Analysis of emerging and related pollutants in aquatic biota

Water bodies cover approximately 70 % of the earth´s surface, making them ecosystems with a high environmental value and the habitat for numerous species of flora and fauna. Emerging pollutants (EPs) are ubiquitous anthropogenic compounds of environmental concern that can be found at different concentration levels in matrices such as sediment, water and aquatic biota. In addition, EPs can be bioaccumulated and biomagnified, inducing adverse effects on biota, and posing a risk to humans when contaminated biota is consumed. Unlike abiotic matrices, the occurrence of EPs in aquatic biota has not been widely studied. This is probably because their complexity, due to the presence of lipids, proteins and other organic compounds, makes the extraction and analysis of EPs difficult. This review gathers the most relevant analytical methods published between 2014 and 2019, comparing them and evaluating their strengths and weaknesses. It is intended to provide a better understanding of the development of new and improved methods, and to be a reference for researchers who are looking for the best methodology for their studies.     

An Application of Capillary Electrophoresis for the Analysis of Algal Toxins from the Aquatic Environment

In this work capillary electrophoresis (CE) with UV detection has been applied to the analysis of different natural toxins produced in the aquatic environment. This technique is presented as an alternative to other chemical techniques such as HPLC, and the optimisation of analytical methodologies was carried out for diverse marine toxins including Paralytic and Amnesic and some polyether toxins, such as Yessotoxins, as well as for certain microcystin toxins produced by cyanobacteria present in freshwaters. Sample preparation steps were optimised and adequate electrophoretic conditions developed for achieving a complete separation of compounds with similar structures involved in such contamination. The influence of the biological matrices where they are involved has also been studied and the potential use of CE-UV as a tool for monitoring these aquatic toxins is also discussed.     

Applications of particle-tracking analysis to the determination of size distributions and concentrations of nanoparticles in environmental, biological and food samples

The manufacture of nanoparticles (NPs) and nanomaterial-based products is rapidly increasing and their possible occurrence in environment, food or biological tissue is becoming of concern for ecological and human health. However, there is a lack of suitable methods to analyze and to characterize NPs in low concentrations in complex matrixes. We compare several particle-tracking methods using video microscopy and a new technique called nanoparticle-tracking analysis (NTA). Video microscopy has been widely applied to investigate particle movement in biological samples, micro-rheology, and velocity profiles in fluids, whilst NTA was devised for determination of size distributions and concentrations in liquid samples. We critically discuss the advantages and the limitations of NTA for such applications.     

Evaluating engineered nanoparticles in natural waters

With the accelerating introduction of engineered nanomaterials into commercial products and their potential use in water-treatment processes, it is inevitable that these materials will ultimately reside at some level in our recreational and drinking waters, thereby creating a critical need to detect and to quantify them in those media.Much is known about the diversity of engineered nanoparticles (ENPs) in the environment but almost nothing about their characterization and detection in the natural aquatic environment.There is no conventional treatment that can absolutely protect the consumer from exposure to ENPs either through recreational use or consumption of drinking waters. The question is whether this exposure poses a significant public health risk.Unfortunately, we are far from having methods to obtain data on occurrence levels, fate, and transport of ENPs in aquatic systems. Before a sound analytical approach can be developed, we need a fuller understanding of the nanomaterial domain which requires an evaluation of the matrix of source materials, their transformation in the natural aquatic environment, and their physical/chemical behavior that is specific to the water medium.We review characterization techniques that are used for identifying different types of ENP, and then, by extrapolation from isolation techniques appropriate for extracting ENPs from water, suggest approaches to analyzing them in a variety of waters.     

The role of the acquisition methods in the analysis of natural and synthetic steroids and cholic acids by gas chromatography-mass spectrometry

An exhaustive GC-MS acquisition study was performed, for the simultaneous analysis of natural and synthetic steroids and cholic acids (in order to insert them into the last tierce of our multiresidue analysis system), such as androsterone, β-estradiol, transdehydroandro-sterone, transdehyroandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxyprogesterone-acetate, lithocholic acid, stigmasterol, cholic acid, chenodeoxycholic acid, β-sitosterol, ursodeoxycholic acid, 3-hydroxy-7-ketocholic acid and dehydrocholic acid, in total 26 compounds. As novelties to the field, for the trimethylsilyl (TMS) oxime ether/ester derivatives of steroids and cholic acids, at first, a tandem mass spectrometric (MS/MS), multiple reaction monitoring (MRM) type acquisition method has been developed in a single run; also for the first time, the three acquisition techniques, the full scan (FS), the selective ion monitoring (SIM), in our case the multiple ion monitoring (MIM) and the currently optimized MRM methods, have been compared; all three, in parallel, under strictly the same derivatization/instrumental conditions, both in matrix free solutions and municipal wastewater from two Hungarian wastewater treatment plants (WWTPs). Critical evaluation of the three acquisition protocols was collated on their analytical performances and validated under the same conditions. The data of six point calibration curves for FS, MIM and MRM methods, showed that both R2 (0.9995, 0.9858, 0.9975) and RSD (5.3, 5.8, 5.0), for two parallel derivatizations, each injected three times, proved to be independent of the acquisition processes. Whereas, for the method limit of quantification (LOQ) and the instrument limit of quantification (ILQ) values showed considerable differences. LOQ data, were decreasing in the FS, MIM, MRM line (expressed in ng/L), for all steroids and cholic acids. The same trend was determined in terms of the ILQ values. The practical utility of the optimized acquisition techniques was confirmed by the quantitation of the steroids and cholic acids contents of wastewater samples. Results confirmed the importance of the MRM acquisition method, even in comparison to the MIM one: with particular interest in selected cases: avoiding the extreme overestimation of the β-estradiol (156-1325%) and that of the ethinylestradiol (582-831%) concentrations in the wastewater samples.     

