magistrsko delo
Ivan Mitevski (Avtor), Helena Prosen (Mentor), Iztok Turel (Član komisije za zagovor), Mitja Kolar (Član komisije za zagovor)

Povzetek

Alkilfenoli so zelo razširjeni produkti razgradnje površinsko aktivnih snovi. So toksične, ksenobiotične snovi, uvrščene med endokrine motilce z negativnim učinkom na hormonski sistem številnih organizmov, vključno s človekom. Zaradi njihove stabilnosti in ogrožanja okolja je pomemben razvoj novih tehnik za kvalitativno in kvantitativno določanje alkilfenolov. V naši študiji je bil poudarek na treh najbolj pogostih alkilfenolih: 4-tert-oktilfenolu, 4-oktilfenolu in 4-nonilfenolu. Od teh je bilo največ pozornosti namenjeno 4-tert-oktilfenolu, saj je bila optimizirana metoda namenjena analizi vzorcev, ki vsebujejo neionsko površinsko aktivno snov Triton X-100. To je alkilfenol polietoksilat, kjer je polietilen glikolna veriga na koncu zaključena s 4-tert-oktilfenilno skupino. Sam po sebi ni zelo toksičen, vendar so problem produkti razgradnje in 4-tert-oktilfenol je eden izmed njih. Za določanje alkilfenolov sem razvil GC-MS/MS metodo. Ker so alkilfenoli v dejanskih vzorcih prisotni v zelo nizkih koncentracijah, jih je bilo potrebno predkoncentrirati z ekstrakcijo na trdno fazo s C8 reverzno-fazno ekstrakcijsko kolono. Vzorce sem pred ekstrakcijo predobdelal z uravnavanjem ionske jakosti in sicer z NaCl (2 %) ter z razredčeno mravljično kislino nastavil pH na 3. Volumen vzorcev je bil prav tako optimiziran in v končnem postopku nastavljen na 20 mL. Alkilfenole sem eluiral s 4 mL etil acetata in nato eluent odparel z rahlim tokom N2 do 2 mL. Za povečanje hlapnosti analitov sem uporabil postopek derivatizacije z N,O-bis(trimetilsilil)trifluoroacetamidom. Kot interni standard sem uporabil 2,4,6-trijodofenol. Optimiziranih je bilo več parametrov derivatizacije: količina eluenta, internega standarda in reagenta; topilo, čas in temperatura. Izkoristki končnega postopka, vključno z ekstrakcijo, so bili 86,3 % za 4-tert-oktilfenol; 46,1 % za 4-oktilfenol in 29,7 % za 4-nonilfenol z RSD okoli 6 % za vse alkilfenole. Optimiziran postopek sem uporabil na realnih vzorcih raztopine Triton X-100, izpostavljenih elektrooksidacijski obdelavi. Dodatno je bila ista metoda uporabljena za določanje in spremljanje koncentracije 4-nonilfenol dietoksilata in 4-tert-oktilfenol monoetoksilata. Optimizirana je bila tudi HPLC-DAD metoda za določanje Triton X-100.

Ključne besede

alkilfenoli;alkilfenol polietoksilati;elektrooksidacija;GC-MS/MS;ekstrakcija na trdno fazo;optimizacija metode;magistrska dela;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.09 - Magistrsko delo
Organizacija: UL FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik: [I. Mitevski]
UDK: 543.544.3:543.51(043.2)
COBISS: 254644995 Povezava se bo odprla v novem oknu
Št. ogledov: 120
Št. prenosov: 27
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: Development and testing of a GC-MS/MS method with derivatization for alkylphenols determination in aqueous samples
Sekundarni povzetek: Alkylphenols are widely spread degradation products of surfactants. They are toxic, xenobiotic substances, also classified as endocrine disruptors with a negative effect on the hormonal system of many organisms including humans. Due to their stability and the threat to environment, the development of new techniques for the qualitative and quantitative determination of alkylphenols is important. In our study, the focus was on three typically encountered alkylphenols: 4-tert-octylphenol, 4-octylphenol and 4-nonylphenol. Out of these, the greatest attention was given to 4-tert-octylphenol because the optimized method was intended for the analysis of samples containing nonionic surfactant Triton X-100, which is an alkylphenol polyethoxylate where poly(ethylene glycol) is terminated with a 4-tert-ocylphenyl group at the end. This compound on its own is not very toxic, but the problem are the degradation products and 4-tert-octylphenol is one of them. GC-MS/MS method was developed for the analysis of alkylphenols. Since alkylphenols are present in very low concentrations in real samples, they had to be pre-concentrated with solid-phase extraction on a C8 reverse phase cartridge. Samples were pretreated before extraction by adjusting the ionic strength with NaCl (2%) and pH to 3 with diluted formic acid. Volume of the samples was also optimized and set to 20 mL. In the final procedure alkylphenols were eluted with 4 mL of ethyl acetate and then the eluent was dried with a gentle stream of N2 to 2 mL. To increase the volatility of analytes, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide was included. 2,4,6-triodophenol was used as an internal standard. Several derivatization parameters were optimized: volumes of eluent, internal standard, and reagent; solvent, time and temperature. Recoveries of the final procedure including extraction were 86.3% for 4-tert-octylphenol; 46.1% for 4-octylphenol and 29.7% for 4-nonylphenol with RSD around 6% for all alkylphenols. Optimized procedure was applied on real samples of Triton X-100 solution subjected to electro-oxidation treatment. Additionally, the same method was used for determination and concentration monitoring of 4-nonylphenol diethoxylate and 4-tert-octylphenol monoethoxylate. HPLC-DAD method was also optimized for determination of Triton X-100.
Sekundarne ključne besede: alkylphenols;alkylphenol etoxylates;GC-MS/MS;solid-phase extraction;electro-oxidation;Kromatografija;Masna spektrometrija;Univerzitetna in visokošolska dela;
Vrsta dela (COBISS): Magistrsko delo/naloga
Študijski program: 1000375
Konec prepovedi (OpenAIRE): 1970-01-01
Komentar na gradivo: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Strani: 1 spletni vir (1 datoteka PDF (62 str.))
ID: 27382885