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Application of commercial protease in protein hydrolysis from shrimp waste
No full textEnzimi su biološki katalizatori koji u posebno definiranim uvjetima ubrzavaju biokemijske reakcije u živim organizmima. Upravo u tu skupinu organskih makromolekula ubrajamo i proteaze. Prilikom izrade ovog rada, u eksperimentalnom dijelu su korištene tri komercijalne proteaze: Alkalaza, Novozyme 37071 i Novo-Pro D. Proteaze su korištene s ciljem hidrolize proteina u otpadu ljuski kozica. Provedbom te reakcije uklanjaju se proteini što predstavlja jedan od koraka koji bi omogućio izdvajanje preostalih korisnih spojeva koji u prirodi često dolaze zajedno. Ovaj način izdvajanja ima brojne prednosti u usporedbi s drugim poznatim metodama. Rezultati ukazuju na to da su enzimi bili vrlo efikasni u provođenju proteolitičke reakcije te se osobito iskazao biokatalizator Novo-Pro D.Enzymes are biological catalysts that accelerate biochemical reactions in organisms under specifically required conditions. Proteases also belong to the group of organic macromolecules called enzymes. Three commercial proteases were used in the experimental work in the laboratory: Alcalase, Novozyme 37071 and Novo-Pro D. The proteases were used to hydrolyze proteins found in shrimp waste. Protein hydrolysis removes the proteins, which is one of the steps that would allow the extraction of the remaining beneficial compounds that often occur together in nature. This type of extraction has many advantages over other methods that can be used. The results show that the proteases used for the experiments were very efficient in performing the proteolytic reaction, with Novo-Pro D being the most efficient
Crystallization control of active pharmaceutical ingredients
No full textŠaržna kristalizacija jedan je od najvažnijih toplinsko-separacijskih procesa kojim se ostvaruje visoka čistoća u proizvodnji specijalnih kemikalija, hrane i farmaceutskih proizvoda. U svrhu poboljšavanja vođenja procesa kristalizacije djelatne tvari, izrađen je program koji na primjeru kalijevog sulfata izračunava temperaturni profil koji, što je bolje moguće, ispunjava funkciju cilja kojom se definira omjer veličina kristala nastalih nukleacijom i onih dodanih cijepljenjem (na kraju procesa). Taj program primjenjuje se za simuliranje i razvoj laboratorijskog sustava za vođenje šaržne kristalizacije hlađenjem. Izvedeni algoritam primjenjuje model momenta za kontinuiranu procjenu prosječne dimenzije i količine nastalih kristala rješavanjem sustava običnih diferencijalnih jednadžbi. Program uz temperaturni profil računa i koncentraciju otopine, relativno prezasićenje i karakteristične veličine vezane uz dimenzije kristala tijekom odvijanja procesa. Rješenja dobivena ovim programom ukazuju na njegovu primjenjivost za vođenje kristalizacije djelatnih tvari.Batch crystallization is one of the most important heat-separation processes that achieve high purity in the production of special chemicals, food and pharmaceutical products. In order to improve the control of the crystallization process of active pharmaceutical ingredients, a program was created that using the example of potassium sulfate, calculates a temperature profile that fulfills the objective function defined with the ratio of size of crystals formed by nucleation and those formed by seeding (at the end of the process). This program is used to simulate and develop a laboratory system for conducting batch crystallization by cooling. The derived algorithm applies the method of moments for continuous estimation of the average dimensions and amount of formed crystals by solving a system of ordinary differential equations. The program calculates the temperature profile alongside of the solution concentration, relative supersaturation and characteristic sizes related to the crystal dimensions during the process. The solutions obtained by this program indicate its applicability for guiding the crystallization of active pharmaceutical ingredients
