Unit:
Κατεύθυνση Χημική Ανάλυση-Έλεγχος ΠοιότηταςLibrary of the School of Science
Author:
Diamanti Konstantina
Supervisors info:
Νικόλαος Θωμαΐδης, Αναπληρωτής Καθηγητής, Τμήμα Χημείας, ΕΚΠΑ
Αναστάσιος Οικονόμου, Αναπληρωτής Καθηγητής, Τμήμα Χημείας, ΕΚΠΑ
Ευάγγελος Γκίκας, Επίκουρος Καθηγητής, Τμήμα Φαρμακευτικής, ΕΚΠΑ
Original Title:
Retrospective target and suspect screening of new psychoactive substances in raw wastewater by Liquid Chromatography - Quadrupole-Time-of-flight Mass Spectrometry (LC-QTOF-MS)
Translated title:
Retrospective target and suspect screening of new psychoactive substances in raw wastewater by Liquid Chromatography - Quadrupole-Time-of-flight Mass Spectrometry (LC-QTOF-MS)
Summary:
Every substance that is consumed ends up either unchanged or as a metabolite in sewer systems, so the analysis of raw wastewater samples can provide valuable information on the estimation of their consumption. This approach, which is known as wastewater-based epidemiology (WBE), can be applied in monitoring of the usage of New Psychoactive Substances (NPS). These compounds are legal replacements of established narcotic and psychotropic drugs with slightly modified chemical structures and similar or new effects.
This thesis reports the retrospective target and suspect screening of NPS in raw wastewater samples collected on March 2015, 2016, 2017 from the main wastewater treatment plant (WWTP) of Athens. Solid-phase extraction (SPE) with four different sorbent materials that covered a broad range of analytes was used for sample treatment. Extracts were analyzed with reversed-phase liquid-chromatography coupled to quadrupole-time-of-flight mass spectrometry (RPLC-QTOF-MS) and the data were acquired through broad-band Collision Induced Dissociation (bbCID) mode, which provided information on parent and fragment ions without pre-selection of analytes in one run. Validation was performed based on representative compounds of the wide-scope screening method. A database of approximately 200 NPS was used for target screening and the detection was based on mass accuracy, retention time, isotopic pattern and fragmentation products. For the suspect screening, a list of approximately 500 NPS was built and information, such as mass accuracy, predicted retention times and MS/MS library data, led to the tentative identification of the NPS candidates.
Following the aforementioned procedures, few of the investigated compounds were detected in raw wastewater. 15 NPS, some of them for the first time, were detected through target screening in wastewater and the results indicated an occasional use during the week and over the years. 6 NPS were tentatively identified through suspect screening, while the difficulties in the identification of more NPS to a better confidence level were discussed.
Main subject category:
Science
Other subject categories:
Chemistry
Keywords:
New Psychoactive Substances, Wastewater-based epidemiology, LC-QTOF-MS, Target screening, Suspect screening
