Polifenoli su sekundarni biljni metaboliti te važni organski spojevi prisutni u grožđu, moštu i vinu. Važnost polifenolnih
spojeva prisutnih u grožđu uglavnom je vezana uz kakvoću vina obzirom da ...utječu na boju, okus, astringenciju, gorčinu te
potencijal starenja vina. Cilj ovog rada je utvrditi i usporediti kvantitativne i kvalitativne promjene sadržaja polifenola male
molekulske mase u kožici grožđa 11 crnih sorata vinove loze tijekom dozrijevanja grožđa. Uzorci su prikupljani periodično
od početka šare do tehnološke zrelosti. Sadržaj polifenola u kožici boba utvrđen je tekućinskom kromatografijom visoke
djelotvornosti (HPLC) uz prethodnu liofilizaciju i ekstrakciju. Temeljem dobivenih rezultata utvrđene su promjene sastava
i sadržaja pojedinih grupa polifenolnih spojeva tijekom dozrijevanja.
Fenolni spojevi predstavljaju sekundarne biljne metabolite koji imaju vrlo važnu fiziološku i morfološku ulogu u rastu i reprodukciji biljke pružajući joj i zaštitu protiv patogena i predatora. Cilj ...ovoga istraživanja je dobiti pregled promjena u sastavu i sadržaju fenolnih spojeva odnosno flavonola, flavanola, hidroksicimetnih i hidroksibenzojevih kiselina prisutnih u listovima četiri različite crne sorte vinove loze. Ekstrakti su analizirani tekućinskom kromatografijom visoke djelotvornosti. Dobivenim rezultatima utvrđena je značajna varijabilnost u masenim udjelima fenolnih spojeva između sorata po pojedinim terminima uzorkovanja, kao i značajna varijabilnost u sadržaju fenolnih spojeva unutar iste sorte tijekom različitih termina uzorkovanja.
Phenolic compounds represent secondary plant metabolites which play an important physiological and morphological role in plant growth and reproduction. They also provide a protection against pathogens and predators. The aim of this study is to obtain an overview of changes in the composition and phenolic compounds content, more precisely flavonols, flavanols, hydroxycimetic and hydroxybenzoic acids present in the leaves of four different grapevine varieties. The extracts were analyzed by high performance liquid chromatography. Based on the obtained results, significant variability in mass shares of phenolic compounds between varieties was determined by individual sampling terms, as well as significant variability in the content of phenolic compounds within the same variety during different sampling terms.
Bez analitičke kemije nemoguće je zamisliti napredak mnogih područja ljudske djelatnosti. Spomenuti značaj ove grane kemije jedan je od glavnih razloga uspješnog opstanka i kontinuiranog razvoja ...Zavoda za analitičku kemiju unutar jednog tehničkog fakulteta, kao što je današnji Fakultet kemijskog inženjerstva i tehnologije (FKIT) Sveučilišta u Zagrebu. Dinamičnost razvoja analitičke kemije bila je neprestani poticaj nastavnicima Zavoda za prilagođavanjem svjetskim trendovima i sustavnim unaprjeđenjem nastavnog programa i istraživačkog rada.
Početak nastavnog, znanstvenog, ali i stručnog djelovanja Zavoda temeljio se na klasičnim metodama analize, no potaknuta razvojem moderne analitičke opreme ubrzo se intenzivirala primjena brojnih kemijskih i fizikalno-kemijskih metoda analize, od kojih je danas najzastupljenija kromatografija. Naime, konac dvadesetog stoljeća ubrzanim je razvojem instrumentalnih tehnika, uvođenjem računala i činjenicom da su podatci analitičkih mjerenja postali temelj odlučivanja u medicini, zaštiti okoliša, razvoju materijala te osiguravanju kvalitete procesa i proizvoda, dao novi uzlet analitičkoj kemiji, a osobit procvat doživjela je kromatografija kao idealna tehnika za višekomponentnu analizu analita u tragovima.
Without analytical chemistry, it is impossible to imagine the progress of many areas of human activity. The aforementioned importance of this chemistry branch is one of the main reasons for the successful survival and continued development of the Department of analytical chemistry within a technical faculty, such as is the present-day Faculty of Chemical Engineering and Technology (FCET) University of Zagreb. The dynamics of the development of analytical chemistry was a constant encouragement to the teachers of the Department to adapt to world trends, and systematically improve the curriculum and research work.