Priprema i fotofizička karakterizacija pH osjetljivih sol-gel tankih filmova dopiranih kurkuminom
No full textDue to its desirable qualities, such as simplicity, portability, disposability and affordability, optical chemical sensors have been the focus of intensive study and development, including employment of microfluidic devices and lab-on-a-chip technologies. Due to its compatibility, affordability, user-friendliness and abundance, paper, alongside glass, has been used as a substrate material, and paper-based microfluidics have been mostly combined with colorimetric readouts. Furthermore, employment of natural “green” dyes as pH-sensing colorants is rising due to environmental reasons, and curcumin is therefore attracting major interest. Curcumin's various pharmacological actions have been proven by different scientific studies, establishing its ability to operate as a chemo-preventive, as well as potential therapeutic agent against a variety of chronic diseases. Furthermore, curcumin has a bright yellow color in acidic and neutral conditions that turn into a brownish-orange color on exposure to a basic pH solution. This makes it a promising tool for instantaneous detection of analyte with the naked eye, without the need to use the sophisticated instruments. In this study, optical sensors for quick sensing were created utilizing curcumin as pH indicator, immobilized by sol-gel method and deposited on two different types of substrates, glass and paper. Curcumin-based sensors were characterized by UV-Vis absorption and reflectance spectroscopy as well as colorimetry, on exposure to solutions of pH ranging from 4 to 13. In conclusion, curcumin-based paper sensors achieved better results than curcumin-based glass thin films, which lead to their further characterization in terms of stability and reversibility of response.Zbog svojih poželjnih kvaliteta, kao što su jednostavnost, prenosivost, jednokratnost i pristupačnost, optički kemijski senzori su u središtu intenzivnog proučavanja i razvoja, uključujući korištenje mikrofluidnih uređaja i takozvanih tehnologija laboratorija na čipu. Zbog svoje kompatibilnosti, cjenovne pristupačnosti, lakoće korištenja i obilja, papir se, uz staklo, koristi kao materijal za supstrat, a papirna mikrofluidika se uglavnom kombinira s kolorimetrijskim očitanjima. Nadalje, uporaba prirodnih „zelenih“ boja kao pH osjetljivih bojila konstantno raste zbog ekoloških razloga, a među njima se ističe kurkumin, koji je privukao veliko zanimanje. Različita farmakološka djelovanja kurkumina dokazana su znanstvenim studijama, utvrđujući njegovu sposobnost za kemoprevenciju, kao i moguće terapeutsko djelovanje protiv raznih kroničnih bolesti. Nadalje, kurkumin ima jarko žutu boju u kiselim i neutralnim uvjetima, koja se pretvara u smeđe-narančastu kada je izložen bazičnom pH što ga čini obećavajućim alatom za trenutnu detekciju analita golim okom, bez upotrebe sofisticiranih instrumenata. U ovoj studiji, optički senzori za brzo očitavanje pripremljeni su korištenjem kurkumina kao pH bojila, imobiliziranog sol-gelom metodom i položenog na dvije različite vrste podloga, staklo i papir. Izrađeni senzorski materijali temeljeni na kurkuminu karakterizirani su primjenom UV-Vis apsorpcijske i reflektancijske spektroskopije, a kolorimetrijska detekcija ispitana je u rasponu pH vrijednosti od 4 do 13. Zaključeno je da su papirnati senzori na bazi kurkumina postigli bolje rezultate od staklenih senzora, što je dovelo do dodatnog testiranja njihove stabilnosti i reverzibilnosti
Characterization of two-phase liquid-liquid streaming in millireactors
