Spectrophotometric methods are proposed for the determination of drugs containing a phenol group salbutamol sulphate (SLB), ritodrine hydrochloride (RTD), isoxsuprine hydrochloride (IXP) and drugs ...containing an aromatic amine group dapsone hydrochloride (DAP), sulfamethoxazole (SFM), and sulfadiazine (SFD) in pharmaceutical dosage forms. The methods are based on coupling of N, N-diethyl-p-phenylenediamine sulphate with the drugs in the presence of KIO4 to give a green colored product (λmax at 670 nm) and a red colored product (λmax at 550 nm), respectively. Linear relationships with good correlation coefficients (0.9986-0.9996) were found between absorbance and the corresponding concentration of drugs in the range 1-7, 2-22, 1-17, 1.5-12, 2-25, and 2-21 μg mL-1 for SLB, RTD, IXP, DAP, SFM and SFD, respectively. Variable parameters such as temperature, reaction time and concentration of the reactants have been analyzed and optimized. The RSD of intra-day and inter-day studies was in the range of 0.2-1.0 and 0.4-1.0%, respectively. No interference was observed from common pharmaceutical adjuvants. The reliability and performance of the proposed methods was validated statistically; the percentage recovery ranged from 99.5 ± 0.1 to 99.9 ± 0.3%. Limits of detection were 0.14, 0.21, 0.51, 0.44, 0.33 and 0.37 μg mL-1 for SLB, RTD, IXP, DAP, SFM, and SFD, respectively.
U radu je predložena spektrofotometrijska metoda za određivanje lijekova s fenolnom skupinom salbutamol sulfat (SLB), ritodrin hidroklorid (RTD), izoksuprin hidroklorid (IXP) i lijekova s aromatskom amino skupinom dapson hidroklorid (DAP), sulfametoksazol (SFM) i sulfadiazin (SFD) u farmaceutskim dozirnim pripravcima. Metode se temelje na reakciji ljekovitih tvari s N, N-dietil-p-fenilendiamin sulfatom u prisutnosti KIO4, pri čemu nastaje zeleni (λmax pri 670 nm), odnosno crveni produkt (λmax pri 550 nm). Apsorbancije linerano ovise o koncentrancijama lijekova uz visok koeficijent korelacije (0,9986-0,9996) u koncentracijskom području 1-7, 2-22, 1-17, 1,5-12, 2-25 i 2-21 μg mL-1 za SLB, RTD, IXP, DAP, SFM i SFD. Analizirani su i optimirani promjenjivi parametri kao što su temperatura, reakcijsko vrijeme i koncentracija reaktanata. Repetibilnost i intermedijarna preciznost iznosile su 0,2-1,0, odnosno 0,4-1,0%. Nije primjećena nikakva interferencija s uobičajenim farmaceutskim pomoćnim sredstvima. Pouzdanost i izvedbene značajke predložene metode validirane su statistički. Povrat analitičke metode bio je od 99,5 ± 0,1 do 99,9 ± 0,3%. Granice detekcije bile su 0,14, 0,21, 0,51, 0,44, 0,33 i 0,37 μg mL-1 za SLB, RTD, IXP, DAP, SFM, odnosno SFD.
Two spectrophotometric methods for the determination of ceftazidime (CFZM) in either pure form or in its pharmaceutical formulations are described. The first method is based on the reaction of ...3-methylbenzothiazolin-2-one hydrazone (MBTH) with ceftazidime in the presence of ferric chloride in acidic medium. The resulting blue complex absorbs at λmax 628 nm. The second method describes the reaction between the diazotized drug and N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to yield a purple colored product with λmax at 567 nm. The reaction conditions were optimized to obtain maximum color intensity. The absorbance was found to increase linearly with increasing the concentration of CFZM; the systems obeyed the Beer's law in the range 2-10 and 10-50 μg mL-1 for MBTH and NEDA methods, resp. LOD, LOQ and correlation coefficient values were 0.15, 0.79 and 0.50, 2.61. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, sensitive, accurate and suitable for quality control applications.
