Determination of 19 volatile organic compounds in wastewater effluents from different treatments by purge and trap followed by gas-chromatography coupled to mass spectrometry

Traditional methods and biosensors for detecting disinfection by-products in water: A review

In recent years, pollution caused by disinfection by-products (DBPs) has become a global concern. Initially, there were fewer contaminants, and the mechanism of their generation was unclear; however, the number of contaminants has increased exponentially as a result of rapid industrialization and numerous economic activities (e.q., during the outbreak of COVID-19 a surge in the use of chlorinated disinfectants was observed). DBP toxicity results in various adverse health effects and organ failure in humans. In addition, it profoundly affects other forms of life, including animals, plants, and microorganisms. This review comprehensively discusses the pre-treatment methods of traditional and emerging DBPs and the technologies applied for their detection. Additionally, this paper provides a detailed discussion of the principles, applicability, and characteristics of traditional large-scale instrumentation methods (such as gas/liquid/ion chromatography coupled with mass spectrometry) for detecting DBPs based on their respective detection techniques. At the same time, the design, functionality, classification, and characteristics of rapid detection technologies (such as biosensors) are also detailed and analyzed.

Trihalomethanes in water samples: Recent update on pretreatment and detection methods

Trihalomethanes (THMs) are classified as volatile organic compounds, considered to be a disinfection by-product during water disinfection process. THMs have been shown to be cytotoxic, genotoxic and mutagenic, with a risk of cancer when they contact with people directly. To protect public health and monitor water quality, it is important to monitor and measure THMs in drinking water. Therefore, it is crucial to develop fast, accurate, highly sensitivity and green analysis methods of THMs in various complicated matrices. Here, this review presents an overall summary of the current state of the pretreatment and detection methods for THMs in various sample matrices since 2005. In addition to the traditionally used pretreatment methods for THMs (such as headspace extraction, microwave-assisted extraction, liquid-liquid extraction), the new-developed methods, including solid-phase extraction, QuEChERS and different microextraction methods, have been summarized. The detection methods include gas chromatography-based methods, sensors and several other approaches. Additionally, benefits and limitations of different techniques were also discussed and compared. This study is anticipated to offer fruitful insights into the further advancement and widespread applications of pretreatment and detection technologies for THMs as well as for related substances.

Comprehensive chemical characterization of dissolved organic matter in typical point-source refinery wastewaters

In petroleum refineries, the electric desalting, distillation, and stripping processes could generate large amounts of wastewaters that contain toxic substances. In this study, eight wastewater samples were collected from the three typical refining processes for comprehensive chemical characterization of the dissolved organic matter (DOM) using excitation emission matrix fluorescence spectroscopy, gas chromatography-mass spectrometry, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Results showed that protein-like components and benzene were ubiquitous in all these wastewaters. Oxygen-containing volatile organic compounds had higher contents in crude distillation and stripping wastewater than those in electric desalting wastewater. Among the three refinery processes, molecular composition of DOM in the stripping wastewater had the highest complexity. The O_x and O_xS_y class species assigned from the negative-ion electrospray ionization FT-ICR MS were dominant in all wastewaters. The O_xS₂ class species which were effectively removed during stripping treatment had highest relative abundance in stripping influent. These results are instructive to guide the development of "divide and conquer" and would improve the treatment and management of refinery wastewater streams.

Abatement of Polychoro-1,3-butadienes in Aqueous Solution by Ozone, UV Photolysis, and Advanced Oxidation Processes (O3/H2O2 and UV/H2O2)

The abatement of 9 polychloro-1,3-butadienes (CBDs) in aqueous solution by ozone, UV-C(254 nm) photolysis, and the corresponding advanced oxidation processes (AOPs) (i.e., O₃/H₂O₂ and UV/H₂O₂) was investigated. The following parameters were determined for 9 CBDs: second-order rate constants for the reactions of CBDs with ozone (k_O3) (<0.1-7.9 × 10³ M^-1 s^-1) or with hydroxyl radicals (k_^•OH) (0.9 × 10⁹ - 6.5 × 10⁹ M^-1 s^-1), photon fluence-based rate constants (k') (210-2730 m² einstein^-1), and quantum yields (Φ) (0.03-0.95 mol einstein^-1). During ozonation of CBDs in a natural groundwater, appreciable abatements (>50% at specific ozone doses of 0.5 gO₃/gDOC to ∼100% at ≥1.0 gO₃/gDOC) were achieved for tetra-CBDs followed by (Z)-1,1,2,3,4-penta-CBD and hexa-CBD. This is consistent with the magnitude of the determined k_O3 and k_^•OH. The formation of bromate, a potentially carcinogenic ozonation byproduct, could be significantly reduced by addition of H₂O₂. For a typical UV disinfection dose (400 J/m²), various extents of phototransformations (10-90%) could be achieved. However, the efficient formation of photoisomers from CBDs with E/Z configuration must be taken into account because of their potential residual toxicity. Under UV-C(254 nm) photolysis conditions, no significant effect of H₂O₂ addition on CBDs abatement was observed due to an efficient direct phototransformation of CBDs.

