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Increased proliferation of nanotechnology has led to concerns regarding its implication to the water environment. Gold nanoparticles (AuNP) were used as a model nanomaterial to investigate the fate and dynamics of nanoparticles in the complex water environment. A column study was performed to examine the fate and transport of gold nanoparticles with two different coatings in porous media. The resulting data suggested that gold nanoparticles aggregate significantly in the porespace of the column interior, a finding that is not predicted by traditional colloidal filtration theory or Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Surface-enhanced Raman spectroscopy (SERS) was developed as a new technique to investigate AuNP aggregation in water with varying salt levels. The SERS technique proved valuable as an analytical technique, elucidating information about aggregation as well as AuNP surface interactions with dissolved halides in water. A thorough investigation examining Aunt aggregation with monovalent and divalent salts utilizing SERS, ultraviolet-visible light (UV-Vis) spectroscopy, and dynamic light scattering (DLS) was conducted. Each technique provided data describing different aspects of the dynamic behavior of AuNPs in complex water environments. Results suggest that in addition to attractive and repulsive interactions described by DLVO theory, chemical interactions between the AuNP surface and dissolved halides were also a significant driving force for aggregation and other transformative behaviors of AuNPs in water. The SERS technique developed in this work was shown to be a viable tool to help unveil the vastly complex dynamics of nanomaterial in the water environment. / Ph. D. / Nanotechnology is everywhere. It is in our smartphones, in our food, in our clothes, even if we do not recognize it is there. And this is a good thing, because nanotechnology – that is, technology that utilizes nanomaterials – can provide things that traditional technology often cannot. This is all because many nanomaterials have “superpowers” due to their size range: they are generally larger than what we may think of when we think of chemical molecules, but much smaller than macroscopic materials whose behaviors can be approximated by classic physics and chemistry. For example, we all know that gold has a shiny yellow metallic appearance. However, if we make little particles of gold – and these are going to be very tiny, with diameters about 10,000 times smaller than that of a strand of human hair (but about 100 times larger than what we would typically think of as molecules of chemicals) – and put them in water, the resulting mixture will be ruby-red like wine. One of the “superpowers” these gold nanoparticles possess is that they interact with light in a very different way than bulk gold. Currently, researchers in the biomedical field are producing promising work employing these particles in nextgeneration imaging, and much more. In this study, we were interested in what happens to these materials once they are released to the water environment. Because of the “superpowers” these gold nanoparticles possess, we really do not know how they will behave once they are released to either surface or groundwater because the physics and chemistry of those environments can be quite variable and complex. In this work, we have shown that traditional assumptions about particulate contaminants in water systems do not necessarily hold for gold nanoparticles. Laboratory simulations show that interactions between these particles and the surrounding environment that were once thought to be negligible, are in fact highly significant. As our title suggests, we are developing new and advanced “photonics” methods to help us discover the dynamic complexity dictating the fate of these gold nanoparticles once they are in the water environment. Photonics methods are techniques that employ light as a probing tool. These techniques use a well understood laser light source that is directed towards the particles in a water environment, and we then measure changes in the scattered light after it has interacted with the particles. The technique we have employed here (called surface-enhanced Raman spectroscopy, or SERS) simultaneously provides us information about different behaviors of gold nanoparticles in water, including how they may aggregate (that is, stick to one another and form big clumps) and how they interact with existing dissolved chemicals that may be present in the natural water environment. By pairing this method with other existing methods, we were able to paint a more complete picture of how these nanoparticles behave in the water environment, and we can answer some questions as to why they do not follow some previously held assumptions. In the end, the work in this dissertation will help future scientists continue to unlock the complexity of nanomaterial fate and dynamics in the water environment.