No full textU ovom radu provedena je karakterizacija dvofaznog strujanja kapljevina − kapljevina u milireaktorima izrađenim aditivnom proizvodnjom. Kao modelne kapljevine, koje predstavljaju nemješljive fluide u petrokemijskoj, farmaceutskoj i drugim industrijama, odabrane su redestilirana voda i dodekan. Određen je utjecaj promjera cijevi reaktora, vrste milimiješala, brzine protoka kapljevina te omjer protoka faza na vrstu strujanja. Provedeno je ukupno 84 pokusa u tri vrste milireaktora s različitim vrstama milimiješala (T i Y) i promjera cijevi (2,5 mm i 1,5 mm). Ispitane su vrste strujanja te bezdimenzijske značajke (Reynoldsov, kapilarni, Webbberov i Bondov broj). Na temelju rezultata moguće je zaključiti sljedeće: oblik milimiješala nema značajan utjecaj na uspostavljanje režima strujanja kao kod mikroreaktora. Izračunom Bondove značajke za milireaktore s promjerom cijevi od 2,5 mm, uočen je utjecaj gravitacijske sile; dok kod promjera cijevi od 1,5 mm dominiraju sile međupovršinske napetosti i viskoznosti. Geometrija i prisustvo zavoja utječu na stabilnost i režim strujanja u milireaktorima. Aditivna proizvodnja rastaljenim filamentom pokazala se kao brza, jednostavna i jeftina metoda izrade milireaktora. Dobiveni rezultati predstavljaju doprinos upotrebi milireaktora za sustave nemješljvih kapljevina te na temelju kojih je moguće predvidjeti vrstu strujanja te optimirati kemijske procese (sinteza, ekstrakcija, separacija).In this work, the characterization of the two-phase flow of liquid−liquid in millireactors made by additive manufacturing was carried out. Redistilled water and dodecane, which represent immiscible fluids in the petrochemical, pharmaceutical and other industries, were chosen as model liquids. The influence of reactor channel diameter, type of millimixer, liquid flow rate and phase flow ratio on the flow type was determined. A total of 84 experiments were conducted in three types of millireactors with different millimixers (T and Y) and channel diameters (2,5 mm and 1,5 mm). Flow types and dimensionless features were examined. Based on the results, it is possible to conclude the following: the shape of the millimixers does not have a significant influence on the establishment of the flow regime as it is in the case of microreactors. Flow types and dimensionless features (Reynolds, capillary, Webber and Bond numbers) were examined. By calculating the Bond number feature for millireactors with a tube diameter of 2.5 mm, the influence of the gravitational force was observed; while with a pipe diameter of 1.5 mm the forces of interfacial tension and viscosity dominate. Geometry and the presence of bends influence the stability and flow regime in millireactors. Fused filament fabrication, FFF, has proven to be a fast, simple and inexpensive method of manufacturing millireactors. The obtained results represent a contribution to the use of millireactors for systems of immiscible liquids , on the basis of which it is possible to predict the type of flow and optimize chemical processes (synthesis, extraction, separation)
Optimizacija metode metiliranja za analizu masnih kiselina
No full textThe fatty acids profile of castor oil was evaluated by gas chromatography (GC), with major focus on the optimum condition for the methylation of the fatty acids. Single, double, and triple methylation processes were studied with the heating time and concentration of obtained fatty acid methyl esters (FAMEs) observed. The result obtained showed that subsequent methylation resulted in lesser concentration of FAMEs obtained. In addition, generally for most methylation experiments carried out in this research, the results showed that the highest total yield of FAMEs was obtained by operating at 100°C for 40 minutes. The results that were obtained was compared with results in various literatures regarding the optimum conditions for highest conversion of fatty acids to methyl esters. The comparison showed that the operating temperature, time, fatty acids matrix, and methylation method influences the concentration of converted fatty acid derived from the process. Design of experiment was used in modelling the process. In addition, the analysis of variance (ANOVA) was successfully analyzed for the methylation process. At optimal conditions, R^2 obtained for the methylation of the fatty acids was 0.9702, which signifies excellent linearity. The equation that best describes the process was also obtained in terms of