Quality classification of Spanish olive oils by untargeted gas chromatography coupled to hybrid quadrupole-time of flight mass spectrometry with atmospheric pressure chemical ionization and metabolomics-based statistical approach

The novel atmospheric pressure chemical ionization (APCI) source has been used in combination with gas chromatography (GC) coupled to hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) for determination of volatile components of olive oil, enhancing its potential for classification of olive oil samples according to their quality using a metabolomics-based approach. The full-spectrum acquisition has allowed the detection of volatile organic compounds (VOCs) in olive oil samples, including Extra Virgin, Virgin and Lampante qualities. A dynamic headspace extraction with cartridge solvent elution was applied. The metabolomics strategy consisted of three different steps: a full mass spectral alignment of GC-MS data using MzMine 2.0, a multivariate analysis using Ez-Info and the creation of the statistical model with combinations of responses for molecular fragments. The model was finally validated using blind samples, obtaining an accuracy in oil classification of 70%, taking the official established method, "PANEL TEST", as reference.

Correlation of selected molecular properties and recovery values in volatile organic compounds analysis: comparison of two water matrices

This study investigates if certain molecular properties can influence the recovery of 18 volatile organic compounds (VOCs) in water under the applied analytical conditions, a P&T GC method with MS detection.

Priority organic compounds in wastewater effluents from the Mediterranean and Atlantic basins of Andalusia (Spain)

A comprehensive survey of the occurrence of organic compounds in 30 wastewater (WW) effluent samples from 21 urban wastewater treatment plants (WWTPs) from both secondary and tertiary treatments was carried out in the Mediterranean and Atlantic basins of the Andalusia region (south of Spain). For each sample, a total of 226 compounds including pesticides and some transformation products, polycyclic aromatic hydrocarbons (PAHs), phenolic compounds and volatile organic compounds (VOCs) were monitored with the aim of evaluating their occurrence in urban WW effluents. Compounds belonging to each class were detected. Among pesticides, insecticides such as clorfenvinphos and diazinon as well as herbicides such as diuron, sebuthylazine, terbuthylazine and terbuthylazine desethyl were the most frequently detected. The ubiquity of some compounds such as fluorene, phenanthrene and pyrene was also demonstrated. The compounds evaluated were detected at low concentrations (in general below 1 μg L(-1)), except 4-tert-octylphenol, which was detected at extremely high concentrations (up to 443 μg L(-1)). PAHs and VOCs were the compounds most frequently detected in the assayed samples, and they are the main sources of contamination in WWTPs, as well as some herbicides and transformation products.

Systematic study of the contamination of wastewater treatment plant effluents by organic priority compounds in Almeria province (SE Spain)

The occurrence of priority organic pollutants in wastewater (WW) effluents was evaluated in a semi-arid area, characterized by a high agricultural and tourism activity, as Almeria province (Southeastern Spain). Twelve wastewater treatment plants (WWTPs) were sampled in three campaigns during 2011, obtaining a total of 33 WW samples, monitoring 226 compounds, including pesticides, polycyclic aromatic hydrocarbons (PAHs), phenolic compounds and volatile organic compounds (VOCs). Certain banned organochlorine pesticides such as aldrin, pentachlorobenzene, o,p'-DDD and endosulfan lactone were found, and the most frequently detected pesticides were herbicides (diuron, triazines). PAHs and VOCs were also detected, noting that some of these pollutants were ubiquitous. Regarding phenolic compounds, 4-tertoctylphenol was found in all the WW samples at high concentration levels (up to 89.7 μg/L). Furthermore, it was observed that WW effluent samples were less contaminated in the second and third sampling periods, which corresponded to dry season. This evaluation revealed that despite the WW was treated in the WWTP, organic contaminants are still being detected in WW effluents and therefore they are released into the environment. Finally the risk of environmental threat due to the presence of some compounds in WWTP effluents, especially concerning 4-tertoctylphenol must be indicated.