Rapid liquid chromatography–tandem mass spectrometry-based method for the analysis of alcohol ethoxylates and alkylphenol ethoxylates in environmental samples

SPE-UPLC-MS/MS for Determination of 36 Monomers of Alkylphenol Ethoxylates in Tea

Alkylphenol ethoxylates (APEOs) represent a non-ionic surfactant widely used as adjuvants in pesticide formulation, which is considered to cause an endocrine-disrupting effect. In the current study, we established a detection method for the APEOs residue in tea based on solid-phase extraction (SPE) for the simultaneous analysis of nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) by UPLC-MS/MS. In the spiked concentrations from 0.024 to 125.38 μg/kg for 36 monomers of APEOs (n_EO = 3-20), the recoveries of APEOs range from 70.3-110.7% with RSD ≤ 16.9%, except for OPEO₂₀ (61.8%) and NPEO₂₀ (62.9%). The LOQs of OPEOs and NPEOs are 0.024-6.27 and 0.16-5.01 μg/kg, respectively. OPEOs and NPEOs are detected in 50 marketed tea samples with a total concentration of 0.057-12.94 and 0.30-215.89 µg/kg, respectively. The detection rate and the range of the monomers of NPEOs are generally higher than those of OPEOs. The current study provides a theoretical basis for the rational use of APEOs as adjuvants in commercial pesticide production.

Rapid determination of polyethoxylated tallow amine surfactants in human plasma by LC-MSMS

The potential exposure to the widely used glyphosate-based herbicides, including attempted suicide by ingestion, is of world-wide concern. Whilst the major focus to date has been on managing exposure to the active ingredient glyphosate, it is now recognised that a common major 'inert' surfactant ingredient, polyethoxylated tallow amine (POEA) and related compounds, may be more toxic. However, the information on the toxicokinetics of POEA surfactants after exposure is limited, in part, due to the lack of suitable methods for their analysis in biological matrices. We therefore developed and validated a robust LC-MSMS method that allowed, for the first time, a rapid analysis of 11 POEA homologues in human plasma. Chromatographic separation was achieved on a Kinetex EVO C18 column under a 5 min gradient elution with mobile phase A containing water/acetonitrile/formic acid (95:5:0.1, v/v/v) and mobile phase B containing acetonitrile/water/formic acid (95:5:0.1, v/v/v). Amlodipine was chosen as the internal standard (IS) for this assay. Amlodipine-d4 would be an ideal alternative IS to expand the applicability of the established method especially in antihypertensive patients. Multiple reaction monitoring (MRM) methods were optimized for 11 POEA homologues and the IS. Sample pre-treatment was performed using simple protein precipitation with methanol at a ratio of 4:1, requiring only 20 μL plasma. The validated method showed good specificity, accuracy and precision with lower limits of quantification (LLOQ) ranging from 0.35 to 10.8 ng mL^-1 for all selected POEA homologues. The method was then used to measure concentrations of the various POEA surfactants in more than 600 human plasma samples from 151 patients admitted to hospital with acute glyphosate intoxication. The highest concentrations ranged from 1.07 ng mL^-1 for C₁₈u(EO)₄-362.70 ng mL^-1 for C₁₆s(EO)₂. The analysis of POEA surfactants plasma concentrations as described here underpins the assessment of POEA internal exposure and the relationships between POEA related glyphosate toxicity and the extent of poisoning.

Cetyl Alcohol Polyethoxylates Disrupt Metabolic Health in Developmentally Exposed Zebrafish