Razvijene su dvije spektrofotometrijske metode za određivanje ceftazidima (CFZM), čistog ili u farmaceutskim pripravcima. Prva metoda se temelji na reakciji 3-metilbenzotiazolin-2-on hidrazona (MBTH) sa ceftazidimom u prisutnosti željezovog(III) klorida u kiselom mediju. Nastaje plavi kompleks s maksimumom apsorpcije pri λmax 628 nm. Druga metoda se temelji na reakciji između diazotiranog lijeka i N-(1-naftil)etilendiamin dihidroklorida (NEDA), pri čemu nastaje ljubičasti produkt s λmax pri 567 nm. Reakcijski uvjeti su optimirani da se dobije maksimalni intenzitet boje. Apsorbancija raste linearno s porašću koncentracije CFZM; sustavi slijede Beerov zakon u koncentracijskom području 2-10 za MBTH metodu i 1050 μg mL-1 za NEDA metodu. LOD i LOQ te vrijednosti korelacijskog koeficijenta su 0,15, 0,79 i 0,50, 2,61. Uobičajene pomoćne tvari ne smetaju određivanju ceftazidima. Predložene metode su jednostavne, osjetljive, točne i pogodne za primjenu u kontroli kvalitete.
A simple and sensitive spectrophotometric method has been developed for the assay of lercanidipine hydrochloride (LER) in bulk and in formulations. The method is based on the formation of coloured ...species between the drug and 1,2-naphthaquinone-4-sulphonic acid sodium salt (NQS) by means of nucleophilic substitution reaction. Absorbance was measured at λmax = 460 nm. The method was analyzed statistically. The system obeyed the Beer's law in the range 20-100 μg mL-1. Molar absorptivity value was found to be 4.79 × 103 L mol-1 cm-1. Limits of detection and quantification were found to be as low as 0.04 and 0.13 μg mL-1. Precision (RSD, 0.4 %) and accuracy (recovery 99.2 ± 0.6 to 101.1 ± 0.8 %) of the developed method were evaluated.
Razvijena je osjetljiva spektrofotometrijska metoda za određivanje lerkanidipin hidroklorida (LER) u čistoj tvari i ljekovitim oblicima. Metoda se temelji na stvaranju obojenih produkata između ljekovite tvari i natrijeve soli 1,2-naftakinon-4-sulfonske kiseline (NQS) reakcijom nukleofilne supstitucije. Apsorbancija je mjerena pri λmax = 460 nm. Metoda je obrađena statistički. Sistem je slijedio Beerov zakon u koncentracijskom području 20-100 mg mL-1. Molarni apsorpcijski koeficijent iznosio je 4,79 × 103 L mol-1 cm-1, granice detekcije i kvantifikacije 0,04, odnosno 0,13 mg mL-1. Nepreciznost i ispravnost metode iznosile su 0,4 %, odnosno 99,2 ± 0,6 do 101,1 ± 0,8 %.
A simple, accurate and sensitive spectrophotometric method for determination of H2-receptor antagonists: cimetidine (CIM), famotidine (FAM), nizatidine (NIZ), and ranitidine hydrochloride (RAN) has ...been fully developed and validated. The method was based on the reaction of these drugs with NBS and subsequent measurement of the excess N-bromosuccinimide by its reaction with p-aminophenol to give a violet colored product (λmax at 552 nm). Decrease in the absorption intensity (ΔA) of the colored product, due to the presence of the drug, was correlated with its concentration in the sample solution. Different variables affecting the reaction were carefully studied and optimized. Under optimal conditions, linear relationships with good correlation coefficients (0.9988--0.9998) were found between ΔA values and the corresponding concentrations of the drugs in a concentration range of 8--30, 6--22, 6--25, and 4--20 μg mL-1 for CIM, FAM, NIZ, and RAN, respectively. Limits of detection were 1.22, 1.01, 1.08, and 0.74 μg mL-1 for CIM, FAM, NIZ, and RAN, respectively. The method was validated in terms of accuracy, precision, ruggedness, and robustness; the results were satisfactory. The proposed method was successfully applied to the analysis of the above mentioned drugs in bulk substance and in pharmaceutical dosage forms; percent recoveries ranged from 98.5 ± 0.9 to 102.4 ± 0.8% without interference from the common excipients. The results obtained by the proposed method were comparable with those obtained by the official methods.
