Direct Analysis In Real Time Time-of-flight Mass Spectrometry Research Articles

Wood Species Differentiation: A Comparative Study of Direct Analysis in Real-Time and Chromatography Mass Spectrometry

This study reports for the first time the fingerprinting extractives analysis of the indigenous wood species of Podocarpus totara from New Zealand, Eucalyptus saligna from Australia and Pinus radiata imported from California, USA and grown in New Zealand. We evaluated the use of analytical techniques for wood species discrimination. We compared the chemical fingerprinting of extractive compounds obtained using traditional chromatographic techniques with direct analysis in real-time–time of flight-mass spectrometry (DART-TOF-MS) with the auxiliary of chemometrics and principal component analysis. The traditional wet chemistry analysis of wood extracts provided a comprehensive characterisation of all extractive components. However, the more eco-friendly, sustainable and faster DART-TOF-MS technique effectively distinguished between wood species when heartwood and sapwood samples were combined. Notably, neither wet chemistry nor DART-TOF-MS could clearly differentiate between heartwood and sapwood within the same wood species. DART-TOF-MS analysis demonstrates potential as a reliable quality control tool for identifying wood species necessary in commercial and timber trading markets as well as for detecting the illicit trade of counterfeit wood products.

A novel method to analyse DART TOFMS spectra based on Convolutional Neural Networks: A case study on methanol extracts of wool fibres from endangered camelids

Monitoring the illegal trade of wool fibres of wild vicuña (Vicugna vicugna) and guanaco (Lama guanicoe) is highly desirable. The high market value of fleece from these camelid species poses a threat to their wild populations. A previous study showed that direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) effectively identifies wool fibres to species. Producing high-resolution data in a short period of time makes DART-TOFMS a reliable identification tool, even though data analysis can still be improved. The present study proposes a novel data analysing pipeline based on Convolutional Neural Networks (CNN), applicable to any kind of DART-TOF MS data. We tested our proposed method on keratin fibres of four camelid species (Vicugna vicugna: n = 19; Vicugna pacos: n = 20; Lama guanicoe: n = 20, and Lama glama: n = 20). Analyses showed that selecting 512 ions with the highest relative intensity provides the best resolution and yields 100% accuracy for species identification.

Method development for forensic oil identification by direct analysis in real time time-of-flight mass spectrometry.

The current well-established chromatography and mass spectrometry based oil spill identification procedures, such as those outlined by the European Committee for Standardization, are highly reliable as methods, highly defensible in the court of law, and widely applicable to the majority of oil spill situations. Nevertheless, the methodology is time consuming and labour intensive, which may not be ideal when dealing with an emergency oil spill situation. In this study, direct analysis in real time time-of-flight mass spectrometry (DART/TOFMS) was used to successfully develop an efficient oil identification method. To confirm the accuracy of this method spilled oil samples were tested from five previous years of blind round robin testing organized by the oil spill identification network of experts (OSINET) under the Bonn Agreement. Heatmap inspection, principal component analysis and finally discriminant analysis of principal components were used to arrive at final predictions regarding the identities of the spilled oil samples. The results were compared with the results of previous gas chromatography flame ionization detection (GC/FID) and gas chromatography triple quadrupole mass spectrometry (GC/MS/MS) analyses of the same oils. While taking only about a tenth of the time, the DART/TOFMS analysis produced results similar to those of classical GC/FID and GC/MS/MS (EI+) procedures. The ability of DART/TOFMS to display this level of validity exemplifies its potential to be a new tool for supplementing classical analyses for oil spill forensics.