Alcohol polyethoxylates (AEOs), such as cetyl alcohol ethoxylates (CetAEOs), are high-production-volume surfactants used in laundry detergents, hard-surface cleaners, pesticide formulations, textile production, oils, paints, and other products. AEOs have been suggested as lower toxicity replacements for alkylphenol polyethoxylates (APEOs), such as the nonylphenol and octylphenol polyethoxylates. We previously demonstrated that nonylphenol polyethoxylates induced triglyceride accumulation in several in vitro adipogenesis models and promoted adiposity and increased body weights in developmentally exposed zebrafish. We also demonstrated that diverse APEOs and AEOs were able to increase triglyceride accumulation and/or pre-adipocyte proliferation in a murine pre-adipocyte model. As such, the goals of this study were to assess the potential of CetAEOs to promote adiposity and alter growth and/or development (toxicity, length, weight, behavior, energy expenditure) of developmentally exposed zebrafish (Danio rerio). We also sought to expand our understanding of ethoxylate chain-length dependent effects through interrogation of varying chain-length CetAEOs. We demonstrated consistent adipogenic effects in two separate human bone-marrow-derived mesenchymal stem cell models as well as murine pre-adipocytes. Immediately following chemical exposures in zebrafish, we reported disrupted neurodevelopment and aberrant behavior in light/dark activity testing, with medium chain-length CetAEO-exposed fish exhibiting hyperactivity across both light and dark phases. By day 30, we demonstrated that cetyl alcohol and CetAEOs disrupted adipose deposition in developmentally exposed zebrafish, despite no apparent impacts on standard length or gross body weight. This research suggests metabolic health concerns for these common environmental contaminants, suggesting further need to assess molecular mechanisms and better characterize environmental concentrations for human health risk assessments.

Methods for the analysis of endocrine disrupting chemicals in selected environmental matrixes

Endocrine disrupting chemicals (EDCs) are heterogenous in structure, chemical and physical properties, and their capacity to partition into various environmental matrixes. In many cases, these chemicals can disrupt the endocrine systems of vertebrate and invertebrate organisms when present at very low concentrations. Therefore, sensitive and varied analytical methods are required to detect these compounds in the environment. This review summarizes the analytical methods and instruments that are most used to monitor for EDCs in selected environmental matrixes. Only those matrixes for which there is a clear link between exposures and endocrine effects are included in this review. Also discussed are emerging methods for sample preparation and advanced analytical instruments that provide greater selectivity and sensitivity.

Unraveling the Complex Composition of Produced Water by Specialized Extraction Methodologies

Produced water (PW), a waste byproduct of oil and gas extraction, is a complex mixture containing numerous organic solubles and elemental species; these constituents range from polycyclic aromatic hydrocarbons to naturally occurring radioactive materials. Identification of these compounds is critical in developing reuse and disposal protocols to minimize environmental contamination and health risks. In this study, versatile extraction methodologies were investigated for the untargeted analysis of PW. Thin-film solid-phase microextraction with hydrophilic-lipophilic balance particles was utilized for the extraction of organic solubles from eight PW samples from the Permian Basin and Eagle Ford formation in Texas. Gas chromatography-mass spectrometry analysis found a total of 266 different organic constituents including 1,4-dioxane, atrazine, pyridine, and PAHs. The elemental composition of PW was evaluated using dispersive solid-phase extraction followed by inductively coupled plasma-mass spectrometry, utilizing a new coordinating sorbent, poly(pyrrole-1-carboxylic acid). This confirmed the presence of 29 elements including rare earth elements, as well as hazardous metals such as Cr, Cd, Pb, and U. Utilizing chemometric analysis, both approaches facilitated the discrimination of each PW sample based on their geochemical origin with a prediction accuracy above 90% using partial least-squares-discriminant analysis, paving the way for PW origin tracing in the environment.

A multi-family offline SPE LC-MS/MS analytical method for anionic, cationic and non-ionic surfactants quantification in surface water

Of the large number of emerging pollutants discharged from wastewaters into surface waters, surfactants are among those with the highest concentrations. However, few monitoring in river waters of these substances have already been performed and only on a few families, mostly anionic. This work aimed to develop a multi-family analytical strategy suitable for the quantification of low concentrations of surfactant in surface waters. Twelve families of surfactants, anionic, cationic and non-ionic were selected. Their quantification by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and their extraction by SPE were optimized by comparing different retention mechanisms. The best performances were obtained with a C18 grafted silica LC column and a hydrophilic-lipophilic balanced (HLB) polymeric SPE cartridge. The final analytical method was validated and applied for the quantification of surfactants in 36 river water samples. Method limits of quantification (LQ), intra and inter days precision and trueness were evaluated. With LQ between 15 and 485 ng/L, and trueness over 80%, this method was suitable for monitoring surfactants in surface water. Application on French river water samples revealed the presence of anionic, cationic and non-ionic surfactants with median concentrations from 24 ng/L for octylphenol ethoxylates (OPEO), up to 4.6 μg/L regarding linear alkylbenzene sulfonates (LAS).

