Suspect screening of natural toxins in surface water reservoirs

[eng] Natural toxins include a multitude of toxic secondary metabolites produced by animals, bacteria, fungi algae, and plants that are generally not intended as environmental contaminants of concern for water quality. However, the presence of anthropogenic waste in the aquatic environment, both with the climate changes and the increase of temperatures, is creating favorable conditions for the development of undesired organisms able to produce natural toxins that sum with other well known anthropogenic pollutants such as pesticides. Among them, natural toxins produced by algae (cyanotoxins), fungi (mycotoxins), and plants (phytotoxins) are the most encountered in surface water environments. Some of them have various toxic effects on the human body. Carcinogenic, dermotoxic, and neurotoxic effects are generally associated with these compounds. Concern about the effects of cyanobacteria on human health has recently grown in many countries. Several human and livestock poisoning events, due to the contamination of water sources (especially lakes) attributed to toxic cyanobacterial bloom, resulted in a dramatic rise of interest in these toxins. Despite that, their presence in surface water was not evenly regulated, and only the highly toxic microcystin-LR was limited at 1 µg/L by the Drinking Water Directive (Consolidated text: Council Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption) of the World Health Organization. Additionally, studies on their occurrence, chemical persistence, buoyancy, and the algal blooms onset prediction in the environment are still scarce. The environmental risk assessment is difficult and the degree of toxicity into surface water ecosystems is still poorly studied. Their fate in the environment can be described by distribution coefficients such as the octanol-water partitioning (Kow). Other data able to define other distribution and partition parameters are generally obtained using in-silico prediction tools. The identification and quantification are still difficult due to the availability of certified standards. Moreover, these compounds are found mixed with other groups of chemicals at low concentrations. Most of the published methods for their determination are specifically designed to identify a single compound or a group of toxins with similar characteristics, making stressful and time-consuming the process to identify other known-unknown compounds using non-targeted approaches. Since the dangerousness of natural toxins in surface water was recently reported by different authors, valuable data were produced and published to assess their presence and concentration in surface water environments. Several analytical techniques have been reported for their qualitative and quantitative analysis, among them MALDI- TOF/MS, LC-ESI/HRMS, LC-ESI-QqQ are the most used. However, due to the thousands of compounds and their extreme heterogeneity, suspect screening has taken a central role as screening purposes. Over the years, the suspect screening involved the use of in-silico approaches for the tentative identification of natural toxins, becoming one of the preferred methods for the suspect analysis of known-unknown compounds in surface water. It is of primary importance to develop and optimize new methods able to identify natural toxins in a various range of polarities, ranging from the most hydrophobic to the highest water affine. The screening approaches are generally focused on cyanotoxins with no implementations regarding plant toxins and mycotoxins which are very poorly studied in surface water. In this framework, this thesis has aimed to increase the knowledge about natural toxins in surface water. The first part of the study was focused on the recent advances in the detection of natural toxins retrieving a multitude of analytical approaches for their determination in surface and drinking water. Finally, two suspect screening approaches using suspect and target analysis with data- dependent (DDA) and data-independent acquisition (DIA) methods exploring the performances for the determination of multitargeted compounds have been proposed. The tentative compounds have been firstly filtered using a suspect list of 2784 compounds retrieved by different databases available in the literature. The validated methods were then applied to analyse surface water samples coming from different sites in Europe. The presence of natural toxins produced by both plants, fungi, and cyanobacteria is a reality in different water environments showing their presence at low levels also in unexpected zones with not favorable conditions for their production. Almost 80% of the natural toxins encountered were phytotoxins, while a small number of cyanotoxins and mycotoxins have been tentatively identified. The chemical diversity is generally driven by the botanical diversity and the anthropization of the area. Besides, the seasonality and the precipitations are crucial parameters to understand the presence of phytotoxins respect to the cyanotoxins which have been encountered also in unexpected seasons. However, the quantification was not possible for all natural toxins, since only 32 standards were available in our study. In conclusion, the work presented in this thesis, allowed to fill some of the gaps in the analysis of natural toxins presenting two approaches to increase the knowledge about the identification of natural toxins in surface waters. In the future, should be crucial to update the latest determination approaches with the newest quantification strategies to finally implement the suspect screening approaches and reach both determination and quantification of suspect compounds when standards are not available.