Timber origin verification using mass spectrometry: Challenges, opportunities, and way forward

To fight the illegal timber trade, there is an increasing need to accurately verify or determine the harvest origin of timber. Next to genetic methods, mass spectrometry is being pushed forward as a possible tool towards this problem, especially via stable isotope ratio analysis (SIRA) and direct analysis in real time – time of flight mass spectrometry (DART-TOFMS). However, there are key scientific questions that need to be answered before these techniques can be scaled up and routinely and robustly applied. For SIRA, we need to understand better the effects of single ring versus ring pooling, cellulose versus whole wood and species or site differences. For DART-TOFMS, we need to investigate what drives the differences in metabolomic fingerprint between locations, and how much of that difference can be attributed to environmental or genetic effects, especially if we want to advance the use of DART-TOFMS for timber origin questions. In this paper, the important difference between origin verification and determination is discussed, a review of the state of the art is provided and a way forward and experimental design is presented to tackle these scientific questions.

Inference of origin of Pterocarpus timber by chemical profiling of ambient ionization mass spectra

In Pterocarpus, three out of 46 tree species (P. erinaceus, P. santalinus, and P. tinctorius) are listed as endangered and protected under Appendix II of CITES, and the status of several Pterocarpus species suggests that more will find a place on CITES in the future. As unsustainable forest exploitation has increased, regulations for timber traceability have also increased with the creation of such laws as the 2005 Lacey Act in the United States (Lacey Act, 2005) and the European Union Timber Regulation (EUTR) in 2013. These laws were implemented to ensure that members of the timber trade operated in accordance with guidelines and practiced due diligence, with the goal of halting illegal timber imports (FAO, 2016). Unfortunately, the illegal timber trade remains prevalent and has progressed into the third largest transnational crime (Mavrellis, 2017). To combat the prevalence of illegal timber, researchers have utilized Direct Analysis in Real Time Time-of-Flight Mass Spectrometry (DART-TOFMS). With the success found using DART-TOFMS for species identification, we investigated whether the method could be used to identify the original geographic region of timber through analysis of 211 samples taken from 12 Pterocarpus species taken from the Neotropics, Africa, South Asia, and Southeast Asia. We found that analysis using DART-TOFMS could identify the broad geographical provenances of the timber with an accuracy of 98%. This research demonstrated that DART-TOFMS can be used to detect the phytochemical trends that exist between timber species occupying broad geographic regions.

Characterizing the Dyes of Pre-Columbian Andean Textiles: Comparison of Ambient Ionization Mass Spectrometry and HPLC-DAD

The complex and colorful textiles of ancient Peru have long been a focus of technical study, particularly to characterize the sources of the wide variety of dyes utilized by these Andean artisans. This manuscript describes the characterization of the dyes of both primary (red, blue, and yellow) and secondary (purple, orange, and green) colors sampled from textiles spanning five major civilizations: the Paracas Necropolis, the Nazca, the Wari, the Chancay, and the Lambayeque, all from Peru. All but the Paracas Necropolis samples were part of technical conservation studies of the ancient South American textiles collections of the Michael C. Carlos Museum. Analysis of the dyes was carried out utilizing direct analysis in real time time-of-flight mass spectrometry (DART-MS) and paper spray MS. To validate these ambient ionization MS methods, the samples were further investigated using high-performance liquid chromatography (HPLC) with ultraviolet-visible diode array detection (DAD). These results show that ambient ionization MS methods are simple and fast for characterization of the general classes of dyes, e.g., plant reds vs. insect reds, and indigoids in blues and greens. Due to the myriad possible sources of yellow dyes and their tendency to undergo oxidative decomposition, positively identifying those components in these yarns was difficult, though some marker compounds and flavonoid decomposition products were readily identified by ambient ionization mass spectrometry.

