1. Diversity and content of carotenoids and other pigments in the transition from the green to the red stage of Haematococcus pluvialis microalgae identified by HPLC-DAD and LC-QTOF-MSJaša Veno Grujić, Biljana Todorović, Roman Kranvogl, Terezija Ciringer, Jana Ambrožič-Dolinšek, 2022, original scientific article Abstract: H. pluvialis is a unicellular freshwater alga containing many bioactive compounds, especially carotenoids, which are the strongest antioxidants among the pigments. This study evaluates
the composition and content of carotenoids and other pigments in both stages of algae life cycle,
especially in the green vegetative stage, less studied in comparison to the red stage. To determine
the composition and content of carotenoids, a combination of HPLC-DAD and LC-QTOF-MS was
used. The content of carotenoids in the green vegetative stage was significantly lower than in the
red vegetative stage. In the green vegetative stage, 16 different carotenoids and other pigments were
identified. Among the total 8.86 mg g−1 DW of pigments, 5.24 mg g−1 DW or 59% of them were
chlorophyll a with its derivatives, and 3.62 mg g−1 DW or 41% of them were free carotenoids. After
the transition from the green to the red stage, the carotenoid composition was replaced by secondary
carotenoids, astaxanthin and its esters, which predominated in the whole carotenoid composition.
In addition to free astaxanthin, 12 astaxanthin monoesters, 6 diesters and 13 other carotenoids were
determined. The majority of 37.86 mg g−1 DW pigments were monoesters. They represented 82% of
all pigments, and their content was about 5 times higher than both, diesters (5.91 mg g−1 DW or 12%
of all) and free carotenoids (2.4 mg g−1 DW or 6% of all). The results of the study contribute to the
data on the overall pigment composition and content of H. pluvialis algae and provide the basis for
further improvement of cultivation of the H. pluvialis algae.
Keywords: antioxidants, astaxanthin, chlorophylls, bioactive compounds, algae, Haematococcus, life cycle, pigment composition, secondary carotenoids
Published in DKUM: 21.05.2024; Views: 164; Downloads: 8
 Full text (2,92 MB)
This document has many files! More... |
2. Uporaba UHPLC-HRMS za določanje organskih spojin v vzorcih psihoaktivnih snovi in prehranskih dopolnil : magistrsko deloGal Bjelovučić, 2023, master's thesis Abstract: Magistrsko delo predstavlja uporabo tekočinske kromatografije ultra visoke ločljivosti,
sklopljene z masno spektrometrijo visoke ločljivosti (angl. ultra high performance liquid
chromatography – high resolution mass spectrometry, UHPLC-HRMS) za analizo
psihoaktivnih snovi in prehranskih dopolnil. Razvili smo metodo za identifikacijo večjega
števila organskih snovi.
Za določanje organskih snovi v vzorcih je bila uporabljena kombinacija na novo razvite
metode UHPLC-HRMS z metodami infrardeče spektroskopije s Fourierovo transformacijo na
oslabljen totalni odboj (angl. attenuated total reflectance Fourier-transform infrared
spectroscopy, ATR-FTIR), tekočinske kromatografije visoke ločljivosti z detektorjem z nizom
diod (angl. high performance liquid chromatography with diode aray detector, HPLC-DAD)
in plinske kromatografije, sklopljene z masno spektrometrijo (angl. gas chromatography –
mass spectrometry, GC-MS), ki jih uporabljajo v Nacionalnem laboratoriju za zdravje, okolje
in hrano (NLZOH). Analizirani so bili trije vzorci psihoaktivnih snovi na osnovi
heksahidrokanabinola (angl. hexahydrocannabinol, HHC) in 58 vzorcev prehranskih dopolnil.