coded and actual factors respectively.Profil masnih kiselina ricinusovog ulja evaluiran je plinskom kromatografijom (GC), s glavnim fokusom na optimalne uvjete za metiliranje masnih kiselina. Proučavani su procesi jednostrukog, dvostrukog i trostrukog metiliranja uz promatranje vremena zagrijavanja i koncentracije dobivenih metil estera masnih kiselina (FAME). Dobiveni rezultat pokazao je da je naknadno metiliranje rezultiralo manjom koncentracijom dobivenih FAME. Osim toga, općenito za većinu eksperimenata metiliranja provedenih u ovom istraživanju, rezultati su pokazali da je najveći ukupni prinos FAME dobiven radom na 100°C tijekom 40 minuta. Dobiveni rezultati uspoređeni su s različitim rezultatima u literaturi o optimalnim uvjetima za najveću konverziju masnih kiselina u metilne estere. Usporedba je pokazala da radna temperatura, vrijeme, matrica masnih kiselina i metoda metiliranja utječu na koncentraciju pretvorene masne kiseline izvedene iz procesa. U modeliranju procesa korišten je eksperimentalni dizajn. Osim toga, analiza varijance (ANOVA) uspješno je analizirana za proces metiliranja. U optimalnim uvjetima, R^2 dobiven za metiliranje masnih kiselina bio je 0,9702, što označava izvrsnu linearnost. Jednadžba koja najbolje opisuje proces također je dobivena u smislu kodiranih odnosno stvarnih faktora
Design of hydrogels based on cellulose by using different irradiation doses
No full textU ovom radu sintetizirani su hidrogelovi na bazi celuloze kojoj je dodan još jedan vodotopivi polimer sklon formiranju hidrogelova. Pripravljene su reakcijske smjese koje sadrže 30, 50 i 70 mas% prethodno sintetiziranih polimera poli(vinil-pirolidona) (PVP), poli(N-vinilkaprolaktama) (PVCLA) i poli(dimetilaminoetil-metakrilata) (PDMAMEA). Neotapalo za pojedini sustav birano je na temelju preliminarnih pokusa u kojima je ispitana sposobnost bubrenja i sastav dobivenih hidrogelova. Za sustav PVP-celuloza odabrane su pare etanola, a za ostala dva sustava pare acetona u kojima je gelirana i otopina čiste celuloze za usporedbu. Hidrogelovi su gelirani 24 i 168 h kako bi se utvrdila razlika u svojstvima s promjenom vremena geliranja. S namjerom postizanja boljeg umrežavanja, reakcijske smjese su prije geliranja zračene γ-zrakama doze 200 kGy. Dobivenim zračenim i nezračnim hidrogelovima određeni su koeficijenti bubrenja, sastav, reološka svojstva, ciklički voltamogrami u različitim elektrolitima te morfologija. Najmanje koeficijente bubrenja pokazuju hidrogelovi PVP-celuloza, a najveće uzorci PDMAMEA-celuloza. Svi dvokomponentni hidrogelovi osim onog s 30 % PVP-a imali su veće koeficijente bubrenja od čiste celuloze. Kod svih zračenih i nezračenih uzorka koji su gelirani 24 h, koeficijenti bubrenja rastu sa smanjenjem udjela celuloze u reakcijskoj smjesi. Duže vrijeme geliranja omogućilo je bolju ugradnju dodanog polimera kod svih uzoraka sustava PVCLA-celuloza dok je za druga dva sustava povećanje uočeno samo za neke smjese. Koeficijenti bubrenja znatno su viši za hidrogelove koji su duže gelirali kod sustava PVCLA-celuloza, PDMAMEA-celuloza te za hidrogel od čiste celuloze dok je za sustav PVP-celuloza bubrenje slabije kada je hidrogel duže geliran. Određivanje reoloških svojstava na uzorcima geliranim 168 h pokazalo je da su G’ i G’’ kod svih nezračenih hidrogelova niži nego za hidrogel od čiste celuloze što ukazuje da su dobiveni hidrogelovi slabije umreženi. Iako su zračenjem za gotovo sve uzorke dobiveni hidrogelovi s nešto većim sadržajem celulozi dodanog polimera i u nekim slučajevima većim koeficijentima bubrenja, mehanička i reološka svojstva tih hidrogelova bila relativno loša. Postoji mogućnost da je korištena doza zračenja previsoka ili da je intenzitet zračenja od 23,7 kGy h^-1 prevelik pa je umjesto do boljeg umrežavanja došlo do raspadanja polimernih lanaca što čini dobivene hidrogelove vrlo krhkima.In this paper, cellulose based hydrogels were synthesized to which another water-soluble polymer, prone to forming hydrogels, was added. Reaction mixtures containing 30, 50 or 70 