Raman Spectroscopic and Sensory Evaluation of Cocoa Liquor Prepared with Ecuadorian Cocoa Beans Treated with Gamma Irradiation or Induced Electromagnetic Field Fermentation.

Cocoa liquor is the primary precursor of the worldwide highly appreciated commodity chocolate. Its quality depends on several factors, such as the type of cocoa, the fermentation process, and the control of the contaminants in the fermented beans. This study aims to evaluate whether the induced magnetic field treatment during the fermentation process or the pathogen reduction with gamma irradiation after the fermentation affect the characteristics of the cocoa liquor obtained from Ecuadorian cocoa beans. For this purpose, liquor samples from controls (standard process), from beans treated with an induced magnetic field up to 80 mT, and from beans irradiated with nominal doses up to 3 kGy were characterized through Raman spectroscopic analysis and sensorial evaluation. The most relevant bands of the cocoa liquor were assigned according to reports from the literature, spectroscopic data, and chemometrics. The spectra corresponding to different treatments and doses were visually very similar, but they could be discriminated using OPLS-DA models, where the most intense Raman signals were attributed to the lipid components. The sensorial evaluation rated the presence of floral, fruity, almondy, acid, and bitter flavors, along with astringency and intense aroma, and these attributes exhibited variable behavior depending on the dose of the irradiation or magnetic treatment. Therefore, both treatments may exert an influence on cocoa beans and, therefore, on the cocoa liquor quality.

Forensic analysis of biological fluid stains on substrates by spectroscopic approaches and chemometrics: A review.

BACKGROUND: Bodily fluid stains are one of the most relevant evidence that can be found at the crime scene as it provides a wealth of information to the investigators. They help to report on the individuals involved in the crime, to check alibis, or to determine the type of crime that has been committed. They appear as stains in different types of substrates, some of them porous, which can interfere in the analysis. The spectroscopy techniques combined with chemometrics are showing increasing potential for their use in the analysis of such samples due to them being fast, sensitive, and non-destructive. FINDINGS: This is a comprehensive review of the studies that used different spectroscopic techniques followed by chemometrics for analysing biological fluid stains on several surfaces, and under various conditions. It focuses on the bodily fluid stains and the most suitable spectroscopic techniques to study forensic scientific problems such as the substrate's characteristics, the influence of ambient conditions, the aging process of the bodily fluids, the presence of animal bodily fluids and non-biological fluids (interfering substances), and the bodily fluid mixtures. The most widely used techniques were Raman spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR). Nonetheless, other non-destructive techniques have been also used, like near infrared hyperspectral imaging (HSI-NIR) or surface enhanced Raman spectroscopy (SERS), among others. This work provides the criteria for the selection of the most promising non-destructive techniques for the effective in situ detection of biological fluid stains at crime scene investigations. SIGNIFICANCE AND NOVELTY: The use of the proper spectroscopic and chemometric approaches on the crime scene is expected to improve the support of forensic sciences to criminal investigations. Evidence may be analysed in a non-destructive manner and kept intact for further analysis. They will also speed up forensic investigations by allowing the selection of relevant samples from occupational ones.

Differentiation of blood and environmental interfering stains on substrates by Chemometrics-Assisted ATR FTIR spectroscopy.

Blood is the most common and relevant bodily fluid that can be found in crime scenes. It is critical to correctly identify it, and to be able to differentiate it from other substances that may also appear at the crime scene. In this work, several stains of blood, chocolate, ketchup, and tomato sauce on five different substrates (plywood, metal, gauze, denim, and glass) were analysed by ATR FTIR spectroscopy assisted with orthogonal partial least square-discriminant analysis (OPLS-DA) models. It was possible to differentiate blood from the environmental interfering substances independently of the substrate they were on, and to differentiate bloodstains according to the substrate they were deposited on. These results represent a proof-of-concept that open new horizons to differentiate bloodstains from other interfering substances on common substrates present in crime scenes.

Classification of Various Marijuana Varieties by Raman Microscopy and Chemometrics.

