1,721,076 research outputs found
Forensic analysis of fibres by vibrational spectroscopy
No full textFibres are extremely common. They can originate directly from human and animal hair, and also from textiles in the form of clothing, upholstery and carpets. Hair and textile fibres are relatively easily shed and transferred, which means that it is highly likely that fibres will be found at crime scenes. If such fibres are carefully characterised they can be of immense value in the forensic environment. Vibrational spectroscopy is one of the most important methods for the characterisation of natural and synthetic fibres. The vibrational spectrum, whether mid-IR or Raman, can be considered to be a fingerprint of the molecular structure of the fibre and as such has a very high information content
Raman spectroscopic analysis of a unique linen artefact: the HMS Victory Trafalgar sail
No full textThe Battle of Trafalgar took place in 1805 and is generally accepted to mark the last occasion of combat between major fleets of sailing ships, when a combined Franco-Spanish force of 33 battleships was defeated by a British fleet of 27 battleships blockading Cadiz and the approaches to the Mediterranean Sea. The HMS Victory Trafalgar sail, the fore-topsail from Admiral Lord Nelson’s flagship, was severely damaged and has since suffered significant natural deterioration. As the only extant early 19th century sail in the world, it is a unique artefact and arguably Britain’s foremost maritime textile treasure. Prior to its display at the bicentennial exhibition in 2005, the sail was analysed by Raman spectroscopy. Complementary tensile tests were also completed on loose yarn from around the damaged areas. The mechanical data and Raman spectral comparisons suggest a good correspondence between the historic sailcloth and surrogate
specimens. The latter were prepared by subjecting modern linen canvas to a four-stage regime of artificial ageing in an attempt to reproduce the weakened state of the 200-year-old sailcloth, and provide model material to help appreciate the properties of the historic canvas. Detailed analysis suggests that certain Raman signatures are characteristic of ageing and may correlate with reduced performance of the fabric, suggesting that the technique could offer a non-destructive approach to informing the preservation of a national textile heritage
Vibrational spectroscopic techniques (Raman, FT-IR and FT-NIR spectroscopy) as a means for the solid-state structural analysis of pharmaceuticals
No full textThe aim of this work was to assess the suitability of vibrational spectroscopic
techniques (Raman, FT-IR and FT-NIR spectroscopy) as a means for the solid-state
structural analysis of pharmaceuticals. Budesonide, fluticasone propionate, salbutamol
hemisulfate, terbutaline hemisulfate, ipratropium bromide, polymorphic forms of
salmeterol xinafoate and two polymorphic forms of sulfathiazole were selected since
they are used in the management of certain respiratory disorders and from different
chemical and pharmacological entities along with some pharmaceutical excipients.
Conventional visual examination is not sufficient to identify and differentiate spectra
between different pharmaceuticals. To confirm the assignment of key molecular
vibrational band signatures, quantum chemical calculations of the vibrational spectra
were employed for better understanding of the first five selected drugs. The nondestructive
nature of the vibrational spectroscopic techniques and the success of
quantum chemical calculations demonstrated in this work have indeed offered a new
dimension for the rapid identification and characterisation of pharmaceuticals and
essentially warrant further research.
The application of simultaneous in situ Raman spectroscopy and differential
scanning calorimetry for the preliminary investigation of the polymorphic
transformation of salmeterol xinafoate polymorphs and two polymorphic forms of
sulfathiazole has also been explored in this work leading to the development of a new
method for the solid-state estimation of the transition temperature of
entantiotropically related pharmaceutical polymorphs which represents the first
analytical record of the use of this approach for pharmaceutical polymorphs
Applications of Raman Spectroscopic Techniques in Forensic and Security Contexts. The detection of drugs of abuse and explosives in scenarios of forensic and security relevance using benchtop and portable Raman spectroscopic instrumentation
Full text linkDrug trafficking and smuggling is an ongoing challenge for law enforcement agencies. Cocaine smuggling is a high-value pursuit for smugglers and has been attempted using a variety of concealment methods including the use of bottled liquids, canned milk, wax and suspensions in cans of beer. In particular, traffickers have used clothing impregnated with cocaine for smuggling. Handling, transportation or re-packaging of drugs of abuse and explosives will inevitably leave residual material on the clothing and other possessions of the involved persons. The nails and skin of the person may also be contaminated through the handling of these substances.
