Characterization of gunpowder samples using time-of-flight secondary ion mass spectrometry (TOF-SIMS)

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was utilized to obtain characteristic mass spectra from three different smokeless powders and six different black powder samples. In these mass spectra, peaks indicative of both the organic and inorganic additive constituents in the gunpowders were observed. TOF-SIMS was able to successfully differentiate between the different black and smokeless gunpowder samples analyzed with the aid of principal components analysis (PCA), a multivariate statistical analysis approach often used to reduce the dimensionality of complex data. TOF-SIMS was also used to obtain information about the spatial distribution of the various additives contained within the gunpowder samples. SIMS imaging demonstrated that that the samples could potentially be characterized by their 2-D structure, which varied from sample to sample. These results clearly demonstrate the feasibility of utilizing TOF-SIMS as a tool for the characterization and differentiation of gunpowder samples for general forensic applications.     

Differentiating writing inks using direct analysis in real time mass spectrometry

Writing ink analysis is used in establishing document authenticity and the sources and relative ages of written entries. Most analytical methods require removing samples or visibly altering the document. Nondestructive, in situ analysis of writing inks on paper without visible alteration is possible using mass spectrometry with a new ion source called Direct Analysis in Real Time. Forty-three different black and blue ballpoint, black fluid, and black gel inks were examined. Both dyes and persistent but thermally labile components of the inks contribute to the mass spectra, principally as protonated molecules [M+H](+). Numerous ink components were identified from the spectra. The spectra were placed in a searchable library, which was then challenged with two spectra from each of the 43 inks. The best match for each of the challenge spectra was correct for all but one ink, which matched with a very similar ink by the same manufacturer.     

Characterization of Printing Inks Using DART‐Q‐TOF‐MS and Attenuated Total Reflectance (ATR) FTIR

The rise in improved and widely accessible printing technology has resulted in an interest to develop rapid and minimally destructive chemical analytical techniques that can characterize printing inks for forensic document analysis. Chemical characterization of printing inks allows for both discrimination of inks originating from different sources and the association of inks originating from the same source. Direct analysis in real‐time mass spectrometry (DART‐MS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) were used in tandem to analyze four different classes of printing inks: inkjets, toners, offset, and intaglio. A total of 319 samples or ~ 80 samples from each class were analyzed directly on a paper substrate using the two methods. DART‐MS was found to characterize the semi‐volatile polymeric vehicle components, while ATR‐FTIR provided chemical information associated with the bulk components of these inks. Complimentary data results in improved discrimination when both techniques are used in succession resulting in >96% discrimination for all toners, 95% for all inkjets, >92% for all offset, and >54% for all intaglio inks.     

Basic forensic identification of artificial leather for hit-and-run cases

Single fibers retrieved from a victim's garments and adhered to the suspect's automobile have frequently been used to prove the relationship between victim and suspect's automobile. Identification method for single fiber discrimination has already been conducted. But, a case was encountered requiring discrimination of artificial leather fragments retrieved from the victim's bag and fused fibers from the bumper of the suspect's automobile. In this report, basic studies were conducted on identification of artificial leathers and single fibers from leather materials. Fiber morphology was observed using scanning electron microscopy (SEM), color of these leather sheets was evaluated by microspectrophotometry (MSP), the leather components were measured by infrared micro spectrometry (micro-FT-IR) and the inorganic contents were ascertained by micro-X-ray fluorescence spectrometry (micro-XRF). These two methods contribute to other analytical methods too, in the case of utilized single fiber analytical methods. The combination of these techniques showed high potential of discrimination ability in forensic examinations of these artificial leather samples. In regard with smooth surface artificial leather sheet samples, a total of 182 sheets were obtained, including 177 colored sheets directly from 10 of 24 manufacturers in Japan, and five of them were purchased at retail circulation products. Nine samples of suede-like artificial leather were obtained, 6 of them were supplied from 2 manufacturers and 3 sheets were purchased as retailing product. Single fibers from the smooth surface artificial leather sheets showed characteristic for surface markings, and XRF could effectively discriminate between these sheets. The combination of results of micro-FT-IR, color evaluation by MSP and the contained inorganic elements by XRF enabled to discriminate about 92% of 15,576 pairs comparison. Five smooth surface samples form retailing products were discriminated by their chemical composition into four categories, and in addition color information to this result, they were clearly distinguished. Suede-like artificial leather sheets showed characteristic extra-fine fibers on their surface by the observation of SEM imaging, providing high discriminating ability, in regard with suede-like artificial leather sheets were divided into three categories by micro-FT-IR, and the combination of these results and color evaluation information, it was possible to discriminate all the nine suede-like artificial leather sheets examined.     