The Raman analysis of marijuana is challenging because of the sample's easy photo-degradation caused by the laser intensity. In this study, optimization of collection parameters and laser focusing on marijuana trichome heads allowed collecting Raman spectra without damaging the samples. The Raman spectra of Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) standard cannabinoids were compared with Raman spectra of five different types of marijuana: four Sativa varieties (Amnesia Haze, Amnesia Hy-Pro, Original Amnesia, and Y Griega) and one Indica variety (Black Domina). The results verified the presence of several common spectral bands that are useful for marijuana characterization. Results were corroborated by the quantum chemical simulated Raman spectra of their acid-form (tetrahydrocannabinol acid (THCA), cannabidiol acid (CBDA)) and decarboxylated cannabinoids (THC, CBD, and CBN). A chemometrics-assisted method based on Raman microscopy and OPLS-DA offered good classification among the different marijuana varieties allowing identification of the most significant spectral bands.

Forensic examination of textile fibres using Raman imaging and multivariate analysis.

Vibrational spectroscopic techniques have shown to be highly suitable for the identification and comparison of textile fibres and clothing fabrics. On the other hand, new chemical imaging modes based on these spectroscopic techniques are becoming useful in multiple fields. This is particularly important to, for instance, chemically visualize and screen different samples including forensic evidence (crime scene investigation), chemical and food products (quality control), biological tissues and living beings (medical imaging), among others. This study explores the forensic examination and selective chemical visualization of textile fibres and clothing fabrics using Raman imaging. Four experiments were performed, which were focused on the screening of (i) white different materials made of 100 % cotton (gauze, cotton wool, t-shirt, and swab), (ii) polyester and cotton fabrics evidence of the same colour, (iii) five different coloured cotton fabrics, and (iv) textile fibres of different materials (acrylic, cotton, nylon, polyester, and silk). Several methods of multivariate chemometric analysis including principal component analysis (PCA), multivariate analysis of variance (MANOVA), and multivariate curve resolution (MCR) were applied to enhance the limited visual comparison of the spectra accomplished with the unaided eye. The results evidenced the suitability of Raman imaging to statistically discriminate textile fibres and fabrics due to the chemical composition of both the clothing material and the dyestuff.

Gender-based differences in perceptions about sexual violence, equality and drug­facilitated sexual assaults in nightlife contexts. / Diferencias de género en percepciones sobre violencia sexual, igualdad y agresiones sexuales facilitadas por drogas en ocio nocturno.

Sexual violence, including drug-facilitated sexual assaults, is a serious issue that is becoming increasingly common in leisure nightlife contexts. This study provides information about the attitudes and perceptions of Spanish youths towards sexual violence within that setting. The participants were recruited by a snowball sampling scheme. A bivariate analysis was performed to identify possible sociodemographic and nightlife recreational habit factors related to gender. The statistical significance of the differences between the studied variables was assessed using the chi-squared and Fisher's exact tests. Women perceived a low level of personal security, as well as the existence of social perceptions penalizing female more than male drug use, and blaming women for the sexual violence they suffer. Women also recognised less explicit violent behaviours as violence significantly more than men did. Men were more willing to have sexual intercourse with someone unable to express consent because of drugs. In addition, they believed more strongly that sexual assaults take place because of the victim's use of alcohol or other drugs. In a leisure nightlife context, women are prone to perceive a lack of social support for themselves and the feeling of impunity for the perpetrators. Furthermore, numerous misconceptions surround drug-facilitated sexual assaults, with the majority of respondents believing that assaults happen after the surreptitious administration of substances to the victim by an unknown assailant. Moreover, the involvement of alcohol was underestimated. Our findings are useful for designing prevention efforts, demystifying the drug-facilitated sexual assaults and enhancing social support for victims.