This Diploma Thesis is focused on study of electrochemical behavior of 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (picric acid) on finding the optimum conditions for their determination using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a mercury meniscus modified silver solid amalgam electrode (m-AgSAE) in the solution of Britton-Robinson (BR) and on finding of the limit of quantification (LQ) for these substances. Practical applicability of the newly developed methods was verified on direct determination of TNT and picric acid in model samples of drinking and river water. Moreover, the electrochemical behaviors of TNT and picric acid was studied using cyclic voltammetry (CV). Optimum medium for the determination of TNT at m-AgSAE was: methanol-BR buffer pH 4.0 (1:9). Upon the DCV it is proper to apply regeneration potentials Ereg,1= 0 mV and Ereg,2= -1100 mV and upon the DPV was apply regeneration potentials Ereg,1= 0 mV and Ereg,2= -600 mV were applied. The concentration dependence of the peak current was found to be linear for both techniques over the concentration range of 1·10-6 -1·10-4 mol/l with LQ of 0.54 µmol/l (for DCV) and 0.46 µmol/l (for DPV). The method developed for the determination of TNT were verified on the model samples of drinking...

The aim of presented Diploma Thesis was to study an electrochemical behavior of nitroimidazole drugs metronidazole and ornidazole and to find optimal conditions for their voltammetric determination at a mercury meniscus modified silver solid amalgam electrode using DC voltammetry (DCV) and differential pulse voltammetry (DPV). Voltammetric behavior of selected drugs was investigated in dependence on the pH of the medium used (realized using a Britton-Robinson buffer (BR buffer)) and a mechanism of the reduction of both drugs was investigated using cyclic voltammetry (CV). The optimum medium for voltammetric determination of studied nitroimidazole drugs at the m-AgSAE in a region of cathodic potentials was found to be the BR buffer of pH 8.0. Then, the concentration dependences were measured in this optimum medium in the concentration range from 2·10-7 mol/L to 1·10-4 mol/L. The limits of quantification (LQs) for both metronidazole and ornidazole were found in the concentration order of 10-7 mol/L by using DCV and DPV at the m-AgSAE. The applicability of the newly developed voltammetric methods of the determination of nitroimidazole drugs was verified on the model samples of drinking and river water, with LQ ≈ 2·10-7 mol/L for both DC voltammetry and differential pulse voltammetry at the m-AgSAE....

Histidinkinase-Rhodopsine (HKRs) können als besondere Gruppe der Hybrid-Histidinkinasen beschrieben werden, deren N-terminale sensorische Domäne ein mikrobielles Rhodopsin ist. HKR-codierende Sequenzen konnten in den Genomen verschiedener Algen, Pilze und Amoeben gefunden werden doch ihre Aufgaben und Wirkungsweisen sind bisher ungeklärt. Im Rahmen dieser Arbeit wurden die rekombinanten Rhodopsin-Domänen von zwei HKRs mit verschiedenen spektroskopischen Techniken charakterisiert. Sie zeigten mehrere Besonderheiten. Das Rhodopsin-Fragment von Cr-HKR1 aus Chlamydomonas reinhardtii kann durch alternierende kurzwellige und langwellige Belichtung zwischen zwei stabilen Absorptionsformen konvertiert werden: einer Blaulicht-absorbierenden (Rh-Bl) und einer UVA-Licht-absorbierenden Form (Rh-UV). Dies resultiert aus der ungewöhnlichen thermischen Stabilität des Zustandes mit deprotonierter Schiff’scher Base. Das zweite charakterisierte HKR, die Os-HKR-Rhodopsin-Domäne aus der marinen Picoalge Ostreococcus tauri, zeigt eine Dunkelabsorption von 505 nm. Auch Os-HKR ist photochrom und die deprotonierte Spezies kann effizient akkumuliert werden. Diese P400-Absorptionsform ist jedoch nicht völlig stabil sondern es kommt nach Belichtungsende zur langsamen Dunkelzustands-Regeneration. Überraschenderweise konnte die Bindung sowie die transiente Abgabe eines Anions während des Os-HKR-Photozyklus festgestellt werden. Somit beeinflusst nicht nur das Licht, sondern auch das Salz in der Umgebung die Os-HKR-Reaktionen. Aufgrund ihrer photochromen Eigenschaften werden die HKRs als wirksame lichtinduzierte Schalter für die C-terminalen