Razvijena je i validirana ispravna, jednostavna i osjetljiva spektrofotometrijska metoda za određivanje antagonista H2-receptora: cimetidina (CIM), famotidina (FAM), nizatidina (NIZ) i ranitidin hidroklorida (RAN). Metoda se temelji na reakciji tih ljekovitih tvari s N-bromsukcinimidom (NBS). Višak N-bromsukcinimida određuje se nakon reakcije s p-aminofenolom s kojim daje ljubičasti produkt (λmax pri 552 nm). Smanjenje apsorpcijskog intenziteta (ΔA) obojenog produkta, zbog prisutnosti ljekovite tvari korelirano je s njegovom koncentracijom u otopini uzorka. Proučavane su različite varijable koje utječu na reakciju. Linearno koncentracijsko područje za CIM, FAM, NIZ i RAN, s koeficijentom korelacije od 0,9988 do 0,9998, iznosi 8--30, 6--22, 6--25 odnosno 4--20 μg mL-1. Granice detekcije bile su 1,23, 1,02, 1,09 i 0,75 g mL-1 za CIM, FAM, NIZ, odnosno RAN. Predložena metoda je uspješno primijenjena za analizu navedenih ljekovitih tvari i ljekovitih pripravaka. Nepreciznost od 0,7 do 1,2% i visoka ispravnost (analitički povrat između 98,5 i 102,4%), bez interferencije uobičajenih pomoćnih tvari, ukazuju na dobru analitičku metodu. Rezultati dobiveni predloženom metodom usporedivi su s rezultatima dobivenim službenom metodom.
Two spectrophotometric methods are proposed for the assay of lansoprazole (LPZ) in bulk drug and in dosage forms using ceric ammonium sulphate (CAS) and two dyes, methyl orange and indigo carmine, as ...reagents. The methods involve addition of a known excess of CAS to LPZ in acid medium, followed by determination of residual CAS by reacting with a fixed amount of either methyl orange, measuring the absorbance at 520 nm (method A), or indigo carmine, measuring the absorbance at 610 nm (method B). In both methods, the amount of CAS reacted corresponds to the amount of LPZ and the measured absorbance was found to increase linearly with the concentration of LPZ, which is corroborated by the correlation coefficients of 0.9979 and 0.9954 for methods A and B, respectively. The systems obey Beer's law for 0.5-7.0 μg mL-1 and 0.25-3.0 μg mL-1 for methods A and B, respectively. The apparent molar absorptivities were calculated to be 3.0 x 104 and 4.4 x 104 L mol-1 cm-1 for methods A and B, respectively. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.08 and 0.25 μg mL-1 for method A, and 0.09 and 0.27 μg mLs-1 for method B, respectively. The intra-day and inter-day precision and accuracy of the methods were evaluated according to the current ICH guidelines. Both methods were of comparable accuracy (er ≤ 2 %). Also, both methods are equally precise as shown by the relative standard deviation values < 1.5%. No interference was observed from common pharmaceutical adjuvants. The accuracy of the methods was further ascertained by performing recovery studies using the standard addition method. The methods were successfully applied to the assay of LPZ in capsule preparations and the results were statistically compared with those of the literature UV-spectrophotometric method by applying Student's t-test and F-test.
Predložene su dvije spektrofotometrijske metode za određivanje lansoprazola (LPZ) kao čiste supstancije i u doziranim ljekovitim pripravcima koristeći cerijev amonijev sulfat (CAS) i dvije boje, metiloranž i indigo karmin. Metode uključuju dodatak suviška CAS-a u otopinu LPZ u kiselom mediju, nakon čega višak reagensa reagira s poznatom količinom metiloranža (metoda A, mjerenje apsorbancije na 520 nm) ili indigo karminom (metoda B, mjerenje apsorbancije na 610 nm). U obje metode, količina CAS-a koja reagira odgovara količini LPZ i izmjerena apsorbancija linearno ovisi o koncentraciji LPZ-a, uz koeficijent korelacije 0,9979 i 0,9954 za metodu A odnosno B. Oba sustava slijede Beerov zakon u koncentracijskom rasponu 0,5-7,0, odnosno 0,25-3,0 μg mL1. Molarni apsorpcijski koeficijent određen metodom A iznosio je 3,0 x 104 a metodom B 4,4 x 104 L mol1 cm-1. Granica detekcije (LOD) i kvantifikacije (LOQ) bile su 0,08 i 0,25 μg mL-1 za metodu A, te 0,09 i 0,27 μg mL-1 za metodu B. Preciznost i ispravnost metoda procijenjena je prema važećim ICH smjernicama. Obje metode su podjednako ispravne (er ≤ 2%) i precizne (RSD < 1,5%). Nije primijećena interferencija s uobičajenim pomoćnim tvarima. Ispravnost je procijenjena i metodom standardne adicije. Rezultati su statistički uspoređeni s referentnom UV-spektrofotometrijskom metodom pomoću Studentovog t-testa i F-testa.