Application of the micro-FTIR spectroscopy, Raman spectroscopy and XRF method examination of inks

In routine examination of inks on questioned documents non-destructive analytical methods, such as microscopic and optical techniques are applied first. However, they are often insufficient to identify the inks used for the preparation of the document. In such cases, it is necessary to apply chemical methods that normally cause partial destruction of the examined material. The aim of this work was to evaluate the possibility of discrimination between inks by the use of spectrometric methods, i.e. micro-FTIR spectroscopy, Raman spectroscopy and XRF. About 70 samples of blue and black ballpoint pen and gel inks were examined. It was found that about 90% of the samples of the same type and colour could be distinguished using these methods.     

红外光谱结合化学计量学方法在激光打印原装黑色墨粉分析中的应用研究

目的 采用红外光谱比较分析不同原装黑色墨粉（31个样本）的差异,探讨化学计量学方法在墨粉种类识别中的适用性.方法 对打印样本纸张上的黑色墨粉进行烫熨提取后直接分析检测.IR分析条件：显微红外光谱仪,常温透射模式,扫描范围为4 000～400 cm-1,分辨率为16cm-1,累计扫描次数为64次.结果 墨粉树脂主要为聚苯乙烯/甲基丙烯酸甲酯和聚对苯二甲酸/环氧树脂.采用主成分析（Principal Component Analysis,PCA）与系统聚类法（Hierarchical Cluster Analysis,HCA）对不同种类墨粉进行聚类分析与建模预报.基于前两主成分得分值（53.3％）不同树脂成分的墨粉样本聚类效果明显,同时在第三个主成分方向上黑白与彩色激光墨粉样本获得良好区分.结论 红外光谱法结合化学计量学方法用于不同种类树脂及打印类型原装黑色墨粉的聚类分析与建模预报方法可行,结果准确可靠.     

傅立叶变换拉曼光谱法鉴别黑色墨水的研究

采用傅立叶交换拉曼光谱法对6种黑色墨水字迹进行检验分析实验结果表明,能对黑色墨水样品进行有效的鉴别。该方法具有快速、简便、不破坏样品的特点。     

Validation of X-ray fluorescence spectrometry for determining osseous or dental origin of unknown material

Forensic anthropological examinations typically involve the analysis of human skeletal remains, but in cases where samples are very small and/or physically compromised, it may first be necessary to determine whether the material is even osseous or dental in origin. X-ray fluorescence spectrometry (XRF) is a technique that reveals the elemental composition of materials and is hypothesized to have utility in such cases. XRF analysis was conducted on a variety of tissues and materials in unaltered and altered (damaged) states. With few exceptions, osseous and dental tissues in unaltered and altered conditions contained characteristic levels of calcium and phosphorus, while other materials did not. Materials could be accurately identified as osseous or dental in origin based on the calcium and phosphorus levels identified by XRF, and we therefore conclude that XRF analysis is a valid and effective means of determining osseous or dental origin of unknown material.     

微束X射线荧光分析法鉴别激光打印机墨粉的研究

目的利用微束X射线荧光分析法（μ-XRF）研究激光打印机用墨粉的鉴别。方法利用μ-XRF对9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉所含元素进行定性、半定量的分析。结果根据检出元素种类的不同,可将9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉分成7类、4类、4类,区分率分别为94.4%、75%、69.4%。结论本研究所建立的μ-XRF鉴别激光打印机墨粉方法具有微区、原位无损检验等优点,对提高激光打印文件检验水平具有现实意义。     

The discrimination potential of ultraviolet-visible spectrophotometry, thin layer chromatography, and Fourier transform infrared spectroscopy for the forensic analysis of black and blue ballpoint inks

The knowledge of the discriminating power of analytical techniques used for the differentiation of writing inks can be useful when interpreting results. Ultraviolet-visible (UV-VIS) spectrophotometry, thin layer chromatography (TLC), and diffuse reflectance Fourier transform infrared spectroscopy (FT-IR) were used to examine a population of 21 black and 12 blue ballpoint writing inks. Based on corroborative results of these methods, the discrimination power for UV-VIS, TLC, and FT-IR was determined to be 100% and 98% for the black and blue inks, respectively. Generally, TLC and UV-VIS can be used to differentiate the colorant components (i.e., dyes and some pigments) found in inks. As FT-IR can be utilized to identify some of the noncolorant components, it was determined to be an excellent complementary technique that can be implemented into an analytical scheme for ink analysis.     