Signaltransduktionsdomänen postuliert. Schwingungsspektroskopische Analysen deckten eine Heterogenität hinsichtlich der im Protein gebundenen Retinal‐Konfiguration sowie die Existenz von zwei parallelen Photozyklen auf. Jeder dieser Photozyklen geht aus einer der beiden Retinal-Isomere hervor. / Histidine kinase rhodopsins (HKRs) can be described as hybrid histidine kinases with a microbial rhodopsin as N-terminal sensory domain. HKR-encoding sequences were found in the genomes of various unicellular organisms such as algae, fungi and amoeba but their mechanistic and physiologic function is unknown. During this work the absorptive properties of the recombinant rhodopsin domains of two HKRs were studied by the usage of different spectroscopic techniques. Both HKRs showed unusual characteristics. The rhodopsin fragment of Cr‐HKR1 from Chlamydomonas reinhardtii can be interconverted between two stable absorbance forms by the alternate application of short‐ and long‐wavelength light: a blue light-absorbing dark form (Rh-Bl) and a UVA light-absorbing form (Rh-UV). This unusual photocycle results from the uncommon thermal stability of the absorbance state with a deprotonated retinal Schiff base. The second studied HKR, the Os‐HKR rhodopsin domain from the marine picoalga Ostreococcus tauri, shows an absorbance maximum at 505 nm in darkness. Likewise Cr‐HKR1 the Os‐HKR is photochromic and the deprotonated form P400 can be efficiently accumulated. But the Os-HKR P400-form is not completely stable. A slow dark state recovery occurs. Surprisingly the dark state absorbance of Os‐HKR was found to be dependent on anion binding in the protein. Furthermore during the photocycle the transient anion release occurs and therefore not only light but also salt impacts the Os-HKR-reactions. Due to their pronounced photochromic properties, the HKRs are postulated to act as effective molecular switches for the C-terminal signal transduction domains in response to the light conditions. Vibrational spectroscopy revealed the heterogeneity with regard to the retinal configuration bound in the HKRs suggesting the existence of two parallel photocycles. Either of these photocycles originates from one of the two retinal isoforms.

O cloridrato de ranitidina, um antagonista dos receptores H2 da histamina, foi determinado em comprimidos e injetáveis por espectrofotometria no ultravioleta, a 313nm, e por espectrofotometria no visível, a 615nm, utilizando o cloridrato da hidrazona da 3-metil-2-benzotiazolinona (MBTH) a 0,35% em HCl 0,M e cloreto férrico a 0,40% em HCl 0,1M, como reagentes de cor. Na espectrofotometria no ultravioleta a lei de Beer foi obedecida no intervalo de concentração de 5,0 a 18,0 µg/mL. Quatro amostras comerciais foram analisadas. Os coeficientes de variação foram 0,36% e 0,71% para comprimidos, e 0,51% e 0,24% para injetáveis. A média de recuperação foi 99,88%. Na espectrofotometria no visível a lei de Beer foi obedecida no intervalo de concentração de 1,44 a 5,76 µg/mL. Os coeficientes de variação foram 0,72% e 0,59% para comprimidos, e 0,53% e 0,61% para injetáveis. A média de recuperação foi 99,39%. Os resultados foram comparados estatisticamente e foram compatíveis para as amostras que se encontravam em bom estado de conservação. / Ranitidine hydrochloride, a histamine H2-receptor antagonist, was determined in tablets and injections by ultraviolet spectrophotometry at 313nm , and visible spectrophotometry using as color reagent 0,35% 3-methyl-2-benzothiazolinone hydrochloride in HCl 0,1M and 0,40% ferric chloride in HCl 0,1M. In ultraviolet spectrophotometry, Beer\'s law was obeyed in the range of concentration from 5,0 to 18,0 µg/mL. Four commercially available were analyzed. The coefficients of variation were 0,36% and 0,71% for tablets, and 0,51% and 0,24% for injections. The recovery average was 99,88%. In visible spectrophotometry, Beer\'s law was obeyed in the range of concentration from 1,44 to 5,76 µg/mL. The coefficients of variation were 0,72% and 0,59% for tablets, and 0,53% and 0,61% for injections. The recovery average was 99,39%. The results obtained by using the two methods were statistically compared and were compatible when samples were kept in good conditions of storage.