[cat] La presència de residus antropogènics al medi aquàtic, tant amb els canvis climàtics com a l’augment de les temperatures, crea condicions favorables per al desenvolupament d’organismes no desitjats capaços de produir toxines naturals que es combinen amb els altres contaminants antropogènics coneguts. Les toxines naturals inclouen multitud de metabòlits secundaris tòxics produïts per animals, bacteris, algues fongs i plantes que no solen estar concebuts com a contaminants ambientals que preocupin la qualitat de l’aigua. Entre elles, les toxines naturals produïdes per algues (cianotoxines), fongs (micotoxines) i plantes (fitotoxines) són les més freqüents en entorns d’aigües superficials. Alguns d’ells expliquen diversos efectes tòxics contra el cos humà. Els efectes cancerígens, dermotòxics i neurotòxics s’associen generalment a aquests compostos. La preocupació pels efectes dels cianobacteris sobre la salut humana ha crescut en molts països en els darrers anys per diversos motius. Aquests inclouen casos d’intoxicacions atribuïdes a cianobacteris tòxics i la consciència de la contaminació de les fonts d’aigua (especialment els llacs) que es tradueix en un augment del creixement de la cianobacteria. Malgrat això, la seva presència a les aigües superficials no estava regulada ni limitada de manera uniforme, i només la microcistina-LR altament tòxica estava limitada a 1 µg / L per la Directiva sobre aigua potable (Text consolidat: Directiva 98/83 / CE del Consell, de 3 de novembre de 1998 sobre la qualitat de l’aigua destinada al consum humà) de l’Organització Mundial de la Salut. A més, els estudis sobre la seva aparició, persistència química, flotabilitat i predicció de l'aparició de les flors d'algues al medi ambient encara són escassos. L'avaluació del risc ambiental és difícil i el grau de toxicitat en els ecosistemes d'aigües superficials encara està poc estudiat. La identificació i quantificació són difícils a causa de la manca d’estàndards certificats disponibles i el seu destí a l’entorn es pot descriure mitjançant coeficients de distribució com el repartiment octanol-aigua (Kow). Altres dades capaces de definir altres paràmetres de distribució i partició s’obtenen generalment mitjançant eines de predicció in silico. A més, aquests compostos es troben barrejats amb altres grups de productes químics a baixes concentracions. La majoria dels mètodes publicats per a la seva determinació estan dissenyats específicament per identificar un sol compost o un grup de toxines amb característiques similars, cosa que fa que el procés d’identificació de diferents compostos sigui estressant i requereixi temps mitjançant enfocaments específics. Atès que s’ha determinat la perillositat de les toxines naturals a l’aigua superficial, es van produir i publicar dades valuoses per avaluar-ne la presència i la concentració. S'han informat de diverses tècniques analítiques per a la seva anàlisi quantitativa, entre les quals s'utilitzen MALDI-TOF/MS, LC-ESI/HRMS, LC-ESI-QqQ. No obstant això, a causa dels milers de compostos i de la seva extrema heterogeneïtat, el “suspect screening” ha tingut un paper central com a propòsit de idenficació de compostos desconeguts. Al llarg dels anys, el "suspect screening” va implicar l’ús de metòdiques “in-silico” per a la identificació provisional de toxines naturals, convertint-se en un dels mètodes preferits per a l’anàlisi sospitós de compostos desconeguts en aigües superficials. És de primera importància desenvolupar i optimitzar nous mètodes capaços d’identificar toxines naturals en diversos rangs de polaritats, des de les més hidròfobes fins a les més afines a l’aigua. Les proves es centren generalment en cianotoxines sense implementacions quant a toxines vegetals i les micotoxines que estan molt poc estudiades en aigües superficials. En aquest marc, aquesta tesi té com a objectiu augmentar el coneixement sobre les toxines naturals de les aigües superficials. La primera part de l’estudi es va centrar en els recents avenços en la detecció de toxines naturals que recuperen multitud d’enfocaments analítics per a la seva determinació en aigua superficial i potable. Finalment, s’han introduït dos enfocaments de detecció de sospitosos que utilitzen anàlisis de sospitosos i objectius amb mètodes d’adquisició dependents de dades (DDA) i d’adquisició independent de dades (DIA) que exploren el rendiment per a la determinació de compostos multidirectius. Els compostos provisionals s'han filtrat en primer lloc mitjançant una llista sospitosa de 2784 compostos recuperats per diferents bases de dades disponibles a la literatura. A continuació, es van aplicar els mètodes validats per analitzar mostres d’aigua superficial procedents de diferents llocs d’Europa. La presència de toxines naturals produïdes per les plantes, els fongs i els cianobacteris és una realitat en diferents ambients aquàtics que mostren la seva presència a nivells baixos també en zones inesperades amb condicions no favorables per a la seva producció. Gairebé el 80% de les toxines naturals trobades eren fitotoxines, mentre que només s’han identificat provisionalment poques cianotoxines i micotoxines. La diversitat química es basa generalment en la diversitat botànica i l'antropització de la zona. A més, l'estacionalitat i les precipitacions són paràmetres crucials per entendre la presència de fitotoxines respecte a les cianotoxines que s'han trobat també en estacions inesperades. No obstant això, la quantificació no va ser possible per a totes les toxines naturals, ja que només hi havia 32 estàndards disponibles al nostre estudi. En conclusió, el treball presentat en aquesta tesi va permetre omplir alguns dels buits de l’anàlisi de toxines naturals presentant dos enfocaments per augmentar el coneixement sobre la identificació de toxines naturals en aigües superficials. En el futur, hauria de ser crucial actualitzar el darrer enfocament de determinació amb mètodes de quantificació més nous implementant les metòdiques analítiques fent possible la caracterització i la quantificació amb el mateix mètode