V vzorcih psihoaktivnih snovi smo identificirali štiri različne nove psihoaktivne snovi (NPS),
in sicer HHC, heksahidrokanabinol acetat (angl. hexahydrocannabinol acetate, HHC-O),
heksahidrokanabiforol (angl. hexahydrocannabiphorol, HHC-P) in
hidroksiheksahidrokanabinol (angl hydroxyhexahydrocannabinol, OH-HHC), ter 37 različnih
organskih spojin v vzorcih prehranskih dopolnil. Na Evropski center za spremljanje drog in
zasvojenosti z drogami (angl. European Monitoring Centre for Drugs and Drug Addiction,
EMCDDA) smo poročali prvo identifikacijo HHC-O v Sloveniji. Pri analizi vzorcev
prehranskih dopolnil so bile ugotovljene nepravilnosti pri 15 % analiziranih vzorcev.
Problematični so bili predvsem izdelki, kupljeni na spletu, ki so vsebovali zaviralce
fosfodiesteraze tipa 5 (angl. phosphodiesterase type 5, PDE5) in njihove derivate ter
anorektike, kot je sibutramin.
Razvita metoda predstavlja dobro orodje za analize tako psihoaktivnih snovi, katerih
proizvodnja se zelo hitro razvija, kot tudi prehranskih dopolnil, ki so na spletu prosto dostopne
vsakomur, vendar lahko vsebujejo zdravju škodljive ali celo življenjsko nevarne snovi.
Metoda omogoča identifikacijo velikega števila organskih spojin, z uporabo raztopin
standardov pa bi z njo lahko v prihodnosti določali tudi vsebnost teh potencialno nevarnih
spojin v vzorcih in tako preprečili morebitne zdravstvene zaplete pri njihovi uporabi.
Keywords: UHPLC-HRMS, psihoaktivne snovi, NPS, prehranska dopolnila, identifikacija
Published in DKUM: 03.01.2024; Views: 448; Downloads: 46
Full text (5,11 MB) |
3. Characterization of Slovenian coal and estimation of coal heating value based on proximate analysis using regression and artificial neural networksDarja Kavšek, Adriána Bednárová, Miša Biro, Roman Kranvogl, Darinka Brodnjak-Vončina, Ernest Beinrohr, 2013, original scientific article Abstract: Chemical composition of Slovenian coal has been characterised in terms of proximate and ultimate analyses and the relations among the chemical descriptors and the higher heating value (HHV) examined using correlation analysis and multivariate data analysis methods. The proximate analysis descriptors were used to predict HHV using multiple linear regression (MLR) and artificial neural network (ANN) methods. An attempt has been made to select the model with the optimal number of predictor variables. According to the adjusted multiple coefficient of determination in the MLR model, and alternatively, according to sensitivity analysis in ANN developing, two descriptors were evaluated by both methods as optimal predictors: fixed carbonand volatile matter. The performances of MLR and ANN when modelling HHV were comparable; the mean relative difference between the actual and calculated HHV values in the training data was 1.11% for MLR and 0.91% for ANN. The predictive ability of the models was evaluated by an external validation data set; the mean relative difference between the actual and predicted HHV values was 1.39% in MLR and 1.47% in ANN. Thus, the developed models could be appropriately used to calculate HHV.
Keywords: Slovenian coal, higher heating value, HHV, regression, artificial neural network
Published in DKUM: 03.04.2017; Views: 29233; Downloads: 370
Full text (749,77 KB)
This document has many files! More... |
4. Prediction of wine sensorial quality by routinely measured chemical propertiesAdriána Bednárová, Roman Kranvogl, Darinka Brodnjak-Vončina, Tjaša Jug, 2014, original scientific article Abstract: The determination of the sensorial quality of wines is of great interest for wine consumers and producers since it declares the quality in most of the cases. The sensorial assays carried out by a group of experts are time-consuming and expensive especially when dealing with large batches of wines. Therefore, an attempt was made to assess the possibility of estimating the wine sensorial quality with using routinely measured chemical descriptors as predictors. For this purpose, 131 Slovenian red wine samples of different varieties and years of production were analysed and correlation and principal component analysis were applied to find inter-relations between the studied oenological descriptors. The method of artificial neural networks (ANNs) was utilised as the prediction tool for estimating overall sensorial quality of red wines. Each model was rigorously validated and sensitivity analysis was applied as a method for selecting the most important predictors. Consequently, acceptable results were obtained, when data representing only one year of production were included in the analysis. In this case, the coefficient of determination (R2) associated with training data was 0.95 and that for validation data was 0.90. When estimating sensorial quality in categorical form, 94 % and 85 % of correctly classified samples were achieved for training and validation subset, respectively.
