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In this study, the extraction efficiency of natural deep eutectic solvents (NADES) based on choline chloride as a hydrogen bond acceptor (HBA) and five different hydrogen bond donors (HBD lactic acid, 1,4-butanediol, 1,2-propanediol, fructose and urea) was evaluated for the first time for the isolation of valuable bioactive compounds from Achillea millefolium L. The phytochemical profiles of NADES extracts obtained after ultrasound-assisted extraction were evaluated both spectrophotometrically (total phenolic content (TPC) and antioxidant assays) and chromatographically (UHPLC-MS and HPLC-UV). The results were compared with those obtained with 80% ethanol, 80% methanol, and water. The highest TPC value was found in the lactic acid-based NADES (ChCl-LA), which correlated with the highest antioxidant activity determined by the FRAP analysis. On the other hand, the highest antiradical potential against ABTS$^{+•}$ was determined for urea-based NADES. Phenolic acids (chlorogenic acid and dicaffeoylquinic acid isomers), flavones (luteolin and apigenin), and their corresponding glucosides were determined as the dominant individual phenolic compounds in all extracts. The antibacterial and antifungal properties of the extracts obtained against four bacterial cultures and two yeasts were evaluated using two methods: the agar dilution method to obtain the minimum inhibitory concentration (MIC) and the minimum bactericidal or fungicidal concentration (MBC or MFC), and the disc diffusion method. ChCl-LA had the lowest MIC and MBC/MFC with respect to all microorganisms, with an MIC ranging from 0.05 mg mL$^{−1}$ to 0.8 mg mL$^{−1}$, while the water extract had the weakest inhibitory activity with MIC and MBC/MFC higher than 3.2 mg mL$^{−1}$.

Phenolic antioxidants are usually grouped into flavonoids and non-flavonoids, according to their structure. With regard to the tannic character, phenolic antioxidants are further subdivided to tannic phenols and non-tannic phenols. Collectively, these compounds contribute to the high antioxidant capacity of wine. In this work, we compare determination of gallic acid, catechin, epicatechin, resveratrol, quercetin, dihydrobenzoic acid, sinapic acid, vanillic acid, caffeic acid, chlorogenic acid, ferullic acid, ellagic acid, p-coumaric acid and caftaric acid in 141 wine samples using two liquid chromatographic methods and detection systems, i.e. with UV detection and mass-spectrometric detection. In addition, we applied the conventional Folin-Ciocalteu spectrophotometric method for determination of the total phenolic content in wine samples and compared the results with those obtained using the chromatographic methods. Despite satisfactory correlations statistically significant differences between HPLC-UV/VIS and LC/MS/MS were established, which could be related to coelution not detectable with UV/VIS detectors. The correlations between results of the spectrophotometric method and sum of LC/MS/MS determinations are not satisfactory and are different for white, red, and rosé wines. Glede na kemijsko sestavo delimo fenolne antioksidante na flavonoide in neflavonoide. Glede na taninski značaj jih delimo na taninske in netaninske fenole. Omenjene fenolne komponente so odgovorne za visok antioksidativni potencial vina. Primerjali smo določanje galne kisline, katehina, epikatehina, resveratrola, kvercetina dihidrobenzojske kisline, sinapinske kisline, vanilinske kisline, kavne kisline, klorogenske kisline, ferulne kisline, elaginske kisline, p-kumarne kisline in kaftarjeve kisline v številnih vzorcih vin z uporabo dveh metod tekočinske kromatografije z UV/VIS detekcijo in z masnospektrometrično detekcijo (LC/MS/MS). Uporabili smo konvencionalno spektrofotometrično metodo s Folin-Ciocalteu-jevim reagentom za določanje vsebnosti skupnih fenolov in rezultate primerjali z rezultati kromatografskih metod. Kljub zadovoljivim korelacijam smo ugotovili statistično signifikantne razlike med HPLC-UV/VIS in LC/MS/MS, kar je lahko posledica koelucije, ki je z UV/VIS detektorjem ne zaznamo. Primerjava med rezultati, dobljenimi s spektrofotometrično metodo in vsoto fenolnih komponent, določanih z LC/MS/MS je pokazala različne korelacijske premice za rdeča, rosé in bela vina.