Recent advances in detection of natural toxins in freshwater environments

Natural toxins can be classified according to their origin into biotoxins produced by microorganisms (fungal biotoxins or mycotoxins, algal and bacterial toxins), plant toxins or phytotoxins and animal toxins. Biotoxins are generated to protect organisms from external agents also in the act of predation. Among the different groups, bacterial toxins, mycotoxins and phytotoxins can produce damages in the aquatic environment including water reservoirs, with the consequent potential impact on human health. In the last few decades, a substantial labour of research has been carried out to obtain robust and sensitive analytical methods able to determine their occurrence in the environment. They range from the immunochemistry to analytical methods based on gas chromatography or liquid chromatography coupled to mass spectrometry analysers. In this article, the recent analytical methods for the analysis of biotoxins that can affect freshwater environments, drinking water reservoirs and supply are reviewed

Analysis, levels and seasonal variation of cyanotoxins in freshwater ecosystems

Nutrient over-enrichment in freshwater environments, together with the on-going climate change, favour the toxin-producing cyanobacteria bloom. Human health hazard may arise from drinking contaminated water. Additionally, cyanobacterial blooms affect other economic areas such as tourism, recreation, commercial fishery, water management and monitoring. Nowadays there is a scarcity of information on seasonal variations of cyanotoxins in various regions. Understanding of historical trends and seasonal variation patters is a foundation for forecasting and will help to develop effective water management strategies. This review gives an overview of cyanotoxins' analysis and levels in freshwater environments with particular emphasis on seasonal variations in Europe. Recent analytical approaches are discussed and the seasonal patterns for three major European climate zones (Mediterranean, continental, and Atlantic) were distinguished. Additionally, data from multi-year studies showed a tendency of increasing cyanotoxins' levels

