Mikrovalno potpomognuta ekstrakcija benzoilcikloheksanonskih i benzoilpirazolnog herbicida iz poljoprivrednog tla

master's thesis

• Title (english): Microwave-assisted extraction of benzoylcyclohexanone and benzoylpyrazole herbicides from agricultural soil
• Author: Milena Milaković
• Mentor: Sanja Stipičević (mentor)
• Mentor: Nenad Judaš (mentor)
• Committee member: Iva Juranović Cindrić (predsjednik povjerenstva)
• Committee member: Nenad Judaš (član povjerenstva)
• Committee member: Jasna Lajtner (član povjerenstva)
• Committee member: Željka Soldin (član povjerenstva)
• Committee member: Perica Mustafić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2016-07-08, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Istraženi su uvjeti mikrovalno potpomognute ekstrakcije benzoilpirazolnog herbicida topramezona i benzoilcikloheksanonskih herbicida tembotriona i mezotriona, kao i dva razgradna produkta mezotriona (2-amino-(4-metilsulfonil)benzojeva kiselina, AMBA i 4-metilsulfonil-2-nitrobenzojeva kiselina, MNBA) iz poljoprivrednog tla (udio organskog ugljika 0,9 %; pH = 7,3). Masene koncentracije spojeva u ekstraktu tla određene su tekućinskom kromatografijom visoke djelotvornosti uz UV detektor s nizom dioda i kalibraciju vanjskim standardima pripravljenim u deioniziranoj vodi. Topramezon, tembotrion, mezotrion i MNBA djelotvorno su ekstrahirani iz suhog tla smjesom otapala (metanol, 0,1 mol L1 klorovodična kiselina) = 9 : 1 pri 60 C tijekom 5 min uz magnetno miješanje suspenzije tla i otapala u omjeru 1 : 6. Analitički povrat spojeva dodanih u tlo u masenim udjelima od 97 do 204 ng g1 bio je u rasponu od 80 % za mezotrion i MNBA do 94 % za topramezon, uz relativno standardno odstupanje do 11 %. Granica detekcije svih spojeva bila je 5 ng g1. Predložena metoda nije prikladna za ekstrakciju AMBA iz tla. Analitički povrat svih spojeva iz kiselog tla (pH = 5,4) bio je manji od 50 %, vjerojatno kao rezultat jače sorpcije ili hidrolize neutralnih molekula herbicida u tlu. Zbog smanjene selektivnosti i preciznosti, povrat određivanja herbicida u tlu s 2,9 % udjela organskog ugljika iznosio je približno 60 %. Djelotvornost ekstrakcije herbicida iz vlažnog tla bila je u rasponu od 60 do 67 %, dok je povrat MNBA bio 95 %. Predloženi postupak ekstrakcije optimiran je za kvantitativnu analizu topramezona, tembotriona, mezotriona i MNBA u neutralnom, slabo humusnom i suhom tlu, dok bi se njihova analiza u neutralnom, humusnom i vlažnom tlu trebala provesti uz kalibraciju unutarnjim standardom ili vanjskim standardima pripravljenim u ekstraktu matrice. U metodičkom dijelu diplomskog rada dan je pregled nastavnih sadržaja koji se bave metodama razdvajanja smjesa u osnovnoškolskom i srednjoškolskom (gimnazijskom) nastavnom programu. Uz to je dan prijedlog srednjoškolskog nastavnog sata koji se temelji na nastavnoj strategiji učenja otkrivanjem na temu ekstrakcije i kemijske ravnoteže, a uz njega je dan i kratki metodički komentar.

Abstract (english)

The factors that affect the microwave-assisted extraction of the benzoylpyrazole herbicide topramezone and the benzoylcyclohexanone herbicides tembotrione and mesotrione, as well as two mesotrione degradation products (2-amino-4-methylsulfonyl-benzoic acid, AMBA and 4-methylsulfonyl-2-nitrobenzoic acid, MNBA) from agricultural soil (organic carbon content 0.9 %; pH = 7.3) were investigated. The mass concentrations of compounds in soil extracts were determined by high-performance liquid chromatography coupled with an UV diode array detector and calibration with external standards prepared in deionised water. Topramezone, tembotrione, mesotrione and MNBA were efficiently extracted from dry soil with solvent mixture (methanol, 0.1 mol L1 hydrochloric acid) = 9 : 1 at 60 C for 5 min with magnetic stirring of suspension at 1 : 6 of soil-to-solvent ratio. The analytical recovery from soil fortified with analytes at mass fractions ranging from 97 to 204 ng g1 was between 80 % for mesotrione and MNBA and 94 % for topramezone, with a relative standard deviation under 11 %. The limit of detection for all of the analytes was 5 ng g1. The proposed method is not suitable for the extraction of AMBA from soil. The analytical recovery of all of the compounds from acidic soil (pH = 5.4) was under 50 %, probably as a result of a higher sorption or a higher hidrolysis of neutral herbicide molecules in soil. Reduced selectivity and precision of herbicide determination in soil with 2.9 % of organic carbon content resulted in nearly 60 % of their analytical recoveries. The extraction efficiency of herbicides from wet soil ranged from 60 to 67 %, while MNBA recovery was 95 %. The proposed extraction procedure was optimised for quantitative analysis of topramezone, tembotrione, mesotrione and MNBA in neutral, low humic and dry soil, whereas their analysis in neutral, humic and wet soil should be performed using either internal standard or matrix-matched external standard calibration. The analysis of the elementary and high school chemistry syllabuses with respect to the separation methods of mixtures is given in the methodical part of the diploma thesis. Also, an high school chemistry lesson that deals with extraction and chemical balance and is based on guided inquiry learning strategy was designed and commented in details.

• Keywords: ekstrakcija potpomognuta mikrovalovima; mezotrion; tekućinska kromatografija; tembotrion; tlo; topramezon
• Keywords (english): liquid chromatography; mesotrione; microwave-assisted extraction; soil; t embotrione; topramezo
• Language: croatian
• URN:NBN: urn:nbn:hr:217:510058
• Study programme: Title: Integrated undergraduate and graduate university study of Biology and Chemistry Education; specializations in: Integrated undergraduate and graduate university study of Biology and Chemistry Education; Course: Integrated undergraduate and graduate university study of Biology and Chemistry Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije biologije i kemije (magistar/magistra edukacije biologije i kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-01-26 16:13:43