Emerging contaminants: A tutorial mini-review

Nowadays, the scientific community has focused and prioritised research on "emerging pollutants". The term "emerging pollutants" stands for the substances that are released in the environment for which currently no regulations are established for their environmental monitoring. Their occurrence is reported worldwide in a range of aquatic environments, such as lakes, rivers, freshwater catchments, estuaries, reservoirs and marine waters. Nevertheless, due to their large number (ranging in an order of thousands), only few of these compounds are toxicologically evaluated. Published data concerning occurrence and potential toxicological effects is limited. The contamination source of the aquatic environment is mainly the effluents from the sewage treatment plants (STPs). Reliable methods are available for residue analysis of these pollutants down to low ng L-1 levels. However, an urgent need is highlighted for the investigation (primarily in environmental media and following in biological ones) of the toxicity and transformation pathways of all emerging pollutants. The aims of this mini-review are to briefly present: (a) the major classes of emerging pollutants; (b) the reasons why these substances constitute an environmental issue; and (c) developments and applications of environmental analysis in this field. © 2012 Global NEST Printed in Greece. All rights reserved

Development and Validation of a Multi-residue Method for the Determination of Pesticides in Chios Mastic Gum by QuEChERS and Liquid Chromatography–Tandem Mass Spectrometry

A simple, rapid, and sensitive method was developed for the simultaneous determination of 21 pesticides from different chemical classes (organophosphorus, triazines, carbamates, and anilinopyrimidine pesticides) in Chios mastic gum (Pistacia lentiscus L. var. Chia). Quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique was used for the extraction of the target analytes; the mastic gum samples were initially extracted with acetonitrile (ACN), and then, the extracts were purified by dispersive solid-phase extraction using primary secondary amine (PSA) and C18 as sorbents. The determination of pesticides in the final extract was carried out by liquid chromatography coupled with tandem mass spectrometry with electrospray ionization (LC-ESI-MS/MS). The method was validated for linearity, accuracy, precision (repeatability and inter-laboratory reproducibility), limits of detection and quantification, and the matrix effect factor. Recoveries of the pesticides fortified at 5, 50, and 500 ng g−1 ranged from 49.7 % (quinalphos) to 127 % (pirimiphos-ethyl) and reproducibility (RSDR, n = 2 × 3) ranged from 4.4 % (propham) to 20 % (pirimiphos-methyl, propham, and triazophos). The detection limits of the method were 0.8 (mecarbam, pyrazophos) to 23 ng g−1 (parathion-ethyl). The uncertainty of the method was also calculated based on the Eurachem/Citac Guidelines, and the contribution of each independent parameter was investigated. © 2014, Springer Science+Business Media New York

Qualitative multiresidue screening method for 143 veterinary drugs and pharmaceuticals in milk and fish tissue using liquid chromatography quadrupole-time-of-flight mass spectrometry

A wide-scope screening methodology has been developed for the identification of veterinary drugs and pharmaceuticals in fish tissue and milk using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). The method was validated using a qualitative approach at two concentration levels. The detection of the residues was accomplished by retention time, accurate mass, and the isotopic fit using an in-house database. Product-ion spectra were used for unequivocal identification of the compounds. Generic sample treatment was applied. The majority of the compounds were successfully detected and identified at concentration levels of 150 ng mL-1 in milk and 200 μg kg-1 in fish (>80% of the compounds in both matrices), whereas satisfactory results were also obtained at concentration levels of 15 ng mL-1 in milk and 20 μg kg-1 in fish (>60% of the compounds detected and identified). © 2015 American Chemical Society

Liquid chromatography–tandem mass spectrometric methods for the determination of spinosad, thiacloprid and pyridalyl in spring onions and estimation of their pre-harvest interval values

Two liquid chromatography–tandem mass spectrometric methods were developed and validated to determine spinosyn A and D, thiacloprid and pyridalyl in spring onions cultivated under Egyptian field conditions. The degradation rates, the pre-harvest interval (PHI) values and the half-life values of the three pesticides were estimated. QuEChERS was used for sample preparation and the separation was performed on an X-Bridge C18 column with ACN-formic acid 0.1% as the mobile phase. Linear range, method detection limits (MDLs), precision, recovery and matrix effects were estimated. The multi-residue MDLs ranged from 0.02 μg/kg (spinosyn A & D) to 0.05 μg/kg for pyridalyl. All the investigated pesticides showed high degradation rates. For spinosad the half-life value was 1.2 days, for thiacloprid it reached 2.2 days and for pyridalyl 4.4 days. Furthermore, the calculated PHI values, according to the maximum residue levels set by the EU, were 0 days for spinosad, 9.8 days for thiacloprid and 39.4 days for pyridalyl. © 2016 Elsevier Lt