Suspect screening of natural toxins in surface and drinking water by high-performance liquid chromatography high-resolution mass spectrometry

Besides anthropogenic contamination, freshwater environments can also be affected by the presence of natural toxins. Mycotoxins, plant toxins and cyanotoxins are the most relevant groups that can be found in the aquatic system. However, until now, only cyanotoxins have been more carefully studied. In the present work, single workflow for the assessment of natural toxins in waters, based on suspect screening and target screening of a selected group of toxins is presented. The approach is based on a triple-stage solid-phase extraction (SPE) able to isolate a wide range of natural toxins of different polarities, followed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ddHRMS2) using a Q-Exactive Orbitrap analyser. The acquisition was performed in full-scan (FS) and data-dependant acquisition (ddMS2) mode, working under positive and negative mode. For the tentative identification, different on-line databases such as ChemSpider and MzCloud and an in-house natural toxins list with 2384 structures, that includes cyanotoxins, plant toxins and mycotoxins, were used. Also, thanks to the MS2 data, it was possible to achieve a high level of tentative identification confidence, but confirmation was only possible comparing the standards of the suspected compounds. For those, the analytical parameters of the developed method were also validated, and the quantification was possible by external calibration. Validation showed recoveries in the range between 53 and 95 %, and method limits of detection (MDL) between 0.02 and 1.22 μg/L. This approach was applied to study natural toxins in 4 sampling sites along the Ter River in Catalonia (NE Spain). In this preliminary study 23 natural toxins were tentatively identified, and 9 of them confirmed (aflatoxin B1, anatoxin-a, nodularin, microcystin-LR, baicalein, kojic acid, cinchonine, B-asarone and atropine). The results of the quantification of these compounds showed concentrations below 1 μg/L in all cases, that is considered safe according to the actual legislation. This suspect screening approach allows a more comprehensive assessment of natural toxins in natural waters

Effect of monoglycerides and fatty acids on a ceramide bilayer

Monoglycerides and unsaturated fatty acids, naturally present in trace amounts in the stratum corneum (top layer of skin) lipid matrix, are commonly used in pharmaceutical, cosmetic and health care formulations. However, a detailed molecular understanding of how the oil additives get incorporated into the skin lipids from topical application and, once incorporated, how they affect the properties and integrity of the lipid matrix remains unexplored. Using ceramide 2 bilayers as skin lipid surrogates, we use a series of molecular dynamics simulations with six different natural oil ingredients at multiple concentrations to investigate the effect of the oils on the properties and stability of the bilayers. The six oils: monoolein, monostearin, monoelaidin, oleic acid, stearic acid and linoleic acid – all having the same length of the alkyl chain, C18, but a varying degree of saturation, allow us to systematically address the effect of unsaturation in the additives. Our results show that at low oil concentration (∼5%) the mixed bilayers containing any of the oils and ceramide 2 (CER2) become more rigid than pure CER2 bilayers due to more efficient lipid packing. Better packing also results in the formation of larger numbers of hydrogen bonds between the lipids, which occurs at the expense of the hydrogen bonds between lipids and water. The mixed bilayers with saturated or trans-unsaturated oils remain stable over the whole range of oil concentration. In contrast, the presence of the oils with at least one cis-double bond leads to bilayer instability and complete loss of bilayer structure at the oil content of about 50–65%. Two cis-double bonds in the lipid tail induce bilayer disruption at even lower concentration (∼30%). The mixed bilayers remain in the gel phase (without melting to a fluid phase) until the phase transition to a non-bilayer phase occurs. We also demonstrate that the stability of the bilayer strongly correlates with the order parameter of the lipid tails

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Suspect and target screening of natural toxins in the Ter River catchment area in NE Spain and prioritisation by their toxicity

