Ozonation of ranitidine: effect of experimental parameters and identification of intermediates

The aim of this study was to reveal the effects of various operational parameters on the ozonation kinetics of the histamine-2 blocker drug ranitidine (RAN) in aqueous solutions and to detect and identify possible transformation products (TPs) of RAN produced during the ozonation experiments. The influence of the solution’s pH value, the initial concentrations of the oxidant and analyte, the matrix effect and the organic matter presence on RAN’s removal were evaluated. Results indicated high reactivity of RAN with molecular aqueous ozone. Initial ozone concentration and pH were proven major process parameters. Alkaline pH values and increased ozone initial concentrations promoted degradation kinetics and overall mineralization. Although RAN mineralization at neutral and acidic pH was restricted (maximum 22%), it increased at pH 10. Dissolved Organic Matter (DOM) acts as an antagonistic agent to RAN degradation, limiting its % removal. The effect of inorganic ions in the matrix did not seem to affect RAN ozonation. Eleven (11) TPs were identified and structurally elucidated, using Reversed Phase (RP) and HILIC LC-Q-ToF-MS. Most of the TPs (P-304, P-315b, P-299b, P-333, P-283) are generated by the attack of ozone at the double bond or the adjacent secondary amine, with the abstraction of NO2 moiety, forming TPs with an aldehyde group and an imine C=N bond. Oxidized derivatives with a carboxylic group (P-315a, P-331a, P-331b, P-299a) are also formed. Ranitidine S-oxide was identified as an ozonation product (P-330) and its structure was confirmed through the analysis of a reference standard. P-214, was also produced during ozonation, through the C-N bond rupture adjacent to the NO2 moiety. HILIC was successfully used complementary to RP, either for the successful separation and identification of isomeric TPs or for the elution of new TPs that were not eluted in the RP chromatographic system. Retention time (tR) prediction was also used as a complementary tool for the identification of TPs. The obtained results supported the proposed structures, since the predicted tR of most compounds in both RP and HILIC were in accordance with the experimental ones

A collaborative evaluation of LC-MS/MS based methods for BMAA analysis: soluble bound BMAA found to be an important fraction.

Exposure to β-Ν-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D3BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D3BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery ( < 10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis

