Detection of carbonate, phosphate minerals and cyanobacteria in rock from the Tomtor deposit, Russia, by Raman spectroscopy.

Samples of rock from the Tomtor Nb - REE (rare-earth elements) deposit (Russia) have been investigated by Raman micro-spectroscopy using visible 532 nm wavelength excitation. Raman spectra of different samples of this rock confirm their composition as calcites and other carbonates such as rhodochrosite, and mixed solid solution phases (Ca, Mn, Fe, Mg, Ba, Sr, REE)(CO3). An association between cyanobacteria and the apatite crystals has been noted Cyanobacteria exhibited Raman modes at 1520-1517 cm-1 located in the double bonds of the central part of the polyene chain of carotenoids. A slight shift of this mode in the apatite-containing samples are dependent upon the compositions of carotenoids, the ratio of the rare earth elements adsorbed by cyanobacteria as well as their interaction with the environment. Laser-induced photoluminescence of REE and Mn+2, obtained as an analytical artifact in the Raman spectra, has been observed in most cases with significant spectral intensity. The luminescence emission of Mn 2+, Sm3+, Eu 3+, Pr3+, Ho3+, Er 3+ in the spectra of the apatite-containing samples obtained with 532 nm excitation can be attributed both to apatite and to other mineral phases with a low concentration which contain these elemental ions. The results obtained in this study allowed us to confirm that the biogenic presence of the cyanobacterial mat had a significant impact on the formation of the unique Nb-REE Tomtor deposit.

Miniaturized Raman instrumentation detects carotenoids in Mars-analogue rocks from the Mojave and Atacama deserts.

This study is primarily focused on proving the potential of miniaturized Raman systems to detect any biomolecular and mineral signal in natural geobiological samples that are relevant for future application of the technique within astrobiologically aimed missions on Mars. A series of evaporites of varying composition and origin from two extremely dry deserts were studied, namely Atacama and Mojave. The samples represent both dry evaporitic deposits and recent evaporitic efflorescences from hypersaline brines. The samples comprise halite and different types of sulfates and carbonates. The samples were analysed in two different ways: (i) directly as untreated rocks and (ii) as homogenized powders. Two excitation wavelengths of miniaturized Raman spectrometers were compared: 532 and 785 nm. The potential to detect carotenoids as biomarkers on Mars compared with the potential detection of carbonaceous matter using miniaturized instrumentation is discussed.

The role of mobile instrumentation in novel applications of Raman spectroscopy: archaeometry, geosciences, and forensics.

The applications of analytical Raman spectroscopy in the characterisation of materials associated with archaeologically excavated artefacts, forensic investigations of drugs of abuse, security and crime scenes, minerals and rocks and future astrobiological space missions are now well established; however, these applications have emphasised the need for new developments in the area of miniaturised instrumentation which extends the concept and breadth of the analytical requirement to facilitate the provision of data from 'in field' studies. In this respect, the apparently unrelated themes of art and archaeology, forensic science, geological science and astrobiology as covered by this review are unified broadly by the ability to record data nondestructively and without resorting to sampling and the subsequent transfer of samples to the analytical laboratory. In studies of works of art there has long been a requirement for on-site analysis, especially for valuable paintings held under strict museum security and for wall paintings which cannot physically be removed from their setting; similarly, the use of portable Raman spectroscopy in archaeological and geological field work as a first-pass screening device which obviates the necessity of multiple and wasteful specimen collection is high on the wish-list of practicing spectroscopists. As a first-pass screening probe for forensic crime scenes, Raman spectroscopy has proved to be of inestimable value for the early detection of dangerous and prohibited materials such as drugs of abuse, explosives and their chemical precursors, and banned contraband biomaterials such as ivories and animal products; in these applications the advantage of the Raman spectroscopic technique for the recognition of spectral signatures from mixtures of inorganic and organic compounds is paramount and not afforded by other less portable instrumental techniques. Finally, in astrobiological work, these requirements also apply but with the additional prerequisite for system operation remotely - often over distances of several hundred million kilometres - as part of instrumental suites on robotic spacecraft and planetary landers; this necessitates robust and reliable instrumentation for the observation of unique and characteristic spectral features from the planetary geological surface and subsurface which are dependent on the assignment of both biological and geological band signatures.