wt% of previously synthesized polymers polyvinylpyrrolidone (PVP), poly(N-vinylcaprolactam) (PVCLA) and poly (dimethylaminoethyl methacrylate) (PDMAMEA) were prepared. The non-solvent for each system was chosen based on preliminary experiments in which the swelling ability and composition of the obtained hydrogels were tested. For the PVP-cellulose system, ethanol vapors were selected, and for the other two systems, acetone vapors were used. Pure cellulose hydrogel was also prepared for comparison. Hydrogels were gelled for 24 and 168 h in order to determine the difference in properties with the change of gelation time. In order to achieve better cross-linking, the reaction mixtures were subjected to a gamma ray source, with gamma-ray absorbed doses of 200 kGy before gelation. The swelling coefficients, composition, rheological properties, cyclic voltammograms in different electrolytes and morphology were determined for the obtained irradiated and non-irradiated hydrogels. The lowest swelling coefficients were seen in the PVP-cellulose system, and the highest in PDMAMEA-cellulose hydrogels. All two-component hydrogels except the one with 30 % PVP had higher swelling coefficients than pure cellulose. In all irradiated and non-irradiated samples that were gelled for 24 h, the swelling coefficients increase with a decrease in cellulose concentration of the reaction mixture. A longer gelation time enabled a more efficientincorporation of the added polymer in all samples of the PVCLA-cellulose system, while for the other two systems an increase was observed only for some mixtures. For PVCLA-cellulose, PDMAMEA-cellulose and pure cellulose hydrogels swelling coefficients are significantly higher for hydrogels that have gelled longer, while for the PVP-cellulose system swelling is weaker with the increase of the gelation time. Determination of rheological properties of samples gelled for 168 h showed that G’ and G’' in all non-irradiated hydrogels are lower than for pure cellulose hydrogel, which indicates that the obtained hydrogels are less cross-linked. Although the irradiation mostly produced hydrogels with a slightly higher content of polymer added to cellulose and in some cases higher swelling coefficients, the mechanical and rheological properties of these hydrogels were fairly poor. There is a possibility that the radiation dose used was too high or that the radiation intensity of 23.7 kGy h^-1 was too high, so instead of better cross-linking, polymer chains degraded, which made the obtained hydrogels very fragile
The synthesis of new aryl-substituted 1,2,3-triazole purine and purine bioisosteres
No full textCilj ovog rada bila je sinteza novih aril-supstituiranih 1,2,3-triazolnih derivata purina i purinskih bioizostera 7–11, kao racemične smjese, s potencijalnim antitumorskim djelovanjem. U tu svrhu sintetizirani su propargilirani derivati indola, benzimidazola, 6-klor-9H-purina, 4-klor-7H-pirolo[2,3-d]pirimidina i 4-klor-1H-imidazo[4,5-c]piridina 1–5 te odgovarajući aromatski 1,2-azidoalkohol. Reakcijama 1,3-dipolarne cikloadicije odgovarajućeg azida 6 i terminalnih alkina 1 ̶ 5 uz Cu(I) kao katalizator, koje su provedene primjenom ultrazvuka, dobiveno je pet novih konjugata purina i purinskih bioizostera 7–11. Strukture svih sintetiziranih spojeva potvrđene su 1H NMR i 13C NMR spektroskopijom.The aim of this work was the synthesis of new aryl-substituted 1,2,3-triazole purine and purine bioisosteres 7–11, as racemic mixture, with potential antitumor activity. For this purpose, propargylated indole, benzimidazole, 6-chloro-9H-purine, 4-chloro-1H-imidazo[4,5-c]pyridine and 4-chloro-7H-pyrrolo[2,3-d]pyrimidine were synthesised. Furthermore, para-bromo substituted phenacyl bromides were treated with NaN3, followed by fast reduction with NaBH4 to afford corresponding azido alcohol with secondary hydroxyl group. Triazole derivatives of purine and purine bioisosteres were then prepared using 1,3-dipolar cycloaddition of the corresponding azide 6 and terminal alkynes 1–5 with Cu(I) as catalyst using ultrasound irradiation. The structures of all synthesised compounds were confirmed by 1H NMR and 13C NMR spectroscopy