In der vorliegenden Arbeit wurde der lichtinduzierte Reaktionszyklus des bakteriellen Phytochroms Agp2 aus Agrobacterium tumefaciens mit FTIR‑ und UV‑Vis‑Spektroskopie untersucht. Der Photorezeptor besteht aus einem photosensorischen Modul und einer signalgebenden Histidin-Kinase-Domäne. Das photosensorische Modul bindet das Tetrapyrrol Biliverdin als Chromophor. Der Grundzustand von Agp2 (Pfr, 750 nm) ist gegenüber dem lichtaktivierten Zustand (Pr, 700 nm) rotverschoben, weshalb Agp2 den Bathyphytochromen zugeordnet wird. Die Untersuchungen erfolgten unter Verwendung von Isotopenmarkierung, H/D-Austauschexperimenten und ortsspezifischer Mutagenese. Daraus ließen sich folgende molekulare Änderungen charakterisieren, welche im Reaktionszyklus von Agp2 erfolgen: Die lichtinduzierte Isomerisierung des Chromophors führt zu einem Übergang vom Pfr- in den Pr-Zustand, wobei zwei Intermediate, Lumi‑F und Meta‑F, durchlaufen werden. Neben der Konformationsänderung des Chromophor‑D‑Rings ist auch die C‑Ring-Propionsäureseitenkette an der Photoreaktion beteiligt. Die C-Ring-Propionsäureseitenkette ist im Pfr-Zustand protoniert und wird im Übergang von Meta-F zu Pr deprotoniert. Der Pr-Zustand weist eine pH-Abhängigkeit auf, welche auf die pH-abhängige Ladung des Histidins 278 der Chromophortasche zurückzuführen ist. Je nach Ladung des Histidins 278 wird die Keto‑ bzw. Enolform der C(19)=O‑Gruppe des D‑Rings stabilisiert. Die Keto/Enol-Tautomerie ist auf eine innerhalb des Chromophors erfolgende Protontranslokation zurückzuführen und moduliert die Relaxation in den Pfr-Zustand. Änderungen der Amid-I-Absorption im Pfr-Pr-Übergang werden der Umstrukturierung der Tongue-Region des photosensorischen Moduls von einer Alpha-helikalen zu einer Beta‑Faltblatt-Struktur zugeordnet. Diese Strukturänderung wird als möglicher Weg der proteininternen Signaltransduktion zwischen photosensorischem und signalgebendem Modul vorgeschlagen. / In this thesis the light-induced reaction cycle of the bacterial phytochrome Agp2 from Agrobacterium tumefaciens was investigated using FTIR and UV‑vis spectroscopy. The photoreceptor comprises a photosensitive module and a signalling histidine kinase domain. The photosensitive module binds the biliverdin tetrapyrrol as chromophore. The Agp2 ground state (Pfr, 750 nm) is red-shifted in comparison with its light-activated state (Pr, 700 nm). Therefore, Agp2 is assigned to the group of bathy phytochromes. The investigations were conducted using isotopically labelled protein, labelled chromophore as well as hydrogen‑deuterium (H‑D) exchange and site-directed mutagenesis. Based on these the following molecular changes could be characterized that occur in the reaction cycle of Agp2: The light-induced isomerization of the chromophore leads to a transition from the Pfr to the Pr state, involving two intermediates, Lumi-F and Meta-F. Besides conformational changes of the chromophore D-ring, the C-ring propionic side chain is involved in the photoreaction as well. The C-ring propionic side chain is protonated in the Pfr state and gets deprotonated in the Meta-F to Pr transition. The Pr state exhibits pH‑dependent alterations which can be explained by pH dependent polarity changes of histidine 278 in the chromophore pocket. Depending on the charge of histidine, the D‑ring C(19)=O group is stabilized either in keto or enol form. The keto/enol tautomerism involves a proton translocation within the chromophore and modulates the relaxation to the Pfr state. The changes in the amide I region in the Pfr-Pr transition are associated with an alpha‑helix to beta‑sheet secondary structure change of the PHY domain tongue‑region. This structural change is proposed as the potential path of signal transduction between the photosensitive and the signalling module.