This research study describes the development of Raman spectroscopic techniques for the detection of drugs of abuse and explosives on biomaterials of forensic relevance including undyed natural and synthetic fibres and dyed textile specimens, nail and skin. Confocal Raman microscopy has been developed and evaluated for the detection and identification of particulates of several drugs of abuse and explosives on different substrates. The results show that excellent spectroscopic discrimination can be achieved between single particles and substrate materials, giving a ubiquitous non-destructive approach to the analysis of pico-gram quantities of the drugs and explosives in-situ. Isolating the particle in this way corresponds with an analytical sensitivity comparable with the most sensitive analytical techniques currently available e.g. the highly sensitive, yet destructive ionization desorption mass spectrometry. With the confocal Raman approach, this work demonstrates that definitive molecular-specific information can be achieved within seconds without significant interference from the substrate. The potential for the application of this technique as a rapid preliminary, forensic screening procedure is obvious and attractive to non-specialist operators as it does not involve prior chemical pretreatment
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or detachment of the analyte from the substrate. As a result, evidential materials can be analysed without compromising their integrity for future investigation.
Also, the applications of benchtop and portable Raman spectroscopy for the in-situ detection of drugs of abuse in clothing impregnated with the drugs have been demonstrated. Raman spectra were obtained from a set of undyed natural and synthetic fibres and dyed textiles impregnated with these drugs. The spectra were collected using three Raman spectrometers; one benchtop dispersive spectrometer coupled to a fibre-optic probe and two portable spectrometers. High quality spectra of the drugs could be acquired in-situ within seconds and without any sample preparation or alteration of the evidential material. A field-portable Raman spectrometer is a reliable instrument that can be used by emergency response teams to rapidly identify unknown samples. This method lends itself well to further development for the in-situ examination by law enforcement officers of items associated with users, handlers and suppliers of drugs of abuse in the forensics arena.
In the last section of this study, a portable prototype Raman spectrometer ( DeltaNu
Advantage 1064) equipped with 1064 nm laser excitation has been evaluated for the analysis of drugs of abuse and explosives. The feasibility of the instrument for the analysis of the samples both as neat materials and whilst contained in plastic and glass containers has been investigated. The advantages, disadvantages and the analytical potential in the forensics arena of this instrument have been discussed.Egyptian Government and Sohag Universit
Synthetic, Spectroscopic and Computational Studies of Aromatic Compounds. Structure, Fragmentation and Novel Dimerisation of Indoles under Electrospray Conditions, and Innovative Nitrogen to Carbon Rearrangement of Orthogonally Protected Sulphonamides and Related Compounds
Full text linkThe complementary value of vibrational spectroscopy and mass spectrometry in obtaining structural information on a range of tricyclic indoles with various ring patterns has been investigated, focusing particularly on whether these heterocycles with a functional group containing oxygen in the third ring should be described as ketoindoles or hydroxindolenines. Parallels between certain fragmentations of ionised indoles and electrophilic substitution in solution have been identified.
A mechanistically interesting and analytically useful interesting dimerisation, leading to the formation of [2M-H]+ ions, has been discovered in the positive ion electrospray mass spectra of 3-alkylindoles. This dimerisation, which occurs in the nebuliser of the instrument, offers a potential new route to bisindoles under milder conditions than those employed in classical solution chemistry. Facile formation of C=N bonds by condensation of C=O and H2N has been shown to provide a means of preparing protonated imines and protonated quinoxalines from mixtures of the requisite (di)carbonyl compounds and (di)amines, thus further illustrating how organic synthesis is possible in the droplets in the nebuliser of the instrument.
Possible metal catalysed coupling reaction routes to bisindoles have been explored. Acyl transfer reactions from nitrogen to carbon have been investigated in 1-acyl-2-methylindoles and orthogonally protected sulphonamides. These processes have been shown to be intermolecular and intramolecular, respectively. The latter rearrangement, which may be prevented when necessary by choosing the nitrophenylsulphonamide protecting group, offers a route to acyl, carboalkoxy and carboaryloxy aromatic compounds, some of which are difficult to prepare
Structural studies of organic crystals of pharmaceutical relevance. Correlation of crystal structure analysis with recognised non-bonded structural motifs in the organic solid state
Full text linkPharmaceutical solids tend to exist in different physical forms termed as polymorphs. Issues about pharmaceutical systems are mainly concerned with the active ingredient's physico-chemical stability and bioavailability.
The main aim of this study is to investigate the non-bonded interactions in pharmaceutical solids that govern the physical pharmaceutics performance of such materials and through the use of structural techniques and correlation of these results with crystal structural database to establish the presence of physical motifs in selected systems. Structural motifs were identified by the use of single crystal and crystal packing analysis on diverse range of pharma-relevant materials including chalcones, cryptolepines, biguanides and xanthines. These selected systems were validated using functional group and molecular analysis and correlating them to the Cambridge Structural Database. Crystallization studies are done on these selected systems as well as exploiting those using synthetic analogues.
