Dissertation committee:
Δρ. Αντώνιος Καλοκαιρινός, Καθηγητής, Τμήμα Χημείας ΕΚΠΑ
Δρ. Αναστασία Χισκιά, Ερευνήτρια Α΄, ΕΚΕΦΕ «Δημόκριτος»
Δρ. Αναστάσιος Οικονόμου, Καθηγητής, Τμήμα Χημείας ΕΚΠΑ
Δρ. Νικόλαος Θωμαϊδης, Καθηγητής, Τμήμα Χημείας ΕΚΠΑ
Δρ. Ευάγγελος Μπακέας, Αναπληρωτής Καθηγητής, Τμήμα Χημείας ΕΚΠΑ
Δρ. Εμμανουήλ Δασενάκης, Καθηγητής, Τμήμα Χημείας ΕΚΠΑ
Δρ. Θεόδωρος Τριάντης, Ερευνητής Β’, ΕΚΕΦΕ «Δημόκριτος»
Summary:
Cyanobacteria, also known as blue-green algae, are present in surface waters and under favorable environmental conditions can form extensive algal blooms and release hazardous toxic compounds (cyanotoxins), posing a significant risk to aquatic ecosystems, drinking water sources and human health. Cyanotoxins comprise a large group of organic compounds, with a variety of physicochemical properties, chemical structures and toxic activity (hepatotoxicity, neurotoxicity, cytotoxicity, dermatotoxicity). Cyanotoxins are classified based on their structure on cyclic peptides (i.e. Microcystins, Nodularins), alkaloids (i.e. Cylindrospermopsin, Anatoxin), lipopolysaccharides and amino acids. Most of the studies on the occurrence of cyanotoxins have been targeted to specific compounds or to variants within a class of cyanotoxins. In this thesis, a fast, simple and sensitive analytical method was developed for the simultaneous determination of multi-class cyanobacterial and algal toxins in water in one run. The target compounds were: Cylindrospermopsin, Anatoxin-a, Nodularin, 12 Microcystins ([D-Asp3]MC-RR, MC-RR, MC-YR, MC-HtyR,[D-Asp3]MC-LR, MC-LR, MC-HilR, MC-WR, MC-LA, MC-LY, MC-LW and MC-LF), Okadaic acid and Domoic acid. Analytes were determined using liquid chromatography–tandem mass spectrometry (LC–MS/MS) in MRM mode. A dual Solid Phase Extraction (SPE) cartridge assembly (two tandem SPE cartridges, Oasis HLB and Hyper PGC) was applied for the efficient extraction of target compounds from water. Moreover, a method was developed for the simultaneous extraction of several cyanotoxins (Cylindrospermopsin, Anatoxin-a and Microcystins) from lyophilized cyanobacterial biomass. During method development several extraction parameters were evaluated. Detection and identification of cyanotoxins Cylindrospermopsin, Anatoxin-a and a wide range of Microcystins in Greek lakes for the first time have demonstrated the applicability and efficiency of the proposed methods.
Apart from the natural contaminants of water there are also anthropogenic contaminants with emerging concern. The latest EU Directive on Environmental Quality Standards (EQS Directive 2013/39/EU) has proposed new strategies against water pollution and novel monitoring methods for priority substances. Additionally, the EU Decision 2015/495/EE has established a watch list of emerging contaminants for Union-wide monitoring in the field of water policy. The above directives and decisions implements revised and stricter EQS and making necessary the development and validation of novel multi-residue methods for the determination of micropollutants of water. In this thesis, the development of a novel method for the simultaneous determination of various organic pollutants (i.e. pesticides, endocrine disruptors, pharmaceuticals) in water is presented. The 29 target compounds (17α-Ethinylestradiol, β-Estradiol, Diclofenac, Alachlor, Atrazine, Chlorfenvinphos, Chlorpyriphos, Diuron, Isoproturon, Simazine, Trifluralin, Pentachlorophenol, 2.4.6-Trichlorophenol, Azinphos-ethyl, Azinphos-methyl, Chlorotoluron, Cyanazine, Diazinon, Dimethoate, Ethion, Fenthion, Linuron, Malathion, Methidathion, Metribuzine, Monuron, Phosalone, Propazine and Triazophos), 13 of which are either considered as priority substances or included in watch list and the rest 16 were widely used pesticides many of them have been banned, were determined using liquid chromatography–tandem mass spectrometry (LC–MS/MS) in MRM mode. SPE method, utilizing Oasis HLB cartridges, was developed for sample clean-up and analytes preconcentration from water, enabling high sensitivity with LODs at ng/L level.