Monitoring of heavy metals content in soil collected from city centre and industrial areas of misurata, libya.

The present paper deals with the assessment of heavy metals in soil and roadside dust around Misurata City Centre and industrial areas/roads in the period of October 2011-May 2012. The levels of Pb, Fe, Zn, Ni, Cd, Cr, and Cu in settled dust samples collected near small streets, playgrounds, gas stations and main streets in the Misurata Area have been determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Also, the levels of same heavy metals in industrial areas have been determined. Metal concentration trend variation was also discussed in relation with traffic density and other sources of fugitive emission around different sites on each road/area. The overall mean concentration for main streets was significantly higher (P < 0.05) than for other small streets, where Misurata has been the centre of fierce fighting and is located in a frontline battle zone in the Libyan war; therefore most of metal concentrations in surface soil in the fighting area Tripoli Street and Benghazi Street were higher than those from the other sites (outside fighting area).

Bacterioruberin and salinixanthin carotenoids of extremely halophilic Archaea and Bacteria: a Raman spectroscopic study.

Laboratory cultures of a number of red extremely halophilic Archaea (Halobacterium salinarum strains NRC-1 and R1, Halorubrum sodomense, Haloarcula valismortis) and of Salinibacter ruber, a red extremely halophilic member of the Bacteria, have been investigated by Raman spectroscopy using 514.5nm excitation to characterize their carotenoids. The 50-carbon carotenoid α-bacterioruberin was detected as the major carotenoid in all archaeal strains. Raman spectroscopy also detected bacterioruberin as the main pigment in a red pellet of cells collected from a saltern crystallizer pond. Salinibacter contains the C40-carotenoid acyl glycoside salinixanthin (all-E, 2'S)-2'-hydroxy-1'-[6-O-(methyltetradecanoyl)-ß-d-glycopyranosyloxy]-3',4'-didehydro-1',2'-dihydro-ß,ψ-carotene-4-one), for which the Raman bands assignments of are given here for the first time.

Discrimination of zeolites and beryllium containing silicates using portable Raman spectroscometric equipment with near-infrared excitation.

In this paper Raman spectra were obtained for a series of zeolites (thomsonite, stilbite, natrolite) and beryllium containing silicates (beryl, chrysoberyl, euclase, phenacite, bavenite, milarite) using a portable Raman specrometer with a 785 nm laser excitation to show the possibility to apply this setting for unambiguous detection and discrimination of these silicate minerals. Obtained spectra contain the most intense Raman bands at the same positions ±2-4 cm(-1) as reported in the literature. The use of these bands permits the unambiguous identification of these phases. Data show the possibility to discriminate individual species of similar whitish color and aspect. Measurements showed an excellent correspondence of Raman bands obtained using the portable system and a laboratory Raman microspectrometer (with the same excitation laser wavelenght). However, for several minerals of these groups (chrysoberyl, bertrandite, chiavennite) Raman spectra were not of sufficient quality to permit unambiguous identification. The reasons are discussed. Raman spectrum of chiavennite CaMnBe(2)Si(5)O(13)(OH)(2)·2(H(2)O) - a transformation product occurring together with bavenite on the surface of beryl crystals was obtained for the first time using the laboratory Raman spectrometer.

Evaluation of portable Raman instrumentation for identification of ß-carotene and mellitic acid in two-component mixtures with halite.