Pterocarpus wood identification by independent and complementary analysis of DART-TOFMS, microscopic anatomy, and fluorescence spectrometry

Abstract Attention to illegal logging practices and demanding policies in transnational timber trade have driven the need for species-level identification of timber. Historically wood has been identified to genus level using microscopy and anatomical characteristics, however, new chemometric and imaging methods have been developed to increase the speed and precision of timber identification. This study approaches species identification using a combination of complementary methods: Direct Analysis in Real Time–Time-of-Flight Mass Spectrometry (DART-TOFMS), wood anatomy, and fluorescence spectroscopy. Seven commercially and environmentally significant species in Pterocarpus, including P. erinaceus (CITES Appendix II), P. santalinus (CITES Appendix II), P. tinctorius (CITES Appendix II), P. indicus, P. macrocarpus, P. dalbergioides, and P. soyauxii were studied. It was found that DART-TOFMS paired with discriminant analysis of principal components (PCA) could classify species with an accuracy of 95–100%, while anatomy in combination with PCA applied to fluorescence spectra could be used to classify CITES Appendix II species. In the absence of access to DART-TOFMS, a combination of wood anatomy and fluorescence spectrometry can permit more accurate identification than anatomy alone.

Mass propagation of Juniperus procera Hoechst. Ex Endl. From seedling and screening of bioactive compounds in shoot and callus extract

BackgroundJuniperus procera Hoechst. ex Endl. is a medicinal tree in Saudi Arabia, primarily in the Enemas region, but it is locally threatened due to die-back disease and difficulties regarding seed reproduction (seed dormancy and underdeveloped embryonic anatomy, and germination rate < 40%). Hence, the alternative methods for reproduction of Juniperus procera are really needed for conservation and getting mass propagation for pharmaceutical uses.ResultsIn this manuscript, we articulated the successful in vitro shoot multiplication and callus induction of J. procera by using young seedling as explants and detected an important antibacterial and antitumor product. Explants were grown on different types of media with the supplement of different combinations of Plant Growth Regulators (PGRs) at different concentrations. The best media for shoot multiplication was Woody Plant Media (WPM) supplemented with PGRs (0.5 μM of IAA and 0.5 μM BAP or 0.5 μM IBA and 0.5 μM BAP). Whereas for callus induction and formation Woody Plant Media (WPM) with the addition of PGRs (0.5 μM 2,4-D and 0.5 μM BAP) was better than the Chu Basal Salt Mixture (N6), Gamborg’s B-5 Basal Medium (B5), and Murashige and Skoog media. The possibility of multiplication of J. procera in vitro creates significant advantages to overcome the difficulties of seeds dormancy for the reproduction of plants, conservation of trees, and getting mass propagation material for pharmaceutical studies. The shoot and callus extract of J. procera was detected using gas chromatography-mass spectrometry analysis and revealed more than 20 compounds related to secondary metabolites, which contained antibacterial and antitumor agents, such as ferruginol, Retinol, and Quinolone as well as confirmed by Direct Analysis in Real Time, Time of Flight Mass Spectrometry (DART-ToF-MS). Podophyllotoxin (PTOX) was detected in callus material by HPLC with sigma standard and confirmed by DART-ToF-MS and UV spectra.ConclusionWe successfully conducted in vitro shoot multiplication and callus induction from J. procera seedlings using WPM and a different combination of PGRs and, detected an important antibacterial and antitumor product such as ferruginol and podophyllotoxin. According to our findings, J. procera has become a new natural source of novel bioactive compounds.

Localization of Major Ephedra Alkaloids in Whole Aerial Parts of Ephedrae Herba Using Direct Analysis in Real Time-Time of Flight-Mass Spectrometry.

Mass spectrometry-based molecular imaging has been utilized to map the spatial distribution of target metabolites in various matrixes. Among the diverse mass spectrometry techniques, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) is the most popular for molecular imaging due to its powerful spatial resolution. This unparalleled high resolution, however, can paradoxically act as a bottleneck when the bio-imaging of large areas, such as a whole plant, is required. To address this issue and provide a more versatile tool for large scale bio-imaging, direct analysis in real-time-time of flight-mass spectrometry (DART-TOF-MS), an ambient ionization MS, was applied to whole plant bio-imaging of a medicinal plant, Ephedrae Herba. The whole aerial part of the plant was cut into 10–20 cm long pieces, and each part was further cut longitudinally to compare the contents of major ephedra alkaloids between the outer surface and inner part of the stem. Using optimized DART-TOF-MS conditions, molecular imaging of major ephedra alkaloids of the whole aerial part of a single plant was successfully achieved. The concentration of alkaloids analyzed in this study was found to be higher on the inner section than the outer surface of stems. Moreover, side branches, which are used in traditional medicine, represented a far higher concentration of alkaloids than the main stem. In terms of the spatial metabolic distribution, the contents of alkaloids gradually decreased towards the end of branch tips. In this study, a fast and simple macro-scale MS imaging of the whole plant was successfully developed using DART-TOF-MS. This application on the localization of secondary metabolites in whole plants can provide an area of new research using ambient ionization mass spectroscopy and an unprecedented macro-scale view of the biosynthesis and distribution of active components in medicinal plants.