This study presents the application of a suspect screening approach to screen a wide range of natural toxins including mycotoxins, bacterial toxins, and plant toxins in surface waters. The method is based on a generic solid-phase extraction procedure, using three sorbent phases in two cartridges that are connected in series, hence covering a wide range of polarities, followed by liquid chromatography coupled to high-resolution mass spectrometry. The acquisition was performed in full-scan and data-dependent modes while working under positive and negative ionisation conditions. This method was applied in order to assess natural toxins in the Ter River water reservoirs, which are used to produce drinking water for Barcelona city (Spain). The study was carried out during a period of seven months, covering the expected prior, during, and post-peak blooming period for natural toxins. Fifty-three (53) compounds were tentatively identified, and nine of these were confirmed and quantified. Phytotoxins were identified as the most frequent group of natural toxins in water, particularly the alkaloids group. Finally, the toxins identified to levels 2 and 1 were prioritised according to their bioaccumulation factor, biodegradability, frequency of detection and toxicity. This screening and prioritisation approach resulted in different natural toxins that should be further assessed for their ecotoxicological effects and considered in future studies

Suspect screening of natural toxins in surface and drinking water by high performance liquid chromatography and high-resolution mass spectrometry

Besides anthropogenic contamination, freshwater environments can also be affected by the presence of natural toxins. Mycotoxins, plant toxins and cyanotoxins are the most relevant groups that can be found in the aquatic system. However, until now, only cyanotoxins have been more carefully studied. In the present work, single workflow for the assessment of natural toxins in waters, based on suspect screening and target screening of a selected group of toxins is presented. The approach is based on a triple-stage solid-phase extraction (SPE) able to isolate a wide range of natural toxins of different polarities, followed by liquid chromatography coupled to high-resolution mass spectrometry (HPLC-ddHRMS2) using a Q-Exactive Orbitrap analyser. The acquisition was performed in full-scan (FS) and data-dependant acquisition (ddMS2) mode, working under positive and negative mode. For the tentative identification, different on-line databases such as ChemSpider and MzCloud and an in-house natural toxins list with 2384 structures, that includes cyanotoxins, plant toxins and mycotoxins, were used. Also, thanks to the MS2 data, it was possible to achieve a high level of tentative identification confidence, but confirmation was only possible comparing the standards of the suspected compounds. For those, the analytical parameters of the developed method were also validated, and the quantification was possible by external calibration. Validation showed recoveries in the range between 53 and 95%, and method limits of detection (MDL) between 0.02 and 1.22 μg/L. This approach was applied to study natural toxins in 4 sampling sites along the Ter River in Catalonia (NE Spain). In this preliminary study 23 natural toxins were tentatively identified, and 9 of them confirmed (aflatoxin B1, anatoxin-a, nodularin, microcystin-LR, baicalein, kojic acid, cinchonine, B-asarone and atropine). The results of the quantification of these compounds showed concentrations below 1 μg/L in all cases, that is considered safe according to the actual legislation. This suspect screening approach allows a more comprehensive assessment of natural toxins in natural waters.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 722493 (NaToxAq); and by the Generalitat de Catalunya (Consolidated Research Group “2017 SGR 1404 - Water and Soil Quality Unit”)Peer reviewe

Recent advances in detection of natural toxins in freshwater environments

Natural toxins can be classified according to their origin into biotoxins produced by microorganisms (fungal biotoxins or mycotoxins, algal and bacterial toxins), plant toxins or phytotoxins and animal toxins. Biotoxins are generated to protect organisms from external agents also in the act of predation. Among the different groups, bacterial toxins, mycotoxins and phytotoxins can produce damages in the aquatic environment including water reservoirs, with the consequent potential impact on human health. In the last few decades, a substantial labour of research has been carried out to obtain robust and sensitive analytical methods able to determine their occurrence in the environment. They range from the immunochemistry to analytical methods based on gas chromatography or liquid chromatography coupled to mass spectrometry analysers. In this article, the recent analytical methods for the analysis of biotoxins that can affect freshwater environments, drinking water reservoirs and supply are reviewed