Investigation of interaction between pesticides and microplastic particles
No full textOnečišćenje mora plastičnim otpadom jedan je od najhitnijih globalnih problema morskog okoliša u cijelom svijetu. Privukao je svjetsku pozornost vlada, javnosti, znanstvene zajednice, medija i nevladinih organizacija te je postao vruća tema u aktualnoj morskoj ekologiji i istraživanju okoliša. Cilj ovog rada bio je istražiti utjecaj temperature i starosti mikroplastike poli(etilen- tereftalata) (PET) na adsorpciju pesticida simazina (SMZ). Korištene su čestice mikroplastike (10-100 μm) pripremljene iz nestarenih filmova PET-a te filmova podvrgnutim ubrzanom starenju 56 dana pod UV zračenjem. Nakon usitnjavanja u kriomlinu određena je raspodjela veličina čestica mikroplastike, pri čemu su za razdvajanje frakcija korišteni vibrirajuća tresilica sa sitima i laboratorijsko sito sa zračnim mlazom. Adsorpcijski eksperimenti provedeni su korištenjem termostatirane laboratorijske tresilice, a promjene koncentracije simazina praćene su tekućinskom kromatografijom visoke djelotvornosti (HPLC). Na kraju su ispitani pojedinačni štetni učinci mikroplastike i simazina te ukupni učinci mikroplastike s adsorbiranim onečišćivalom, provedbom standardnih testova akutne toksičnosti na zelene mikroalge Pseudokirchneriella subcapitata (ISO 8692). Rezultati ATR-FTIR spektroskopijesu pokazali da se UV starenjem povećava udio manjih frakcija čestica mikroplastike, što znači da je zbog utjecaja starenja materijal više podložan fragmentaciji, te je došlo do oksidativne razgradnje koja rezultira stvaranjem funkcionalnih skupina koje sadrže kisik (smanjena hidrofobnost materijala). Rezultati adsorpcije simazina slijede Langmuirovom model što ukazuje na adsorpciju u monosloju te je raspodjela aktivnih mjesta na adsorbensu homogena. Adsorpcija je izraženija u slučaju starenih uzoraka u odnosu na uzorke mikroplastike koji nisu stareni, te je najveća adsorpcija simazina postignuta uz PET 56 pri temperaturi od 20°C. Ispitivanje toksičnosti na zelenim mikroalgama Pseudokirchneriella subcapitata pokazalo je najveću toksičnost kod kombiniranih uzoraka simazina sa starenom mikroplastikom (PET 56) i CaCl2.The pollution of the sea by plastic waste is one of the most urgent global problems of the marine environment all over the world. It has attracted worldwide attention from governments, the public, the scientific community, the media and non-governmental organizations and has become a hot topic in current marine ecology and environmental research. The aim of this work was to investigate the influence of temperature and age of poly(ethylene-terephthalate) (PET) microplastics on the adsorption of the pesticide simazine (SMZ). Microplastic particles (10-100 μm) prepared from pristine PET films and films subjected to accelerated aging were used 56 days under UV radiation were used. After grinding in a cryomill, the particle size distribution of microplastics was determined, using a vibrating shaker with sieves and a laboratory sieve with an air jet were used to separate the fractions. Adsorption experiments were carried out using a thermostated laboratory shaker, and changes in simazine concentration were monitored by high-performance liquid chromatography (HPLC). In the end, the individual harmful effects of microplastics and simazine and the overall effects of microplastics with adsorbed pollutant were tested by performing standard acute toxicity tests on the green microalgae Pseudokirchneriella subcapitata (ISO 8692). The results of ATR-FTIR spectroscopy showed that UV aging increases the proportion of smaller fractions of microplastic particles, which means that due to the influence of aging, the material is more susceptible to fragmentation, and oxidative decomposition has occurred, which results in the formation of functional groups containing oxygen (reduced hydrophobicity of the material). The results of simazine adsorption follow the Langmuir model, which indicates adsorption in a monolayer and the distribution of active sites on the adsorbent is homogeneous. Adsorption is more pronounced in the case of aged samples compared to pristine microplastic samples, and the highest simazine adsorption was achieved with PET 56 at a temperature of 20°C. The toxicity test on the green microalgae Pseudokirchneriella subcapitata showed the highest toxicity with the combined samples of simazine with aged microplastic (PET 56) and CaCl2