A total of 51 crystal structures were investigated including 16 new structure determinations. Addition synthesis of new xanthines to investigate novel intermolecular patterns was also undertaken. The understanding and exploitation of intermolecular interactions involving hydrogen bonds and coordination complexation during packing can be used in the design and synthesis of solid state molecular structures with desired physical and chemical properties
Design and synthesis of new metallo-organic complexes and their evaluation as anti-cancer agents. Synthesis, characterisation and biological evaluation of novel, late first row transition metal schiff base complexes, as anti-cancer metallopharmaceuticals
No full textThis work is concerned with the design and synthesis of the cheap, late first row transition metal complexes of Schiff base ligand systems. The prepared complexes readily afford systematic variation in order to probe potency and understand the role of metal, chelating ligands and anionic ligands when carrying out their cytotoxic effect. This study has lead to a better understanding of the action of these classes of complex and will be used to direct the design of new anti-cancer metallopharmaceuticals going forward.
This thesis details the synthesis of a library of Schiff base macroacyclic ligands and their novel late first row transition metal complexes with varying anionic counterparts. The creation of a library with several degrees of variability provides a wide array of parameters to afford subtle variation in structure and chemistry e.g. denticity, co-ordination mode, chelate hole size, metal centred redox potentials, hydrolysis rates, co-ordinative saturation, lipophilicity, solubility and more.
Complexation of the ligands was carried out by the free ligand and a novel macroacyclic metal template approach using the cheap late first row transition metal salts of Cobalt (II), Nickel (II), Copper (II) and Zinc (II) plus one Ru (III) complex. Structural studies of the 80 generated complexes was carried out by vibrational spectroscopy, elemental analysis, mass spectrometry, magnetic susceptibility and NMR.
Single crystal X-ray structures have been determined with 20 reported in this thesis. All ligands act as tridentate ligands in all except one case to form monomeric distorted trigonal-bipyramidal, square-pyramidal or octahedral structures. In the case of zinc nitrate, the ligand L2PhMe acts as a tetradentate ligand to give a distorted octahedral structure. Paramagnetic NMR and solution magnetic susceptibility of paramagnetic complexes was achieved by the Evans NMR method and analysis of the solution NMR showed that L2R and L3R ligands display 2-fold symmetry and are likely either tetradentate in solution or a fast exchange between imine N-donar sites is occurring even down to -65°C.
The majority of the resulting complexes of L1R were screened against a panel of three cancer cell lines. Several categories of complex were able to afford structure activity relationships. It was discovered that the ligand is indeed essential for activity of the metal salts against the panel of cell lines and it was largely discovered that the variation in ¿tail group¿ and anionic coordinating ligands played little role in providing a dramatic variation in activity of the metal salt. In general all L1R complexes displayed moderate cytotoxicity showing a trend in activity with respect to the metal in the order RuIII¿CoII>CuII¿ZnII>NiII, over a 6 day exposure to the three cell panel RuIII was shown to be the most potent metal of the L1R series providing IC50 values of 4.6 (0.7) and 7.5 (1.2) ¿M against the DLD-1 and H460 cell lines respectively, which is Ca. 4.6 and 15
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times less potent than cisplatin to the same cell panel respectively. RuIII was also discovered to be the only metal to provide an IC50 value from a 1 hour exposure to the DLD-1 cell panel. The value of 20.4 (3.5) ¿M is a moderate figure but again Ca. 10 fold less potent than cisplatin for the same test.
The L2R and L3R complexes could not be screened by the same comprehension due to their low solubilities. However the lone screen that was possible from the very sparingly soluble complex [CuCl2(L3Bui)] gave the most exciting result and most potent complex of this thesis. After a 6 day exposure, [CuCl2(L3Bui)] gave IC50 values of 4.3 (0.1) and 2.9 (0.1) ¿M against the DLD-1 and H460 cell lines respectively. These values are merely 4 and 6 fold more than Cisplatin to the same cell lines respectively and demonstrates the potential of this class of complex as cytostatic agents.
