Tracking Aromatic Amines from Sources to Surface Waters

Triazine based probes for nitroaniline: Comprehensive optical and DFT approach for dual-phase detection and fingerprint sensing

Extended conjugation in fluorescent probes is crucial for efficient optical characteristics. Herein, two novel triazine based organic compounds ITA and DIT with extraordinary photophysical properties were synthesized through palladium catalyzed Suzuki and Sonogashira coupling reactions, respectively. Solvatochromism and solid-state based comprehensive study of photophysical properties of probes ITA and DIT was investigated for developing dual phase and extremely sensitive and selective fluorescent probes for detection of 4-nitroanilne (4-NA). The probes ITA and DIT were also utilized in the formulation of latent fingerprint sensing and invisible ink. Furthermore, the outstanding fluorescence properties of probes ITA and DIT were efficiently used for the selective sensing of 4-nitroanilne (4-NA) in real samples and portable paper-strips were constructed for the on-site sensing of 4-NA. The sensing approach for selective detection of 4-NA was comprehensively evaluated with the help of spectroscopic analysis including titration NMR, UV-visible spectroscopy, fluorescence studies, dynamic light scattering (DLS) and DFT calculations. DFT calculations included the calculation of RDG analysis, thermodynamic stability, charge transfer and molecular orbital studies as well as QTAIM. All the analysis and theoretical studies supported the existence of non-covalent interactions between probes and 4-NA.

Characterizing the distribution of aromatic amines between polyester, cotton, and wool textiles and air

Textiles play an important role in the accumulation of harmful chemicals and can serve as a secondary source of chemical pollutants in indoor environments, releasing these chemicals back into indoor air, as well as a vector from which indoor pollution can be released by laundering to wastewater systems. Among harmful indoor pollutants, aromatic amines (AAs) are particularly concerning due to their mutagenic and carcinogenic properties, but have received limited attention in non-occupational indoor environments. We have characterized the distribution of 19 AAs between cotton, wool, and polyester textiles and air. Chamber exposure experiments were conducted under controlled laboratory conditions to quantify textile-air distributions of AAs and identify key parameters impacting the distribution. The mass-normalized textile/air distribution coefficients (KTA) of AAs for polyester, cotton, and wool range from 5.28 to 9.52 log units (L kg-1). The findings suggest that cotton generally exhibits higher distribution coefficients than polyester and wool for most analytes. Overall, the results show a strong positive relationship between octanol-air distribution coefficients (KOA) and KTA values. The consistent uptake capacity of all tested textiles for AAs highlights the potential for textiles to play a key role in AA indoor distributions.

Machine Learning-based Classification for the Prioritization of Potentially Hazardous Chemicals with Structural Alerts in Nontarget Screening

Nontarget screening (NTS) with liquid chromatography high-resolution mass spectrometry (LC-HRMS) is commonly used to detect unknown organic micropollutants in the environment. One of the main challenges in NTS is the prioritization of relevant LC-HRMS features. A novel prioritization strategy based on structural alerts to select NTS features that correspond to potentially hazardous chemicals is presented here. This strategy leverages raw tandem mass spectra (MS2) and machine learning models to predict the probability that NTS features correspond to chemicals with structural alerts. The models were trained on fragments and neutral losses from the experimental MS2 data. The feasibility of this approach is evaluated for two groups: aromatic amines and organophosphorus structural alerts. The neural network classification model for organophosphorus structural alerts achieved an Area Under the Curve of the Receiver Operating Characteristics (AUC-ROC) of 0.97 and a true positive rate of 0.65 on the test set. The random forest model for the classification of aromatic amines achieved an AUC-ROC value of 0.82 and a true positive rate of 0.58 on the test set. The models were successfully applied to prioritize LC-HRMS features in surface water samples, showcasing the high potential to develop and implement this approach further.