Keywords: overall sensorial quality, prediction, Slovenian wine, artificial neural networks, multivariate data analysis
Published in DKUM: 03.04.2017; Views: 1593; Downloads: 396
Full text (1,02 MB)
This document has many files! More... |
5. Simultaneous determination of phthalates, their metabolites, alkylphenols and bisphenol a using GC-MS in urine of men with fertility problemsRoman Kranvogl, Jure Knez, Alen Miuc, Ernest Vončina, Darinka Brodnjak-Vončina, Veljko Vlaisavljević, 2014, original scientific article Abstract: A GC-MS method was successfully applied to measure simultaneously the concentrations of endocrine disrupting compounds (5 dialkyl phthalates, 9 phthalate monoesters, 3 alkylphenols and bisphenol A) in 136 male urine samples. In the present study the method was validated and concentrations of EDCs were determined. The results were compared with results from other studies. Correlations between endocrine disrupting compounds and also correlations of endocrine disrupting compounds with two semen quality parameters are presented and evaluated. Significant positive correlations were found between almost all the endocrine disrupting compounds. The parameter sum of DEHP (SUM DEHP) was positively correlated to all the endocrine disrupting compounds but negatively to two semen quality parameters. Negative correlations between the endocrine disrupting compounds and the semen quality parameters could indicate that endocrine disrupting compounds could cause reproductive problems by decreasing the semen count and quality. This research will have helped to evaluate human exposure to endocrine disrupting compounds.
Keywords: endocrine disrupting compounds, fertility, fertility, phthalates, bisphenol A, alkylphenols, human urine
Published in DKUM: 21.12.2015; Views: 1929; Downloads: 166
Full text (103,03 KB)
This document has many files! More... |
6. Characterization of Slovenian wines using multidimensional data analysis from simple enological descriptorsAdriána Bednárová, Roman Kranvogl, Darinka Brodnjak-Vončina, Tjaša Jug, Ernest Beinrohr, 2013, original scientific article Abstract: Determination of the product's origin is one of the primary requirements when certifying a wine's authenticity. Significant research has described the possibilities of predicting a wine's origin using efficient methods of wine components' analyses connected with multivariate data analysis. The main goal of this study was to examine the discrimination ability of simple enological descriptors for the classification of Slovenian red and white wine samples according to their varieties and geographical origins. Another task was to investigate the inter-relations available among descriptors such as relative density, content of total acids, non-volatile acids and volatile acids, ash, reducing sugars, sugar-free extract, $SO_2$, ethanol, pH, and an important additional variable - the sensorial quality of the wine, using correlation analysis, principal component analysis (PCA), and cluster analysis (CLU). 739 red and white wine samples were scanned on a Wine Scan FT 120, from wave numbers 926 $cm^{–1}$ to 5012 $cm^{–1}$. The applied methods of linear discriminant analysis (LDA), general discriminant analysis (GDA), and artificial neural networks (ANN), demonstrated their power for authentication purposes.
Keywords: wine authentication, enological descriptors, classification techniques, ANN
Published in DKUM: 10.07.2015; Views: 2897; Downloads: 63
Full text (261,13 KB)
This document has many files! More... |
7. DOLOČEVANJE ENDOKRINIH MOTILCEV V URINU Z GC/MS IN KEMOMETRIJSKA KARAKTERIZACIJARoman Kranvogl, 2014, doctoral dissertation Abstract: V doktorski nalogi smo proučevali vpliv nekaterih spojin okoljskih endokrinih motilcev na plodnost moških z namenom, da bi preverili hipotezo ali vplivajo endokrini motilci na kakovost semenčic. V študijo smo vključili 136 parov, ki so se zdravili zaradi neplodnosti.