5-hidroksimetilfurfural (5-HMF) se v medu največkrat tvori preko sladkorjev, ki so prisotni v medu. Tvorba 5-HMF se pospeši s segrevanjem medu, pri predelavi, pridelavi ter z nepravilnim shranjevanjem. V diplomski nalogi sem določala vsebnost 5-HMF v različnih vzorcih medu, analizo pa sem izvajala na LC/MS instrumentu. Preverila sem ponovljivost, linearnost in točnost metode ter stabilnost raztopin standardov in vzorca. Vsebnost 5-HMF sem najprej primerjala med vzorci medu iz različnih botaničnih vrst, nato v vzorcih kremnega medu z dodatki, na koncu pa sem v štirih botaničnih vrstah izbrala vzorce z najnižjo vsebnostjo. Kasneje sem vzorce tri dni segrevala na temperaturi 65 °C, zatem pa še dodatnih sedem dni in nato primerjala vsebnosti 5-HMF. Rezultati nakazujejo, da se 5-HMF v medu tvori pri povišani temperaturi in je tako lahko pokazatelj starosti medu ali neustreznega skladiščenja le-tega. 5-hidroksimetilfurfural is mostly formed in honey through the sugars present in the honey. The formation of 5-HMF is accelerated by heating the honey, during processing, production and with improper storing. In my diploma thesis, I analyzed the content of 5-HMF in different samples of honey, I performed the analysis on LC/MS instrument. I checked not only repeatability, linearity and accuracy of the method but also the stability of the standards and the sample. I first compared the 5-HMF content between honey samples from different botanical species, then in samples of creamed honey with additives, and in the end I chose samples from four botanical species with the lowest content. Later, I heated the samples at a temperature of 65°C for three days and later for additional seven days and than i compared the content. The results indicate that 5-HMF in honey is formed at elevated temperature and thus may be an indicator of honey age or inadequate honey storage.

Kovine v pivu imajo velik vpliv na kvaliteto, okus ter izgled piva prav tako pa na potek alkoholne fermentacije. V 6 različnih vzorcih piva sem določal vsebnost izbranih kovin (baker, železo, mangan in cink). Vzorce sem pripravil tako, da sem jih prefiltriral oz. pripravil samo s kislinskim mikrovalovnim razklopom. Kovine imajo v pivu vsebnost na ravni sledov, zato klasične metode niso primerne za uporabo. Koncentracije sem zato določal z atomsko absorpcijsko in optično emisijsko spektroskopijo s pomočjo umeritvene krivulje. ICP-OES nam za razliko od AAS omogoča, da naenkrat določamo več elementov v vzorcu. Vsebnosti kovin v vzorcih sem primerjal z rezultati drugih raziskav, poleg tega pa sem primerjal tudi razlikovanje rezultatov pri obeh uporabljenih metodah. Metals in beer have a big influence on quality, taste and looks of the beer, and also on the process of fermentation. Therefore, I determined the contents of selected metals in 6 different samples of beer (copper, iron, manganese, zinc). The samples were prepared by filtering or by acid microwave digestion. The metals in beer are present in traces, consequently classical methods are not suitable for use. The concentrations were determined by atomic absorption and optical emission spectroscopy with the use of calibration curve. On the contrary to AAS, ICP-OES allows us to measure more elements in a sample at once. Contents of metals in the samples were compared to results of other researches. In addition, also difference of results in both methods was compared.

Vinska kislina je organska spojina, ki jo pogosto najdemo v naravi v obliki same vinske kisline, hidrogentartrata in tartrata. Uporabljamo jo kot kiralno molekulo pri ločevanju, kot izhodno molekulo za tvorbo novih kiralnih molekul, v živilski, farmacevtski in kozmetični industriji. Kislina ima dve hidroksilni in dve karboksilni skupini, prek katerih lahko tvori komplekse z večkrat nabitimi ioni, kot sta tudi železov(III) in bakrov(II) ion. Namen magistrskega dela je bil ugotoviti, pri katerih pH pride do tvorbe kompleksov in kakšna je njihova stehiometrija. Vse to sem ugotavljala s pomočjo Jobove metode in ciklične voltametrije. Pripravila sem raztopine pri pH 1 (samo pri ciklični voltametriji), 3, 5 in 7 ter posnela njihove UV-VIS spektre in ciklične voltamograme. Iz rezultatov sem določila konstante stabilnosti in jih primerjala s teoretičnimi. Tartaric acid is an organic compound often found in nature in the form of tartaric acid, hydrogentartrate and tartrate. It is used as a chiral acid for racemic resolution and as a starting material for organic synthesis of new chiral compounds. It can often be used in pharmaceutical, cosmetic and food industry as well. Tartaric acid contains two hydroxyl and two carboxylic functional groups through which it can form coordinate compounds with multiply-charged ions such as iron(III) and copper(II) ion. The goal of the master's thesis was to determine the stoichiometry and the pH values of solutions in which coordinate compounds can be formed. This was done using the Job's method and cyclic voltammetry. Solutions of pH 1 (only for cyclic voltammetry), 3, 5 and 7 were prepared and the corresponding UV-VIS spectra and cyclic voltammograms were scanned. Out of all collected data stability constants were calculated and compared to theoretical values.

