20.500.12556/DKUM-54120 Določevanje monosaharidov v izvlečku make (Lepidium meyenii) z GC-MS GC-MS determination of monosaccharides in maca (Lepidium meyenii) extract 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. 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. fruktoza glukoza plinska kromatografija masna spektrometrija maka Lepidium meyenii fructose glucose gas chromatography mass spectrometry maca Lepidium meyenii true true false [D. Kermc] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2015-08-22 15:22:58 2015-10-22 10:05:31 2022-06-04 03:10:48 2021-05-09 03:32:03 2015 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 543.544.3:543.51(043.2) 19035158 URN:SI:UM:DK:ITKLCRJD UN_Kermc_Domen_2015.pdf UN_Kermc_Domen_2015.pdf 1 AC7B32D2539BFE64C3ABE038AB707C64 de9f2184938c017ceaeefa58dd1058b5dcfa8817d4dee42fa6eab2be8332804a 9f9b2f12-7c07-11eb-bb7a-00155d0001ca https://dk.um.si/Dokument.php?lang=slv&id=80484 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0