Development of Specific LC-ESI-MS/MS Methods to Determine Bifenthrin, Lufenuron, and Iprodione Residue Levels in Green Beans, Peas, and Chili Peppers Under Egyptian Field Conditions

The dissipation of bifenthrin, lufenuron, and iprodione was studied in green beans, peas, and chilli peppers under Egyptian field conditions. For this purpose, three specific and one multi-analyte liquid chromatography-electrospray ionization-tandem mass spectrometry methods were developed and validated according to SANCO guidelines for the determination of bifenthrin, iprodione, and lufenuron residues in the selected commodities. Sample preparation was carried out by the QuEChERs approach, and determination was performed in positive ionization mode for iprodione and bifenthrin and in negative mode for lufenuron. Optimization of the ionization parameters and the chromatographic conditions was performed for each method developed. All methods showed satisfactory performance criteria. Linear dynamic range, limits of detection (LOD) and quantification (LOQ), precision, recovery, and matrix effects were estimated, and the calculated LODs were in the micrograms-per-kilogram range, namely 0.14, 0.61, and 1.4 μg/kg for bifenthrin, lufenuron, and iprodione, respectively. Field trials were carried out in one of the biggest farms in Egypt (Blue Nile) that exports significant quantities of vegetables to the European Union (EU) countries. All the examined pesticides showed high degradation rates. The t 1/2 values for bifenthrin were 3.3, 2.1, and 9.6 days in green beans, peas, and chili peppers, respectively. For iprodione, they reached 2.4 and 14.4 days in green beans and peppers. Furthermore, the calculated pre-harvest interval (PHI) values, according to the maximum residue limits set by EU, were 0, 4, and 0 days for bifenthrin in green beans, peas, and peppers, respectively, and for iprodione, 2 days in green beans and 0 days in peppers. In case of lufenuron, no t 1/2 and PHI were estimated as no residues were found in all pea samples. © 2012 Springer Science+Business Media New York

Quantitative Structure-Retention Relationship Models to Support Nontarget High-Resolution Mass Spectrometric Screening of Emerging Contaminants in Environmental Samples

Over the past decade, the application of liquid chromatography-high resolution mass spectroscopy (LC-HRMS) has been growing extensively due to its ability to analyze a wide range of suspected and unknown compounds in environmental samples. However, various criteria, such as mass accuracy and isotopic pattern of the precursor ion, MS/MS spectra evaluation, and retention time plausibility, should be met to reach a certain identification confidence. In this context, a comprehensive workflow based on computational tools was developed to understand the retention time behavior of a large number of compounds belonging to emerging contaminants. Two extensive data sets were built for two chromatographic systems, one for positive and one for negative electrospray ionization mode, containing information for the retention time of 528 and 298 compounds, respectively, to expand the applicability domain of the developed models. Then, the data sets were split into training and test set, employing k-nearest neighborhood clustering, to build and validate the models' internal and external prediction ability. The best subset of molecular descriptors was selected using genetic algorithms. Multiple linear regression, artificial neural networks, and support vector machines were used to correlate the selected descriptors with the experimental retention times. Several validation techniques were used, including Golbraikh-Tropsha acceptable model criteria, Euclidean based applicability domain, modified correlation coefficient (rm2), and concordance correlation coefficient values, to measure the accuracy and precision of the models. The best linear and nonlinear models for each data set were derived and used to predict the retention time of suspect compounds of a wide-scope survey, as the evaluation data set. For the efficient outlier detection and interpretation of the origin of the prediction error, a novel procedure and tool was developed and applied, enabling us to identify if the suspect compound was in the applicability domain or not. © 2016 American Chemical Society

Targeted and non-targeted liquid chromatography-mass spectrometric workflows for identification of transformation products of emerging pollutants in the aquatic environment

Identification of transformation products (TPs) of emerging pollutants is challenging, due to the vast number of compounds, mostly unknown, the complexity of the matrices and their often low concentrations, requiring highly selective, highly sensitive techniques. We compile background information on biotic and abiotic formation of TPs and analytical developments over the past five years. We present a database of biotic or abiotic TPs compiled from those identified in recent years. We discuss mass spectrometric (MS) techniques and workflows for target, suspect and non-target screening of TPs with emphasis on liquid chromatography coupled to MS (LC-MS). Both low- and high-resolution (HR) mass analyzers have been applied, but HR-MS is the technique of choice, due to its high confirmatory capabilities, derived from the high resolving power and the mass accuracy in MS and MS/MS modes, and the sophisticated software developed. © 2014 Elsevier B.V

Mass loading and fate of linear and cyclic siloxanes in a wastewater treatment plant in Greece

