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1.
Effects of Photodegradation in TLS Measurements: Troubleshooting and Applications in Photochemistry and Photocatalysis
Mladen Franko, 2023, published scientific conference contribution abstract (invited lecture)

Abstract: Most analytical applications of thermal lens spectrometry (TLS) and related theoretical models consider absorbance of the sample constant during a single excitation by the pump laser beam. For photolabile analytes intensive excitation light can cause photodegradation, which significantly affects the results of TLS measurements. Theoretical models have been developed to account for changes in concentration and consequent changes in absorbance, caused by chemical reactions of different orders. Furthermore, abnormal TLS signal transients were observed for fast photochemical reactions on millisecond time scale, and the contributions of photodegradation as well as molecular diffusion were analyzed in detail. It has also been demonstrated that such effects can be reduced by performing TLS measurements in flowing systems such as in the case of flow injection analysis (FIA) or microfluidics. These findings were utilized to study the kinetics of chemical reactions, processes such as photostability of the soybean oil and thermal stability of biodiesel, or to improve the sensitivity of TLS detection in case of photolabile analytes. Furthermore, in combination with the concept of biomolecular recognition, FIA-TLS was exploited to study the efficiency of photocatalytic degradation of some neurotoxic substances such as organophosphate insecticides and revealed the formation of even more toxic degradation products. High sensitivity of TLS has enabled discrimination between photocatalytic and photosensitization mechanisms in photocatalytic degradation of textile dyes as well as between photodegradation and photocatalysis as will be demonstrated by the results of latest research in this field.
Keywords: Spektrometrija TLS, fotolabilnost, CrIVI), fotokataliza, fotorazgradnja
Published in RUNG: 23.10.2023; Views: 1664; Downloads: 0
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2.
Določanje tiametoksama na solati v času karence : diplomsko delo
Tjaša Lojpur, 2015, undergraduate thesis

Abstract: V diplomskem delu sem predstavila rezultate in ugotovitve po izvedbi poskusa na terenu. Podala sem dnevne koncentracije neonikotinoida tiametoksama, enega novejših kontaktnih sistemičnih insekticidov, ki sem ga uporabila na rdeči solati »Red Salad Bowl« (Lactuca sativa), posejani na kmetijski površini. Aktivno snov tiametoksam sem na solato nanesla v obliki fitofarmacevtskega pripravka Actara WG 25, ki se ga uporablja za zatiranje listnih uši in nato spremljala njeno koncentracijo vsak dan v času 7-dnevne karence ter 3. in 7. dan po njej. V ta namen sem uporabila optimizirano metodo za določanje vsebnosti tiametoksama v vzorcih solate. Izvedla sem klasično kemijsko analizo na osnovi tekočinske kromatografije visoke ločljivosti s spektrofotometrijskim detektorjem z diodno matriko (HPLC-DAD). Za obdelavo podatkov sem uporabila osnovne statistične metode (povprečna vrednost, standardni odmik, R²). Z raziskavo sem potrdila, da je v času 7-dnevne karence koncentracija tiametoksama upadla pod mejno vrednost ostankov pesticida (MRL), ki znaša 5 mg/kg in to že 4. dan po nanosu fitofarmacevtskega sredstva, ko je koncentracija njegove aktivne snovi na solati znašala 4,94 mg/kg. Izkoristek ekstrakcije, ki sem jo izvedla v vodi, je znašal 89,71 %, meja detekcije (LOD) pa 0,24 mg/kg. Ugotavljala sem tudi, kako različni meteorološki pojavi, kot so prisotnost sonca, oblačnost in obilnejše deževje vplivajo na hitrost razgradnje tiametoksama na solati. Izkazalo se je, da koncentracija tiametoksama pod vplivom svetlobe upada, ravno tako pa koncentracija znatno upade ob obilnejšem deževju. Za potrebe določanja koncentracije aktivne snovi med samim poskusom sem pripravila tudi umeritveno premico z R²=0,9996 in sicer na način, da sem na HPLC-DAD izvedla meritve vzorcev znanih koncentracij tiametoksama na solati (3,125 mg/kg, 6,25 mg/kg, 12,5 mg/kg, 25 mg/kg in 50 mg/kg).
Keywords: fotorazgradnja, tiametoksam, karenca, solata, hidroliza, diplomske naloge
Published in RUNG: 27.03.2015; Views: 6785; Downloads: 441
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3.
Stabilnost klorantraniliprola v vinogradu
Sašo Gabršček, 2012, undergraduate thesis

Keywords: diplomske naloge, vinogradništvo, ekologija, fotorazgradnja, pesticidi, obstojnost
Published in RUNG: 15.10.2013; Views: 8654; Downloads: 388
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4.
Oxidation and degradation of organophosphorus compounds
Mojca Bavcon Kralj, 2007, doctoral dissertation

Keywords: pesticidi, insekticidi, fotorazgradnja, strupenost, inhibitorji, disertacije
Published in RUNG: 15.10.2013; Views: 6197; Downloads: 419
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5.
Uporaba Suntesta za študij razgradnje izbranih neonikotinoidov v zemlji
Barbara Krašovec, 2012, undergraduate thesis

Keywords: imidakloprid, acetamiprid, fotorazgradnja, Suntest, diplomske naloge
Published in RUNG: 15.10.2013; Views: 5741; Downloads: 406
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6.
Kemija izbranih organskih spojin v okolju
Polonca Trebše, Mladen Franko, 2011, published scientific conference contribution (invited lecture)

Keywords: izobraževanje, pesticidi, fotorazgradnja, razgradni produkti
Published in RUNG: 15.10.2013; Views: 6760; Downloads: 42
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