V naprej določenemu koncentracijskemu gradientu treh težkih kovin (svinec, cink, kadmij) sem dodajal ligande (EDTA, citronska kislina in huminska kislina). Z meritvami na osnovi atomske absorpcijske spektroskopije (AAS) sem za vsako kombinacijo določil umeritveno krivuljo in njen naklon. S primerjavo naklonov sem določal vpliv dodanega liganda na določanje posamezne kovine oz. njihovi zmesi v različnih medijih (nevtralnem in kislem) na metodo za določanje teh kovin. Svinec se je izkazal za najbolj robustnega na spreminjajoče se dejavnike, medtem ko je bil kadmij najbolj podvržen spremembam naklona zaradi spreminjajočih se dejavnikov. I added ligands (EDTA, citric acid, and humic acid) in a predetermined gradient of 3 heavy metals (lead, zinc, and cadmium). The calibration curve and slope for each combination were determined using atomic absorption spectroscopy (AAS) measurements. By comparing the slopes, I studied the influence of the added ligand to the individual element solution or their mixtures in different media (neutral and acidic) on the method for determining the concentration. Lead was found to be the most resistant to factor changes, whereas cadmium was most prone to slope changes because of factor changes.

V diplomski nalogi sem določal hlapne komponente v cvetličnem in gozdnem medu. Uporabljal sem HS-SPME-GC-MS. Preveril sem ponovljivost in linearnost metode, ki sta bili zadovoljivi. Določil sem 40 najbolj zastopanih hlapnih spojin v vsaki od vrst medu, ki so ustrezale določenim izbirnim kriterijem. Razdelil sem jih na skupne in na specifične spojine, prisotne le v eni od vrst medu. Skupnih je bilo 26, prevladovali so estri, terpeni in derivati benzena. V obeh vrstah medu so največji odziv dale skupne spojine hotrienol, p-(1-propenil)toluen, metil nonanoat, metil-(Z)-9-oktadecenoat in metil oktanoat. Od specifičnih so bili v cvetličnem medu najbolj zastopani 1,2-dihidronaftalen, benzil nitril in 1-metoksi-4-metilbenzen. V gozdnem so največji odziv imeli terpinen-4-ol, α-terpineol in metil (E)-2-nonenoat. Od teh se 1,2-dihidronaftalen in benzil nitril nista pojavila v niti enem od vzorcev gozdnega medu. Od naštetih spojin, specifičnih za gozdni med, se ni nobena pojavila v niti enem od vzorcev cvetličnega medu. Te spojine bi bile lahko uporabne kot določitveni markerji za slovenski cvetlični in gozdni med. In this thesis I determined the volatile components of mixed floral and forest honey. I used HS-SPME-GC-MS. I examined the reproducibility and linearity of the method, which were satisfactory. I identified the 40 most represented volatile compounds in both types of honey that met certain selection criteria. I divided them into common and into specific compounds, present in only one type of honey. There were 26 common compounds, predominantly esters, terpenes and benzene derivatives. In both honeys, the common compounds hotrienol, p-(1-propenyl) toluene, methyl nonanoate, methyl-(Z)-9-octadecenoate and methyl octanoate were the most abundant. Of the specific components, 1,2-dihydronaphthalene, benzyl nitrile and 1-methoxy-4-methylbenzene had the highest signal in floral honey, while terpinene-4-ol, α-terpineol and methyl (E)-2-nonenoate appeared in forest honey with the highest signal. Of these, 1,2-dihydronaphthalene and benzyl nitrile were not present in any of the forest honeys. None of the listed forest-specific volatiles appeared in any of the floral honey samples. The stated compounds could be used as identification markers for Slovenian mixed floral and forest honey.