The beginning of the teaching, the scientific, as well as the professional activities of the Department of Analytical Chemistry was based on classical methods of analysis. However, stimulated by the development of modern analytical equipment, the application of numerous chemical and physicochemical methods of analysis was intensified, of which the most common being chromatography. Namely, the end of the twentieth century accelerated the development of instrumental techniques, the introduction of computers, and the fact that analytical measurement data became the basis of decision-making in medicine, environmental protection, material development, and assuring the quality of processes and products gave rise to analytical chemistry, especially chromatography, which is an ideal technique for multicomponent trace analyte analysis.
Olanzapine is a thienobenzodiazepine class antipsychotic that strongly antagonises the 5-HT2A serotonin receptor, but acute poisonings are reported rarely. Symptoms of an overdose include disorder of ...consciousness, hypersalivation, myosis, and coma. Serum concentration higher than 0.1 mg/L is toxic, while concentration above 1 mg/L can be fatal. Here we report key data about 61 patients admitted to the National Poison Control Centre in Belgrade, Serbia over olanzapine poisoning in 2017 and 2018. The ingested doses ranged from 35 to 1680 mg, and time from ingestion to determination from two to 24 hours. In 34 patients olanzapine serum concentrations were in the therapeutic range and in 27 in the toxic range. In five patients they were higher than fatal, but only one patient died. The most common symptoms of poisoning were depressed consciousness (fluctuating from somnolence to coma), tachycardia, hypersalivation, hypotension, myosis, and high creatine kinase. All patients but one recovered fully after nonspecific detoxification and symptomatic and supportive therapy.
Microfiltration is a common step in liquid chromatography – tandem mass spectrometry (LC-MS), a method of choice in determining several mycotoxins in a solution at once. However, microfiltration may ...entail filter-analyte interactions that can affect the accuracy of the procedure, and underestimate exposure. The aim of our study was to assess how five different membrane materials for syringe filters (nylon, polytetrafluoroethylene, polyethersulphone, mixed cellulose ester, and cellulose acetate) affect microfiltration and recovery of EU-regulated mycotoxins, including aflatoxins B1, B2, G1, and G2, deoxynivalenol, fumonisins B1 and B2, zearalenone, T-2 and HT-2 toxins, and ochratoxin A. Polytetrafluoroethylene filters turned out to least affect microfiltration through mycotoxin loss, followed by more commonly used nylon filters, whereas the remaining three filter membrane materials had such a negative effect on recoveries that we found them incompatible with the procedure. Our findings clearly suggest that it is important to select a proper filter type that suits analyte properties and solution composition and to discard the first few filtrate drops to ensure the accuracy of the analytical procedure.
Diazinon poisoning is an important issue in occupational, clinical, and forensic toxicology. While sensitive and specific enough to analyse diazinon in biological samples, current methods are ...time-consuming and too expensive for routine analysis. The aim of this study was therefore to design and validate a simple dispersive liquid-liquid microextraction (DLLME) for the preparation of urine samples to be analysed for diazinon with high performance liquid chromatography with diode-array detector (HPLC-DAD) to establish diazinon exposure and poisoning. To do that, we first identified critical parameters (type and volume of extraction and disperser solvents, pH, surfactant, and salt concentrations) in preliminary experiments and then used central composite design to determine the best experimental conditions for DLLME-HPLC-DAD. For DLLME they were 800 µL of methanol (disperser solvent) and 310 µL of toluene (extraction solvent) injected to the urine sample rapidly via a syringe. The sample was injected into a HPLC-DAD (C
column, 250×4.6 mm, 5 μm), and the mobile phase was a mixture of acetonitrile and buffer (63:37 v/v, pH 3.2; flow rate: 1 mL/ min). Standard calibration curves for diazinon were linear with the concentration range of 0.5–4 µg/mL, yielding a regression equation Y=0.254X+0.006 with a correlation coefficient of 0.993. The limit of detection and limit of quantification for diazinon were 0.15 µg/mL and 0.45 µg/mL, respectively. The proposed method was accurate, precise, sensitive, and linear over a wide range of diazinon concentrations in urine samples. This method can be employed for diazinon analysis in routine clinical and forensic toxicology settings.