Gegenstand der Untersuchungen war die Reduktion von Stickoxiden (NOx und N2O) an verschiedenartig präparierten Eisenkatalysatoren (Fe-MF, Fe-beta, Fe-SBA-15). Die Katalysatoren wurden nach Synthese, Kalzinierung und Katalyse mittels EPR und UV/VIS-DRS charakterisiert, und darüber hinaus auch in-situ während des Kalzinierens. Isolierte Eisenspezies aggregieren im Verlauf der Kalzinierung bei 873 K. Sowohl höhere Heizraten beim Kalziniervorgang, als auch ein höheres Si/Al-Verhältnis des Trägermaterials verstärken die Neigung zur Aggregatbildung leicht. Die Verwendung des Katalysators für die SCR von NO führt zu weiterem Wachstum und zur Restrukturierung der FexOy-Cluster. Die Eisenkatalysatoren wurden weiterhin mittels in-situ Methoden (EPR, UV/VIS-DRS, FTIR) untersucht während der SCR von NO durch NH3 und Isobutan, der SCR von N2O mit CO, und im Strom der entsprechenden reinen Eduktgase. Die Ergebnisse korrelieren mit dem katalytischen Verhalten der Materialien. Verschiedene Fe3+-Spezies, welche sich durch ein unterschiedliches Redoxverhalten auszeichnen, wurden identifiziert. UV/VIS-Messungen erlauben die Schlußfolgerung, daß isolierte, oktaedrisch koordinierte Fe3+?Spezies leichter zu reduzieren sind als tetradrisch koordinierte. Im Gegensatz zu isoliertem Fe3+ lassen sich FexOx-Cluster leichter oxidieren als reduzieren, und verbleiben daher unter Reaktionsbedingungen trivalent. Durch ihr hohes Oxidationspotential kommt es, vor allem für die Reaktion mit Isobutan, zur unerwünschten Totaloxidation des Reduktanden. Der Anteil isolierter Fe3+ Spezies korreliert mit der Aktivität der Katalysatoren für die SCR von NO und N2O. Weiterhin hängt zumindest für die Reaktion zwischen N2O und CO der Reaktionsmechanismus von der Art der vorliegenden Eisenspezies ab: an isolierten Plätzen erfolgt die Reduktion des N2O an dem an Fe3+ gebundenen CO. An FexOy-Clustern hingegen läuft die Reaktion als Redoxprozeß (Fe3+ / Fe2+) unter Bildung eines radikalischen Intermediates O-. Der Einfluß der Porengeometrie des Trägermaterials auf die katalytische Aktivität wurde an Katalysatoren mit ähnlichem Eisengehalt und ähnlicher Art und Verteilung der Eisenspezies studiert (Fe-MFI, Fe-SBA-15). Die drastisch höhere Aktivität von Fe-MFI belegt, daß die Lokalisierung der aktiven Komponente in einer Pore mit passender Geometrie (Größe und Struktur) essentiell für die katalytischen Eigenschaften ist. Als weitere, die Aktivität stark beeinflussen Größe, wurde für die Reaktion von NO mit Ammoniak und auch mit Isobutan die Azidität identifiziert, die jedoch für die katalytische Zersetzung oder Reduktion mit N2O keine Rolle spielt. / The reduction of nitrogen oxides (NOx and N2O) was investigated over Fe-catalysts (Fe-MFI, Fe-beta and Fe-SBA-15) which were prepared by different methods have been analyzed by EPR and UV/VIS-DRS ex situ after synthesis, calcination and use in catalysis as well as in situ during calcination. It was found that aggregated species are formed at the expense of isolated Fe species upon calcination at 873 K, and that aggregate formation is slightly favored by calcination with higher heating rates as well as by high Si/Al ratio of the support. Use in SCR of NO leads to further growth and restructuring of FexOy clusters. These Fe-catalysts were studied by in situ EPR, in situ UV/VIS-DRS and in situ FT-IR spectroscopy during SCR of NO with NH3 or isobutane and during SCR of N2O with CO as well as during interaction with single feed components. The results were related to the catalytic behaviour. Different types of isolated Fe3+ sites with different reducibility were identified. Based on FT-IR results which revealed that NO reacts preferably with trivalent Fe, it is concluded that Fe3+ ions reduced under reaction conditions to Fe2+ do probably not contribute to catalytic