitored and regulated. Perfluorinated-carbon alkyl chains (PFOA), a type of PFAS, at 70 fg/µL is the current health and safety recommendation. Current testing methods for PFOA and PFAS chemicals include HPLC-MS/MS and molecularly imprinted polymers, which are expensive, time-consuming, and require training. In this work, PFOA and PFOS detection was performed on a paper microfluidic chip using competitive interactions between PFOA/PFOS, cellulose fibers, and various reagents (L-lysine, casein, and albumin). Such interactions altered the surface tension at the wetting front and, subsequently, the capillary flow rate. A smartphone captured the videos of this capillary action. The samples flowed through the channel in less than 2 min. Albumin worked the best in detecting PFOA, followed by casein. The detection limit was 10 ag/µL in DI water and 1 fg/µL in effluent (processed) wastewater. Specificity to other non-fluorocarbon surfactants was also tested, using anionic sodium dodecyl sulfate (SDS), non-ionic Tween 20, and cationic cetrimonium bromide (CTAB). A combination of the reagents successfully distinguished PFOA from all three surfactants at 100% accuracy. This low-cost, handheld assay can be an accessible alternative for rapid in situ estimation of PFOA concentration.

Biodegradation of oil-contaminated aqueous ecosystem using an immobilized fungi biomass and kinetic study.

Remediation of environmental oil pollution with the usage of fungal organisms has proven to be a successful cleanup bioremediation method for organic contaminants. To investigate the breakdown of oil pollutants in water environments, biosurfactant-producing fungi have been isolated from oil-polluted soil samples. 16s rRNA sequencing technique was performed to identify the fungal organism and phylogenetic tree has been constructed. A variety of biosurfactant screening tests have demonstrated the better biosurfactant producing ability of fungi. The emulsion's stability, which is essential for the biodegradation process, was indicated by the emulsification index of 68.48% and emulsification activity of 1.3. In the isolated biosurfactant, important functional groups such as amino groups, lipids, and sugars were found according to thin layer chromatography analysis with a maximum retention value of 0.85. A maximum oil degradation of around 64% was observed with immobilized beads within 12 days. The half-life, and degradation removal rate constant of 20.21 days and 0.03 day-1, respectively, have been determined by the degradation kinetic analysis. GCMS analysis confirmed the highly degraded hydrocarbons such as nonanoic acid and pyrrolidine. The immobilized fungi exhibit better oil biodegradability in aqueous solutions.

Synthetic surfactants in drinking and surface waters in Armenia and apparent non-association with some diseases.

The main goal of this study is to compare the concentrations of anionic synthetic surfactants (ASS) in drinking and surface waters in Armenia and to explore possible relationship with diseases of the skin and digestive system. Surfactants are widely employed in numerous field of the economy, are in contact with the entire population throughout life and can be harmful to human health.The samples of drinking and surface waters (n = 144) were collected in Kotayk province to analyze ASS concentrations, physicochemical parameters and phytotoxic activity. The prevalence of diseases was analyzed for different population groups. ASS concentrations in surface waters were significantly higher in summer compared to spring (p = 0.006). In drinking water, concentrations were also higher in summer, but not significantly. In surface waters, ASS levels were 2.4-3 times higher compared to drinking (p = 0.03) and exceeded the permissible limit by 1.4-2.9 times in summer and fall. No phytotoxic activity and differences in both classes of diseases and age groups were revealed. The determination of ASS in both surface and drinking waters with the same trend showed their interrelation to a certain extent. This study provides important information for future research and action which will contribute to the sustainable development of local communities.

Accelerated transformation of sodium dodecylbenzene sulfonate surfactant in the UV/chlorine process: Kinetics and formation of chlorinated disinfection by-products.

The degradation kinetics of Sodium dodecylbenzene sulfonate (SDBS) surfactant in the UV/chlorine process was comprehensively investigated, and the formation of chlorinated disinfection by-products (Cl-DBPs) were determined. Results showed that the degradation of SDBS by UV, chlorine and UV/chlorine all followed pseudo-first-order kinetics. The rate constant by UV/chlorine in ultrapure water was approximately 3 times higher than the sum of those by UV and chlorine, and decreased from 0.297 to 0.063 min-1 with pH increasing from 5.0 to 9.0. Water matrices such as NO3-, HCO3- and natural organic matter (NOM) inhibited the degradation efficiency to a certain extent. The second-order rate constant of SDBS with HO• was determined as 2.84 × 109 M-1 s-1. Through using different probes, the main contributors to SDBS degradation were found to be UV, HO• and reactive chlorine species (RCS). Meanwhile, 64.0 µg L-1 trichloromethane (TCM) and 8.7 µg L-1 chloral hydrate (CH) were simultaneously formed within 30 min of UV/chlorine treatment. The concentration of total organic chlorine (TOCl) (424.0 µg L-1) was obviously higher than those of TCM and CH. In addition, 414 unknown by-products formed during UV/chlorine treatment were detected by mass spectrometry at a high confidence level, including 64 monochloro-DBPs and 2 dichloro-DBPs. Although UV/chlorine process accelerated SDBS degradation, the associated DBP formation deserves enough attention.