Determination of degradation products of amino and amidino substituted 2-benzothiazoles
No full textDefiniranje stabilnosti lijekova ponajviše se svodi na određivanje neželjenih svojstava uzrokovanih razgradnim produktima i onečišćenjima koji smanjuju kvalitetu, sigurnost i djelotvornost lijeka. U svrhu točnog određivanja procesa proizvodnje, uvjeta skladištenja i transporta, važno je ispitati kako se kvaliteta farmaceutskog proizvoda mijenja pod utjecajem različitih okolišnih čimbenika. Prije početka komercijalne uporabe farmaceutski aktivnih tvari potrebno je, uz ispitivanje stabilnosti, procijeniti njihova svojstva koja mogu imati značajan utjecaj na žive organizme i okoliš. Tek nakon provedenih ispitivanja, farmaceutski aktivni spojevi mogu prijeći u fazu ispitivanja potencijalne implementacije u novim farmaceutskim proizvodima. Jedan od načina ispitivanja stabilnosti jest podvrgavanje aktivnih tvari ekstremnim kemijskim i okolišnim uvjetima, tzv. ispitivanje prisilne razgradnje. Cilj ovog rada bio je odrediti strukturu i svojstva razgradnih produktata dva derivata 2-fenilbenzotiazola. Uzorci spojeva LD-4, IUPAC naziva 2-(4-amidinofenil)-6-aminobenzotiazol-klorid, i LD-5, IUPAC naziva 2-(4-aminofenil)-6-(imidazolin-2-il)benzotiazol-mesilat, ispitivani su u uvjetima kisele hidrolize (0,5 M HCl), bazne hidrolize (0,5 M NaOH), oksidacije peroksidom
(10 % H2O2), povišene temperature (80 ˚C i 100 ˚C) i UV/VIS svjetla (500 Wh/m^2), a identifikacija produkata provedena je pomoću tekućinskog kromatografa visoke djelotvornosti povezanim sa spektrometrom masa visoke razlučivosti (HPLC-QTOF). Na osnovu dobivenih spektara masa određena je struktura razgradnih produkata i predložen razgradni put osnovnih spojeva. Na temelju određene strukture razgradnih produkata procijenjene su vrijednosti razvojne toksičnosti, mutagenosti i biakumulacijskog faktora pomoću T.E.S.T. softverskog programa.Definifing the stability of drugs is mostly reduced to determining the adverse properties caused by degradation products and contaminants that reduce the quality, safety and efficiency of the drug. In order to accurately determine the production process, as well as storage and transport conditions, it is important to examine how the quality of the pharmaceutical product changes under the influence of various environmental factors. Before commencing commercial use of pharmaceutically active substances, it is necessary, in addition to stability testing, to evaluate their properties which may have a significant effect on living organisms and the environment. Only after the tests have been performed, can the pharmaceutically active compounds enter the testing phase of potential implementation in new pharmaceutical products. One way to test stability is to subject the active substances to extreme chemical and environmental conditions, the so-called forced decomposition test. The aim of this study was to determine the structure and properties of degradation products of two 2-phenylbenzothiazole derivates. Samples of the compounds LD-4, IUPAC called
2-(4-amidinophenyl)-6-aminobenzothiazole chloride, and LD-5, IUPAC called