Za analitiko sledov spojin endokrinih motilcev v urinu smo razvili analizno metodo določevanja s plinsko kromatografijo in masno spektrometrijo. Uporabili smo 13C izotopsko označene standardne spojine. Po dodatku internih standardov smo za dekonjugacijo analitov urinu dodali encim β-glukuronidazo. Vzorec smo nato nakisali s HCl na pH 2. Sledila je ekstrakcija z diklorometanom. Čiščenje ekstraktov smo izvedli na SiO2 koloni ter tako odstranili bazične interference, ki jih predstavljajo aminokisline, sečnina, amini in druge bazične spojine. Očiščeni ekstrakt smo odparili do suhega in dodali derivatizacijski reagent N-metil-N-trimetilsilil trifluoroacetamid (MSTFA). Sililirani ekstrakt smo analizirali s plinsko kromatografijo in masno spektrometrijo. Uporabljena je bila tehnika snemanja izbranih masnih fragmentov (SIM).
Sočasno smo določali di-alkil ftalate: di-metil ftalat (DMP), di-etil ftalat (DEP), di-butil ftalat (DBP), benzil-butil ftalat (BzBP) ter di-(2-etil-heksil) ftalat (DEHP), njihove metabolite mono-alkil ftalate: mono-etil ftalat (MEP), mono-izo-butil ftalat (MiBP), mono-n-butil ftalat (MnBP), mono-(2-etilheksil) ftalat (MEHP), mono-benzil ftalat (MBzP), mono-izo-nonil ftalat (MiNP), mono-n-oktil ftalat (MnOP), mono-(2-etil-5-oksoheksil)ftalat (MEOHP) ter mono-(2-etil-5-hidroksiheksil)ftalat (MEHHP). Določali smo alkilfenole: 4-terc-oktilfenol (4-tOP), 4-n-oktilfenol (4nOP) ter 4-n-nonilfenol (4nNP). Prav tako smo določali bisfenol A (BPA).
Izvedli smo validacijo metode. Meja določanja je bila za bisfenol A 0,1 µg L-1, za mono-alkil ftalate in alkilfenole 1 µg L-1, in za di-alkil ftalate 5 µg L-1. Linearnost metode smo preverili v koncentracijskem območju od 1 do 200 µg L-1. Uporabljena metoda se je pri kvantitativnem določanju spojin endokrinih motilcev v vzorcih urinov izkazala za uspešno, saj je natančna, točna in selektivna. Omogoča sočasno določanje endokrinih spojin z nizko mejo zaznavnosti v območju µg L-1. Z uporabo tehnike snemanja celotnega masnega spektra smo določili še 60 drugih spojin v urinu (maščobne kisline, steroide, mono-aromatske spojine in druge spojine).
Kemometrijsko karakterizacijo smo izvedli s pomočjo podatkov pridobljenih z analizami 136 vzorcev urinov moških, ki imajo težave s plodnostjo. Namen raziskave je bil ugotoviti ali obstajajo pomembne razlike med vzorci, ki smo jih uvrstili v dve skupini, glede na normalno ter zmanjšano kakovost semenčic. Skupini se razlikujeta po vrednostih koncentracije in gibljivosti semenčic. Cilj kemometrijske karakterizacije je bil poiskati korelacije med vsebnostjo spojin endokrinih motilcev v urinu, kot so ftalatni estri in njihovi metaboliti, oktil in nonil alkilfenoli in bisfenol A ter kliničnimi parametri kakovosti semenčic kot sta koncentracija in gibljivost semenčic. Dodatno smo iskali korelacije med kakovostjo semenčic in vsebnostjo hormonov: FSH (folikel-stimulativni hormon), LH (luteinizarajoči hormon), estrogen, testosteron, SHBG (spolne hormone vezoči globulin), inhibinB.