activity. In general, the degree of steady-state Fe site reduction during NH3-SCR is markedly lower than during isobutane-SCR. This might be the reason for the lower activity of Fe-catalysts in the latter reaction. UV/VIS-DRS results suggest that isolated Fe3+ in octahedral coordination is easier reduced than tetrahedral Fe3+. In contrast to isolated Fe3+ species, FexOy clusters are much faster reoxidized than reduced and, thus, remain essentially trivalent under reaction conditions. Due to their higher oxidation potential, they cause undesired total oxidation of the reductant being much more severe in the case of isobutane. A correlation was found between the fraction of isolated Fe+3 sites in the catalysts and their activity for SCR of NO and N2O. The reaction mechanism of SCR of N2O with CO is Fe site dependent. Over isolated Fe sites, the reduction of N2O occurs via coordinated CO species on Fe3+ sites. The reaction over FexOy sites proceeds via a redox Fe3+/Fe2+ process with intermediate formation of O- radicals. The effect of pore geometry of the support on the catalytic activity was studied by comparing catalytic performance of Fe-MFI and Fe-SBA-15 which contain similar iron content and show similar nature and distribution of Fe species as evidenced by UV/VIS-DRS and EPR. Fe-MFI revealed to be much more active than Fe-SBA-15 in all reactions studied. This clearly illustrates that the confinement of the iron species in pores of suitable geometry (structure and size) is essential to originate their remarkable catalytic properties. Acidity is essential for SCR of NO with NH3 or isobutane but it is not mandatory for direct decomposition or SCR of N2O.

Dans le present travail de recherche notre équipe s'est interessé à l'étude de la composition chimique -au niveau moléculaire- d'un groupe d'échantillons résineuses provenant d'objects Aztecs et Mayas. Le but ultime de cette étude a été d'établir l'origin botanique de ces résines et d'avoir une vue d'ensemble des formulations utilisées dans les adhésifs ou les figurines, afin de mieux comprendre leurs propriétes physiques.Pour aboutir à cet objectif une stratégie analytique très spécifique a été créeé et mise en oeuvre. Cette stratégie a inclus l'analyse d'échantillons des résines archéologiques mais aussi de résines d'origine botanique certifiée et de résines commerciales, achetées dans des marchés traditionels au Mexique dans une région qui correspond a la one géographique occupée autre fois par l'empire aztèque.L'étude des matériaux a fait appel à des techniques tels que l'observation a l'échelle microscopique, la spectroscopie infrarouge (IRTF), la chromatographie liquide-DAD (HPLC-UV/Vis) et la chromatographie en phase gazeuse couplée à la spéctroscopie de masse (CPG-SM).L'étude moléculaire de ces échantillons, et plus précisement, l'étude leur fraction tritérpenique a permis de : Établir un profil moléculaire des résines pour chaque origine botanique étudiée Idéntifier précisement certain composées tritérpeniques présents dans toutes les échantillons Réperer les molécules tritérpeniques susceptibles d'être utilisées dans l'avenir comme des marqueurs moléculaires d'origine botanique pour les résines frais des espèces étudiées Suggèrer une origine botanique pour les échantillons archéologiques Aztèques Écarter des origines botaniques possibles pour l'échantillon Maya Avoir une vue d'ensemble de l'origine botanique des résines commercialisées au territoire mexicain sous le nom de «copal» Créer un protocole d'analyse simple pour permettre aux professionnels de la conservation et des biomatériaux d'établir l'origine botanique et un profil moléculaire des résines utilisées dans des expériences diverses Caractériser le comportement du copal lors du vieillisement naturel et artificiel Établir des