La violencia sexual, incluyendo las agresiones sexuales facilitadas por drogas, es un serio problema cada vez más común en los contextos de ocio nocturno. Este trabajo estudia las actitudes y percepciones de la juventud española en torno a la violencia sexual en dicho ámbito. Los participantes se reclutaron mediante muestreo en bola de nieve. Se realizó un análisis bivariado para identificar posibles factores sociodemográficos y de ocio nocturno relacionados con género. La significación estadística de las diferencias entre estas variables se evaluó mediante las pruebas de chi-cuadrado y exacta de Fisher. Las mujeres percibieron un menor nivel de seguridad personal, así como la existencia de percepciones sociales que penalizan en mayor medida el consumo de drogas femenino que el masculino, y que culpabilizan a las mujeres por la violencia que sufren. Además, ellos mostraron mayor disposición a mantener relaciones sexuales con personas incapaces de otorgar su consentimiento debido a los efectos de las drogas. Los hombres creen en mayor medida que las agresiones sexuales ocurren debido al uso de alcohol u otras drogas por parte de las víctimas. En el contexto de ocio nocturno, las mujeres son propensas a percibir la existencia de una falta de apoyo social hacia ellas, así como un sentimiento de impunidad social hacia los agresores. Además, existen numerosas concepciones erróneas en torno a las agresiones sexuales facilitadas por drogas. La mayoría cree que las agresiones ocurren tras la administración encubierta de sustancias a la víctima por parte de un agresor desconocido. Además, se subestimó la participación del alcohol. Nuestros hallazgos son útiles para diseñar esfuerzos preventivos bien dirigidos, desmitificar el fenómeno de las agresiones sexuales facilitadas por drogas y mejorar el apoyo social a las víctimas.

Diferencias de género en percepciones sobre violencia sexual, igualdad y agresiones sexuales facilitadas por drogas en ocio nocturno / Gender-based differences in perceptions about sexual violence, equality and drug-facilitated sexual assaults in nightlife contexts

La violencia sexual, incluyendo las agresiones sexuales facilitadas pordrogas, es un serio problema cada vez más común en los contextos de ocionocturno. Este trabajo estudia las actitudes y percepciones de la juventudespañola en torno a la violencia sexual en dicho ámbito. Los participantesse reclutaron mediante muestreo en bola de nieve. Se realizó un análisisbivariado para identificar posibles factores sociodemográficos y de ocionocturno relacionados con género. La significación estadística de lasdiferencias entre estas variables se evaluó mediante las pruebas de chicuadrado y exacta de Fisher. Las mujeres percibieron un menor nivelde seguridad personal, así como la existencia de percepciones socialesque penalizan en mayor medida el consumo de drogas femenino que elmasculino, y que culpabilizan a las mujeres por la violencia que sufren.Además, ellos mostraron mayor disposición a mantener relaciones sexualescon personas incapaces de otorgar su consentimiento debido a los efectosde las drogas. Los hombres creen en mayor medida que las agresionessexuales ocurren debido al uso de alcohol u otras drogas por parte delas víctimas. En el contexto de ocio nocturno, las mujeres son propensasa percibir la existencia de una falta de apoyo social hacia ellas, así comoun sentimiento de impunidad social hacia los agresores. Además, existennumerosas concepciones erróneas en torno a las agresiones sexualesfacilitadas por drogas. La mayoría cree que las agresiones ocurren trasla administración encubierta de sustancias a la víctima por parte de unagresor desconocido. Además, se subestimó la participación del alcohol.Nuestros hallazgos son útiles para diseñar esfuerzos preventivos biendirigidos, desmitificar el fenómeno de las agresiones sexuales facilitadaspor drogas y mejorar el apoyo social a las víctimas. (AU)