Individualised therapy and factors determining such variability among patients are confusing to both physicians and their patients because of the observed therapeutic, metabolic and toxic response. ...The same is true about antifungal azoles. They are under the influence and become targets of metabolic drug-drug interactions where more than one active form of the drug may be involved. The clinical relevance of these interactions may vary upon the azole involved and upon the intention of drug administration. The pharmacodynamics and pharmacokinetics of azole drugs as indicated by the reviewed data make the need for characterization of all their metabolites even more evident. The health care systems also emphasize the identification and quantitation of the metabolites for a comprehensive understanding of the biological safety of individual metabolites, thus, revealing the need and scope of bioanalytical research in metabolite and toxicity profiling of drugs. Availability of protocols for qualitative and quantitative characterization of all metabolites will have many applications for therapeutic drug monitoring, bioequivalence, toxicological and all related studies. Identification of metabolites may be done by a variety of chromatographic and spectroscopic techniques, either alone or in combination with other techniques. Conventional liquid chromatography has been exploited widely in the field of metabolite profiling. The arrival of hyphenated techniques has revolutionized metabolite profiling, by not only separating but also generating data for the structural identification of metabolites as well. Among all techniques, the most exploited are Liquid Chromatography-Mass Spectroscopy, Nuclear Magnetic Resonance spectroscopy, Liquid Chromatography-Nuclear Magnetic Resonance spectroscopy, Liquid Chromatography-Nuclear Magnetic Resonance spectroscopy-Mass Spectroscopy and Extraction-Nuclear Magnetic Resonance spectroscopy. This compilation provides a tool for the metabolic, bioanalytical and biomedical understanding of antifungal azole metabolites.
Individualizovana terapija i faktori koji određuju varijabilnost među pacijentima zbunjuju i lekare i pacijente zbog očiglednog terapeutskog, metaboličkog i toksičnog odgovora. Isto važi i za antifungicidne azole. Oni su pod uticajem, i postaju mete metaboličkih interakcija između lekova, koje mogu obuhvatiti više od jedne aktivne forme leka. Klinički značaj tih interakcija se razlikuje u zavisnosti od azola i cilja primene leka. Farmakodinamika i farmakokinetika azola, prema dosadašnjim podacima, dodatno ističu potrebu za karakterizacijom svih metabolita azola. Sistemi zdravstvene zaštite takođe naglašavaju identifikaciju i kvantifikaciju metabolita u cilju razumevanja biološke bezbednosti pojedinih metabolita, otkrivajući na taj način potrebu i obim bioanalitičkog istraživanja u profilisanju metabolita i toksičnosti lekova. Dostupnost protokola za kvalitativnu i kvantitativnu karakterizaciju svih metabolita omogućiće široku primenu u terapijskom praćenju leka, bioekvivalenciji, toksikološkim i svim srodnim studijama. Identifikacija metabolita može se postići pomoću različitih hromatografskih i spektroskopskih tehnika, pojedinačno, ili u kombinaciji sa drugim tehnikama. Uobičajena tečna hromatografija često se primenjuje u profilisanju metabolita. Podeona tehnika je donela revoluciju u profilisanju metabolita, na taj način što je, pored razdvajanja, pružila i podatke za strukturnu identifikaciju metabolita. Od svih tehnika najviše se koriste tečna hromatografija-masena spektroskopija, spektroskopija nuklearne magnetske rezonancije, tečna hromatografijaspektroskopija nuklearne magnetske rezonancije, tečna hromatografija-spektroskopija nuklearne magnetske rezonancije-masena spektroskopija, i ekstraciona spektroskopija nuklearne magnetske rezonancije. Ova kompilacija može doprineti metaboličkom, bioanalitičkom i biomedicinskom razumevanju antifungicidnih metabolita azola.
A spectrophotometric method is described for assay of pefloxacin mesylate (PFM) in bulk drug and in tablets. The method is based on back extraction of the bromophenol blue dye at pH 5.2 from the ...dye-drug ion pair followed by measurement of the dye absorbance at 590 nm. The working conditions of the method were investigated and optimized. Beer's law plot showed a good correlation in the concentration range of 0.15-1.25 μg mL-1. Sensitivity indices such as molar absorptivity, limits of detection and quantification are reported. Intra-day and inter-day precision, and accuracy of the methods were established according to the ICH guidelines, and the er values were in the range of -1.7 to 1.8% with RSD values ranging from 1.0 to 1.1%. The method was successfully applied to the assay of PFM in tablet preparations with recoveries varying from 97.5 to 101.9%, with standard deviation in the range of 0.6 to 1.9. The results were statistically compared with those of the reference method by applying Student's t-test and F-test. Accuracy evaluated by means of the spike recovery method, range from 97.0 to 106.0%, with precision better than 3%.