Elevated urinary levels of primary aromatic amines in residents from e-waste dismantling area: Associations with oxidative stress and kidney injury

Currently, the adverse effects of carcinogenic primary aromatic amines (PAAs) released from electronic waste (e-waste) dismantling activities on human health remain unclear. Therefore, this study examined the urinary concentrations of 28 PAAs in residents living in both e-waste dismantling and control areas, and the median concentrations (unit: μg/g Cre) of aniline (ANI) (1.06 vs. 0.49), meta-toluidine (m-TD) (0.41 vs. 0.06), 4-ethoxyaniline (4-EA) (1.66 vs. 0.13), 3,4-diaminoanisole (3,4-DAAS) (1.64 vs. 0.82), and Σ7PAAs (5.80 vs. 2.20) (the sum of 7 highly detectable PAAs) in residents living in the e-waste dismantling area were significantly higher (p < 0.01) than those in the control area. Our results indicate that e-waste dismantling activities contribute to human exposure to PAAs. Furthermore, urinary ANI, 4-EA, and m-TD concentrations were significantly positively correlated with oxidative stress biomarkers; additionally, significant positive associations were found between ANI, 4-EA, m-TD, ortho-toluidine (o-TD), and para-toluidine (p-TD) exposure and elevated NGAL levels, suggesting that these compounds may cause kidney damage. To our knowledge, this is the first study to examine the health risks of human exposure to PAAs in e-waste dismantling areas, providing a new perspective for assessing the health risks associated with PAAs in relation to e-waste dismantling activities.

Associations of prenatal urinary melamine, melamine analogues, and aromatic amines with gestational duration and fetal growth in the ECHO Cohort

Melamine, its analogues, and aromatic amines (AAs) were commonly detected in a previous study of pregnant women in the Environmental influences on Child Health Outcomes (ECHO) Cohort. While these chemicals have identified toxicities, little is known about their influences on fetal development. We measured these chemicals in gestational urine samples in 3 ECHO cohort sites to assess associations with birth outcomes (n = 1,231). We estimated beta coefficients and 95% confidence intervals (CIs) using adjusted linear mixed models with continuous dilution-standardized concentrations (log2 transformed and scaled by interquartile range, IQR) or binary indicators for detection. As secondary analyses, we repeated analyses using categorical outcomes. Forty-one of 45 analytes were detected in at least one sample, with > 95 % detection of melamine, cyanuric acid, ammelide, and aniline. Higher melamine concentration was associated with longer gestational age (β^ per IQR increase of log2-transformed: 0.082 [95 % CI: -0.012, 0.177]; 2nd vs 1st tertile: 0.173 [-0.048, 0.394]; 3rd vs 1st tertile: 0.186 [-0.035, 0.407]). Similarly in secondary analyses using categorical outcomes, an IQR increase in log2(melamine) was associated with 1.22 [0.99, 1.50] higher odds of post-term (>40 & ≤42 weeks) as compared to full-term (≥38 & ≤40 weeks). Several AAs were associated with birthweight and gestational length, with the direction of associations varying by AA. Some stronger associations were observed in females. Our findings suggest melamine and its analogs and AAs may influence gestational length and birthweight.

Short-Term Exposure to 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine Induces Colonic Energy Metabolism Disorders in Rats

2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is one of the most abundant heterocyclic aromatic amines generated in thermally processed meat products, and the toxicities of its short-term exposure in the intestines remain unclear. This study aimed to elucidate the short-term PhIP toxicity in colons through administering PhIP orally to rats for 4 weeks. The results indicated that short-term PhIP exposure induced colonic oxidative stress, a significant decrease of serum triglyceride, and a disrupted colonic gene expression pattern associated with mitochondrial electron transport chain and energy metabolism. Thirteen energy metabolites, including lactate and d-erythrose-4-phosphate, showed significant changes under short-term PhIP effects. Energy metabolism pathway analysis revealed that PhIP-induced colonic energy metabolism disorders are characterized by inhibited glycolysis and enhanced tricarboxylic acid cycle. Further investigation found that PhIP altered the energy metabolic phenotype of colon epithelial cells to increase aerobic respiration. In summary, our study provides new insights into the colon toxicity induced by a short-term PhIP exposure.

Investigation of occurrence of aromatic amines in municipal wastewaters using passive sampling

