The role of analytical chemistry in exposure science: Focus on the aquatic environment

Economically feasible strategy for confirmation of pharmaceuticals in hospital effluent using screening analysis

The contamination of aquatic systems by pharmaceuticals has received considerable attention in recent decades, because these substances are increasingly detected in the environment. This is due to the abundant use of pharmaceuticals by the population and, consequently, their constant introduction into aquatic systems through domestic, industrial, and hospital wastewaters. Hospital effluents have highly complex compositions and present potential toxicity towards the environment. In this work, a screening methodology was developed to evaluate the occurrence of pharmaceutical products in hospital wastewater, using a viable, easy, and economical strategy employing commercial pharmaceutical compounds for screening analysis. Six samplings of hospital wastewater were carried out monthly (from winter until summer). The samples were filtered and pre-concentrated/extracted using solid phase extraction (SPE). The pharmaceuticals screening procedure required the construction of two databases, one for each ionization mode (positive and negative), which contained information that allowed the identification of the presence of these pharmaceuticals in the studied samples. Commercial pharmaceutical compounds were used as analytical standards. Based on this strategy and, using liquid chromatography coupled to high resolution mass spectrometry, it was possible to screen 110 pharmaceuticals and, from these, to confirm the presence of 38 pharmaceuticals in analyzed samples. These results indicate the analytes that should be taken into account in the further development of quantitative methods for pharmaceutical analysis.

Recent progresses in analytical GC and LC mass spectrometric based-methods for the detection of emerging chlorinated and brominated contaminants and their transformation products in aquatic environment

This paper is an overview of screening methods recently developed for emerging halogenated contaminants and their transformation products. The target screening methods are available only for a limited number of emerging pollutants since the reference standards for these compounds are not always available, but a risk assessment of those micropollutants in environment must be performed anyhow. Therefore, the chromatographic techniques hyphenated with high resolution mass spectrometry (HRMS) trend to become indispensable methods for suspect and non-target screening of emerging halogenated contaminants. HRMS is also an effective tool for tentatively identification of the micropollutants' transformation products existing in much lower concentrations. To assess the transformation pathway of halogenated contaminants in environment, the non-target screening methods must be combined with biodegradation lab experiments and also with advanced oxidation and reduction processes that can mimic the transformation on these contaminants in environment. It is expected that in the future, the accurate-mass full-spectra of transformation products recorded by HRMS will be the basic information needed to elucidate the transformation pathways of emerging halogenated contaminants in aquatic environment.

Identification of Aquifer Recharge Sources as the Origin of Emerging Contaminants in Intensive Agricultural Areas. La Plana de Castellón, Spain

In urban, industrial, and agricultural areas, a vast array of contaminants may be found because they are introduced into the aquifers by different recharge sources. The emerging contaminants (ECs) correspond to unregulated contaminants, which may be candidates for future regulation depending on the results of research into their potential effects on health and on monitoring data regarding their occurrence. ECs frequently found in wastewater, such as acetaminophen, carbamazepine, primidone, and sulfamethoxazole, may be good indicators of the introduction of the reclaimed water to the aquifers. The resistance of the ECs to removal in wastewater treatment plants (WWTPs) causes them to be appropriate sewage markers. Plana de Castellón (Spain) is a coastal area that has been characterized by intensive citrus agriculture since the 1970s. Traditionally, in the southern sector of Plana de Castellón, 100% of irrigation water comes from groundwater. In recent years, local farmers have been using a mixture of groundwater and reclaimed water from wastewater treatment plants (WWTPs) to irrigate the citrus. The aims of the present study were: (i) to assess the occurrences, spatial distributions, and concentrations of selected ECs, including 32 antibiotics, 8 UV filters, and 2 nonsteroidal anti-inflammatory drugs, in groundwater in a common agricultural context; (ii) to identify the recharge (pollution) sources acting as the origin of the ECs, and (iii) to suggest ECs as indicators of reclaimed water arrival in detrital heterogeneous aquifers. The obtained data provided relevant information for the management of water resources and elucidated the fate and behavior of emerging contaminants in similar contexts.