Sexual violence, including drug-facilitated sexual assaults, is a seriousissue that is becoming increasingly common in leisure nightlife contexts.This study provides information about the attitudes and perceptionsof Spanish youths towards sexual violence within that setting. Theparticipants were recruited by a snowball sampling scheme. A bivariateanalysis was performed to identify possible sociodemographic andnightlife recreational habit factors related to gender. The statisticalsignificance of the differences between the studied variables was assessedusing the chi-squared and Fisher’s exact tests. Women perceived a lowlevel of personal security, as well as the existence of social perceptionspenalizing female more than male drug use, and blaming women for thesexual violence they suffer. Women also recognised less explicit violentbehaviours as violence significantly more than men did. Men were morewilling to have sexual intercourse with someone unable to expressconsent because of drugs. In addition, they believed more strongly thatsexual assaults take place because of the victim’s use of alcohol or otherdrugs. In a leisure nightlife context, women are prone to perceive alack of social support for themselves and the feeling of impunity for theperpetrators. Furthermore, numerous misconceptions surround drugfacilitated sexual assaults, with the majority of respondents believingthat assaults happen after the surreptitious administration of substancesto the victim by an unknown assailant. Moreover, the involvement ofalcohol was underestimated. Our findings are useful for designingprevention efforts, demystifying the drug-facilitated sexual assaults andenhancing social support for victims. (AU)

Evaluation of an Ozone Chamber as a Routine Method to Decontaminate Firefighters' PPE.

Ozone chambers have emerged as an alternative method to decontaminate firefighters' Personal Protective Equipment (PPE) from toxic fire residues. This work evaluated the efficiency of using an ozone chamber to clean firefighters' PPE. This was achieved by studying the degradation of pyrene and 9-methylanthracene polycyclic aromatic hydrocarbons (PAHs). The following experiments were performed: (i) insufflating ozone into PAH solutions (homogeneous setup), and (ii) exposing pieces of PPE impregnated with the PAHs to an ozone atmosphere for up to one hour (heterogeneous setup). The ozonolysis products were assessed by Fourier Transform Infrared Spectroscopy (FTIR), Thin-Layer Chromatography (TLC), and Mass Spectrometry (MS) analysis. In the homogeneous experiments, compounds of a higher molecular weight were produced due to the incorporation of oxygen into the PAH structures. Some of these new compounds included 4-oxapyren-5-one (m/z 220) and phenanthrene-4,5-dicarboxaldehyde (m/z 234) from pyrene; or 9-anthracenecarboxaldehyde (m/z 207) and hydroxy-9,10-anthracenedione (m/z 225) from 9-methylanthracene. In the heterogeneous experiments, a lower oxidation was revealed, since no byproducts were detected using FTIR and TLC, but only using MS. However, in both experiments, significant amounts of the original PAHs were still present even after one hour of ozone treatment. Thus, although some partial chemical degradation was observed, the remaining PAH and the new oxygenated-PAH compounds (equally or more toxic than the initial molecules) alerted us of the risks to firefighters' health when using an ozone chamber as a unique decontamination method. These results do not prove the ozone-advertised efficiency of the ozone chambers for decontaminating (degrading the toxic combustion residues into innocuous compounds) firefighters' PPE.

Human ultra-weak photon emission as non-invasive spectroscopic tool for diagnosis of internal states - A review.

In the knowledge that human ultra-weak photon emission (UPE) is mainly due to the metabolic oxidative stress processes that the skin cells undergo in the presence of reactive oxygen species (ROS), external stressors (like UV radiation), but also internal stressors (like diseases or brain activity) might strongly influence the UPE. This manuscript revises the scientific advances focused on the influence of internal factors on the human UPE. According to literature, the UPE seems to be influenced by some diseases (including diabetes, hemiparesis, protoporphyria, or a typical cold), and even by the cerebral intention/relaxation (brain activity/meditation). These allow to consider UPE as a natural and promising non-invasive spectroscopic tool for helping during the diagnosis of a variety of illnesses or stress- / mood-state disorders. Nonetheless, further research is required for answering some still unresolved controversial points.

Introducing ATR-FTIR Spectroscopy through Analysis of Acetaminophen Drugs: Practical Lessons for Interdisciplinary and Progressive Learning for Undergraduate Students.