Forensic identification of the keratin fibers of South American camelids by ambient ionization mass spectrometry: Vicuña, alpaca and guanaco.

The keratin fleece of the endangered vicuña (Vicugna vicugna) commands a high value in international markets, and this trade has caused illegal poaching and a substantial decrease in vicuña populations. Morphological analysis of hairs does not have the resolution to determine the species of origin of camelid natural fibers. In addition, commerce in camelid fleece also includes the legal trade of alpaca (Vicugna pacos) and guanaco (Lama guanicoe) wool. The keratin fiber spectra of vicuña (n = 19), guanaco (n = 20) and alpaca (n = 20) were collected using X-ray fluorescence (XRF) spectrometry, Horizontal attenuated total reflectance Fourier transform infrared (HATR-FTIR) spectroscopy and direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS). Analysis with each technique evaluated the data to determine if the three taxa could be separated using either descriptive or multivariate statistics. XRF analysis showed that the elements detected and their relative concentrations were similar in all three species, whereas HATR-FTIR analysis could identify alpaca fleece but could not differentiate vicuña from guanaco. Ions detected by ambient ionization using DART-TOFMS, in either positive- or negative-ion mode, gave the best results and showed that each taxonomic group is distinctive. Multivariate analysis of the mass spectra created robust models which resolved each species (LOOCV = 99.9%). The analyses of eight validation samples were correctly assigned to the appropriate species and demonstrated the reliability of DART-TOFMS to infer taxonomic source. The DART-TOFMS spectra of unmodified keratin fibers infer that the chemotype of each species is heavily influenced by fatty acids, cholesterol and its analogs, and that these ions are useful in separating the fleece of vicuña, alpaca and guanaco. We posit that the etiological source of these chemotype differences is consistent with genetic modulations and is less influenced by diet. Accurate taxonomic identification of fleece is important to identify violations and assists in the protection of rare species.

Forensic identification of CITES Appendix I Cupressaceae using anatomy and mass spectrometry

Abstract Alerce (Fitzroya cupressoides (Mol.) Johnst.) and Guaitecas cypress (Pilgerodendron uviferum (Don) Florin) are two of the three closely-related species of conifers in the Cupressaceae that are endemic to southern Chile and Argentina. Both are listed in Appendix I of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). The presence or absence of nodular (conspicuously pitted) end walls in the parenchyma cells provide good diagnostic characters to separate the two species wood anatomically, but the latter is sometimes difficult to distinguish. Therefore, a collaborative project was designed to study the chemical-molecular expression of these species by analyzing the heartwood using DART TOFMS (Direct Analysis in Real-Time (DART) Time-of-Flight Mass Spectrometry (TOFMS). This study compares the anatomical features of heartwood for both species and demonstrates that anatomy in conjunction with chemistry can separate them. DART TOFMS analysis combined with PCA was able to unequivocally determine taxonomic source with a statistical certainty of 99%. The mass spectra results obtained from heartwood demonstrated that identification is feasible after a few seconds, using a very small sample. DART TOFMS is a robust tool for reliable species identification and is useful to identify the taxonomic source of finished products or timber that are suspected of being illegally harvested.

Rapid analysis of carboxylic acids and esters with a direct analysis in real time ion source.