molécules susceptibles de devenir marqueurs moléculairs pour les deux types de vieillisement Établir que l'origine botanique d'un échantillon résineux peut être retrouvée malgré son âge (archéologique) / In the present work, the molecular composition of series of resinous aztec and maya archaeological samples were investigated to determinate their nature.Thus an analytical strategy was specifically designed. This analytical strategy included the analysis of botanically certified resins, freshly collected. It included as well the analysis of commercial samples bought in Mexican traditional markets.The study of all the samples included microscopical techniques, Fourier Inverse Infrared Spectrometry (FTIR) , High Performance Liquid Chromatography coupled to Ultraviolet-visible spectrometry (HPLC-UV/Vis) and Gas Chromatography coupled to Mass Spectrometry (GC-MS).The molecular study of these samples, in particular of their trterpenic composition allowed to : establish the molecular profile of resins from certified botanical origin. Identifiy some of the triterpenic compounds present in samples; Identify triterpenic molecules that could be uses as molecular markers for each botanical origin. Find the botanical origin of archeological astec samples. Discard possible botanic origins for maya archaeological sample. Have an overview of the origin of commercial samples of mexican copal. Create a simple protocol that allows conservation and biomaterials professionals to establish the botanical origin of archaeological and commercial resins, used in conservation interventions. Observe the behavior of copal materials upon ageing, establishing potential markers for natural ageing in copal, under darkness. Asses the botanical origin of a sample can be found regardless the age of the resin

O cloridrato de ranitidina, um antagonista dos receptores H2 da histamina, foi determinado em comprimidos e injetáveis por espectrofotometria no ultravioleta, a 313nm, e por espectrofotometria no visível, a 615nm, utilizando o cloridrato da hidrazona da 3-metil-2-benzotiazolinona (MBTH) a 0,35% em HCl 0,M e cloreto férrico a 0,40% em HCl 0,1M, como reagentes de cor. Na espectrofotometria no ultravioleta a lei de Beer foi obedecida no intervalo de concentração de 5,0 a 18,0 µg/mL. Quatro amostras comerciais foram analisadas. Os coeficientes de variação foram 0,36% e 0,71% para comprimidos, e 0,51% e 0,24% para injetáveis. A média de recuperação foi 99,88%. Na espectrofotometria no visível a lei de Beer foi obedecida no intervalo de concentração de 1,44 a 5,76 µg/mL. Os coeficientes de variação foram 0,72% e 0,59% para comprimidos, e 0,53% e 0,61% para injetáveis. A média de recuperação foi 99,39%. Os resultados foram comparados estatisticamente e foram compatíveis para as amostras que se encontravam em bom estado de conservação. / Ranitidine hydrochloride, a histamine H2-receptor antagonist, was determined in tablets and injections by ultraviolet spectrophotometry at 313nm , and visible spectrophotometry using as color reagent 0,35% 3-methyl-2-benzothiazolinone hydrochloride in HCl 0,1M and 0,40% ferric chloride in HCl 0,1M. In ultraviolet spectrophotometry, Beer\'s law was obeyed in the range of concentration from 5,0 to 18,0 µg/mL. Four commercially available were analyzed. The coefficients of variation were 0,36% and 0,71% for tablets, and 0,51% and 0,24% for injections. The recovery average was 99,88%. In visible spectrophotometry, Beer\'s law was obeyed in the range of concentration from 1,44 to 5,76 µg/mL. The coefficients of variation were 0,72% and 0,59% for tablets, and 0,53% and 0,61% for injections. The recovery average was 99,39%. The results obtained by using the two methods were statistically compared and were compatible when samples were kept in good conditions of storage.