Suspect and Nontarget Screening for Contaminants of Emerging Concern in an Urban Estuary

This study used suspect and nontarget screening with high-resolution mass spectrometry to characterize the occurrence of contaminants of emerging concern (CECs) in the nearshore marine environment of Puget Sound (WA). In total, 87 non-polymeric CECs were identified; those confirmed with reference standards (45) included pharmaceuticals, herbicides, vehicle-related compounds, plasticizers, and flame retardants. Eight polyfluoroalkyl substances were detected; perfluorooctanesulfonic acid (PFOS) concentrations were as high as 72-140 ng/L at one location. Low levels of methamphetamine were detected in 41% of the samples. Transformation products of pesticides were tentatively identified, including two novel transformation products of tebuthiuron. While a hydrodynamic simulation, analytical results, and dilution calculations demonstrated the prevalence of wastewater effluent to nearshore marine environments, the identity and abundance of selected CECs revealed the additional contributions from stormwater and localized urban and industrial sources. For the confirmed CECs, risk quotients were calculated based on concentrations and predicted toxicities, and eight CECs had risk quotients >1. Dilution in the marine estuarine environment lowered the risks of most wastewater-derived CECs, but dilution alone is insufficient to mitigate risks of localized inputs. These findings highlighted the necessity of suspect and nontarget screening and revealed the importance of localized contamination sources in urban marine environments.

Investigation of pharmaceuticals and their metabolites in Brazilian hospital wastewater by LC-QTOF MS screening combined with a preliminary exposure and in silico risk assessment

This work evaluates the occurrence of pharmaceuticals, with special emphasis on their metabolites, in raw hospital wastewater (HWW) using wide-scope screening based on liquid chromatography coupled to high resolution mass spectrometry. The applied strategy uses an extended purpose-built database, containing >1000 pharmaceuticals and 250 metabolites. Raw HWW samples from a hospital located in south Brazil were collected over six months, with a monthly sampling frequency. Accurate-mass full-spectrum data provided by quadrupole-time of flight MS allowed the identification of 43 pharmaceuticals and up to 31 metabolites in the samples under study. Additionally, other four metabolites not included in the initial database could be identified using a complementary strategy based on the common fragmentation pathway between the parent compound and its metabolites. Nine metabolites derived from four pharmaceuticals were identified in the raw HWW samples, whereas their parent compounds were not found in these samples. The results of this work illustrate the importance of including not only parent pharmaceuticals but also their main metabolites in screening analysis. Besides, the inclusion of in silico QSAR predictions allowed assessing the environmental fate and effect of pharmaceuticals and metabolites in terms of biodegradability, as possible Persistent, Bioaccumulative and Toxic (PBT) compounds, and their potential hazard to the aquatic environment.

Ultrasensitive electroanalytical sulfisoxazole sensors amplified with Pd-doped ZnO nanoparticles and modified with 1-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide

In this study, an electrochemical sensor has been introduced by incorporating Pd-doped ZnO nanoparticles (ZnO–Pd/NPs) into a carbon paste (CP) matrix amplified by a conductive binder (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (1H3MIBTMSI), in this case) to determine the concentration of the sulfisoxazole (SFX) drug in urine, tablet, and pharmaceutical wastewater samples.