Izvedli smo korelacijsko analizo, analizo variance (ANOVA), Mann Whitney test, analizo glavnih osi (PCA), hierarhično razvrščanje (CA), linearno diskriminatno analizo (LDA), metodo gradnje regresijskih dreves (CART) in umetne nevronske mreže (ANN).
Študija je pokazala, da obstajajo pomembne razlike med obema skupinama moških, ki imajo težave s plodnostjo, predvsem glede na vsebnost di-(2-etilheksil) ftalata (DEHP), mono-(2-etilheksil) ftalata (MEHP) in obeh sekundarnih metabolitov mono-(2-etil-5-oksoheksil) ftalata (MEOHP) ter mono-(2-etil-5-hidroksiheksil) ftalata (MEHHP). V vzorcih urina moških z zmanjšano kakovostjo semenčic so bile izmerjene vsebnosti endokrinih motilcev v povprečju dvakrat višje od vsebnosti v vzorcih urina moških
Keywords: Ftalati, metaboliti ftalatov, alkilfenoli, bisfenol A, plinska kromatografija, masna spektrometrija, urin, kemometrija.
Published in DKUM: 11.07.2014; Views: 3489; Downloads: 540
Full text (4,07 MB) |
8. VPLIV VRSTE KATALIZATORJA NA HITROST REAKCIJE V REAKTORJU Z NASUTJEMRoman Kranvogl, 2010, undergraduate thesis Abstract: Hidroliza saharoze je reakcija, ki lahko poteka s kemijskim ali encimskim katalizatorjem. Z raziskavami v okviru diplomskega dela smo to reakcijo izvajali v kemijskem in biološkem reaktorju z nasutjem. Namen dela v prvi fazi je bil ugotoviti, s katerim katalizatorjem, kemijskim ali encimskim, dosežemo najvišjo presnovo reakcije hidrolize saharoze.
Za načrtovanje reaktorjev je potrebno poznati vpliv procesnih spremenljivk na potek reakcije. Zato smo izbrano reakcijo izvajali pri različnih temperaturah, volumskih pretokih reaktanta in pri različnih začetnih koncentracijah encima. Uporabili smo laboratorijski reaktor z nasutjem.
Pri delu smo dali večji poudarek biološkemu reaktorju. Uporabili smo encim invertazo in študirali reakcijo hidrolize saharoze. Osrednji cilj drugega dela raziskav je bila določitev osnovnih kinetičnih parametrov encimske reakcije, kot so aktivacijska energija, predeksponentni faktor, Michaelis—Menten-ova konstanta itd. Pri izvajanju reakcije v kemijskem reaktorju smo uporabili katalizator Amberlite IR—120, s povprečno zrnavostjo delcev, d = 533 µm. V tem primeru smo reakcijo izvajali pri različnih temperaturah.
Na osnovi eksperimentalnih meritev v kemijskem reaktorju smo določali le presnovo reakcije, saj so bile kinetične študije izvedene že predhodno. Z meritvami v biološkem reaktorju smo dokazali, da izbrana encimska reakcija dobro sledi Michaelis—Menten-ovi kinetiki. Določili smo vrednost aktivacijske energije, Ea = (17,9 — 20) kJ/mol in Michaelis—Menten-ove konstante, KM = (27,2 — 28,5) mmol/L. Obe vrednosti kažeta dobro ujemanje z literaturnimi.
Primerjava kemijskega in biokemijskega reaktorja pokaže, da je presnova pri uporabi encimskega katalizatorja mnogo višja, kar za 20 %, gledano pri srednji koncentraciji encima. Kljub temu, da je encimski katalizator dražji in da je potreben daljši čas za vzpostavitev stacionarnega stanja, bi se odločili za uporabo biokemijskega reaktorja, saj so obratovalne temperature pri encimskem katalizatorju bistveno nižje kot pri kemijskem katalizatorju.
Keywords: hidroliza saharoze, invertaza, katalizator, aktivacijska energija, reaktor z nasutjem.
Published in DKUM: 20.07.2010; Views: 3783; Downloads: 417
Full text (1,74 MB) |