Coal oxidation produces carboxylic acids (CAs), including aliphatic acids, benzoic acids, and benzenepolycarboxylic acids, which are important fine chemicals which could be used to understand the structural features of coals. However, detecting CAs usually presents great challenges due to extremely troublesome pretreatments. Therefore, it is essential to develop an analytical method for the rapid detection of CAs from coal oxidation. A series of model compounds (MCs) of oxidation products and two practical samples were investigated by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) under three different analytical conditions (ionizing gas temperature, organic solvent, and MC concentration). Ionizing methyl benzoate, dimethyl phthalate, and dimethyl adipate produces typical ions of methyl esters, including [M-OCH3 ]+ , [M+H]+ , and [M+NH4 ]+ . In contrast, the characteristic ions generated from CAs are polymer ions, such as [2M+NH4 ]+ , [3M+NH4 ]+ , [4M+NH4 ]+ , and [5M+NH4 ]+ , indicating the strong intermolecular hydrogen-bond interaction among CAs. Results suggest that DART-TOFMS could rapidly analyze CAs or esters in coal oxidation products according to their typical ions to further gain deep insights into the coal structure.

Chemical differentiation of Bolivian Cedrela species as a tool to trace illegal timber trade

Combating illegal timber trade requires the ability to identify species and verify geographic origin of timber. Forensic techniques that independently verify the declared species and geographic origin are needed, as current legality procedures are based on certificates and documents that can be falsified. Timber from the genus Cedrela is among the most economically valued tropical timbers worldwide. Three Cedrela species are included in the Appendix III of CITES: C. fissilis, C. odorata and C. angustifolia (listed as C. lilloi). Cedrela timber is currently traded with false origin declarations and under a different species name, but tools to verify this are lacking. We used Direct Analysis in Real Time Time-of-Flight Mass Spectrometry (DART-TOFMS) to chemically identify Cedrela species and sites of origin. Heartwood samples from six Cedrela species (the three CITES-listed species plus C. balansae, C. montana and C. saltensis) were collected at 11 sites throughout Bolivia. Mass spectra detected by DART-TOFMS comprised 1062 compounds; their relative intensities were analysed using Principal Component Analyses, Kernel Discriminant Analysis (KDA) and Random Forest analyses to check discrimination potential among species and sites. Species were identified with a mean discrimination error of 15–19 per cent, with substantial variation in discrimination accuracy among species. The lowest error was observed in C. fissilis (mean = 4.4 per cent). Site discrimination error was considerably higher: 43–54 per cent for C. fissilis and 42–48 per cent for C. odorata. These results provide good prospects to differentiate C. fissilis from other species, but at present there is no scope to do so for other tested species. Thus, discrimination is highly species specific. Our findings for tests of geographic origin suggest no potential to discriminate at the studied scale and for the studied species. Cross-checking results from different methods (KDA and Random Forest) reduced discrimination errors. In all, the DART-TOFMS technique allows independent verification of claimed identity of certain Cedrela species in timber trade.

DART-MS: A New Analytical Technique for Forensic Paint Analysis

Automotive paint evidence is one of the most significant forms of evidence obtained in automotive-related incidents. Therefore, the analysis of automotive paint evidence is imperative in forensic casework. Most analytical schemes for automotive paint characterization involve optical microscopy, followed by infrared spectroscopy and pyrolysis-gas chromatography mass spectrometry ( py-GCMS) if required. The main drawback with py-GCMS, aside from its destructive nature, is that this technique is relatively time intensive in comparison to other techniques. Direct analysis in real-time-time-of-flight mass spectrometry (DART-TOFMS) may provide an alternative to py-GCMS, as the rapidity of analysis and minimal sample preparation affords a significant advantage. In this study, automotive clear coats from four vehicles were characterized by DART-TOFMS and a standard py-GCMS protocol. Principal component analysis was utilized to interpret the resultant data and suggested the two techniques provided analogous sample discrimination. Moreover, in some instances DART-TOFMS was able to identify components not observed by py-GCMS and vice versa, which indicates that the two techniques may provide complementary information. Additionally, a thermal desorption/pyrolysis DART-TOFMS methodology was also evaluated to characterize the intact paint chips from the vehicles to ascertain if the linear temperature gradient provided additional discriminatory information. All the paint samples were able to be discriminated based on the distinctive thermal desorption plots afforded from this technique, which may also be utilized for sample discrimination. On the basis of the results, DART-TOFMS may provide an additional tool to the forensic paint examiner.