Comprehensive ethoxymer characterization of complex alcohol ethoxy sulphate products by mixed-mode high-performance liquid chromatography coupled to charged aerosol detection

The present work describes a simultaneous mixed-mode high performance liquid chromatography (HPLC) method combined with a universal and non-selective-response detector for the complete ethoxymer profiling of alcohol ethoxy sulphate mixtures. The optimized HPLC methodology combines the dual hydrophilic (HILIC) and reversed-phase selectivity of a surfactant-type column in order to render a comprehensive and simultaneous separation of more than 50 endogenous ethoxymers in a single analysis. Furthermore, an accurate quantitation of every single analyte was achieved using a final universal charged aerosol detector (CAD) including specific mathematical processing tools. Results obtained helped describing a complete alkyl chain and ethoxymer distribution of the investigated AES samples. Method validation evidences provided reliability of the individual ethoxymer contributions determined with the proposed HPLC-CAD methodology. Regarding accuracy including independent nuclear magnetic resonance (NMR) experiments, an excellent correlation was found between the structural information provided by a COSY NMR spectrum and the CAD results regarding the mono/polyethoxylated and the non-ethoxylated/ethoxylated distribution. Additional calculations including the average molecular weight and the degree of ethoxylation for the reference AES sample showed minimum differences (relative error < 1 %) between the two considered techniques. An outstanding precision and linearity along the working concentration range (r²>0.999) was also observed. The individual limit of detection for the target sulphate ethoxymers was determined to be in the low ppm range. Further validated distribution profiles for a large number of AES samples demonstrated the applicability of the optimized HPLC-CAD methodology to routine surfactant screenings. Therefore, the hereby developed methodology provided extensive information regarding the detailed individual ethoxymer profile of AES formulations, which can be extremely useful for the surfactant industry in order to gain information on specific synthesis routes and/or detergency properties.

Analysis of Derivatized N-Acyl Amino Acid Surfactants Using HPLC and HPLC/MS

A method for the analysis of weak anionic surfactants based on N-acyl amino acids was developed. The surfactants were derivatized using 2,4′-dibromoacetophenone yielding 4′-bromophenacyl esters suitable for spectrophotometric detection. Surfactants containing glycine, threonine and glutamic acid were analyzed after derivatization using reversed-phase liquid chromatography with UV/Vis and MS detection. The gradient profile was optimized using isocratic retention data of N-acyl-linked fatty acid homologues. The relative content of the homologues of N-acyl-linked fatty acids was expressed using the determined method. The intraday repeatability and stability of the prepared derivatives was tested. The relative content of fatty acids in the surfactants was correlated with the most common sources of fatty acids, showing high Pearson’s correlation coefficients with the typical fatty acids profile of a coconut oil.

Characterization of ethoxylated alcohols in friction reducers using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

RATIONALE

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) provides detailed information for the analysis of ethoxylated alcohols and polymers. In this study, five friction reducers used in commercial hydraulic fracturing processes were analyzed in their as-received form to identify their ethoxylated alcohol content. The friction reducers were then subjected to lab-simulated downhole conditions. Characterization of friction reducers before and after being subjected to reactive conditions can provide fingerprints associated with produced oilfield waste for source apportionment and information on the stability of these key hydraulic fracturing additives.

