diplomsko delo
Domen Kermc (Author), Mitja Kolar (Mentor), Maša Islamčević Razboršek (Co-mentor)

Abstract

Ogljikove hidrate običajno določamo s tekočinsko kromatografijo visoke ločljivosti (HPLC) in UV-zaznavo ali s plinsko kromatografijo v povezavi z masno spektrometrijo (GC-MS). Ker so enostavni ogljikovi hidrati, kot sta fruktoza in glukoza, v raztopinah prisotni v različnih oblikah (aciklična, ciklična – furanozna in ciklična – piranozna), lahko po pripravi vzorcev za analizo pride do neželenega pojava več kromatografskih vrhov. Z zastavljenim obsegom raziskav smo razvili metodo za ločevanje in določanje monosaharidov fruktoze in glukoze v trgovsko dosegljivih vzorcih make (Lepidium meyenii) z uporabo GC-MS. Metoda po tvorbi trimetilsililiranih derivatov z reagentom N-metil-N-(trimetilsilil)trifluoroacetamidom (MSTFA) omogoča dobro ločevanje in kvantitativno določanje fruktoze in glukoze. Postopek sililiranja smo izvajali na peščeni kopeli pri temperaturi od 70 °C do 80 °C, 90 min. Izvedli smo kvantitativno analizo vzorcev make, pripravljenih z ekstrakcijo trdno-tekoče z vodo ali metanolom (0,5 g vzorca/10 mL topila) pri različnih temperaturah (40 °C, 50 °C, 70 °C, 100 °C) in različnih časovnih intervalih (1 h, 3 h). Vsebnosti fruktoze in glukoze smo določili iz umeritvenih krivulj z uporabo fenil-β-D-glukopiranozida kot internega standarda. Ugotovili smo, da so bile najvišje vsebnosti preiskovanih spojin v vzorcu make, ekstrahiranem z deionizirano vodo in segrevanjem 3 h pri 50 °C, kjer je bila povprečna vsebnost fruktoze 33 mg/g, glukoze pa 45 mg/g suhe zatehte vzorca. Vsebnost preiskovanih spojin smo določili tudi po hidrolizi vzorca, izvedeni z vodno raztopino HCl (koncentracije 0,1 M, 0,5 M, 1 M; 0,5 g vzorca/10 mL topila) pri različnih temperaturah (50 °C, 70 °C) in različnih časovnih intervalih (1 h, 3 h). Najvišje vsebnosti fruktoze in glukoze smo določili v vzorcu make, hidroliziranem z vodno raztopino HCl koncentracije 0,5 M in segrevanjem 3 h pri 70 °C. Povprečna vsebnost fruktoze je bila 224 mg/g, glukoze pa 303 mg/g suhe zatehte vzorca. V vzorcu make smo ob preiskovanih spojinah v višjih koncentracijah zasledili tudi nekatere druge ogljikove hidrate, kot sta inozitol in saharoza, vendar jih nismo kvantitativno ovrednotili.

Keywords

fruktoza;glukoza;plinska kromatografija;masna spektrometrija;maka;lepidium meyenii;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher: [D. Kermc]
UDC: 543.544.3:543.51(043.2)
COBISS: 19035158 Link will open in a new window
Views: 1967
Downloads: 203
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Other data

Secondary language: English
Secondary title: GC-MS determination of monosaccharides in maca (Lepidium meyenii) extract
Secondary abstract: Carbohydrates are usually analysed using high performance liquid chromatography (HPLC) and UV detection, or with gas chromatography coupled with mass spectrometry (GC-MS). Due to the fact that simple carbohydrates such as fructose and glucose exist in various forms in solutions (acyclic, cyclic – furanose and cyclic – pyranose) multiple chromatographic peaks can appear after the sample is prepared for analysis. A GC-MS method for the separation and quantification of the monosaccharides fructose and glucose in real, commercially available maca (Lepidium meyenii) samples was developed. With a formation of trimethylsilyl derivates with reagent N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) the method enables good separation and quantitative determination of fructose and glucose. The silylation procedure was carried out on a sand bath at a temperature between 70 °C and 80 °C for 90 min. Quantitative analysis of the maca samples was carried out after solid-liquid extraction using water or methanol as an extraction solvent (0.5 g of sample/10 mL of solvent) at various temperatures (40 °C, 50 °C, 70 °C, 100 °C) and various time intervals (1 h, 3 h). The contents of fructose and glucose were determined from calibration curves using phenyl-β-D-glucopyranoside as an internal standard. The highest concentrations of both analysed compounds were determined in a maca sample extracted with deionised water and heated for 3 h at 50 °C. The average concentrations of fructose and glucose were 33 mg/g and 45 mg/g of dry weight sample respectively. We also determined the contents of fructose and glucose after the hydrolysis of the sample using an aqueous solution of HCl (concentrations 0.1 M, 0.5 M and 1 M; 0.5 g of sample/10 mL of solvent) at various temperatures (50 °C, 70 °C) and various time intervals (1 h, 3 h). The highest concentrations of investigated compounds were determined in a maca sample hydrolysed with 0.5 M aqueous solution of HCl and heated for 3 h at 70 °C. The average concentrations of fructose and glucose were 224 mg/g and 303 mg/g of dry weight sample respectively. We found that a maca sample also contains some other carbohydrates in larger quantities, such as inositol and sucrose, but these were not quantitatively determined.
Secondary keywords: fructose;glucose;gas chromatography;mass spectrometry;maca;Lepidium meyenii;
URN: URN:SI:UM:
Type (COBISS): Bachelor thesis/paper
Thesis comment: Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages: VII, 39 str.
ID: 8887669