Infrared (IR) spectroscopy is a vibrational spectroscopic technique useful in chemical, pharmaceutical, and forensic sciences. It is essential to identify chemicals for reasons spanning from scientific research and academic practices to quality control in companies. However, in some university degrees, graduate students do not get the proficiency to optimize the experimental parameters to obtain the best IR spectra; to correlate the IR spectral bands with the molecular vibrations (chemical elucidation); to have some criteria for any substance identification (especially relevant in quality control to recognize counterfeit); and to apply chemometrics for comparing, visualizing, and classifying the IR spectra. This work presents an experimental laboratory practice for an introductory teaching of the IR instrumental conditions in the identification of substances based on visual spectra comparison and statistical analysis and matching. Then, the selected IR conditions are applied to different commercial drugs, in the solid state or in solution, mostly composed of acetaminophen. Finally, the students apply chemometrics analysis to the IR data. This practice was designed for the training in a chemistry subject for undergraduate students of the chemistry, pharmacy, or forensics degrees, among others related to science, medical, food, or technological sciences.

Comparison between computed tomography and silicone-casting methods to determine gunshot cavities in ballistic soap.

Current methods used in terminal ballistics to determine the volume of temporary cavities created by projectiles in soft tissue simulants (such as ballistic soap) usually involve silicone-casting to obtain the cavity moulds. However, these methods have important drawbacks including their little sensitivity and precision, besides the fact that they are destructive. Imaging techniques such as computed tomography (CT) might not only overcome those limitations but also offer useful tools for digitally reporting the scientific results. This work accomplished the 3D digital reconstruction of the cavities created by different projectiles in ballistic soap blocks. This way, the total volume of the cavities, the projectile penetration depths, and other measurements were determined, rendering better capabilities when compared to the current silicone method. All these features were achieved through the CT analysis and 3D Slicer imaging software. In addition, it is worth mentioning that the method can preserve the evidence by digitally obtaining, signing, and storing the infographic videos displaying the 3D-reconstructed cavities. Graphical abstract.

A Morphological and Morphometric Dental Analysis as a Forensic Tool to Identify the Iberian Wolf (Canis Lupus Signatus).

Depredation by the Iberian wolf (Canis lupus signatus) is currently thought to be a problem in some areas of Spain. However, there are few technically validated forensic tools available to determine the veracity of claims with a high degree of scientific confidence, which is important given that such attacks may lead to compensation. The analysis of bite marks on attacked animals could provide scientific evidence to help identify the offender. Thus, the aim of this study was to assess the morphological and morphometric characteristics of Iberian wolf dentition. This data collection would serve as a base-point for a more accurate identification of the wolves thorough their bite marks. For the first time, 36 dental variables have been studied in wolves' skulls, employing univariate and multivariate analyses. The general morphological dental characteristics of wolves are very similar in terms of their dental formula and tooth structure to other canids, like domestic dogs. Sex differentiation was evident, principally in terms of the maxillary distance between the palatal surfaces of the canine teeth (UbC) and the width of the left mandibular canine teeth (LlCWd). New morphometric reference information was obtained that can aid the forensic identification of bite marks caused by the Iberian wolf with greater confidence.

Microplastics in sediments of artificially recharged lagoons: Case study in a Biosphere Reserve.

We studied the occurrence of microplastics in sediments of artificially and non-artificially recharged lagoons from the network of endorheic wetlands called "La Mancha Húmeda", declared Biosphere Reserve by UNESCO. The particles sampled in this study covered the 25 µm-5 mm range. Films were the dominant microplastic typology in non-artificially recharged lagoons, while fibres and fragments were more abundant in those receiving wastewater. The concentration of microplastics in sediments reached up to 24.4 ± 5.2 microplastics/g, while plastic litter counts yielded <1 particle/g in non-wastewater receiving lagoons. Eleven types of plastic were identified using Micro-Fourier Transform Infrared Spectroscopy (micro-FTIR), the most abundant being the polyolefins polyethylene and polypropylene, and polyester and acrylic fibres. The statistical analysis of FTIR spectra confirmed the similarity between samples taken from recharged lagoons and wastewater treatment plant effluents. Overall, our results showed that endorheic lagoons are very sensitive to the accumulation of persistent pollutants, which include microplastics. The recharge of lagoons with wastewater effluents to maintain water levels, even if correctly treated according to current standards, is not a sustainable practice. Due to the closed character of endorheic basins, the continuous input of wastewater led to the accumulation of microplastics in sediments of wastewater receiving lagoons up to 40 times over non-recharged lagoons.