Chemical discrimination of lubricant marketing types using direct analysis in real time time-of-flight mass spectrometry.

In comparison to other violent crimes, sexual assaults suffer from very low prosecution and conviction rates especially in the absence of DNA evidence. As a result, the forensic community needs to utilize other forms of trace contact evidence, like lubricant evidence, in order to provide a link between the victim and the assailant. In this study, 90 personal bottled and condom lubricants from the three main marketing types, silicone-based, water-based and condoms, were characterized by direct analysis in real time time of flight mass spectrometry (DART-TOFMS). The instrumental data was analyzed by multivariate statistics including hierarchal cluster analysis, principal component analysis, and linear discriminant analysis. By interpreting the mass spectral data with multivariate statistics, 12 discrete groupings were identified, indicating inherent chemical diversity not only between but within the three main marketing groups. A number of unique chemical markers, both major and minor, were identified, other than the three main chemical components (i.e. PEG, PDMS and nonoxynol-9) currently used for lubricant classification. The data was validated by a stratified 20% withheld cross-validation which demonstrated that there was minimal overlap between the groupings. Based on the groupings identified and unique features of each group, a highly discriminating statistical model was then developed that aims to provide the foundation for the development of a forensic lubricant database that may eventually be applied to casework. Copyright © 2017 John Wiley & Sons, Ltd.

Source identification of western Oregon Douglas-fir wood cores using mass spectrometry and random forest classification.

Premise of the study:We investigated whether wood metabolite profiles from direct analysis in real time (time-of-flight) mass spectrometry (DART-TOFMS) could be used to determine the geographic origin of Douglas-fir wood cores originating from two regions in western Oregon, USA.Methods:Three annual ring mass spectra were obtained from 188 adult Douglas-fir trees, and these were analyzed using random forest models to determine whether samples could be classified to geographic origin, growth year, or growth year and geographic origin. Specific wood molecules that contributed to geographic discrimination were identified.Results:Douglas-fir mass spectra could be differentiated into two geographic classes with an accuracy between 70% and 76%. Classification models could not accurately classify sample mass spectra based on growth year. Thirty-two molecules were identified as key for classifying western Oregon Douglas-fir wood cores to geographic origin.Discussion:DART-TOFMS is capable of detecting minute but regionally informative differences in wood molecules over a small geographic scale, and these differences made it possible to predict the geographic origin of Douglas-fir wood with moderate accuracy. Studies involving DART-TOFMS, alone and in combination with other technologies, will be relevant for identifying the geographic origin of illegally harvested wood.

Analysis of carbohydrates in Fusarium verticillioides using size-exclusion HPLC – DRI and direct analysis in real time ionization – time-of-flight – mass spectrometry (DART-MS)

Direct analysis in real time – time of flight – mass spectrometry (DART-TOF-MS) and size-exclusion chromatography (SEC) are used to analyze carbohydrates inF. verticillioides, such as trehalose.