METHODS

Five different industrially used friction reducers were analyzed for their ethoxylated alcohol content using MALDI-TOF-MS. Three different matrices were assessed for optimal response: α-cyano-4-hydroxycinnamic acid, 2,5-dihydroxybenzoic acid, and 2,5-dihydroxybenzoic acid with 2,2,2-trifluoroethanol (2,5-DHB + E). Reaction times, temperatures, and sample matrices (deionized water, produced water inorganic, produced water, and produced water + shale core) were varied to assess changes in molecular weight distribution and polydispersity of the ethoxylated alcohols relative to their as-received content.

RESULTS

A preference for the 2,5-DHB + E matrix was observed. The friction reducers were found to contain ethoxylated alcohols with carbon chain lengths of 12 and 14 with degrees of ethoxylation ranging from 6 to 18. Upon being subjected to 100°C for 24 hours, the ethoxylated alcohols tended to polymerize further, returning higher average molecular weights. Less polymerization was seen in more complex matrices, as supported by dispersity calculations.

CONCLUSIONS

Ethoxylated alcohol content was effectively determined in friction reducers using MALDI-TOF-MS. Although this is not a new technique to characterize ethoxylated alcohols, it has proven to be a quick and effective way to determine ethoxylated alcohol content in friction reducers in complex oilfield matrices. This technique can be used as a rapid and straightforward way to determine ethoxylated alcohol content in friction reducers and hydraulic fracturing wastewater for fingerprinting.

Determination of dodecanol and ethoxylated fatty alcohols from environmental samples using diatomaceous earth as a green sorbent for solid-phase extraction

This study describes the use of diatomaceous earth during solid-phase extraction as an efficient sorbent for separation and concentration of dodecanol and ethoxylated dodecanol containing 1-9 ethoxyl groups. The efficiency of different eluents was evaluated for model samples which allowed to select methanol and chloroform for tests with river water samples. During model experiments, it was observed that the recovery rates of specific compounds in the studied mixture were influenced by the character of the solvent used for desorption. Hydrophobic compounds, such as dodecanol and ethoxylated dodecanol with 1-3 ethoxyl groups, were eluted by chloroform with 100% efficiency. In case of the remaining compounds, which were more hydrophilic, a 97% recovery rate was achieved during elution with methanol. Such dependencies were not observed in case of river water samples, as the results obtained for both studied sorbent-eluent systems were comparable. In both variants the recovery of dodecanol and ethoxylated dodecanol containing 1-9 ethoxyl groups ranged from 33 to 99%.

Using High-Resolution Mass Spectrometry to Identify Organic Contaminants Linked to Urban Stormwater Mortality Syndrome in Coho Salmon

Urban stormwater is a major threat to ecological health, causing a range of adverse, mostly sublethal effects. In western North America, urban runoff is acutely lethal to adult coho salmon ( Oncorhynchus kisutch) that spawn each fall in freshwater creeks. Although the mortality syndrome is correlated to urbanization and attributed to road runoff contaminant(s), the causal agent(s) remain unknown. We applied high-resolution mass spectrometry to isolate a coho mortality chemical signature: a list of nontarget and identified features that co-occurred in waters lethal to coho spawners (road runoff from controlled exposures and urban receiving waters from two field observations of symptomatic coho). Hierarchical cluster analysis indicated that tire wear particle (TWP) leachates were most chemically similar to the waters with observed toxicity, relative to other vehicle-derived sources. Prominent road runoff contaminants in the signature included two groups of nitrogen-containing compounds derived from TWP, polyethylene glycols, octylphenol ethoxylates, and polypropylene glycols. A (methoxymethyl)melamine compound family, previously unreported in North America, was detected in road runoff and urban creeks at concentrations up to ∼9 and ∼0.3 μg/L, respectively. The results indicate TWPs are an under-appreciated contaminant source in urban watersheds and should be prioritized for fate and toxicity assessment.

