Naslov
The Influence of Mobile Phase in HPSEC of Small Non-polymeric Compound

Autori
Šegudović, Nikola

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
7th Balaton Symposium on High-Performance Separation Methods In Memoriam Szabolcs Nyiredy, Book of Abstracts / Klebovic, Imre ; Gazdag, Maria - Siófok : Hungarian Society for Separation Sciences, 2007, 42-42

ISBN
978-963-06-2925-6

Skup
7th Balaton Symposium on High-Performance Separation Methods In Memoriam Szabolcs Nyiredy

Mjesto i datum
Siófok, Mađarska, 05.09.2007. - 07.09.2007

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
mobile phase; HPSEC; small molecules

Sažetak
Crude oil and its products are very complex mixtures and they contain a huge number of aliphatic, olefinic, naphthenic, aromatic and alkyl aromatic hydrocarbon compounds. There are three techniques used to measure molecular mass averages (MM) and molecular mass distribution (MMD) : cryoscopy, vapour pressure osmometry, and size exclusion chromatography (SEC). The MMD is suitable for characterising oil fractions since the molecular distribution is closely related to the boiling point distribution and SEC is often used for high molecular component- asphaltenes. The main problem when using the selected SEC technique is to discriminate between the different hydrocarbon families eluting at different rates owing to their varying geometrical molecular size, and the choice of solvent (mobile phase) is very important. Many asphalt applications can be successfully carried out using tetrahydrofurane (THF), but in case of other samples one of the important drawbacks of using THF is the structure dependence of the observed elution volumes ; aliphatic compound eluted more quickly than cyclic ones of the similar MM, followed by aromatic components. Both adsorption and size exclusion mechanism effect the separation using THF as eluent. The use of 1-methyl-2-pyrolidinone (NMP) as a eluent minimizes the adsorption effect but asphaltene components are only partially soluble in NMP. It is known that the aromatic hydrocarbons (HC) display an anomalous deviation in SEC on the styrene-divinyl benzene gel. The elution range of aromatics lies beyond the gel size separation range. and the effect is generally denoted as the gel adsorption effect. In such cases a choice of aromatic eluents ( toluene ) is recommended. Introduction of an alkyl group into the aromatic HC molecules brings about a significant change in the elution characteristic, because the alkyl part of the molecules obeys the separation principle more strictly. The knowledge of group-type composition of samples obtained by reverse-phase liquid chromatography (RP HPLC) helps decide which eluent to take for analysis.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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