The occurrence and fate of 5 cyclic (D3 to D7) and 12 linear (L3 to L14) siloxanes were investigated in raw and treated wastewater (both particulate and dissolved phases) as well as in sludge from a wastewater treatment plant (WWTP) in Athens, Greece. Cyclic and linear siloxanes (except for L3) were detected in all influent wastewater and sludge samples at mean concentrations of (sum of 17 siloxanes) 20 μg L-1 and 75 mg kg-1, respectively. The predominant compounds in wastewater were L11 (24% of the total siloxane concentration), L10 (16%), and D5 (13%), and in sludge were D5 (20%) and L10 (15%). The distribution of siloxanes between particulate and dissolved phases in influents differed significantly for linear and cyclic siloxanes. Linear siloxanes showed higher solid-liquid distribution coefficients (log K d) than did cyclic compounds. For 10 of the 16 compounds detected in influents, the removal efficiency was higher than 80%. Sorption to sludge and biodegradation and/or volatilization losses are important factors that affect the fate of siloxanes in WWTPs. The mean total mass of siloxanes that enter into the WWTP via influent was 15.1 kg per day-1, and the mean total mass released into the environment via effluent was 2.67 kg per day-1. © 2013 American Chemical Society

Determination of benzotriazoles and benzothiazoles in human urine by liquid chromatography-tandem mass spectrometry

Benzotriazole (BTR) and benzothiazole (BTH) derivatives are used in a wide variety of industrial and consumer products and have been reported to occur in the environment. Owing to a lack of analytical methods, human exposure to BTR and BTH is still unknown. In this study, a liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI(+)MS/MS) method was developed for simultaneous determination of five 1,2,3-benzotriazoles and five 1,3-benzothiazoles in human urine. The target benzotriazoles were 1H-benzotriazole, 1-hydroxy-benzotriazole, tolyltriazole, xylyltriazole (or 5,6-dimethyl-1H-benzotriazole), and 5-chloro-benzotriazole, and the target benzothiazoles were benzothiazole, 2-hydroxy-benzothiazole, 2-methylthio- benzothiazole, 2-amino-benzothiazole, and 2-thiocyanomethylthio-benzothiazole. Urine specimens were enzymatically deconjugated with β-glucuronidase and extracted by a solid-phase extraction (SPE) procedure for the measurement of total concentrations (i.e., free + conjugated forms) of BTRs and BTHs. Additionally, a liquid-liquid extraction (LLE) method was developed for comparison of extraction efficiencies between SPE and LLE. The limits of detection (LODs) ranged from 0.07 (2-amino-benzothiazole) to 4.0 ng/mL (benzothiazole) for the SPE method and from 0.04 (tolyltriazole) to 6.4 ng/mL (benzothiazole) for the LLE method. A total of 100 urine specimens, collected from Athens, Greece, were analyzed by enzymatic deconjugation and SPE. Benzothiazole and tolyltriazole were found frequently, and their concentrations were on the order of a few ng/mL. To our knowledge, this is the first study on the occurrence of 10 BTR and BTH compounds in human urine. © 2012 American Chemical Society

Removal of endocrine disruptors and non-steroidal anti-inflammatory drugs through wastewater chlorination: The effect of pH, total suspended solids and humic acids and identification of degradation by-products

Endocrine disrupting chemicals (EDCs) and non-steroidal anti-inflammatory drugs (NSAIDs) are two groups of emerging pollutants the significance of which rests on their persistent detection in the aquatic environment and their possible adverse effects. Wastewater treatment plants are one of the major ways for transporting such chemicals in the aquatic environment. Chlorination is usually the last stage of treatment before wastewater being disposed to the aquatic environment. This work focuses on the evaluation of the effect of chlorine dose and specific wastewater characteristics (pH, total suspended solids and humic acids) on the removal of target EDCs and NSAIDs through chlorination. Another objective of this study is the identification of chlorination by-products of specific EDCs and NSAIDs and their dependence on contact time. Based on the results it is concluded that the effect of chlorine dose and humic acids concentration on the degradation of target compounds during chlorination is minimal. On the contrary, pH is a critical parameter which highly affects process performance. Moreover, it is concluded that not only the free available chlorine species, but also the properties of EDCs and NSAIDs under different pH conditions can affect chlorination process performance. The effect of TSS on the degradation of the target compounds during chlorination is more profound for chemicals with high Kow values and therefore higher affinity to partition to the particulate phase (i.e. nonylphenols, triclosan). Several degradation by-products were identified through chlorination of nonylphenol, bisphenol A and diclofenac. The dependence of these by-products on chlorination contact time is also demonstrated. © 2014 Elsevier Ltd