Survey of selected personal care products in surface water of coral reefs in Kenting National Park, Taiwan

Kenting National Park (KNP) located in the Hengchun Peninsula in southern Taiwan is a popular tourist spot, annually attracting millions of visitors, who engage in water sport and amusement activities. In this region, sewage is directly discharged into the marine environment. In this study, the concentrations of five organic UV filters [benzophenone (BP), 2,4-dihydroxy benzophenone (BP-1), 2-hydroxy-4-methoxy benzophenone (BP-3), 2,2'-dihydroxy-4-methoxy benzophenone (BP-8), and 4-methylbenzylidene camphor], five preservatives [methylparaben (MeP), ethylparaben, propylparaben (PrP), butylparaben, and benzylparaben], one disinfectant [triclosan (TCS)], and twenty-four detergent derivatives [nonylphenol (NP), nonylphenol ethoxylates (NP2EO-NP12EO), octylphenol (OP) and octylphenol ethoxylates OP2EO-OP12EO] were detected in seawater and river water samples collected from eight beaches in KNP and two major river estuaries in the Hengchun Peninsula. BP-3 was detected at all sampling sites and was higher in concentration than the other organic UV filters. The highest concentration of BP-3 was 1233 ng/L collected from Wanlitong Beach. MeP and PrP were the main preservative components in seawater. The highest total content of preservative agents was 164 ng/L collected from Houwan Beach. Moreover, NP was detected at all sampling sites, with the highest concentration found at Sail Rock Beach (26.5 ng/L). The highest concentration of OP was 113 ng/L in the Boli River estuary. The widespread use of personal care products (PCPs) has resulted in the release of their major ingredients into natural ecosystems. Therefore, the potential long-term effects of multi-PCPs at low concentration exposure to on the coral reef ecosystem in KNP must be considered and monitored.

Liquid chromatography coupled to quadrupole-Orbitrap high resolution mass spectrometry based method for target analysis and suspect screening of non-ionic surfactants in textiles

In this study, we describe a high-throughput and sensitive method for textiles analysis, using liquid chromatography coupled to quadrupole-Orbitrap high resolution mass spectrometry (LC-Q-Orbitrap HRMS), for the simultaneously quantitative analysis of 40 target alkylphenol polyethoxylates (APEO) oligomers with reference standards and screening of 160 alcohol polyethoxylates (AEO) oligomers without standards in textiles. The APEOs contain nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) with an EO number of ethylene oxide of 1-20, while AEOs focus on C₁₁EOs-C₁₈EOs with an EO number of 1-20. After ultrasonic extraction in methanol, the extract was directly separated using a core-shell CORTECS C₁₈⁺ column and analyzed by Full MS/dd-MS² (data dependent acquisition) scan in ESI positive mode. Two best sensitivity experimental conditions for APEOs with short EO chains (AP(EO)_1-2) and long EO chains (AP(EO)_3-20) were investigated, respectively. Most APEO oligomers had wide concentration ranges and the correlation coefficients (R²) were higher than 0.999. The limit of quantitation (LOQ) values for NP(EO)_3-20 oligomers ranges from 16.00 to 52.80μg/kg and for OP(EO)_3-20 oligomers is from 2.40 to 8.00μg/kg. LOQ for NP(EO)₁ and NP(EO)₂, OP(EO)₁ and OP(EO)₂ was 2.40mg/kg and 0.24mg/kg, 1.20mg/kg and 0.16mg/kg, respectively. The average recovery for each APEO oligomer in cotton and polyester matrix was between 78% and 110% at three spiked levels and the relative standard deviation (RSD%) was below 10%. As to AEOs suspects, a HRMS compound database containing 160 AEO oligomers was built and several parameters such as exact m/z, isotopic patterns, predicted product ions and predicted retention time were used for screening and confirmation. The established method was successfully applied for analysis of 40 commercial textile samples. Compared with OPEOs, NPEOs, especially NP(EO)_3-15 oligomers, were widely detected in samples and the total concentration ranged from 1.56 to 1376.31mg/kg. AEOs were also found in most samples, among which C_12-14, C₁₆ and C₁₈ compounds appeared more frequently and the EO chains mainly ranged from 3 to 15.