Železo je element, ki je bistven za človeško telo. Sodeluje v številnih presnovnih procesih in tako omogoča normalno delovanje telesa. Ker železo dobimo v telo s hrano, dnevne potrebe po njem v telesu niso vedno dosežene. Da bi se izognili pomanjkanju železa v krvi in s tem pojavu anemije, se kot prehransko dopolnilo uporablja laboratorijsko sintetizirana oblika železa. Ta prehranska dopolnila so komercialno na voljo v obliki tablet, šumečih tablet, kapsul in tekočine.Namen magistrskega dela je bilo ugotoviti vsebnostbiorazpoložljivega železa v petih različnih prehranskih dopolnilih. V ta namen se železo, ki ga najdemo v prehranskih dopolnilih, raztopi v različnih koncentracijah šibkih kislin ob prisotnosti nekaterih ligandov, ki se lahko nahajajo v hrani. Kisline, ki sem jih uporabljala za raztapljanje, so bile: ocetna, citronska, mravljinčna, oksalna in vinska kislina. Izvedla sem tudi dodatno raztapljanje prehranskih dopolnil v različnih ligandih – fitinski kislini in EDTA. Meritve vsebnosti železa sem opravila z AAS in določena je bila vsebnost sproščenega železa v takih pogojih. Celotno vsebnost železasem določila z raztapljanjem prehranskega dopolnila v močni kislini (HCl, HNO3, H2SO4, H3PO4). Raztapljanje prehranskih dopolnil v vseh zgoraj omenjenih kislinah in ligandihpotekala v dveh serijah, in sicer: prva serija -raztapljanje v ultrazvočni kopeli, to je raztapljanje pri sobni temperaturi, in druga serija raztapljanje s segrevanjem do vrenja, tj. raztapljanje pri povišani temperaturi. Izvedla sem tudi analizo prisotnosti Fe(II) in Fe(III) ionov in določilanjihovo vsebnost z 1,10-fenantrolinom. Meritve sem opravila z UV-Vis spektofotometrom pri valovni dolžini 511nm. Glede nadobljene rezultate sem ugotovila, da imata dva vzorca približno enako biorazpoložljivost železa v vseh kislinah, ki smo jih uporabili za analizo, medtem ko je v ostalih treh biorazpoložljivost železa odvisna od vrste kisline in se z nižanjem koncentracij kisline zmanjšuje. Iz rezultatov analize Fe(II) in Fe(III)ionov je razvidno, da je v vseh vzorcih prisoten Fe(II) ion, kot je navedeno na njihovi deklaraciji. Iron is an element that is essential for the human body. It participates in many metabolic processes and thus enables the body to function normally. Since we get iron in the body through food, the daily needs for it in the body are not always reached. In order to avoid a lack of iron in the blood and thus the appearance of anemia, a laboratory-synthesized form of iron is used as a dietary supplement. These dietary supplements are commercially available in tablets, effervescent tablets, capsules, and liquid form. The purpose of the Master's thesis was to determine the content of bioavailable iron in five different dietary supplements. For this purpose, the iron found in food supplements is dissolved in various concentrations of weak acids in the presence of certain ligands that may be found in food. The used acids for dissolution were: acetic, citric, formic, oxalic, and tartaric acids. Also an additional dissolution of nutritional supplements in different ligands - phytic acid and EDTA were performed. The iron contentwas measured with AAS and the content of released iron was determined under such conditions. The total iron content was determined by dissolving the dietary supplement in strong acid (HCl, HNO3, H2SO4, H3PO4). The dissolution of nutritional supplements in all the above-mentioned acids and ligands took place in two series, namely: the first series - dissolution in an ultrasonic bath, i.e. dissolution at room temperature, and the second series - dissolution by heating to boiling, i.e. dissolution at elevated temperature. The presence of Fe(II) and Fe(III) ions and determined their content with 1,10-phenanthroline was also analized. The measurements with a UV-Vis spectrophotometer were performed ata wavelength of 511 nm. According to the obtained results, for two samples were found that they have approximately the same bioavailability of iron in all the acids used for analysis, while in the other three, the bioavailability of iron depends on the type of acid and decreases with decreasing acid concentrations. From the results of the analysis of Fe(II) and Fe(III) ions, it can be seen that Fe(II) ion is present in all samples, as stated in their declaration.

