Use of nanomaterials in the pretreatment of water samples for environmental analysis

The challenge of providing clean drinking water is of enormous relevance in today’s human civilization, being essential for human consumption, but also for agriculture, livestock and several industrial applications. In addition to remediation strategies, the accurate monitoring of pollutants in water sup-plies, which most of the times are present at low concentrations, is a critical challenge. The usual low concentration of target analytes, the presence of in-terferents and the incompatibility of the sample matrix with instrumental techniques and detectors are the main reasons that renders sample preparation a relevant part of environmental monitoring strategies. The discovery and ap-plication of new nanomaterials allowed improvements on the pretreatment of water samples, with benefits in terms of speed, reliability and sensitivity in analysis. In this chapter, the use of nanomaterials in solid-phase extraction (SPE) protocols for water samples pretreatment for environmental monitoring is addressed. The most used nanomaterials, including metallic nanoparticles, metal organic frameworks, molecularly imprinted polymers, carbon-based nanomaterials, silica-based nanoparticles and nanocomposites are described, and their applications and advantages overviewed. Main gaps are identified and new directions on the field are suggested.publishe

Environment-Responsive Alkanol-Based Supramolecular Solvents: Characterization and Potential as Restricted Access Property and Mixed-Mode Extractants

Self-assembly, the process by which supramolecular solvents (SUPRAS) with an ordered structure are produced, provides unique opportunities to obtain tailored solvents with advanced functional features. In this work, environment-responsive (C₇–C₁₄) alkanol-based SUPRAS were synthesized and their potential for analytical extractions was assessed. The global composition of the solvent, the size of the coacervate droplets that form it, and the aqueous cavities of the inverted hexagonal arrangement of the alkanols can be tailored by controlling the environment [specifically, the tetrahydrofuran (THF):water ratio in the bulk solution] for alkanol self-assembly. Interestingly, supramolecular solvents are highly adaptive and the previous features can all be reversed by modifying the environment. The spontaneous self-assembly of these solvents followed predictable routes, and their composition and volume can be accurately predicted from equations derived in this work. The solvents were structurally elucidated by light and cryo-scanning electron microscopy. Extractive applications exploiting the molecular size-based restricted access properties of SUPRAS were developed and their ability to engage in mixed-mode mechanisms for solute solubilization was established. Thus, solutes of increasing molecular weight were extracted from food and environmental samples with recoveries dependent on vacuole size in the SUPRAS, while macromolecules such as proteins, carbohydrates, and humic acids were excluded. The ability of SUPRAS to establish hydrogen-bonding and dispersion interactions was exploited to extract carcinogenic chlorophenols (CCPs) from environmental waters, and a simple and fast method was developed with quantitation limits (e.g., 0.21–0.23 μg·L^–1) low enough to comply with legislation (e.g., maximum permitted levels for pentachlorophenol are in the range 0.4–1 μg·L^–1)

In Vitro Human Metabolism of the Flame Retardant Resorcinol Bis(diphenylphosphate) (RDP)

Resorcinol bis­(diphenylphosphate) (RDP) is widely used as a flame retardant in electrical/electronic products and constitutes a suitable alternative to decabrominated diphenyl ether. Due to its toxicity and its recently reported ubiquity in electronics and house dust, there are increasing concerns about human exposure to this emerging contaminant. With the aim of identifying human-specific biomarkers, the in vitro metabolism of RDP and its oligomers was investigated using human liver microsomes and human liver cytosol. Mono- and dihydroxy-metabolites, together with glucuronidated and sulfated metabolites, were detected. Regarding RDP oligomers, only a hydroxy-metabolite of the dimer could be detected. RDP and its oligomers were also readily hydrolyzed, giving rise to a variety of compounds, such as diphenyl phosphate, <i>para</i>-hydroxy-triphenyl phosphate, and <i>para</i>-hydroxy RDP, which were further metabolized. These degradation products or impurities are possibly of environmental importance in future studies

A Novel Brominated Triazine-based Flame Retardant (TTBP-TAZ) in Plastic Consumer Products and Indoor Dust

The presence of a novel brominated flame retardant named 2,4,6-tris­(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) is reported for the first time in plastic parts of consumer products and indoor dust samples. TTBP-TAZ was identified by untargeted screening and can be a replacement of the banned polybrominated diphenyl ethers. Analysis techniques based on ambient mass spectrometry and on liquid chromatography with atmospheric pressure chemical ionization combined with high resolution time-of-flight mass spectrometry were developed for the screening, detection and quantification of this low volatility and high molecular weight compound. TTBP-TAZ was present in 8 of 13 plastic parts of consumer products (from mainly electric and electronic equipment acquired in 2012) at estimated concentrations of 0.01–1.9% by weight of the product (%, w/w). It was not present in any of the older 13 plastic samples that were collected in a recycling park (manufacture date before 2006), this suggests a recent use of TTBP-TAZ. It was also found in 9 of 17 house dust samples in the range of 160–22150 ng g^–1, with the highest levels being found in samples collected on electronic and electrical equipment. These preliminary results highlight the need for further research on TTBP-TAZ and the potential of using alternative analysis methods for the identification of new flame retardants