Freely dissolved concentration profile and Hyalella azteca toxicity of cationic surfactant C12-benzalkonium in spiked-sediment toxicity test.

The freely dissolved concentrations (Cfree) have been considered a useful metric for exposure of aquatic organisms to organic contaminants. However, Cfree for cationic surfactants has rarely been measured, and its use in sediment toxicity tests has not been evaluated. In this study, Cfree of the cationic surfactant benzyldodecyldimethylammonium (C12-benzalkonium; C12-BAC) in water-only and spiked-sediment toxicity tests with the amphipod Hyalella azteca was analyzed using a passive sampling method. Polyacrylate-coated glass fibers were adopted as the passive sampler. Sorption isotherms of C12-BAC to the polyacrylate fibers were measured in chemical conditions comparable to those of the toxicity tests and used for Cfree calculation in both tests. Detailed concentration analysis in the sediment toxicity test demonstrated a high concentration gradient of C12-BAC between sediment and overlying water; Cfree in pore water was 17-78 times higher than Cfree in overlying water and was 7.2-13 times higher than Cfree at the sediment-water interface. The 50 % lethal concentration and bioconcentration factor of H. azteca obtained in the water-only test (23 µg/L and 140 ± 70 L/kg-wet, respectively) agreed with those calculated based on Cfree in pore water in the sediment test (49 µg/L and 140 ± 90 L/kg-wet, respectively), indicating that H. azteca is exposed mainly to the freely dissolved fraction in pore water. We concluded that Cfree in pore water is a useful exposure metric for H. azteca to cationic surfactants.

Removal of pesticide residues from apple and tomato cuticle.

Pesticide residues are always an unsolved problem in the world despite all kinds of prevention measures. The present research work is based on a scientific hypothesis, i.e., "The removal of average pesticide residue is inversely proportional to the thickness of cuticle." The effects of boron-containing products and plant-based surfactants were tested for the removal of five pesticides (lambda-cyhalothrin, chlorpyrifos, diflubenzuron, metaflumizone, acetamiprid) on tomatoes and apples. Boron-containing products were able to remove the pesticide residues on average between 58.0 and 72.6% in tomatoes and 33.2-58.8% in an apple. While plant-based surfactants removed residues on average between 58.5 and 66.6% in tomatoes and 41.0-53.2% in an apple. The highest removal rate was 72% with etidot at 1%. The solution of 1% C8-C10 provided 66.6% average removal for tomatoes. Less removal was achieved in apples. For an apple, Log Kow and molecular mass (independent variables) were significant with p < 0.01, and the coefficient of determination (R2) was > 0.87. However, the multiple linear regression analysis for ground colemanite was significant with R2 of 0.96. In tomatoes, neither Log Kow nor molecular mass as significant. The correlation was found between the physical and chemical properties of pesticides, but it is estimated that the thickness of the cuticle is effective in removing pesticides.

The Role of pH, Electrodes, Surfactants, and Electrolytes in Electrokinetic Remediation of Contaminated Soil.

Electrokinetic remediation has, in recent years, shown great potential in remediating polluted environments. The technology can efficiently remove heavy metals, chlorophenols, polychlorinated biphenyls, phenols, trichloroethane, benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and entire petroleum hydrocarbons. Electrokinetic remediation makes use of electrolysis, electroosmosis, electrophoresis, diffusion, and electromigration as the five fundamental processes in achieving decontamination of polluted environments. These five processes depend on pH swings, voltage, electrodes, and electrolytes used in the electrochemical system. To apply this technology at the field scale, it is necessary to pursue the design of effective processes with low environmental impact to meet global sustainability standards. It is, therefore, imperative to understand the roles of the fundamental processes and their interactions in achieving effective and sustainable electrokinetic remediation in order to identify cleaner alternative solutions. This paper presents an overview of different processes involved in electrokinetic remediation with a focus on the effect of pH, electrodes, surfactants, and electrolytes that are applied in the remediation of contaminated soil and how these can be combined with cleaner technologies or alternative additives to achieve sustainable electrokinetic remediation. The electrokinetic phenomenon is described, followed by an evaluation of the impact of pH, surfactants, voltage, electrodes, and electrolytes in achieving effective and sustainable remediation.

Implications of microbial enhanced oil recovery and waterflooding for geochemical interpretation of recovered oils.