Razvili smo metodo tekočinske kromatografije visoke ločljivosti sklopljene s tandemsko masno spektrometrijo za določitev askorbinske kisline in njenega izomera, eritorbinske kisline. Za separacijo smo uporabili Aminex HPX-87H kolono in izokratsko elucijo z 0,1 % mravljično kislino v vodi. Kvantifikacijo smo izvedli z uporabo ESI ionizacije v negativnem načinu s prekurzorskim ionom m/z 174,9 in produktnim ionom m/z 115 za obe kislini. Da se izognemo lažno pozitivnim rezultatom, smo pri vsaki meritvi spremljali še produktni ion m/z 87, ki je služil kot kontrola. Študirali smo stabilnost standardov, linearnost, meje zaznave in ponovljivost instrumenta. Ugotovili smo, da standardi na sobni temperaturi zelo hitro razpadajo in se odločili za uporabo reducenta TCEP. Območje linearnosti je bilo od meje zaznave do 2000 ppb, meja zaznave za askorbinsko kislino 69 ppb, za eritorbinsko pa 61 ppb. RSD meritev je bil pod 10 %. Preučevani parametri metode so bili v sprejemljivih območjih kar je vodilo do zanesljive določitve askorbinske in eritorbinske kisline. Metodo smo ovrednotili na različnih realnih vzorcih: šumečih in navadnih tabletah ter na sokovih. Rezultati analize tablet so odstopali od deklarirane vrednosti največ ±10 %. Preverili smo tudi homogenost tablet in ugotovili dobro homogenost tako znotraj tablet kot med tabletami. Pri vseh analiziranih vzorcih je bila koncentracija eritorbinske kisline pod mejo zaznave, kar je zelo pomembno zaradi njene nizke aktivnosti v primerjavi z askorbinsko kislino. A high-performance liquid chromatography coupled with tandem mass spectrometry method for determination of ascorbic acid and its isomer, erythorbic acid was developed. The separation was performed on Aminex HPX-87H column using isocratic elution with 0,1 % formic acid in water. Quantification was done using ESI ionization in negative mode with m/z 174,9 as a precursor ion and m/z 115 as a product ion for both acids. In order to avoid false positive results, the product ion m/z 87 was also recorded at each measurement and was used as a confirmation. The stability of standards, linearity, limits of detection and instrument repeatability were studied. The standards were found to degrade very quickly at room temperature. Because of that, TCEP was used as a reducing agent. The linear range was from the limit of detection to 2000 ppb while the limits of detection were 69 ppb and 61 ppb for ascorbic and erythorbic acid, respectively. RSD of measurements was below 10 %. The studied parameters were within the acceptable ranges which lead to the reliable determination of ascorbic and erythorbic acid. The method was evaluated on different real samples: effervescent and ordinary tablets and on juices. The results for tablets deviated from the value on the label by a maximum of ±10 %. The tablets were found to be homogeneous with good homogeneity both within and between tablets. The concentration of erythorbic acid was below the limit of detection in all the analyzed samples which is very important due to its low activity compared to ascorbic acid.

V vzorcu Herbalife Nutrition sem določeval riboflavin (vitamin B2), pantotensko kislino (vitamin B5), biotin (vitamin B7) in vitamin B12 s tehniko tekočinske kromatografije visoke ločljivosti (HPLC). Vsebnost pantotenske kisline sem določil z uporabo standardnega dodatka. Vsebnost riboflavina, biotina in vitamina B12 sem določal s pomočjo umeritvene krivulje. V vzorcu sem poleg vitaminov določil tudi vsebnost dveh mineralov, in sicer mangana in železa s tehniko atomske absorpcijske spektroskopije (AAS). Koncentracijo sem določil preko umeritvene krivulje. Naredil sem dve paralelki in ugotovil, da je metoda zelo ponovljiva. Ugotovil sem, da se dobljene vrednosti dobro ujemajo z deklariranimi. Največje odstopanje dobim pri vsebnosti železa, kjer je dobljena vrednost 15 % večja od deklarirane vrednosti. In the Herbalife Nutrition sample, I determined riboflavin (vitamin B2), pantothenic acid (vitamin B5), biotin (vitamin B7) and vitamin B12 using a high-performance liquid chromatography (HPLC). I evaluated the content of pantothenic acid using a standard additive. Content of riboflavin, biotin and vitamin B12 are determined using an external standard (calibration curve). In addition, I determined the content of two minerals, manganese and iron using atomic absorption spectroscopy (AAS). The concentration was determined using a calibration curve. I made two parallels and found the method to be very reproducible. I have found that the resulting values are in good correspondence with the declared values. The largest deviation is for iron content, where the resulting value is 15% higher than the declared value.