Opisana je spektrofotometrijska metoda za određivanje pefloksacin mesilata (PFM) kao čiste supstancije i u tabletama. Metoda se temelji na povratnoj ekstrakciji bromfenol modrila pri pH 5,2 iz ionskog para boja-ljekovita tvar te mjerenju apsorbancije boje na 590 nm. Ispitivani su i optimirani reakcijski uvjeti. Sustav slijedi Beerov zakon u koncentracijskom rasponu 0,15-1,25 Mg mL-1 (R = 0,9986). Prema važećim ICH uputama procijenjeni su indeksi osjetljivosti kao Što su molarni apsorpcijski koeficijent, granica detekcije i granica određivanja; također su procijenjeni ispravnost i preciznost. Relativna pogreška kretala se u rasponu -1,7 do 1,8%, a RSD vrijednosti između 1,0 i 1,1%. Metoda je uspješno primjenjena za određivanje PFM u tabletama s analitičkim povratom od 97,5 do 101,9% uz RSD od 0,6 do 1,9%. Rezultati su statistički uspoređeni s referentnom metodom pomoću Studentovog t-testa i F-testa, ukazujući na usporedivu preciznost i ispravnost obiju metoda. Ispravnost procijenjena metodom standardne adicije kretala se u rasponu od 97,0 do 106,0%, s preciznošu (RSD) boljom od 3%.
Thin film structures own significantly different properties than the bulk
material and consequently they found applications in various fields of modern
nanotechnology. In the past few decades, ...special attention was paid to
research in the field of ion beams modification of thin films. Among the
techniques ion implantation is particularly emphasized, as a method that
allows the incorporation of impurity atoms in the material with the
possibility of precise control of process parameters. As non-equilibrium
technique (not controlled by diffusion laws), ion implantation enables
production of a new materials, that can not be produced with other
conventional methods. The main objective of this research was to gain new
fundamental knowledge in the field of modification of thin film/Si systems
induced by ion irradiation. The present work consists of two parts. In the
first part of the experiment the changes induced by ion implantation inside
of the thin layer were examined – effects of different ionic species on the
microstructure, optical and electrical properties of chromium nitride (CrN)
were investigated. The second part of the experiment refers to the
examination of changes at the thin film/substrate interface due to ion
implantation – the influence of ion bombardment on the ion beam mixing of
Co/Si system was investigated as well as formation of cobalt-silicides during
the process of ion irradiation and./.or annealing of the samples. Rutherford
backscattering spectrometry (RBS) was used to obtain concentration depth
profiles of elements and to determine the stoichiometry of the layers.
Structural and phase analyses of the systems were performed by X-ray
diffraction (XRD), transmission electron microscopy combined with selected
area diffraction (TEM/ SAD) and high-resolution electron microscopy analysis
together with fast Fourier transformations (HRTEM/FFT). Optical properties of
modified CrN layers were determined using infrared spectroscopy (IR) and
electrical resistivity was measured using four point probe method. CrN thin
films (thickness of ~280 nm) were deposited by reactive sputtering on
crystalline silicon substrates and then implanted with 200 keV Ar+ and 80 keV
V+ ions. In the case of Ar+ ions the samples were implanted in the range of
5×1015–20×1015 ions/cm2, while V+ ions were implanted to the fluence of
1×1017 and 2×1017 ions/cm2. The energies were chosen in such a way that all
ions are stopped inside the layer, to avoid any atomic mixing and possible
reactions at the thin film./.substrate interface. It turned out that
different ionic species produces different effects in the layer, which is
manifested in both the microstructural changes, as well as changes in optical
and electrical properties of this material. After irradiation with Ar+ ions
there are no significant changes in the composition of the layer. However,
the changes were observed in the microstructure of the samples. In the
implantation region the initial columnar structure of the layer firstly
becomes broken and with increasing of ion fluence completely destroyed. The
accumulation of defects within this area produces damage and the internal
stresses in the layer, which affects the size of crystalline grains and the