2-(4-aminophenyl)-6-(imidazolin-2-yl)benzothiazole mesylate, were tested under conditions of acid hydrolysis (0,5 M HCl), basic hydrolysis (0,5 M NaOH), peroxide oxidation (10 % H2O2), elevated temperatures (80 ˚C i 100 ˚C) and UV/VIS light (500 Wh/m^2), and product identification was performed using a high performace liquid chromatograph connected to a high resolution mass spectrometer (HPLC-QTOF). Based on the obtained mass spectra, the structure of degradation products was determined and the degradation pathway of basic compounds was proposed. Based on the specific structure of degradation products, the values of developmental toxicity, mutagenicity and bioaccumulation factor were estimated using T.E.S.T. software program
Spectrophotometric determination of dissociation constant
No full textVrijednost konstante disocijacije kiseline nam govori o stupnju disocijacije kiseline, odnosno o odnosu ravnotežnih koncentracija disociranog i nedisociranog oblika molekule. Kako fizikalno-kemijska svojstva disociranog i nedisociranog oblika mogu biti bitno drugačija, poznavanje vrijednosti pKa je značajano za istraživanje u raznim znanstvenim područjima. Poznavanje konstante disocijacije kiseline važno je i kod kiselo-baznih indikatora koji su široko korišteni u kemijskoj analizi za praćenje kemijskih reakcija. Cilj ovoga rada bio je razmotriti spektrofotometrijsko određivanje konstante disocijacije te odrediti pouzdanost određivanja ovom metodom. Pri tome su korištene dvije računske i dvije grafičke metode za određivanja konstante disocijacije na temelju spektrofotometrijskih mjerenja. Spektrofotometrijski su određene konstante disocijacije tri kiselo-bazna indikatora: bromfenol plavog, bromtimol plavog te fenolftaleina. Otopine indikatora pripremljene su u puferima tako da je pokriven široki raspon pH-vrijednosti. Praćena je ovisnost apsorbancije o pH-vrijednosti pri konstantnoj valnoj duljini te su iz dobivenih rezultata, primjenom Henderson-Hasselbachove jednadžbe, određene konstante disocijacije ispitivanih indikatora. Za indikator bromfenol plavo određene su pKa vrijednosti u rasponu od 3.21 – 3.77 , za indikator bromtimol plavo pKa vrijednosti su u rasponu od 6.61 – 7.37 te za indikator fenolftalein pKa vrijednosti su u rasponu od 7.85 – 9.70. Nakon određivanja apsolutnih i relativnih pogrešaka izračunatih pKa vrijednosti, utvrđeno je da prva grafička metoda daje slične p-vrijednosti konstante disocijacije kao i obje računske metode, dok druga grafička metoda pokazuje najveća odstupanja, dajući najmanje pKa vrijednosti.The acid dissociation constant gives us information about the acid dissociation degree, but also information about the concentration ratio between dissociated and undissociated species of the molecule. Since numerous physicochemical properties of dissociated and undissociated species may vary, knowing the pKa value has a great significance in various scientific fields. Knowing the value of the acid dissociation constant is also very important in the use of acid-base indicators, which are widely used in chemical analysis to observe chemical reactions. The aim of this research was to consider the spectrophotometric determination of the dissociation constant value and to determine the reliability of this method. Two computational and two graphical methods were used to determine the dissociation constant based on spectrophotometric measurements. Three acid-base indicators were analyzed spectrophotometrically, and those are: bromophenol blue, bromothymol blue and phenolphthalein. Samples of indicators were prepared in buffer solutions that covered a wide pH range. The dependence of the absorption on the pH value at a constant maximum wavelength of absorption was monitored, and the dissociation constant was determined from the obtained results using the Henderson-Hasselbach equation. For indicator bromophenol blue determined pKa values were in the range of 3.21 – 3.77, for indicator bromothymol blue pKa values were in the range of 6.61 – 7.37, and for the indicator phenolphthalein pKa values were in the range of 7.85 – 9.70. After determining the absolute and relative errors for the calculated pKa values, it was found that the first graphical method gives similar p-values of the dissociation constant as the both computational methods, while the second graphical method shows the largest deviation giving the smallest pKa values