Απομάκρυνση ρύπων από υπόγεια νερά με χρήση ενεργών διαπερατών φραγμάτων

The main goal of the present Thesis was a comparative examination of the ability of certain adsorptive and reductive materials to remediate polluted water from a series of inorganic and organic pollutants. The materials’ ability to be incorporated in Permeable Reactive Barriers was also investigated. The main adsorptive materials used, were natural zeolite (clinoptilolite) and its modified forms with sodium and iron oxides. The reductive material selected was Zero Valent iron in its powder form. Cadmium, Chromium (valence III and VI) and Imidacloprid (a widely used organic insecticide) were the selected pollutants used for this study. The main objectives of were: a) the study of the modification of selected zeolites (sodium saturated form and iron-oxide form) for the remediation of heavy metals Cd and Cr(III) in batch and column experiments under various parameters and in the presence of ions and organic matter, b) the reductive removal of hexavalent chromate anions Cr(VI) from aqueous solutions, using zero-valent iron, under various physicochemical parameters, c) the reductive transformation of a selected insecticide (Imidacloprid) using zero-valent iron under different redox conditions and the enhancement of the reduction applying other reductive substances. Results indicated that smaller zeolite particle size and higher initial pH values promote the ion-exchange process. Zeolite material modified with iron oxides demonstrated the highest ion exchange capacity, while part of the chromium removal is attributed to the gradual increase of the pH and the inevitable precipitation and co – precipitation of chromium species. In most of the cases, the process was described with a pseudo-first order kinetic model. The presence of divalent antagonistic cations and humic acid in the solution, result in a dramatic reduction of the adsorptive capacity of Cd which is not the case for Cr(III). Sodium saturated zeolite, showed a limited ability to remove metals under continuous flow (column experiments) unlike zeolite modified with iron oxides. demonstrated better results. The application of the BDST model provided data for the calculation of the necessary material mass, for a predefined service time to reach the selected breakthrough value. The removal of chromate ions with zero valent iron is described by a two-stage process each one with different kinetic parameters. pH is a crucial parameter as is the production and removal of various chromium and iron species. In this process chloride and sulfate ions improve the kinetics and efficiency of the method, while calcium and phosphates have the opposite effect. Column experiments indicated the ability of zero valent iron to remove chromate ions effectively under various experimental conditions, simulating the use of a permeable reactive barrier. The reductive transformation of Imidacloprid, depends on the available zero-valent iron surface, the material pretreatment, the redox potential and pH values. The absence of oxygen ensures a protracted service time of the iron surface restricting the formation of the passive iron oxide layer. Various reductive compounds (sulfides and dithionite salts) increase the effectiveness of the reductive transformation. All the transformation by products and reductive forms of the original compound, derive mainly by the reduction of the R-NH-NO2 group. The synergistic effect of these compounds is reflected on the variations of the solution toxicity values.Ο στόχος της παρούσας Διατριβής είναι η συγκριτική διερεύνηση της ικανότητας επιλεγμένων προσροφητικών και αναγωγικών υλικών, να απομακρύνουν μια σειρά ανόργανων και οργανικών ρύπων από ρυπασμένα νερά και η εργαστηριακή αξιολόγησή τους ως πιθανά πληρωτικά υλικά σε Ενεργά Διαπερατά Φράγματα. Τα προσροφητικά υλικά που μελετήθηκαν είναι ο φυσικός ζεόλιθος, και οι τροποποιημένες του μορφές με νάτριο και οξείδια του σιδήρου, ενώ το ενεργό αναγωγικό υλικό ήταν ο Σίδηρος Μηδενικού Σθένους (Zero Valent Iron ZVI). Οι ανόργανοι ρύποι που μελετήθηκαν είναι τα βαρέα μέταλλα κάδμιο και χρώμιο (στην τρισθενή του μορφή και την εξασθενή του μορφή που είναι και η πιο τοξική), καθώς και η οργανική ουσία Imidacloprid. Τα κυριότερα σημεία της έρευνας συνοψίζονται στα εξής: α) παρασκευή και έλεγχος της προσροφητικής ικανότητας ζεόλιθων και τροποποιημένων ζεόλιθων για την απομάκρυνση των μετάλλων Cd(II) και Cr(III) σε ασυνεχή πειράματα και πειράματα συνεχούς λειτουργίας στηλών, β) μελέτη της αναγωγικής δέσμευσης του εξασθενούς χρωμίου, με χρήση σιδήρου μηδενικού σθένους, κάτω από την επίδραση διαφόρων παραμέτρων, την παρουσία ιόντων και οργανικής ύλης, γ) μελέτη του αναγωγικού μετασχηματισμού του νεονικοτινοειδούς παρασιτοκτόνου Imidacloprid με χρήση ZVI κάτω από διαφορετικές οξειδοαναγωγικές συνθήκες και με την υποβοήθηση άλλων αναγωγικών ουσιών. Τα αποτελέσματα δείχνουν πως η χρήση σωματιδίων ζεόλιθου μικρότερης μέσης διαμέτρου, και οι υψηλότερες αρχικές τιμές pH βελτιώνουν την αποτελεσματικότητα της ιονανταλλαγής. Ο τροποποιημένος με οξείδια σιδήρου ζεόλιθος παρουσιάζει την υψηλότερη προσροφητική ικανότητα, ενώ μέρος της απομάκρυνσης στην περίπτωση του χρωμίου αποδίδεται πέρα από την ιονανταλλαγή και στην καταβύθιση των μορφών του χρωμίου εξαιτίας της σταδιακής αύξησης του pH. Στις περισσότερες πειραματικές συνθήκες η κινητική της δράσης περιγράφεται με το μοντέλο ψευδο-πρώτης τάξης. Η παρουσία ανταγωνιστικών δισθενών κατιόντων και χουμικών οξέων, παρεμποδίζει σημαντικά την ιονανταλλαγή των μετάλλων στην επιφάνεια των τροποποιημένων ζεόλιθων. Ο κορεσμένος με νάτριο ζεόλιθος παρουσίασε μειωμένη ικανότητα απομάκρυνσης μετάλλων σε συνθήκες στηλών συνεχούς λειτουργίας, αντίθετα με τον τροποποιημένο με οξείδια σιδήρου ζεόλιθο. Με την εφαρμογή του μοντέλου BDST στα δεδομένα των συνεχών πειραμάτων, είναι δυνατό να υπολογιστεί η απαραίτητη μάζα ιονανταλλακτικού υλικού για την εξασφάλιση της ωφέλιμης λειτουργίας της στήλης μέχρι του επιλεγόμενου οριακού σημείου. Η αναγωγική απομάκρυνση των χρωμικών ιόντων με σίδηρο μηδενικού σθένους περιγράφεται από μια διαδικασία δύο σταδίων με διαφορετικές ταχύτητες αντίδρασης στο καθένα. Το pH η παρουσία ιόντων και η διαθέσιμη επιφάνεια σιδήρου μηδενικού σθένους είναι κρίσιμες παράμετροι στις δράσεις αυτές. Τα αποτελέσματα των στηλών συνεχούς λειτουργίας αποτελούν απόδειξη της ικανότητας του σιδήρου μηδενικού σθένους να χρησιμοποιηθεί σε εφαρμογές Ενεργών Διαπερατών Φραγμάτων για την απομάκρυνση χρωμικών. Τέλος, στην περίπτωση του αναγωγικού μετασχηματισμού της ουσίας Imidacloprid με σίδηρο μηδενικού σθένους, η δράση φαίνεται να εξαρτάται από τις τιμές pH, τη διαθέσιμη ενεργή επιφάνεια υλικού, την προκατεργασία του σιδήρου και τις οξειδοαναγωγικές συνθήκες του διαλύματος. Η απουσία οξυγόνου εξασφαλίζει παρατεταμένο ωφέλιμο χρόνο λειτουργίας στο σίδηρο, καθώς παρεμποδίζει τη δημιουργία παθητικού επιφανειακού στρώματος οξειδίων. Διάφορες θειούχες αναγωγικές ουσίες (θειούχα και διθειονικά άλατα) αυξάνουν αισθητά την αποτελεσματικότητα της αναγωγής. Τα προϊόντα μετασχηματισμού της ένωσης προέρχονται από διαδικασία αναγωγής της κύριας ομάδας R-NH-NO2 και συνεργιστική δράση των ενώσεων που προκύπτουν αντικατοπτρίζεται στις μεταβολές της τοξικότητας του διαλύματος κατά τη διάρκεια της επεξεργασίας