values of the CrN lattice constant. In contrast to the implantation of inert
argon which produces only ion irradiation induced damage, the presence of
vanadium, as the second transition metal, leads to the generation of chemical
effects in the layer. It was observed that in the region of the layer with
the highest concentration of implanted vanadium Cr0,9375 V0,0625N compound
was formed. Due to the formation of a new metallic phase, as deposited CrN
layer with metal/semiconductor properties shows a purely metallic character
after V+ implantation. Co(50nm)/Si bilayers were prepared in high vacuum
conditions, using ion beam assisted deposition technique. Two types of
silicon substrates were used: crystalline (100) wafers and Si wafers
pre-amorphized by low-energy Ar+ ion bombardment. After deposition the layers
were implanted with 400 keV Xe+ ions to the fluence of 2×1015, 4×1015,
6×1015, 8×1015, 10×1015, 15×1015, 20×1015 and 30×1015 ions/cm2. The energy
was chosen so that the effects of ion implantation are most pronounced at the
thin film (Co)./.substrate (Si) interface. Then, as deposited and selected
implanted samples (20×1015 Xe/cm2) were annealed for 2.h in the vacuum
furnace at 200, 300, 400, 500, 600 and 700ºC. The values of atomic mixing
rates showed that the structure of the substrate has a strong influence on
the process of atomic transport induced by ion bombardment. Namely, in the
case of pre-amorphized substrate the mixing rate of Co and Si atoms at the
Co/Si interface is almost for an order of magnitude lower in comparation with
crystalline Si. It is assumed that this is the result of the formation of
large amount of defects, created near the surface of Si substrate during the
Ar+ ions bombardment, which presents a barrier for movement of atoms from one
to the other side of the interface. Low mobility of these defects prevents
also the thermally activated diffusion, so even at the highest annealing
temperature the formation of silicides was not observed. For the irradiated
samples, independently on whether it is crystalline or pre-amorphized
substrate, it is observed similar behavior: up to annealing temperatures of
400ºC poorly pronounced diffusion comes from the effects induced by ion
irradiation, and at temperatures of 500–700ºC thermal mixing becomes dominant
process and conditions for the compound formation were fulfilled. At the
temperature of 500ºC dominant phase is CoSi, and at temperatures ≥600ºC a
pure phase CoSi2 was formed.
Zbog činjenice da posjeduju svojstva koja se znatno razlikuju od komadnog
materijala, tankoslojne strukture su našle primjenu u raznim oblastima
savremenih nanotehnologija. U posljednjih nekoliko decenija posebna pažnja je
posvećena istraživanjima na polju modifikacije tankih slojeva korišćenjem
jonskih snopova. Medu tehnikama se posebno istakla jonska implantacija, kao
metoda koja omogućuje ugrađivanje atoma nečistoća u materijal u strogo
kontrolisanim uslovima. Kao neravnotežna tehnika (nije kontrolisana zakonima
difuzije), jonska implantacija omogućuje dobijanje novih materijala, koji se
drugim postupcima ne mogu formirati. Osnovni cilj ovog istraživanja je
sticanje novih fundamentalnih znanja u oblasti modifikacije sistema tanak
sloj/Si primjenom jonskog zračenja. Predstavljeni rad se sastoji iz dva
dijela. U prvom dijelu eksperimenta su posmatrane promjene koje jonska
implantacija indukuje unutar tankog sloja – ispitivan je efekat različitih
jonskih vrsta na mikrostrukturu, optička i električna svojstva hrom-nitrida
(CrN). Drugi dio eksperimenta se odnosi na ispitivanje promjena koje uslijed
jonske implantacije nastaju na granici tanak sloj/podloga – proučavan je
uticaj jonskog bombardovanja na proces atomskog transporta kod Co/Si sistema
i mogućnost formiranja kobalt-silicida u toku procesa jonskog zračenja i/ili
odgrijavanja uzoraka. Spektrometrija Rutherford-ovim povratnim rasijanjem
(RBS) je iskorišćena za dobijanje dubinskih koncentracionih profila elemenata
i određivanje stehiometrije slojeva. Za strukturnu analizu i identifikaciju
prisutnih faza u uzorcima korišćena je difrakcija X-zračenja (XRD),
transmisiona elektronska mikroskopija u kombinaciji sa elektronskom
difrakcijom na odabranoj površini (TEM/SAD) i visoko-rezoluciona elektronska
mikroskopija uz analizu pomoću Fourier-ove transformacije (HRTEM/FFT).