Enhanced Photocatalytic Activity of Semiconductor Nanocomposites Doped with Ag Nanoclusters Under UV and Visible Light

Emerging contaminants (ECs) represent a wide range of compounds, whose complete elimination from wastewaters by conventional methods is not always guaranteed, posing human and environmental risks. Advanced oxidation processes (AOPs), based on the generation of highly oxidizing species, lead to the degradation of these ECs. In this context, TiO2 and ZnO are the most widely used inorganic photocatalysts, mainly due to their low cost and wide availability. The addition of small amounts of nanoclusters may imply enhanced light absorption and an attenuation effect on the recombination rate of electron/hole pairs, resulting in improved photocatalytic activity. In this work, we propose the use of silver nanoclusters deposited on ZnO nanoparticles (ZnO–Ag), with a view to evaluating their catalytic activity under both ultraviolet A (UVA) and visible light, in order to reduce energetic requirements in prospective applications on a larger scale. The catalysts were produced and then characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and inductively coupled plasma-optical emission spectrometry (ICP-OES). As proof of concept of the capacity of photocatalysts doped with nanoclusters, experiments were carried out to remove the azo dye Orange II (OII). The results demonstrated the high photocatalytic efficiency achieved thanks to the incorporation of nanoclusters, especially evident in the experiments performed under white light.

Geophagus brasiliensis (Teleostei: Cichlidae) as an indicator of toxicity of ornamental stone processing wastes

Massive exploitation of geological resources may lead to environmental issues due to the inadequate disposal of the processing wastes, which are potentially hazard to terrestrial and aquatic environments. To evaluate the toxic effects ornamental stones processing wastes (OSPW), Geophagus brasiliensis fish were contaminated with different concentrations of OSPW (250, 500, 750 and 1000 mg/L). The contaminated aquarium water showed increased total hardness and Ca, Na, K, Mg and Mn content, which lead to bioconcentration of Na⁺, K⁺ and Mg²⁺ in G. brasiliensis gills. The highest concentration of OSPW induced slight to moderate histopathological lesions in gills of exposed fish, such as structural detachment, hyperplasia of the lamellar epithelium and incomplete fusion of several lamellae. Micronucleus and comet assays revealed a dose-dependent genotoxic damage in fish exposed to the contaminant. The biochemical analysis revealed a slight increase in catalase and reduction in superoxide dismutase activities in exposed fish, indicating that OSPW affects the oxidative stress of G. brasiliensis. The no observed effect concentration (NOEC) and lowest observed effect concentration (LOEC) parameters indicate that low concentrations of OSPW (even under 250 mg/L) may be detrimental to exposed organisms by causing oxidative damage. This study demonstrates the toxic potential of OSPW in G. brasiliensis, even in short-term exposure, revealing some morphologic and molecular parameters that may be used as biomarkers in monitoring aquatic ecosystems contaminated with this effluent.

DEET occurrence in wastewaters: Seasonal, spatial and diurnal variability - mismatches between consumption data and environmental detection

DEET (N, N-diethyl-m-toluamide) is one of the most frequently detected trace organic contaminants (TOrC) in wastewaters and is used primarily as an insect repellent. It was introduced for use in the general public in 1957. It is ubiquitously present in the environment and DEET concentrations are usually among the highest reported for TOrCs. Due to recent concerns about possible analytical interferences in detection methods being reported, this study focused on possible artifacts caused by seasonal, spatial, and diurnal variations in wastewater influent concentration of DEET. We also compared usage data to observed wastewater concentrations of seven wastewater treatment plants (WWTPs) in four different regions in the US monitored from November 2014 to November 2016. Consumption data obtained reveal patterns of consumption according to climatic regions and season. During the summer DEET usage accounts for almost 60% of all usage during a year, while during the winter months DEET usage accounts for <5%. Concerning spatial distribution, while per capita consumption of DEET in Florida is three times higher than the one observed in Arizona (44 g vs 14 g), DEET concentrations in wastewater tend to be much higher in Arizona. Regardless of WWTPs or monitoring period, concentrations as high as 15,200 ng/L were observed during the month of October 2016. While DEET has a diurnal variation in the wastewater influent, with a maximum at 18:00, the diurnal variability is not enough to explain the great discrepancies between consumption of DEET versus occurrence in wastewaters. Although LC-MS/MS analysis of isobaric and structural mimics suggests some possibility of interferences, NMR spectroscopy analysis of environmental samples does not support the presence of such mimics in real samples.