Biosurfactants and waterflooding have been widely reported thus far for enhancing oil production. Nevertheless, there is a lack of literature to explore enhanced oil recovered methods effects on its chemical composition. The aim of this work is to investigate the effects of a biosurfactant produced by Bacillus safensis and brine injection on the recovered petroleum composition, and their implications for geochemical interpretation. Original and oils recovered from displacement tests were analyzed by gas chromatography and ultra-high-resolution mass spectrometry, emphasizing saturated and aromatic biomarkers and basic and acidic polar compounds. Geochemical parameters based on some saturated compounds were subtly affected by the recovery methods, showing their reliable applicability in geochemical studies. Contrarily, parameters based on some aromatic compounds were more affected by biosurfactant flooding, mostly the low molecular weight compounds. Thus, these aromatic parameters should be applied with caution after such methods. The distribution of basic and acidic polar compounds can also be modified affecting the geochemical interpretation. In the case of the basic ones, the biosurfactant greatly influenced the N class species with favorable loss of lower aromaticity compounds. In addition to water solubilization, the compositional changes described in this study can be related to fractionation due to adsorption on reservoir rocks.

Utilization of surface-active compounds derived from biosolids to remediate polycyclic aromatic hydrocarbons contaminated sediment soil.

In the present study, surface-active compounds (SAC) were extracted from biosolids using an alkaline treatment process. They were tested for their remediation efficiency of crude oil-contaminated sediment soil and was compared with Triton x-100. The SAC exhibited a similar soil washing efficiency to that of the commercial Triton x-100, and under the optimized soil washing parameters, SAC exhibited a maximum of 91% total polycyclic aromatic hydrocarbons removal. Further, on analysing the toxicity of the soil residue after washing, it was observed that SAC from biosolids washed soil exhibited an average of 1.5-fold lesser toxicity compared to that of Triton x-100 on different test models-earthworm, a monocot, and dicot plants. The analysis of the key soil parameters revealed that the commercial surfactant reduced the soil organic matter and porosity by an average of 1.3-fold compared to SAC. Further, the ability of surfactants to induce toxicity was confirmed by the adsorption of the surfactants on the surface of the soil particles which was in the order of Triton x-100 > SAC. Thus, this study suggests that SAC can be applied as an effective bioremediation approach for contaminated soil for a greener and sustainable ecosystem.

Challenges in direct determination of Glyphosate and aminomethylphosphonic acid in water by liquid chromatography-tandem mass spectrometry at modified reverse phase columns: Effect of matrix interferences in fresh and hard water systems.

This study validated two underivatized methods (M1 and M2) according to the Eurachem guidelines to analyze the herbicide Glyphosate and its major metabolite aminomethylphosphonic acid simultaneously by liquid chromatography-tandem mass spectrometry in both fresh and hard waters. Samples were analyzed directly after filtration through 0.22 µm syringe filters in M1, while samples were acidified with acetic acid before filtration in M2. Spike recoveries were greater than 80% for Glyphosate and aminomethylphosphonic acid in both methods. The limit of quantitation was 0.5 µg/L for M1, and 0.1 µg/L for M2 by using matrix-matched calibrations. The linear regression coefficient of both methods was greater than 0.995. The expanded uncertainty was found to be less than 25% for both. Moreover, M1 has an additional mass spectral confirmation ability, and the column and the mobile phase used in M2 can be used to analyze the inert surfactant used in Glyphosate formulations, Polyethoxylated tallow amine. The accuracy of the developed methods was assured by participating in a proficiency testing program against M2 and conducting the t-test for results generated by both M1 and M2. Both methods, therefore, can be used to determine Glyphosate and aminomethylphosphonic acid content concurrently in fresh and hard waters.

Screening of pesticides and emerging contaminants in eighteen Greek lakes by using target and non-target HRMS approaches: Occurrence and ecological risk assessment.

Lakes, albeit ecosystems of vital importance, are insufficiently investigated with respect to the degradation of water quality due to the organic micropollutants load. As regards Greece, screening of lake waters is scarce and concerns a limited number of contaminants. However, understanding the occurrence of contaminants of emerging concern (CECs) and other micropollutants in lakes is essential to appraise their potential ecotoxicological effects. The aim of this study was to deploy a multiresidue screening approach based on liquid chromatography-high-resolution mass spectrometry (HRMS) to get a first snapshot for >470 target CECs, including pesticides, pharmaceuticals, personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), as well as organophosphate flame retardants (OPFRs) in eighteen Greek lakes in Central, Northern and West Northern Greece. The omnipresent compounds were DEET (N,N-diethyl-meta-toluamide), caffeine and TCPP (tris (1-chloro-2-propyl) phosphate). Maximum concentrations varied among the different classes. DEET was detected at a maximum average concentration of >1000 ng/L in Lake Orestiada, while its mean concentration was estimated at 233 ng/L. The maximum total concentrations for pesticides, PPCPs, PFASs, and OPFRs were 5807, 2669, 33.1, and 1214 ng/L, respectively, indicating that Greek lakes are still threatened by the intense agricultural activity. Besides, HRMS enabled a non-target screening by exploiting the rich content of the full-scan raw data, allowing the 'discovery' of tentative candidates, such as surfactants, pharmaceuticals, and preservatives among others, without reference standards. The potential ecotoxicity was assessed by both the risk quotient method and ECOSAR (Ecological Structure Activity Relationships) revealing low risk for most of the compounds.