Optička svojstva modifikovanih CrN slojeva su određena korišćenjem
infracrvene spektrofotometrije (IR), a električna otpornost je mjerena
metodom ”četiri tačke”. Tanki slojevi CrN (debljine ~280 nm) su deponovani
metodom reaktivnog jonskog rasprašivanja na kristalnim silicijumskim
pločicama, a zatim su implantirani sa 200 keV Ar+ i 80 keV V+ jonima. U
slučaju Ar+ jona uzorci su implantirani u opsegu od 5×1015–20×1015 jona/cm2,
dok su joni V+ implantirani do doze 1×1017 i 2×1017 jona/cm2. Energije su
odabrane tako da se svi joni zaustave u sloju, da bi se izbjeglo atomsko
miješanje i moguće reakcije na granici sloj/podloga. Pokazalo se da različite
jonske vrste proizvode drugačije efekte u sloju, što se manifestovalo kako u
mikrostrukturnim promjenama, tako i u promjenama optičkih i električnih
svojstava ovog materijala. Nakon ozračivanja sa jonima Ar+ ne dolazi do
značajnih promjena u sastavu sloja. Međutim, uočene su promjene u
mikrostrukturi uzoraka. U zoni implantacije prvo dolazi do narušavanja, a sa
povećanjem doze i do potpunog uništenja prvobitne stubičaste strukture sloja.
Nakupljanje defekata unutar ove oblasti proizvodi oštećenja i unutrašnja
naprezanja u sloju, što utiče na veličinu kristalnih zrna i na vrijednost
konstante CrN rešetke. Za razliku od implantacije inertnog argona gdje dolazi
samo do pojave jonskim zračenjem indukovanog oštećenja, prisustvo vanadijuma,
kao drugog prelaznog metala, dovodi do pojave hemijskih efekata u sloju.
Uočeno je da u zoni sloja sa najvećom koncentracijom implantiranog vanadijuma
dolazi do formiranja Cr0,9375 V0,0625.N jedinjenja. Formiranje nove metalne
faze ima za posljedicu da deponovani CrN sloj sa metalno/poluprovodničkim
svojstvima, nakon V+ implantacije pokazuje izraziti metalni karakter.
Dvoslojni sistemi Co(50nm)/Si su pripremljeni u uslovima visokog vakuuma,
korišćenjem metode deponovanja potpomognutog jonskim snopom. Korišćene su
dvije vrste silicijumskih podloga: kristalne pločice orijentacije (100) i
podloge sa površinom amorfizovanom bombardovanjem sa niskoenergetskim Ar+
jonima. Nakon deponovanja slojevi su implantirani sa 400 keV Xe+ jonima do
doze 2×1015, 4×1015, 6×1015, 8×1015, 10×1015, 15×1015, 20×1015 i 30×1015
jona/cm2. Energija je odabrana tako da efekti jonske implantacije budu
najizraženiji na granici tanak sloj (Co)/podloga (Si). Deponovani i odabrani
implantirani slojevi (20×1015 Xe/cm2) su za
Voćna vina sadržavaju brojne polifenolne spojeve različitog biološkog učinka, no u usporedbi s vinom proizvedenim od grožđa, njihov sastav i pozitivan učinak na ljudsko zdravlje znatno su manje ...istraženi. Stoga je svrha ovoga rada bila odrediti polifenolni sastav i biološki učinak različitih komercijalno dostupnih hrvatskih vina od kupine, višnje, maline, crnog ribiza, jagode i jabuke. Ovim istraživanjem je po prvi put provedena sveobuhvatna analiza hrvatskih voćnih vina. Polifenolni sastav voćnih vina određen je spektrofotometrijski i primjenom HPLC-PDA/MS analiza. Antioksidacijski kapacitet voćnih vina određen je metodama ABTS i FRAP, dok je njihov biološki učinak određen in vitro ispitivanjem citotoksičnog učinka na humane stanične linije karcinoma dojke (MCF-7), debelog crijeva (CaCo-2) i vrata maternice (HeLa). Najveći je udjel ukupnih polifenolnih spojeva pronađen u voćnim vinima od kupine, višnje i crnog ribiza, a posljednja su dva tipa vina također imala i najveći udjel ukupnih antocijana. Pojedinačna analiza polifenolnih spojeva pokazala je da svaki tip vina ima specifičan sastav, naročito antocijana. Vina od kupine, višnje, maline i crnog ribiza imala su bitno veći antioksidacijski kapacitet od vina od jagode i jabuke. Voćna vina inhibirala su rast tumorskih stanica in vitro, ovisno o volumnom omjeru vina i uzgojne podloge. Također je zapažena različita osjetljivost upotrijebljenih staničnih linija na djelovanje vina. Najizraženiji citotoksični učinak na tumorske stanične linije imala su vina od kupine, višnje, maline i crnog ribiza u volumnom omjeru od 10 i 20 %. Vina su imala izraženiji inhibicijski učinak na rast stanica HeLa i MCF-7 nego na CaCo-2.