Recently, portable Raman instrumentation has been in demand for geosciences and for future planetary exploration for the identification of both organic and inorganic compounds in situ on Earth and on other planetary bodies, especially on Mars. Here we present the results of the analysis of halite/ß-carotene and halite/mellitic acid mixtures, performed by miniaturized Raman instrumentation equipped with 785 and 1064 nm excitation. Various proportions of organics in the halite matrix were examined. The lowest concentration of ß-carotene detected using the 785 nm laser was 1 mg kg(-1), with slightly better signals observed with shorter exposure times compared with the bench instrument using the same excitation wavelength. Mellitic acid was identified at the concentration level 10 g kg(-1). The 1064 nm excitation provided a lower sensitivity towards low concentration when compared with the 785 nm excitation.

The detection of biomarkers in evaporite matrices using a portable Raman instrument under Alpine conditions.

The detection of relatively low concentrations of the biomarkers in experimentally prepared evaporitic matrices using a portable Raman instrument (Ahura First Defender XL equipped with a 785 nm diode laser and fixed frontal probe) under Alpine conditions was tested. The instrument was able to detect nucleobases thymine (1673 and 984 cm(-1)) and adenine (722 and 536 cm(-1)) at concentrations of 1 wt% in the gypsum matrix outdoors at a low ambient temperature of -10°C and at an altitude of 2860 m(Pitztal, Austria). Amino acids glycine (1324 and 892 cm(-1)) and alanine (1357 and 851 cm(-1)) were unambiguously detected at 10 wt%. The main Raman features: strong, medium and partially weak intensity bands were observed in good agreement with the reference spectra for individual compounds (with a spectral resolution 7-10 cm(-1)) in the wavenumber range 200-1800 cm(-1). In the qualitative part of the experiment it was established that the portable instrument is able to detect the components in the mixture of three biomarkers (glycine, alanine and mellitic acid) and two evaporitic minerals unambiguously. It also detected the majority of the six similar amino acids in the mixture with gypsum and epsomite evaporitic minerals. The results obtained here demonstrate the possibility of a miniaturised Raman spectrometer to be able to cope with the various exobiologically related tasks that can be expected in the future planetary surface exploration missions. Within the payload designed by ESA and NASA for future missions, Raman spectroscopy will represent a unique research instrument.

A forensic case study: the detection of contraband drugs in carrier solutions by Raman spectroscopy.

Recently, cocaine has been concealed by dissolving it in alcohol and then transporting it in solution through ports and airports. At the present time it is very difficult to detect cocaine in this form in these environments. However, it has been shown that Raman spectroscopy can successfully detect the presence of these drugs without removing specimens from their containers. Using two portable 785 nm instruments and a 1064 nm laboratory-based instrument, several common containers used in smuggling were analyzed with varying concentrations of cocaine in ethanol solutions. The presence of cocaine is detectable to about 6% w/v in most containers. Green glass presents a problem at 785 nm due to fluorescence but by switching to 1064 nm this can be removed. To apply this technique to real samples as met within law enforcement scenarios, cocaine was dissolved in a selection of dark and white rums including Lamb's Navy Rum(™) , Brugal Añejo(™) , Bacardi(™) and Captain Morgan(™) ; cocaine was detected in all these rum solutions.

Raman spectra of biomarkers of relevance to analytical astrobiological exploration: hopanoids, sterols and steranes.

The aim of this work is to investigate the viability and potential of three groups of organic compounds as biomarkers in a future robotic analytical exploration of Mars. The three compounds have been identified as suitable candidates for potential biomarkers for extant or extinct life from the terrestrial fossil record. The three groups of compound were all similar in structure, being either tetra- or penta-cyclic compounds. The limits of detection for a sample were also tested to estimate what concentrations it would still be amenable to Raman spectroscopic investigation. This was investigated using both solid mixtures and liquid solutions. The spectra of these compounds are characterised so that they can be added to the Raman database for future Mars missions. This involved identifying functional group characteristics, assigning peaks for each individual sample and characteristic features which would categorise the samples.

An experimental and computational study on the epimeric contribution to the infrared spectrum of budesonide.

Budesonide is a mixture of 22R and 22S epimers. The epimeric content of budesonide was reported in both British and European pharmacopoeias to be within the range of 60-49/40-51 for R and S epimers, respectively. In this work, contribution of the two epimers to the overall infrared spectrum of budesonide has been investigated by quantum chemical calculations.