Derivatization and fragmentation pattern analysis of natural and synthetic steroids, as their trimethylsilyl (oxime) ether derivatives by gas chromatography mass spectrometry: analysis of dissolved steroids in wastewater samples

This paper reports the extension of our multiresidue analysis (MA) procedure with 18 natural and synthetic steroids; permitting the identification and quantification, in total of 81 pollutants from one solution, by a single injection, as their trimethylsilyl (TMS)-oxime ether/ester derivatives, by gas chromatography-mass spectrometry (GC-MS), within 31 min. As a novelty to the field, basic researches, such as fragmentation pattern analysis and derivatization optimization studies were performed for androsterone, transdehydroandrosterone, transandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxy-progesterone-acetate, stigmasterol and β-sitosterol. Results confirmed that (i) the TMS oxime-ether derivatives of the keto steroids provide from 1.40 times (gestodene) up to 4.25 times (norethisterone) higher responses compared to their TMS-ether ones, and (ii) the distribution of syn/anti oximes is characteristic to the ketosteroid species examined. Based on our optimized mass fragmentation, solid phase extraction (SPE) and derivatization studies separations have been performed in the total ion current (TIC) mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Responses, obtained with derivatized standards proved to be linear (hydroxysteroids), or have been calculated from calibration curves (ketosteroids) in the range of 1.88-750ng/L levels. Limit of quantitation (LOQ) values varied between 1.88ng/L and 37.5ng/L concentrations. The most important practical messages of this work are the high androsterone (0.744-4.28μg/L), transandrosterone (0.138-4.00μg/L), coprostanol (2.11-302μg/L), cholesterol (0.308-41μg/L), stigmasterol (1.21-8.40μg/L) and β-sitosterol (1.12-11.0μg/L) contents of influent wastewaters. β-Estradiol (100ng/L) and estriol (54ng/L) were found in one influent sample, only. Reproducibilities, characterized with the relative standard deviation percentages (RSD%) of measurements, varied between 1.73 RSD% (β-estradiol) and 5.4 RSD% (stigmasterol), with an average of 4.82 RSD%.     

Determination of dicofol in aquatic products using molecularly imprinted solid-phase extraction coupled with GC-ECD detection

The novel molecularly imprinted microsphere (MIM) that could be applied as special sorbent was synthesized by aqueous suspension polymerization using 1,1-bis(4-chlorophenyl)-1,2,2,2-tetrachloroethane (α-chloro-DDT) as the dummy template. The obtained MIM exhibited good recognition and selectivity to dicofol and it was successfully applied as selective sorbent of solid-phase extraction for the determination of dicofol from aquatic products. At the optimum conditions of the molecularly imprinted solid-phase extraction (MISPE) coupled with GC-ECD, good linearity for dicofol was achieved in a range of 0.4-100 ng g⁻¹ (r² = 0.9995) and the recoveries at three spiked levels were ranged from 85.8% to 101.2% for aquatic products with the relative standard deviation (RSD) less than 5.6%. The presented MISPE-GC-ECD method exhibited the advantages of simplicity, selectivity and sensitivity, and could be potentially applied to the determination of dicofol in complicated aquatic products.     

气相色谱-电子捕获检测法直接测定水产动物组织中五氯苯酚及其钠盐

建立了不经衍生直接测定水产动物组织中五氯苯酚及其钠盐残留量的气相色谱-电子捕获检测(GC-ECD)方法.目标化合物在酸性条件下转化成五氯苯酚后用正己烷提取,硫酸磺化法净化,浓缩和定容后测定.方法的线性范围为0.5～400 μg/L,相关系数为0.9978;草鱼和虾空白肌肉组织中添加五氯苯酚的质量浓度分别为0.4、2.0...     

STOCHASTIC MODEL OF LAKE SYSTEM INVASION AND ITS OPTIMAL CONTROL: NEURODYNAMIC PROGRAMMING AS A SOLUTION METHOD

Abstract We develop a stochastic model for the process of spread of an aquatic invader in a lake system. The invader is transported along with recreation boats, and treatment of boats allows one to control the invader spread. Optimization of invasion and control costs leads to a dynamic programming problem. However, standard stochastic dynamic programming (SDP) algorithms allow us to solve the problem for at most 13–14 lakes, which is significantly less than the size of systems arising in applications. We have developed a new technique, which is based upon the ideas of reinforcement learning and neurodynamic programming. This approach allows us to obtain approximate but reasonable control policy for essentially greater lake systems. The resulting numerical technique is comparatively easy to implement, and it can be applied to other spatially extended optimal control problems as well.     

Bladder wrack (Fucus vesiculosus) as a multi-isotope bio-monitor in an urbanized fjord of the western Baltic Sea

The spatial variations in the elemental and stable carbon, nitrogen, and sulphur isotope composition of bladder wrack (Fucus vesiculosus) growing along the shore line of the semi-enclosed urbanized Kiel Fjord (western Baltic Sea) was investigated at more than 60 sites. The analyses of the carbon-nitrogen-sulphur (CNS) stoichiometry and C and N stable isotope signature of F. vesiculosus displayed substantial differences between the north-western and the south-eastern parts of the Kiel Fjord. Different size classes displayed in part differences in C:N and C:S ratios, and the carbon isotope composition, reflecting the impact of the boundary conditions during growth. Whereas the sulphur isotope composition was controlled by the assimilation of seawater sulphate, the carbon isotope composition reflected the difference in the composition of surface waters. The δ¹⁵N values of the organic tissue tend to be an integrated monitor of anthropogenic impacts on the fjord. Results are compared to the composition of surface waters.