U radu se prikazuje istraživanje sposobnosti četiriju gljiva bijele truleži (Trametes versicolor, Hypoxylon fragiforme, Chondrostereum purpureum i Pleurotus ostreatus) te jedne gljive smeđe truleži ...(Gloeophyllum trabeum) za razgradnju organoklorova insekticida lindana u tekućim kulturama. Procjena biorazgradnje lindana izvedena je uz pomoću dvaju analitičkih postupaka. Kako bi se izdvojio i pravilno kvantifi cirao preostali lindan u tekućim kulturama gljiva, primijenjena su dva različita ekstrakcijska postupka: ekstrakcija iz filtrata i ekstrakcija iz homogenizirane kulture gljiva. Dokazano je da su gljive bijele truleži razgradile lindan. Količina razgrađenog lindana povećava se s trajanjem izlaganja u tekućim kulturama svih gljiva bijele truleži, osim gljive C. purpureum. Nakon 21 dan izloženosti gljivama T. versicolor, H. fragiforme i P. ostreatus više od 90 % lindana bilo je razgrađeno. Razgradnje lindana od gljive smeđe truleži G. trabeum nije bilo. Postupak ekstrakcije imao je zamjetan učinak na razgradnju nakon 21 dan izlaganja tekućoj kulturi gljiva T. versicolor, H. fragiforme i P. ostreatus. Nasuprot tome, količina preostalog lindana u tekućim kulturama gljiva C. purpureum i G. trabeum znatno ovisi o postupku ekstrakcije. Ovaj rad pokazuje da bi se u istraživanju mikorazgradnje lindana trebala razmotriti i adsorpcija na micelije biomase kao mogući razlog za uklanjanje insekticida iz tekućeg medija, posebno kada se proučavaju kraća razdoblja izloženosti ili kada se koriste gljive s manjim potencijalom razgradnje.
A simple, sensitive and precise RP-HPLC-DAD method was developed and validated for the determination of olmesartan medoxomil (AT-II receptor blocker) in the presence of its degradation products. ...Olmesartan medoxomil and all the degradation products were resolved on a C18 column with the mobile phase composed of methanol, acetonitrile and water (60:15:25, V/V/V, pH 3.5 by orthophosphoric acid) at 260 nm using a photodiode array detector. The method was linear over the concentration range of 1-18 μg mL-1 and precise with RSD < 1 % in intra- and inter-day study. Excellent recoveries of 99.3 ± 0.9 to 100.8 ± 1.2% proved the accuracy of the method. Developed method was specific, as indicated by chromatographic resolution > 2.0 for each peak and sensitive with LOD 0.03 μg mL-1 and LOQ 0.1 μg mL-1. The method was used to study the drug degradation behavior under forced conditions. Four degradation products (DP-I, II, III, IV) were formed during the degradation study in 0.1 mol L-1 HCl whereas only DP-I, II and III were formed in water, 0.01 mol L-1 NaOH and 3% H2O2. No significant thermal or photolytic degradation was observed in solid drug. The method was applied successfully for the assay of olmesartan medoxomil in the tablet dosage form.
U ovom radu razvijena je i validirana jednostavna, osjetljiva i precizna RP-HPLC-DAD metoda za odredivanje olmesartan medoksomila (inhibitor AT-II receptora) u prisutnosti njegovih razgradnih produkata. Olmesartan medoksomil i razgradni produkti kromatografirani su na C18 koloni uz mobilnu fazu metanol/ acetonitril/voda (60:15:25 V/V/V; pH 3,5 podešen ortofosfornom kiselinom) pri 260 nm uz detektor s fotodiodnim nizom. Metoda je linearna u koncentracijskom rasponu 1-18 μg mL-1 i precizna s RSD < 1% tijekom ispitivanja repetabilnosti i intermedijarne ponovljivosti. Povrat od 99,3 ± 0,9 do 100,8 ± 1,2% dokazuje točnost metode. Razvijena metoda je specifična na što ukazuje kromatografsku rezoluciju veću od 2,0 i osjetljiva (LOD = 0,03 μg mL-1 i LOQ = 0,1 μg mL-1). Metoda je upotrebljena za praćenje razgradnje olmesartan medoksomila u uvjetima potencirane razgradnje. U 0,1 mol L-1 HCl detektirana su četiri razgradna produkta (DP-I, II, III, IV), a u vodi, 0,01 mol L-1 NaOH i 3% H2O2 samo DP-I, II i III. U čvrstom agregatnom stanju nije primječena značajna termička ni fotolitička razgradnja ljekovite tvari. Metoda je uspješno primijenjena za odredivanje olmesartan medoksomila u tabletama.