Direct analysis in real time-mass spectroscopy for identification of red dye colourants in Paracas Necropolis Textiles

The Paracas Necropolis on the south coast of Peru is renowned for the elaborate funerary bundles recovered from that dry sandy region. These bundles contained the remains of male leaders within the Paracas communities surrounded by multiple layers of plain cloth and garments with embroidered designs. The methods and materials used in dyeing the yarns used to embellish these ancient fabrics are still not well understood, and the research presented herein seeks to add to that body of knowledge. To investigate the sources of dye colourants in samples from Paracas Necropolis textiles, we applied direct analysis in real time–time-of-flight mass spectrometry (DART-MS). This new methodology has both advantages (analyses are rapid and require little or no sample preparation) and disadvantages (e.g. inability to identify intact carminic acid) compared to existing ones used in the analysis of dye colourants. Direct analysis in real time mass spectra were collected on chemical standards, botanical materials and comparative reference samples prepared with Relbunium roots and cochineal insects (Dactylopius sp.), and the results are compared to red fibres obtained from several different textiles within two different funerary bundles from the Museo Nacional de Arqueología Antropología e Historia in Lima, Peru. The results from the DART-MS analysis of these red fibres show that the compounds present are consistent with the presence of dye obtained from Relbunium species, and cochineal insects were not used to colour these fibres.Statement of significance DART-MS is an efficient and effective method to identify red colourant composition in small samples of fibres removed from archaeological textiles. Of significant note is the ability to differentiate isomers present in Relbunium and other anthraquinone dyes. Colourants in Relbunium are readily distinguished. Although a component of carminic acid from cochineal is less reliably positively identified by DART-MS, it is possible to use a simple extraction and ionization method to confirm or exclude the presence of carminic acid. Relbunium and cochineal are known to have been used in Paracas textiles. Not only does DART-MS aid in identification of colourants using small amounts of material and without significant sample preparation, the information can be used to distinguish fibres that were prepared differently thus indicating past knowledge of dyeing technology. The information can also aid in separating periods of artefact manufacture, and guide development of a conservation strategy.

Identification of anthraquinone dye colourants in red fibres from an Ohio Hopewell mound site by direct analysis in real time mass spectrometry

AbstractAmong prehistoric native groups of North America, the Ohio Hopewell was a particularly notable cultural manifestation that prevailed during the Middle Woodland Period (ca. 2100–1500 BP). The group is defined by the construction of elaborate burial mounds, evidence of ritual burning and cremation ceremonies, and a multitude of intricately decorated objects formed from materials obtained through extensive trade networks. While relatively few textile artefacts survive, those that have been preserved reflect a comprehensive knowledge of plant and animal fibre, dye, and pigment sources, and manipulation of those materials to create complex decorated fabric structures. The research reported herein is part of a programme to understand the materials used and the processes of colouration employed prehistorically. To investigate the sources of dye colourants, we applied direct analysis in real time – time-of-flight mass spectrometry (DART-MS) to both comparative materials and archaeological fibres from thre...

Evaluating agarwood products for 2‐(2‐phenylethyl)chromones using direct analysis in real time time‐of‐flight mass spectrometry

Agarwood is the resinous material harvested from threatened Aquilaria species. We investigated how many protonated 2-(2-phenylethyl)chromone ions were sufficient to make an accurate identification of agarwood. Analysis of 125 reference samples was carried out by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS). The identification criteria developed were applied to commercial samples. We developed a technique that uses DART-TOFMS to detect 2-(2-phenylethyl)chromones. Additionally, we developed a set of criteria to infer the presence of Aquilaria in commercial samples of wood chips, sawdust, incense and liquids. Additionally, we examined other fragrant woods to determine if they contained a chemical profile that could be falsely identified as agarwood. Analysis of reference and commercial samples (n = 151) established that DART-TOFMS provides reproducible mass spectra that are useful for inferring the genus of suspected agarwood samples. We identified 17 ions which were useful for authenticating agarwood. Comparison of the number of chromone ions detected by direct analyses of dry wood chips versus eluent analysis of methanol-extracted wood showed that results were similar. Lastly, analysis of 25 scented woods of other species did not give false positive results. Reliable criteria for inferring agarwood include the presence of diagnostic ions, m/z 319.118 or 349.129, in addition to ten or more ions characteristic of 2-(2-phenylethyl)chromones. Wood anatomists challenged with difficult morphological identifications can use this tool to assist in their analyses. Published 2012. This article is a US Government work and is in the public domain in the USA.