Novel Analytical Methods for Flame Retardants and Plasticizers Based on Gas Chromatography, Comprehensive Two-Dimensional Gas Chromatography, and Direct Probe Coupled to Atmospheric Pressure Chemical Ionization-High Resolution Time-of-Flight-Mass Spectrometry

In this study, we assess the applicability of different analytical techniques, namely, direct probe (DP), gas chromatography (GC), and comprehensive two-dimensional gas chromatography (GC × GC) coupled to atmospheric pressure chemical ionization (APCI) with a high resolution (HR)-time-of-flight (TOF)-mass spectrometry (MS) for the analysis of flame retardants and plasticizers in electronic waste and car interiors. APCI-HRTOFMS is a combination scarcely exploited yet with GC or with a direct probe for screening purposes and to the best of our knowledge, never with GC × GC to provide comprehensive information. Because of the increasing number of flame retardants and questions about their environmental fate, there is a need for the development of wider target and untargeted screening techniques to assess human exposure to these compounds. With the use of the APCI source, we took the advantage of using a soft ionization technique that provides mainly molecular ions, in addition to the accuracy of HRMS for identification. The direct probe provided a very easy and inexpensive method for the identification of flame retardants without any sample preparation. This technique seems extremely useful for the screening of solid materials such as electrical devices, electronics and other waste. GC-APCI-HRTOF-MS appeared to be more sensitive compared to liquid chromatography (LC)-APCI/atmospheric pressure photoionization (APPI)-HRTOF-MS for a wider range of flame retardants with absolute detection limits in the range of 0.5–25 pg. A variety of tri- to decabromodiphenyl ethers, phosphorus flame retardants and new flame retardants were found in the samples at levels from microgram per gram to milligram per gram levels

Impurities of Resorcinol Bis(diphenyl phosphate) in Plastics and Dust Collected on Electric/Electronic Material

Resorcinol bis­(diphenylphosphate) (RDP) is an organophosphorus flame retardant widely used in electric and electronic equipment. It has been detected in house dust of several European countries according to recent literature. Similar to other flame retardants, RDP formulations and products treated with RDP, such as plastics, can contain RDP impurities, byproducts and breakdown products. In this study, we use screening methods based on wide scope solvent extraction and high resolution time-of-flight mass spectrometry for the identification of RDP related compounds in products and in dust. We analyzed both plastics from electrical/electronic equipment that contained RDP and indoor dust collected on and around surfaces of this equipment. A variety of compounds, namely TPHP, hydroxylated TPHP and RDP (<i>meta</i>-HO-TPHP and <i>meta</i>-HO-RDP), dihydroxylated TPHP, RDP with the loss of a phenyl group (RDP-[Phe]) and RDP oligomers were detected in plastics containing high levels of RDP. Regarding dust samples collected on electronics, TPHP <i>meta</i>-HO-TPHP, <i>meta</i>-HO-RDP, RDP-[Phe] and RDP oligomers were detected. High concentrations of <i>meta</i>-HO-TPHP (20–14 227 ng/g), TPHP (222–50 728 ng/g) and RDP (23–29 118 ng/g) were found in many of the dust samples, so that these compounds seem to easily migrate into the environment. These RDP impurities, byproducts and breakdown products are for the first time reported in indoor dust. <i>Meta</i>-HO-TPHP could be relevant for future biomonitoring studies concerning flame retardants

Identification of Novel Brominated Compounds in Flame Retarded Plastics Containing TBBPA by Combining Isotope Pattern and Mass Defect Cluster Analysis

The study of not only main flame retardants but also of related degradation products or impurities has gained attention in the last years and is relevant to assess the safety of our consumer products and the emission of potential contaminants into the environment. In this study, we show that plastics casings of electric/electronic devices containing TBBPA contain also a complex mixture of related brominated chemicals. These compounds were most probably coming from impurities, byproducts, or degradation products of TBBPA and TBBPA derivatives. A total of 14 brominated compounds were identified based on accurate mass measurements (formulas and tentative structures proposed). The formulas (or number of bromine elements) for 19 other brominated compounds of minor intensity are also provided. A new script for the recognition of halogenated compounds based on combining a simplified isotope pattern and mass defect cluster analysis was developed in R for the screening. The identified compounds could be relevant from an environmental and industrial point of view