Acquisition of Raman spectra of amino acids using portable instruments: outdoor measurements and comparison.

Raman spectra of 13 amino acids: L-alanine, ß-alanine, L-asparagine, L-aspartic acid, L-glutamic acid, L-glutamine, glycine, L-methionine, L-proline, L-serine, L-threonine, L-tryptophan and L-tyrosine were acquired outdoors using two portable Raman instruments from the Ahura and Delta Nu manufacturers, both with 785 nm laser excitation. Both instruments provide quality Raman spectra with nevertheless a variable dependence upon the prevailing experimental conditions. The data acquired in these experiments will inform the selection of suitable Raman spectrometers for the in-field detection of biomolecules of relevance to the search for life signatures spectroscopically in terrestrial extreme environments and in extraterrestrial exploration, especially of planetary surfaces and subsurfaces using robotic instrumentation.

Using portable Raman spectrometers for the identification of organic compounds at low temperatures and high altitudes: exobiological applications.

Organic minerals, organic acids and NH-containing organic molecules represent important target molecules for astrobiology. Here, we present the results of the evaluation of a portable hand-held Raman spectrometer to detect these organic compounds outdoors under field conditions. These measurements were carried out during the February-March 2009 winter period in Austrian Alpine sites at temperatures ranging between -5 and -25 degrees C. The compounds investigated were detected under field conditions and their main Raman spectral features were observed unambiguously at their correct reference wavenumber positions. The results obtained demonstrate that a miniaturized Raman spectrometer equipped with 785 nm excitation could be applied with advantage as a key instrument for investigating the presence of organic minerals, organic acids and nitrogen-containing organic compounds outdoors under terrestrial low-temperature conditions. Within the payload designed by ESA and NASA for several missions focusing on Mars, Titan, Europa and other extraterrestrial bodies, Raman spectroscopy can be proposed as an important non-destructive analytical tool for the in situ identification of organic compounds relevant to life detection on planetary and moon surfaces or near subsurfaces.

Microbial colonization of halite from the hyper-arid Atacama Desert studied by Raman spectroscopy.

The hyper-arid core of the Atacama Desert (Chile) is the driest place on Earth and is considered a close analogue to the extremely arid conditions on the surface of Mars. Microbial life is very rare in soils of this hyper-arid region, and autotrophic micro-organisms are virtually absent. Instead, photosynthetic micro-organisms have successfully colonized the interior of halite crusts, which are widespread in the Atacama Desert. These endoevaporitic colonies are an example of life that has adapted to the extreme dryness by colonizing the interior of rocks that provide enhanced moisture conditions. As such, these colonies represent a novel example of potential life on Mars. Here, we present non-destructive Raman spectroscopical identification of these colonies and their organic remnants. Spectral signatures revealed the presence of UV-protective biomolecules as well as light-harvesting pigments pointing to photosynthetic activity. Compounds of biogenic origin identified within these rocks differed depending on the origins of specimens from particular areas in the desert, with differing environmental conditions. Our results also demonstrate the capability of Raman spectroscopy to identify biomarkers within rocks that have a strong astrobiological potential.

The effect of laser wavelength on the Raman Spectra of phenanthrene, chrysene, and tetracene: implications for extra-terrestrial detection of polyaromatic hydrocarbons.

Raman spectroscopy, with visible laser (514 and 633 nm) and near infrared (785 and 1064 nm) excitation, has been used to obtain high quality spectra of phenanthrene, chrysene, and tetracene. Samples with dimensions from a minimum size of 10 microm have been analyzed utilizing a Raman microprobe fitted with a charge-coupled device (CCD) array detector and a FT-Raman instrument. Fluorescence is observed for samples using visible 514, 633 and near infrared 785 nm excitation but most of the samples can be measured with a near infrared 1064 nm Nd:YAG laser.