Micelles Mediated Zone Fluidics Method for Hydrazine Determination in Environmental Samples

An automated flow method for the determination of hydrazine based on the concept of zone-fluidics has been developed. The analyte reacts under flow conditions with p-dimethylamino benzaldehyde (25 mmol L&minus;1) in micellar medium (100 mmol L&minus;1 SDS) to form a stable derivative (460 nm). Micelles mediated catalysis excludes the use of highly acidic environment typical for this kind of reaction. Following careful examination of chemical and instrumental variables, the method allows the determination of hydrazine at the low micromolar level (0.3&ndash;10 &mu;mol L&minus;1) in water samples. Real sample analyses (drinking and boiler feed water) resulted in satisfactory results in terms of accuracy with the percent recoveries being in the range of 82&ndash;114%

Agri-drinking water indicators (ADWIs): Linkage between agricultural practice and good drinking water quality

International audienceAuthors: Nicolas Surdyk (1); Susanne Klages (2); Christophoros Christophoridis (3); Donnacha Doody (4); Birgitte Hansen (5); Claudia Heidecke (2); Abel Henriot (1); Hyojin Kim (5); Sonja Schimmelpfennig (2) "-Submitted to H2020 FAIRWAY project-" To effectively reduce the agricultural impact on the aquatic environments, the cause-effect relations between agricultural practices and water quality should be well understood. For this purpose, models are frequently developed, in order to establish a link between agricultural input and the output in terms of water quality and quantity. However, the establishment of models represents a fairly large challenge as it usually includes the consideration of numerous processes. Efforts to make it as precise as possible most of the times lead to rather complex models, for users hard to understand. Indicators are intended to fill the gap between no information or too detailed information, displaying in rather simple terms what could have an effect on environment. In the FAIRWAY (Farm systems management and governance for producing good water quality for drinking water supplies) project, therefore, we focus on the evaluation and prioritization of indicators that quantitatively and conceptually show the relationship between agricultural practices (driving forces and pressure indicators) and drinking water quality (state indicators), named 'Agri-Drinking Water Indicators' (ADWI). The focus is on drinking water pollution due to nitrates and pesticides. As starting point, we conducted a survey among the 13 FAIRWAY case studies to identify those driving forces and pressure indicators, which are already in use as ADWIs. We accomplished the survey by a literature review. A first prioritisation resulted in a list of possibly applicable agricultural indicators (driving forces and pressure indicators), which are based on existing or easy to acquire data at the European scale. State ADWIs are relatively well standardized among the case studies. A classification of the hydrogeological systems was established and link ADWIs were introduced in order to categorize the dominant pathways and quantify the lag time between agricultural practice and drinking water pollution. The link ADWIs were identified dominantly in scientific literature, mainly because they have not been actively used in practice. In a next step, correlation tests already established between agricultural and state indicators will be carried out in order to evaluate all potentially useful indicators and with available data from all FAIRWAY case studies. In a final evaluation step, the acceptance of the deduced set of indicators will be tested among target users in the case studies (i.e. farmers, agricultural advisors, policy makers)

Cyanobacterial Toxins and Peptides in Lake Vegoritis, Greece

Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This study reports on the co-occurrence of CTs and cyanopeptides (CPs) in Lake Vegoritis, Greece and presents their variant-specific profiles obtained during 3-years of monitoring (2018–2020). Fifteen CTs (cylindrospermopsin (CYN), anatoxin (ATX), nodularin (NOD), and 12 microcystins (MCs)) and ten CPs (3 APs, 4 MGs, 2 AERs and aeruginosamide (AEG A)) were targeted using an extended and validated LC-MS/MS protocol for the simultaneous determination of multi-class CTs and CPs. Results showed the presence of MCs (MC-LR, MC-RR, MC-YR, dmMC-LR, dmMC-RR, MC-HtyR, and MC-HilR) and CYN at concentrations of &lt;1 μg/L, with MC-LR (79%) and CYN (71%) being the most frequently occurring. Anabaenopeptins B (AP B) and F (AP F) were detected in almost all samples and microginin T1 (MG T1) was the most abundant CP, reaching 47.0 μg/L. This is the first report of the co-occurrence of CTs and CPs in Lake Vegoritis, which is used for irrigation, fishing and recreational activities. The findings support the need for further investigations of the occurrence of CTs and the less studied cyanobacterial metabolites in lakes, to promote risk assessment with relevance to human exposure