Further studies utilising a semi-quantitative DNA damaging assay, demonstrated that all first row complexes can damage DNA when in the presence of hydrogen peroxide, with the exception of ZnII complexes. CoII appeared to afford the greatest DNA damage with the most intsense bands for double strand breaks and the CuII complex of the ligand L3Bui also demonstrated a greater DNA damage as opposed to its L1Bui analogue
Raman spectroscopic application for the analysis of organic compounds and minerals of astrobiological significance. The detection and discrimination of organic compounds and mineral analogues in pure and mixed samples of astrobiological significance using raman spectroscopy, XRD and scanning electron microscopy
No full textRaman spectroscopy has been used to characterise both organic and geological samples in order to build a database for the future characterization of biomarker molecules that are of astrobiological relevance. Characteristic geological features and hydrated minerals recently found on the surface of Mars by the NASA planetary rovers Spirit and Opportunity suggest that a possible biosphere could have once existed there. Analytical instrumentation protocols for the unequivocal detection of biomarkers in suitable geological matrices are critical for future unmanned explorations, including the forthcoming ESA ExoMars mission scheduled for 2018. Several geological features found on the surface of Mars by planetary rovers suggest that a possible extinct biosphere could exist based on similar sources of energy as occurred on Earth. For this reason, analytical instrumental protocols for the detection of isolated biomarkers preserved in suitable geological matrices unequivocally and non-destructively have to be evaluated for future unmanned missions. Raman spectroscopy is currently part of the Pasteur instrumentation suite of the ExoMars mission for the remote detection of extant or extinct life signatures in the Martian surface and subsurface. Terrestrial analogues of Martian sites have been identified and the biogeological modifications resulting from extremophilic survival activity have been studied.
Here we present the Raman spectral characterization of several examples of organic compounds which have been recorded using 785 nm, 633 nm and 514 nm laser excitation -polycyclic aromatic hydrocarbons (PAHs), organic acids, chlorophyll and carotenoids. Experimental mixtures of ß-carotene in usnic acid, PAHs in usnic acid and PAHs in mineral matrices have also been investigated. Organic compounds and PAHs located under crystalline minerals samples were identified using a 5x objective lens and 785 nm
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excitation. The pure compounds and compound mixtures were also analysed using X-ray powder diffraction and scanning electron microscopy (SEM). The results of this study indicate that near infrared laser at 785 nm provided the clearest and the most informative spectra due to the reduction of fluorescence emission. Higher energy lasers operating in the visible region have resulted in the emission of significant background fluorescence. Few samples fluoresce even with the use of 785 nm excitation and FT-Raman spectroscopy remains the instrument of choice for the analysis of these samples
Analytical method development for structural studies of pharmaceutical and related materials in solution and solid state. An investigation of the solid forms and mechanisms of formation of cocrystal systems using vibrational spectroscopic and X-ray diffraction techniques
No full textAnalysis of the molecular speciation of organic compounds in solution is essential for the
understanding of ionic complexation. The Raman spectroscopic technique was chosen for
this purpose because it allows the identification of compounds in different states and it
can give information about the molecular geometry from the analysis of the vibrational
spectra. In this research the ionisation steps of relevant pharmaceutical material have been
studied by means of potentiometry coupled with Raman spectroscopy; the protonation
and deprotonation behaviour of the molecules were studied in different pH regions. The
abundance of the different species in the Raman spectra of aqueous salicylic acid,
paracetamol, citric acid and salicylaldoxime have been identified, characterised and
confirmed by numerical treatment of the observed spectral data using a multiwavelength
curve-fitting program. The non-destructive nature of the Raman spectroscopic technique
and the success of the application of the multiwavelength curve-fitting program
demonstrated in this work have offered a new dimension for the rapid identification and
characterisation of pharmaceuticals in solution and have indicated the direction of further
research.
The work also covers the formation of novel cocrystal systems with pharmaceutically
relevant materials. The existence of new cocrystals of salicylic acid-nicotinic acid, DLphenylalanine
, 6-hydroxynicotinic acid, and 3,4-dihydroxybenzoic acid with oxalic acid
have been identified from stoichiometric mixtures using combined techniques of Raman
spectroscopy (dispersive and transmission TRS), X-ray powder diffraction and thermal
analysis. Raman spectroscopy has been used to demonstrate a number of important
aspects regarding the nature of the molecular interactions in the cocrystal. Cocrystals of
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salicylic acid ¿ benzamide, citric acid-paracetamol and citric acid -benzamide have been
identified with similar analytical approaches and structurally characterised in detail with
single crystal X-ray diffraction.
From these studies the high selectivity and direct micro sampling of Raman spectroscopy
make it possible to identify spectral contributions from each chemical constituent by a
peak wavenumber comparison of single-component spectra (API and guest individually)
and the two- component sample material (API/guest), thus allowing a direct assessment of
cocrystal formation to be made. Correlation of information from Raman spectra have
been made to the X-ray diffraction and thermal analysis results.
Transmission Raman Spectroscopy has been applied to the study cocrystals for the first
time. Identification of new phases of analysis of the low wavenumber Raman bands is
demonstrated to be a key advantage of the TRS technique.Libyan government and Misurata Universit
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