A bioanalytical HPLC method with UV detection for the determination of the antiepileptic drug valproic acid in human saliva has been developed and validated. Saliva represents an alternative matrix ...for therapeutic monitoring of antiepileptic drugs due to the increasing interest in free drug concentration. The proposed method involved solid-phase extraction for sample preparation and yielded very good mean recoveries of 99.4 % and 97.9 % for valproic acid and IS, respectively. The calibration function for valproic acid was linear over the concentration range of 1.0-50.0 μg mL-1 (R2 = 0.9989). Within-run and between-run precision and accuracy were studied at four concentrations and RSDs were less than 7.3 and 2.2 %, while accuracy values were higher than 96.8 and 97.5 %, respectively. The described method provides sensitivity, linearity, precision, accuracy and is suitable for analyses of valproic acid in saliva samples.
U radu je opisana i validirana bioanalitička HPLC metoda s UV detekcijom za određivanje antiepileptika valproične kiseline u slini čovjeka. Zbog sve većeg interesa za praćenje koncentracije slobodnog lijeka slina predstavlja alternativni matriks za praćenje antiepileptika. Predložena metoda u pripremi uzorka uključuje ekstrakciju na čvrstoj fazi. Dobiven je vrlo dobar srednji analitički povrat od 99,4 % i 97,9 % za valproičnu kiselinu, odnosno IS. Kalibracijska funkcija za valproičnu kiselinu bila je linearna u koncentracijskom području od 1,0-50,0 μg mL-1 (R2 = 0,9989). Preciznost i točnost procijenjene unutar jednog i više mjernih dana dale su RSD niže od 7,3 i 2,2 %, te vrijednosti za točnost iznad 96,8, odnosno 97,5 %. Opisana metoda je dovoljno osjetljiva, precizna i točna, osigurava linearni odgovor te je pogodna za analizu valproične kiseline u slini.
A high-performance liquid chromatography-tandem mass spectrometric method was developed and validated for the determination of metoprolol in human plasma. The analyte and internal standard, ...nevirapine, were extracted from plasma matrix by liquid-liquid extraction with ethyl acetate. Chromatographic separation was achieved on a C-18 analytical column with an isocratic mobile phase of 15:85 (V/V) 10 mmol L-1 ammonium acetate (pH 5.0)/acetonitrile. The atmospheric pressure chemical ionization technique was used for sample ionization in positive ion mode and enhanced selectivity was achieved by tandem mass spectrometric analysis via two multiple reaction monitoring (MRM) transitions, 268.2 → 116.2 for metoprolol and 267.1 → 226.2 for nevirapine, respectively. The assay was validated for human plasma over a concentration range of 1-200 ng mL-1 with the precision and accuracy ranging from 0.9 to 8.8% and 89.9 to 105.8%, respectively.
U radu je opisano određivanje metoprolola u humanoj plazmi tekućinskom kromatografijom visoke učinkovitosti spregnutom s masenom spektrometrijom. Analit i interni standard, nevirapin, ekstrahirani su iz plazme etil-acetatom. Kromatografsko odjeljivanje provedeno je na C-18 koloni uz mobilnu fazu sljedećeg sastava: 10 mmol L-1 amonijev acetat (pH 5,0)/acetonitril 15:85 (V/V). Ionizacija uzoraka provedena je pri atmosferskom tlaku. Povećanje selektivnosti postignuto je spregnutom masenom spektrometrijskom analizom praćenjem dvaju prijelaza (MRM) - 268,2 → 116,2 za metoprolol, odnosno 267,1 → 226,2 za nevirapin. Metoda je validirana za koncentracijsko područje 1-200 ng mL-1 uz preciznost i točnost od 0,9 do 8,8%, odnosno 89,9 do 105,8%.
PDF
