Emerging Compounds in Mexico: Challenges for Their Identification and Elimination in Wastewater

In recent years, the presence of organic pollutants has received great attention due to their effects on public health and biota. Within this set of compounds, a new range of compounds that are characterized by their high persistence and low degradation have been identified, called Emerging Compounds. Emerging pollutants include a wide variety of products for daily use of different structures, domestic and industrial applications, such as: pesticides, industrial and personal hygiene products, hormones, and drugs, most of which are toxic, persistent and bioaccumulative. A characteristic of these types of pollutants is that current wastewater treatment plants are unable to remove them; they are designed to remove organic matter and nutrients in higher concentrations. In Mexico there is little information on the concentration levels of these compounds, due to the lack of public policies aimed at providing resources to institutions and researchers trained to carry out this type of study. On the other hand, the technological infrastructure of the wastewater treatment plants is insufficient for the country’s demand. This situation represents one of the greatest challenges for the authorities responsible for the management of water resources, in the immediate time if it is intended to preserve said resource and therefore take care of the health of the population

Optimization and Application of a GC-MS Method for the Determination of Endocrine Disruptor Compounds in Natural Water

Bisphenol A (BPA), 4-nonylphenol (4NP), estradiol (E2), and ethinylestradiol (EE2) are considered as endocrine disruptors or mutagens. These compounds are commonly called endocrine disrupter chemicals (EDCs). BPA and 4NP are widely used as plastic additives, lacquers, resins, or surfactants, while E2 is one of the predominant female sex hormones during the reproductive years, and EE2 is an estrogen derived from estradiol, used in the production of contraceptive pills. All of these can be usually found in wastewater. In Mexico, it is common for water from rivers, lakes, and canyons to be reused for different purposes. Unfortunately, there is little information on the concentration of many of the pollutants present in such bodies of water. To determine the presence of these compounds in samples of wastewater in the Apatlaco River, an accurate and reproducible method was developed by coupling gas chromatography to mass spectrometry (GC-MS). A solid-phase extraction with Chromabond RP-18 cartridges was carried out, and the elution was performed with an acetone/methanol mixture. After isolation, the solvent was removed and a silylation step was carried out using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). Recoveries for spiked samples were between 71.8% and 111.0%. The instrumental limits of detection (IDL) ranged between 24.7 and 37.0 ng mL−1. In total, 16 samples were taken in 2015 at the microbasin of the Apatlaco River, located in the state of Morelos. The maximum concentrations found were 4NP (85.5 ng mL−1), BPA (174.6 ng mL−1), E2 103.6 (ng mL−1), and EE2 (624.3 ng mL−1)

Spectral Characteristics Related to Chemical Substructures and Structures Indicative of Organic Precursors from Fulvic Acids in Sediments by NMR and HPLC-ESI-MS

The aim of this work was to determine Fulvic Acids (FAs) in sediments to better know their composition at the molecular level and to propose substructures and structures of organic precursors. The sediment samples were obtained from a priority area for the conservation of ecosystems and biodiversity in Mexico. FAs were extracted and purified using modifications to the International Humic Substances Society method. The characterization was carried out by 1D and 2D nuclear magnetic resonance (NMR) and high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) in positive (ESI+) and negative (ESI−) modes. Twelve substructures were proposed by the COSY and HSQC experiments, correlating with compounds likely belonging to lignin derivatives obtained from soils as previously reported. The analysis of spectra obtained by HPLC-ESI-MS indicated likely presence of compounds chemically similar to that of the substructures elucidated by NMR. FAs studied are mainly constituted by carboxylic acids, hydroxyl, esters, vinyls, aliphatics, substituted aromatic rings, and amines, presenting structures related to organic precursors, such as lignin derivatives and polysaccharides

Occurrence and Risk Assessment of Steroidal Hormones and Phenolic Endocrine Disrupting Compounds in Surface Water in Cuautla River, Mexico

In this study, two hormones 17β-estradiol (E2) and 17α-ethynylestradiol (EE2), and three phenolic compounds, bisphenol A (BPA), 4-N-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP), were determined in surface water in the Cuautla River at the State of Morelos during the dry-season in Mexico. The endocrine disrupting compounds (EDCs) were extracted from water samples using solid-phase extraction (SPE) with end-capped C18, and then the extracts were chemically derivatized to TMS (trimethylsylane)-compounds and analyzed by gas chromatography coupled to mass spectrometry (GCMS). The most abundant compound was BPA (22.46 ± 30.17 ng L−1), followed by 4-t-OP (11.24 ± 11.76 ng L−1), 4-NP (7.53 ± 14.88 ng L−1), EE2 (2.37 ± 4.36 ng L−1) and E2 (0.97 ± 1.82 ng L−1). The residual amounts of target compounds could either reach stream surface water from direct domestic wastewater discharges, conventional wastewater treatment plant or can be a result from the use of agrochemicals in crop areas. The EDCs in Cuautla River exerted a high pressure on the aquatic ecosystem because their presences in surface water caused medium and high potential ecological risk. Besides, it was found that aquatic organisms were exposed to estrogenic activity