Aromatic amines (AAs) are human-made compounds known for their mutagenic properties, entering surface waters from various sources, often originating as transformation products of dyes or pesticides. Despite their low concentrations in surface waters, AAs can exhibit mutagenicity. Our study focused on evaluating three passive samplers (PSs) for enriching these compounds from influent and effluent of a wastewater treatment plant (WWTP) in Brno, Czech Republic. The PSs tested included variants containing AttractSPE™ SDB-RPS sorbent disk, one with and one without a diffusive agarose hydrogel layer, and a modified Speedisk (Bakerbond Speedisk® H2O-Philic). PSs were deployed in wastewater (WW) for one to four weeks in various overlapping combinations, and the uptake of AAs to PSs was compared to their concentrations in 24-hour composite water samples. A targeted LC/MS analysis covered 42 amines, detecting 11 and 13 AAs in daily composite influent and effluent samples, respectively. In the influent, AAs ranged from 1.5 ng L-1 for 1-anilinonaphthalene to 1.0 μg L-1 for aniline, and the highest concentration among all measured amines was observed for cyclohexylamine at 2.9 μg L-1. In the effluent, concentrations ranged from 0.5 ng L-1 for 1-anilinonaphthalene to 88 ng L-1 for o-anisidine. PSs demonstrated comparable accumulation of amines, with integrative uptake up to 28 days in both influent and effluent and detection of up to 23 and 27 amines in influent and effluent, respectively; altogether 34 compounds were detected in the study. Sampling rates (Rs) were estimated for compounds present in at least 50 % of the samples and showing <40 % aqueous concentration variability, with robustness evaluated by comparing values for compounds in WWTP influent and effluent. Although all devices performed similarly, hydrogel-based PS exhibited superior performance in several criteria, including time integration and robustness of sampling rates, making it a suitable monitoring tool for AAs in WW.

Biodegradation characteristics of p-Chloroaniline and the mechanism of co-metabolism with aniline by Pseudomonas sp. CA-1

Co-metabolism is a promising method to optimize the biodegradation of p-Chloroaniline (PCA). In this study, Pseudomonas sp. CA-1 could reduce 76.57 % of PCA (pH = 8, 70 mg/L), and 20 mg/L aniline as the co-substrate improved the degradation efficiency by 12.50 %. Further, the response and co-metabolism mechanism of CA-1 to PCA were elucidated. The results revealed that PCA caused deformation and damage on the surface of CA-1, and the -OH belonging to polysaccharides and proteins offered adsorption sites for the contact between CA-1 and PCA. Subsequently, PCA entered the cell through transporters and was degraded by various oxidoreductases accompanied by deamination, hydroxylation, and ring-cleavage reactions. Thus, the key metabolite 4-chlorocatechol was identified and two PCA degradation pathways were proposed. Besides, aniline further enhanced the antioxidant capacity of CA-1, stimulated the expression of catechol 2,3-dioxygenase and promoted meta-cleavage efficiency of PCA. The findings provide new insights into the treatment of PCA-aniline co-pollution.

Amine Switchable Hydrophilic Solvent Vortex-Assisted Homogeneous Liquid-Liquid Microextraction and GC-MS for the Enrichment and Determination of 2, 6-DIPA Additive in Biodegradable Film

2, 6-diisopropylaniline (2, 6-DIPA) is a crucial non-intentionally organic additive that allows the assessment of the production processes, formulation qualities, and performance variations in biodegradable mulching film. Moreover, its release into the environment may have certain effects on human health. Hence, this study developed simultaneous heating hydrolysis-extraction and amine switchable hydrophilic solvent vortex-assisted homogeneous liquid-liquid microextraction for the gas chromatography-mass spectrometry analysis of the 2, 6-DIPA additive and its corresponding isocyanates in poly(butylene adipate-co-terephthalate) (PBAT) biodegradable agricultural mulching films. The heating hydrolysis-extraction conditions and factors influencing the efficiency of homogeneous liquid-liquid microextraction, such as the type and volume of amine, homogeneous-phase and phase separation transition pH, and extraction time were investigated and optimized. The optimum heating hydrolysis-extraction conditions were found to be a H2SO4 concentration of 2.5 M, heating temperature of 87.8 °C, and hydrolysis-extraction time of 3.0 h. As a switchable hydrophilic solvent, dipropylamine does not require a dispersant. Vortex assistance is helpful to speed up the extraction. Under the optimum experimental conditions, this method exhibits a better linearity (0.0144~7.200 μg mL-1 with R = 0.9986), low limit of detection and quantification (0.0033 μg g-1 and 0.0103 μg g-1), high extraction recovery (92.5~105.4%), desirable intra- and inter-day precision (relative standard deviation less than 4.1% and 4.7%), and high enrichment factor (90.9). Finally, this method was successfully applied to detect the content of the additive 2, 6-DIPA in PBAT biodegradable agricultural mulching films, thus facilitating production process monitoring or safety assessments.