In situ monitoring of pH titration by Raman spectroscopy.

Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen 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. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 degrees C in a solution of ionic strength 0.96moldm(-3) (KNO(3)) and 0.04moldm(-3) (HNO(3)). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information.

Identification of a new co-crystal of salicylic acid and benzamide of pharmaceutical relevance.

Raman spectroscopy, X-ray powder diffraction/X-ray crystallography and differential scanning calorimetry have been used to study the phenomenon of co-crystal formation in stoichiometric mixtures of salicylic acid with benzamide. Raman spectroscopy was particularly useful for the characterization of the products and was used to determine the nature of the interactions in the co-crystals. It was observed that little change in the vibrational modes associated with the phenyl groups of the respective reactants took place upon co-crystal formation, but changes in intensities of the vibrational modes associated with the amide and the carboxylic acid groups were observed upon co-crystal formation. Several new vibrational bands were identified in the co-crystal which were not manifested in the physical mixture of both components and could be used as diagnostic features of co-crystal formation.

Raman spectroscopic analysis of minerals and organic molecules of relevance to astrobiology.

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. Raman spectroscopy is currently a part of the Pasteur instrumentation suite of the ExoMars mission scheduled for 2018 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 incurred as a result of extremophilic survival activity have been studied. Polyaromatic hydrocarbons (PAHs) are recognised as a class of degradation product that occur from biological processes terrestrially. In this work, various concentrations of polyaromatic hydrocarbons in matrices of gypsum, calcite and quartz have been investigated by Raman microspectrometry to determine the lowest detectable organic levels. The studies are conceived in simulation of their potential PAHs identification in geobiological conditions in Martian scenarios. Two laser source wavelengths, namely, 785 and 633 nm, were adopted to excite Raman spectra from the PAHs, which represent degraded carbons and therefore potentially provide a key bimolecular marker of ancient life.

Fourier-transform Raman spectroscopic study of a Neolithic waterlogged wood assemblage.

The use of Fourier-transform Raman spectroscopy for characterising lignocellulosics has increased significantly over the last twenty years. Here, an FT-Raman spectroscopic study of changes in the chemistry of waterlogged archaeological wood of Pinus sp. and Quercus sp. from a prehistoric assemblage recovered from northern Greece is presented. FT-Raman spectral features of biodeteriorated wood were associated with the depletion of lignin and/or carbohydrate polymers at various stages of deterioration. Spectra from the archaeological wood are presented alongside spectra of sound wood of the same taxa. A comparison of the relative changes in intensities of spectral bands associated with lignin and carbohydrates resulting from decay clearly indicated extensive deterioration of both the softwood and hardwood samples and the carbohydrates appear to be more deteriorated than the lignin. The biodeterioration of the archaeological timbers followed a pattern of initial preferential loss of carbohydrates causing significant loss of cellulose and hemicellulose, followed by the degradation of lignin.

Characterization of paint and varnish on a medieval Coptic-Byzantine icon: novel usage of dammar resin.

A comprehensive study has been undertaken into a 13th century Coptic-Byzantine icon from the St. Mercurius Church, St. Mercurius monastery, Old Cairo, Egypt. The layered structure, pigment composition and varnish identification were revealed by means of optical and Raman microscopy and gas chromatography-mass spectrometry (GC-MS). The structure of the icon comprised six layers; wooden panel, canvas, white ground, two bole layers and a single paint layer. Azurite (2CuCO(3) x Cu(OH)(2)), cinnabar (mercuric (II) sulfide alpha-HgS), yellow ochre (Fe(2)O(3) x H(2)O), hydromagnesite Mg(5)(CO(3))(4)(OH)(2) x 4 H(2)O and lamp black (carbon, C) are the pigments identified in the icon. The green paint area is of interest as it is applied neither with a green pigment nor with a mixture of a blue and yellow pigment. Instead, a yellow layer of dammar resin was applied on top of blue azurite to obtain the green colour. Pinaceae sp. resin mixed with drying oil was used as a protective varnish.