Chemometric approaches for document dating: Handling paper variability.

A non-destructive methodology based on Fourier Transformed Infrared Spectroscopy (FTIR) is proposed in this research to estimate the age of documents of different ages. Due the variability in the samples caused by their different chemical compositions, chemometric approaches were proposed to build one unique regression model able to determine the age of the paper regardless of its composition. PLS models were built employing Generalized Least Squares Weighting (GLSW) and Orthogonal Least Squares (OLS) filters to reduce the variability of samples from the same year. Afterwards, sparse PLS, which is an extension of the PLS model including a variable selection step, was applied to compare its performance with the preprocessing filters. All techniques proposed were compared to the initial PLS models, showing the potential of the chemometric approaches applied to FTIR data to estimate the age of unknown documents.

Selective Monitoring of Oxyanion Mixtures by a Flow System with Raman Detection.

Raman spectroscopy is a selective detection system scarcely applied for the flow analysis of solutions with the aim of detecting several compounds at once without a previous separation step. This work explores the potential of a portable Raman system in a flow system for the selective detection of a mixture of seven oxyanions (carbonate, sulphate, nitrate, phosphate, chlorate, perchlorate, and thiosulphate). The specific bands of these compounds (symmetric stretching Raman active vibrations of carbonate at 1068 cm−1, nitrate at 1049 cm−1, thiosulphate at 998 cm−1, phosphate at 989 cm−1, sulphate at 982 cm−1, perchlorate at 935 cm−1, and chlorate at 932 cm−1) enabled their simultaneous detection in mixtures. Although the oxyanions’ limit of detection (LOD) was rather poor (in the millimolar range), this extremely simple system is very useful for the single-measurement detection of most of the oxyanions in mixtures, without requiring a previous separation step. In addition, quantitative determination of the desired oxyanion can be performed by means of the corresponding calibration line. These are important advantages for controlling in-line processes in industries like those manufacturing fertilizers, pharmaceuticals, chemicals, or food, among others.

Measuring the Human Ultra-Weak Photon Emission Distribution Using an Electron-Multiplying, Charge-Coupled Device as a Sensor.

Ultra-weak photon emission (UPE) is the spontaneous emission from living systems mainly attributed to oxidation reactions, in which reactive oxygen species (ROS) may play a major role. Given the capability of the next-generation electron-multiplying CCD (EMCCD) sensors and the easy use of liquid crystal tunable filters (LCTF), the aim of this work was to explore the potential of a simple UPE spectrometer to measure the UPE from a human hand. Thus, an easy setup was configured based on a dark box for inserting the subject's hand prior to LCTF as a monochromator and an EMCCD sensor working in the full vertical binning mode (FVB) as a spectra detector. Under controlled conditions, both dark signals and left hand UPE were acquired by registering the UPE intensity at different selected wavelengths (400, 450, 500, 550, 600, 650, and 700 nm) during a period of 10 min each. Then, spurious signals were filtered out by ignoring the pixels whose values were clearly outside of the Gaussian distribution, and the dark signal was subtracted from the subject hand signal. The stepped spectrum with a peak of approximately 880 photons at 500 nm had a shape that agreed somewhat with previous reports, and agrees with previous UPE research that reported UPE from 420 to 570 nm, or 260 to 800 nm, with a range from 1 to 1000 photons s-1 cm-2. Obtaining the spectral distribution instead of the total intensity of the UPE represents a step forward in this field, as it may provide extra information about a subject's personal states and relationship with ROS. A new generation of CCD sensors with lower dark signals, and spectrographs with a more uniform spectral transmittance, will open up new possibilities for configuring measuring systems in portable formats.

Revealing the location of semen, vaginal fluid and urine in stained evidence through near infrared chemical imaging.

