Pre-screening of pesticides using straight radiation chemical ionization and Orbitrap mass spectrometry

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http://urn.fi/URN:NBN:fi:hulib-202106183191
Title: Pre-screening of pesticides using straight radiation chemical ionization and Orbitrap mass spectrometry
Author: Partovi, Fariba
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2021
Language: eng
URI: http://urn.fi/URN:NBN:fi:hulib-202106183191
http://hdl.handle.net/10138/331594
Thesis level: master's thesis
Degree program: Kemian ja molekyylitieteiden maisteriohjelma
Master's Programme in Chemistry and Molecular Sciences
Magisterprogrammet i kemi och molekylära vetenskaper
Specialisation: Mathematics / Computer and data science / Physics / Chemistry
Mathematics / Computer and data science / Physics / Chemistry
Mathematics / Computer and data science / Physics / Chemistry
Abstract: Utilization of pesticides in the modern agriculture is often indispensable for gaining good crops. However, pesticides are abundantly being used in too hight quantities which leads to potential health risks for the consumers. Currently there are no pre-screening methods for monitoring the levels of pesticides in food, but only a negligible small percentage of all goods are being tested using the laborious standardized methods. This master’s thesis is an investigation, that was carried out in the wet laboratory of KARSA Oy Ltd, on 10 different pesticides: Glyphosate, Thiabendazole, 2-phenylphenol, Chlorpyrifos, Fludioxonil, Chlormequat, Bupirimate, Diflubenzuron, Fenpyrazamine and 2,4-dichlorophenoxyacetic acid. Pesticides were ionized using straight radiation chemical ionization (SRCI) in positive and negative modes without any added reagent and also using bromide, nitrate, acetonylacetone and acetone as reagents. Charged target molecules and adducts were detected using Thermo fisher Iontrap/Orbitrap (LTQ Orbitrap velos pro upgraded) mass spectrometer. After the initial method development and scoping measurements pesticides were studied both individually and as a mixture of all 10 pesticides. Sample solutions were first injected with syringe so that the solvent and targets evaporated at the same time inside the desorber heating block of SRCI inlet. In these syringe injection measurements, the desorber temperature was set at 150 °C. Mass range at 125–750 has been used for all the pesticides except for Chlormequat (100–750). After the syringe injection measurements, the mixture of 10 pesticides was analysed by TCM filters. Target solutions of 1 µl volume were placed on filters and after the solvents had evaporated the filters were heated from room temperature to 245°C using the same setup as with the syringe injections. In conclusion, with syringe injections 7 pesticides out of 10 were detected using positive and negative mode without any added reagent. The highest target intensities were recorded from TCM filters. Overall, applying the SRCI-Orbitrap setup for pesticide pre-screening from target solutions resulted in the detection of 9 pesticides out of 10.
Subject: pesticides
atmospheric pressure chemical ionization
Orbitrap


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