Quantitative Survey and Structural Classification of Hydraulic Fracturing Chemicals Reported in Unconventional Gas Production

Much interest is directed at the chemical structure of hydraulic fracturing (HF) additives in unconventional gas exploitation. To bridge the gap between existing alphabetical disclosures by function/CAS number and emerging scientific contributions on fate and toxicity, we review the structural properties which motivate HF applications, and which determine environmental fate and toxicity. Our quantitative overview relied on voluntary U.S. disclosures evaluated from the FracFocus registry by different sources and on a House of Representatives ("Waxman") list. Out of over 1000 reported substances, classification by chemistry yielded succinct subsets able to illustrate the rationale of their use, and physicochemical properties relevant for environmental fate, toxicity and chemical analysis. While many substances were nontoxic, frequent disclosures also included notorious groundwater contaminants like petroleum hydrocarbons (solvents), precursors of endocrine disruptors like nonylphenols (nonemulsifiers), toxic propargyl alcohol (corrosion inhibitor), tetramethylammonium (clay stabilizer), biocides or strong oxidants. Application of highly oxidizing chemicals, together with occasional disclosures of putative delayed acids and complexing agents (i.e., compounds designed to react in the subsurface) suggests that relevant transformation products may be formed. To adequately investigate such reactions, available information is not sufficient, but instead a full disclosure of HF additives is necessary.

Monitoring of selected non-ionic surfactants in river water by liquid chromatography-tandem mass spectrometry

Alcohol ethoxylates (AEs) are a significant component of the non-ionic surfactant (NS) flux discharged into surface water. Due to the polydispersity of the majority of NS, they are easily recognizable by their 'fingerprints', i.e. a series of mass peaks which differ by m/z = 44, namely the m/z of a single oxyethylene subunit. Dodecanol ethoxylates (C12EOx) represent AEs from both renewable and petrochemical sources. Therefore, C12Ex are suitable fingerprints of NS in the aquatic environment. The aim of this work was to develop an LC-MS/MS method suitable for AE monitoring in river water. River water samples taken from the River Warta in Poznan (Poland) were extracted with ethyl acetate, evaporated, reconstituted in the mobile phase and processed by the LC - Multistage MS procedure (LC-MS/MS) using optimum multiple reaction monitoring (MRM). The method of multiple standard additions was used for the evaluation of each AE fingerprint concentration. The concentration of C12EOx having 2-9 oxyethylene subunits was determined. Standards for higher C12EOx are not yet available. The developed method offers an LOD of between 1 and 9 ng L(-1), and is suitable for the monitoring of NS fingerprints in river water. The range of C12EO2-9 concentrations determined in the River Warta varied within two orders of magnitude in all cases. The lowest determined concentration was 17 ± 1 ng L(-1), while the highest was 2.6 ± 0.14 μg L(-1). The total concentration of C12EO2-C12EO9 homologues varied between 1.4 and 11.2 μg L(-1). A relatively high concentration of short-chained homologues (2-5 oxyethylene subunits) was observed in the investigated river water. This provides evidence of a biodegradation pathway involving the gradual shortening of the AE oxyethylene chain. Distinct evidence was also obtained of unregulated NS discharges into the river.

A new Iodobismuthate Method with a Low Volume Filtration Device as a New Tool for the Determination of Microgram Oxyethylate Amounts

The standard procedure of non-ionic surfactant detection by using the Bismuth Active Substances method offers low sensitivity, precision and a high consumption of the reagents. A new spectrophotometric (λmax = 460 nm of the visible spectrum) iodobismuthate method was developed, which may be successfully used to determine the presence of non-ionic surfactants at microgram levels. The oxyethylates were precipitated with the modified Dragendorff reagent, filtered, dissolved and afterwards the spectrophotometric determination of the equivalent bismuth amount was carried out. Several key factors, which influence the results of the proposed oxyethylate determination method, were optimized. The consumption of chemical reagents was notably decreased and the sensitivity of the method increased significantly in comparison to the standard method of non-ionic surfactant determination.