Razvijeni su novi analitički postupci temeljeni na spektroskopskim metodama i kemometričkim izračunima za istovremeno kvantitativno određivanje tramadola i paracetamola u tabletama. Spektroskopski ...podaci dobiveni analizom tableta primjenom UV-Vis spektrofotometrije, spektroskopije u bliskom infracrvenom području (NIR) te Ramanove spektroskopije obrađeni su upotrebom metode djelomičnih najmanjih kvadrata (PLS), genetičkih algoritama spregnutih s PLS-om (GA-PLS) i umjetnih neuronskih mreža (ANN). Rezultati dobiveni kemometričkom obradom spektroskopskih podataka statistički su uspoređeni s onima određenima validiranom metodom tekućinske kromatografije ultravisoke djelotvornosti (UHPLC).
Dobiveno je dobro slaganje između količina paracetamola određenih u tabletama primjenom UV spektrofotometrije te PLS, GA-PLS i ANN algoritama i referente UHPLC metode. U slučaju tramadola GA-PLS rezultati pokazali su se pouzdaniji u odnosu na one dobivene PLS-om i ANN-om. Najjednostavniji i najpouzdaniji modeli konstruirani su korištenjem PLS metode za paracetamol i GA-PLS metode za tramadol.
Maseni udjeli paracetamola u tabletama određeni primjenom NIR spektroskopije i kalibracijskih kemometričkih modela izrađenih pomoću PLS, GA-PLS i ANN metoda vrlo se dobro slažu s onima dobivenima UHPLC-om. Rezultati dobiveni primjenom ANN-a i GA-PLS-a međusobno se ne razlikuju znatno, te su pouzdaniji od onih izračunanih upotrebom PLS metode. S druge strane, udjeli tramadola određeni NIR metodom spregnutom s GA-PLS algoritmom znatno su pouzdaniji od onih izračunanih upotrebom druge dvije metode. GA-PLS pristupom obradi podataka pojednostavio se je kalibracijski model te poboljšala točnost i preciznost dobivenih rezultata.
Ramanova spektroskopija spregnuta s PLS, GA-PLS i ANN kemometričkim metodama uspješno je upotrijebljena za kvantitativnu analizu paracetamola, pri čemu su rezultati dobiveni tim metodama usporedivi s referentnim vrijednostima. Algoritam GA-PLS još se jednom pokazao superiornijim u odnosu na PLS i ANN. U slučaju analize tramadola, nijednom uporabljenom metodom nisu dobiveni rezultati usporedivi s referentnim vrijednostima.
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Several new analytical procedures based on spectroscopic methods and chemometric calculations were developed for quantitative determination of tramadol and paracetamol in tablets. Spectroscopic data obtained by analyses of tablets using UV-Vis spectroscopy, spectroscopy in near infrared region (NIR), and Raman spectroscopy were processed by means of partial least squares (PLS), genetic algorithm coupled with PLS (GA-PLS) and artificial neural networks (ANN). Results gained by chemometric processing of the spectroscopic data were statistically compared with those obtained by means of validated ultra-high performance liquid chromatographic (UHPLC) method.
A good agreement between the amounts of paracetamol determined in the tablets using UV spectrophotometry and PLS, GA-PLS, as well as ANN algorithms, and that obtained by referent UHPLC method was found. In the case of tramadol, GA-PLS results were proven to be more reliable compared to those of PLS and ANN. The simplest and the most reliable models were constructed by using PLS method for paracetamol and GA-PLS method for tramadol.
Mass fractions of paracetamol in the tablets determined by means of NIR spectroscopy and calibration chemometric models constructed using PLS, GA-PLS, and ANN methods were in accordance with those gained by UHPLC. There was no significant difference between the results obtained by using ANN and GA-PLS, and they were more reliable than that obtained by PLS method. On the other hand, fractions of tramadol determined by NIR method coupled with GA-PLS algorithm were considerably more reliable than those calculated using other two methods. GA-PLS-based approach reduced the calibration model complexity and improved the accuracy and precision of the results.
Raman spectroscopy coupled with PLS, GA-PLS, and ANN chemometric methods was successfully applied for quantitative analysis of paracetamol, whereby the results obtained by these methods were comparable with the referent values. GA-PLS algorithm was once again proven to be superior over the PLS and ANN. In the case of tramadol analysis, the results gained by applying any of the used method were not comparable with the referent values.
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