Crime scene investigation (CSI) requires the ultimate available technology for a rapid, non-destructive, and accurate detection of a wide variety of evidence including invisible stains of bodily fluids. Particularly crucial is the discrimination of semen in stained evidence from sexual abuse cases. This is because those evidence have high odds of containing the DNA from the aggressor. To this aim, we demonstrated the potential of near infrared hyperspectral imaging (NIR-HSI) to make visible stains of semen, vaginal fluid, and urine on fabrics, which lays the bases to face the challenging visualization and discrimination of semen within bodily fluids mixtures. Combining the NIR-HSI data and simple chemometric techniques such as principal component analysis and classical least squares regression, we have revealed the location of semen, vaginal fluid and urine in bodily fluids stained evidence.

Analytical tools for the analysis of fire debris. A review: 2008-2015.

The analysis of fire debris evidence might offer crucial information to a forensic investigation, when for instance, there is suspicion of the intentional use of ignitable liquids to initiate a fire. Although the evidence analysis in the laboratory is mainly conducted by a handful of well-established methodologies, during the last eight years several authors proposed noteworthy improvements on these methodologies, suggesting new interesting approaches. This review critically outlines the most up-to-date and suitable tools for the analysis and interpretation of fire debris evidence. The survey about analytical tools covers works published in the 2008-2015 period. It includes sources of consensus-classified reference samples, current standard procedures, new proposals for sample extraction and analysis, and the most novel statistical tools. In addition, this review provides relevant knowledge on the distortion effects of the ignitable liquid chemical fingerprints, which have to be considered during interpretation of results.

Study of consumer fireworks post-blast residues by ATR-FTIR.

Specific analytical procedures are requested for the forensic analysis of pre- and post-blast consumer firework samples, which present significant challenges. Up to date, vibrational spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) have not been tested for the analysis of post-blast residues in spite of their interesting strengths for the forensic field. Therefore, this work proposes a simple and fast procedure for the sampling and analysis of consumer firework post-blast residues by a portable FTIR instrument with an Attenuated Total Reflection (ATR) accessory. In addition, the post-blast residues spectra of several consumer fireworks were studied in order to achieve the identification of their original chemical compositions. Hence, this work analysed 22 standard reagents usually employed to make consumer fireworks, or because they are related to their combustion products. Then, 5 different consumer fireworks were exploded, and their residues were sampled with dry cotton swabs and directly analysed by ATR-FTIR. In addition, their pre-blast fuses and charges were also analysed in order to stablish a proper comparison. As a result, the identification of the original chemical compositions of the post-blast samples was obtained. Some of the compounds found were potassium chlorate, barium nitrate, potassium nitrate, potassium perchlorate or charcoal. An additional study involving chemometric tools found that the results might greatly depend on the swab head type used for the sampling, and its sampling efficiency. The proposed procedure could be used as a complementary technique for the analysis of consumer fireworks post-blast residues.

Analysis and differentiation of paper samples by capillary electrophoresis and multivariate analysis.

This work reports an investigation for the analysis of different paper samples using CE with laser-induced detection. Papers from four different manufactures (white-copy paper) and four different paper sources (white and recycled-copy papers, adhesive yellow paper notes and restaurant serviettes) were pulverized by scratching with a surgical scalpel prior to their derivatization with a fluorescent labeling agent, 8-aminopyrene-1,3,6-trisulfonic acid. Methodological conditions were evaluated, specifically the derivatization conditions with the aim to achieve the best S/N signals and the separation conditions in order to obtain optimum values of sensitivity and reproducibility. The best conditions, in terms of fastest, and easiest sample preparation procedure, minimal sample consumption, as well as the use of the simplest and fastest CE-procedure for obtaining the best analytical parameters, were applied to the analysis of the different paper samples. The registered electropherograms were pretreated (normalized and aligned) and subjected to multivariate analysis (principal component analysis). A successful discrimination among paper samples without entanglements was achieved. To the best of our knowledge, this work presents the first approach to achieve a successful differentiation among visually similar white-copy paper samples produced by different manufactures and paper from different paper sources through their direct analysis by CE-LIF and subsequent comparative study of the complete cellulose electropherogram by chemometric tools.