Določanje neonikotinoidnih pesticidov v cvetnem prahu

Ivančič, Zala (author), Prosen, Helena (mentor)

Uporaba pesticidov za zaščito raznih rastlin je močno povečala letne pridelke in vplivala na dvig kvalitete življenja. Ker se dnevno povečuje prebivalstvo sveta, potrebujemo dnevno zagotoviti tudi več hrane. Insekticidi, v mojem primeru neonikotinoidi, ščitijo rastline pred raznimi škodljivci, problem pa je, da škodujejo tudi zelo koristnim žuželkam, kot so na primer čebele. Neonikotinoidi so sistemski pesticidi, kar pomeni, da se prenesejo v vse dele rastlin, tudi v cvetni prah, katerega za hrano uporabijo čebele. V njih so našli ostanke teh pesticidov, zato številne pomore čebeljih družin pripisujejo ravno njim. Zaradi tega so leta 2018 v Evropski uniji prepovedali zunanjo uporabo treh neonikotinoidnih pesticidov: imidakloprida, klotianidina in tiametoksama. Leta 2020 so prepovedali tudi uporabo tiakloprida. Za določanje neonikotinoidov sta za pripravo vzorca največ v uporabi metodi QuEChERS in SPE. Ker je o varstvu okolja ozaveščenih vedno več ljudi, se uporabljajo bolj ''zelene'' tehnike in bolj okolju prijazna metoda je zagotovo QuEChERS. Za analizo se najbolj uporablja LC-MS/MS, ki je tudi najbolj selektivna in občutljiva tehnika vendar je zanjo potrebna bolj zahtevna instrumentacija in pogostejše umerjanje instrumenta. Namen dela je bil pregled različnih ekstrakcij in analiznih metod za določevanje neonikotinoidnih pesticidov in primerjava le-teh, ter izbira metode, ki nam daje najboljše rezultate. V območju koncentracij od 2 do 30 mg/L, kjer sem pripravljala umeritvene premice, so bile te linearne za analizno metodo HPLC-DAD, ta metoda naj bi dajala tudi bolj ponovljive rezultate kot LC-MS/MS. Iz obstoječe literature sem ugotovila, da so bili neonikotinoidni pesticidi prisotni v cvetnem prahu, nektarju, samih čebelah in medu. Njihove koncentracije so bile večinoma majhne, torej niso presegale vrednosti MRL, variirale pa so glede na celino oziroma državo, na/v kateri so bili vzorci odvzeti. Za ekstrakcijo je po mojem mnenju boljša QuEChERS, saj bolj učinkovito odstrani matrico vzorca in je cenejša. Izmed analiznih tehnik pa LC-MS/MS, ker v primerjavi s HPLC z UV/VIS ali DAD detektorjem meri samo odziv analitov, druga dva pa odziv vseh komponent, ki pri tisti valovni dolžini absorbirajo svetlobo.

• Language: Slovenian
• Keywords: neonikotinoidi, cvetni prah, ekstrakcija
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-119315
• COBISS.SI-ID: 27691523
• Publication date in RUL: 08.09.2020

Secondary language

• Language: English
• Title: Determination of neonicotinoid pesticides in pollen

Abstract

The use of pesticides for protection of various plants has increased yearly harvest and increased life quality. Larger quantities of food have to be provided as the population of the world is increasing daily. Insecticides, in my case neonicotinoids, protect the plants from various pests, but the problem is that they also harm beneficial insects, for example, bees. Neonicotinoids are systemic pesticides, which means they are transferred to all parts of the plant, even in the pollen which bees use as food. The residues of these pesticides have been found in the bees, and that is why they contribute to the numerous colony collapse disorders. The external use of three neonicotinoid pesticides: imidacloprid, clothianidin, and thiamethoxam were forbidden in 2018 because of that, and in 2020, the use of thiacloprid was also forbidden. The first step in the determination of neonicotinoids is sample preparation, and the most used methods are QuEChERS and SPE. Nowadays, more people are aware of environmental protection, so we tend to choose a more environmentally friendly method, which is definitely QuEChERS. The most used technique for analysis is LC-MS/MS, which is the most selective and sensitive technique, but it requires more demanding instrumentation and more frequent calibration of the instrument. The purpose of my work was to review the different extractions and analytical methods for the determination of neonicotinoid pesticides, the comparison of these methods and the selection of the method that gives the best results. The calibration curves were linear for analytical method HPLC-DAD in the range of concentration from 2 to 30 mg/L. This method is supposed to give more repeatable results than LC-MS/MS. From the literature I found out that neonicotinoid pesticides were present in pollen, nectar, honey, and in bees themselves. Their concentration was mostly low, and it did not exceed the MRL level. However, it differed according to the continent or the country in which the samples have been taken. In my opinion QuEChERS is better for extraction because it more efficiently removes the matrix of the sample and it is cheaper. In my opinion, LC-MS/MS is better for the analysis because in comparison with the HPLC with UV/VIS or DAD detector, it measures only the response of analytes while the other two measure the response of all the components which absorb the light at the same wavelength.

• Keywords: neonicotinoids, pollen, extraction