Detection of nitro-organic and peroxide explosives in latent fingermarks by DART- and SALDI-TOF-mass spectrometry

The ability of two mass spectrometric methods, surface-assisted laser desorption/ionization-time of flight-mass spectrometry (SALDI-TOF-MS) and direct analysis in real time (DART-MS), to detect the presence of seven common explosives (six nitro-organic- and one peroxide-type) in spiked latent fingermarks has been examined. It was found that each explosive could be detected with nanogram sensitivity for marks resulting from direct finger contact with a glass probe by DART-MS or onto stainless steel target plates using SALDI-TOF-MS for marks pre-dusted with one type of commercial black magnetic powder. These explosives also could be detected in latent marks lifted from six common surfaces (paper, plastic bag, metal drinks can, wood laminate, adhesive tape and white ceramic tile) whereas no explosive could be detected in equivalent pre-dusted marks on the surface of a commercial lifting tape by the DART-MS method due to high background interference from the tape material. The presence of TNT and Tetryl could be detected in pre-dusted latent fingermarks on a commercial lifting tape for up to 29 days sealed and stored under ambient conditions.     

Analysis of Pigmented Inkjet Printer Inks and Printed Documents by Laser Desorption/Mass Spectrometry*,†

Abstract: Anyone with a computer, scanner, and color printer has the capability for creating documents such as identification cards, passports, and counterfeit currency. Laser desorption mass spectrometry (LDMS) has been demonstrated as a powerful tool for colorant analysis. Inkjet printers are now moving largely toward the use of pigments as colorants; their insolubility makes analysis by simpler methods such as thin‐layer chromatography no longer an option. Recent developments in pigmented inkjet printer inks, such as gloss optimizers that coat pigment particles, may prohibit colorant analysis by LDMS. We demonstrate here that pigments used in inks from two Epson printers can be detected and analyzed by LDMS. Also, LDMS spectra of various colors created using a 4‐cartridge (cyan/magenta/yellow/black, CMYK) inkset are evaluated, to begin to develop an approach for unraveling LDMS data from real samples, to determine the number of inks used by a printer, and the chemical composition of the colorants.     

Some Examples of Applications of a Microthermal Desorption Device in the Forensic Laboratory

Abstract:  Several applications of a microthermal desorption device for analysis of small forensic samples are presented. The method uses a solid phase microextraction holder with the fiber removed. In addition to samples of inks on paper, this device was successfully used for analysis of toners, various stains on bank notes, and lipstick stains on paper. Other small items encountered in a forensic science laboratory were also analyzed: particles of smokeless powder, particles of coffee, and automotive clear topcoat layer. The desorbed compounds were analyzed by gas chromatography with a flame ionization detector or by gas chromatography–mass spectrometry. This device can be used in connection with any kind of gas chromatograph. By selection of different injector temperatures, fractionated thermal desorption of samples is achieved. The procedure was demonstrated on samples of ballpoint pen ink of various age.     

Direct identification of various copper phthalocyanine pigments in automotive paints and paint smears by laser desorption ionization mass spectrometry

Direct identification of copper phthalocyanine (CuPc) and chlorinated CuPcs in paints for discrimination between blue automobile paints by means of laser desorption mass spectrometry (LDMS) in the absence of a matrix is reported. The models consisted of eight commercially available CuPc pigments applied to a piece of plain white coating paper. The relationship between the peak intensity at m/z 575 of the CuPc, the number of pulsed laser shots, and laser power was compared to optimize laser abrasion. LDMS analysis of the model paints demonstrated that all characteristic components of the CuPc pigments in the paint films were in good agreement with those in the powder pigments. Further, the chlorinated CuPcs in the paint films could be distinguished. A quantity of 42 blue paint films, representing the paints used for painting Japanese domestic trucks, was examined by LDMS analysis. Results indicate that the paints can be classified into four categories based on the chlorinated CuPc components of the paints. Therefore, LDMS spectra of CuPc pigments would be useful for the identification of paints in forensic investigations. Herein, we report the successful identification of the CuPcs in a paint smear on the frame of a bicycle damaged in a hit-and-run accident, using the LDMS spectra.     

High-performance liquid chromatography-ultraviolet-visible spectroscopy-electrospray ionization mass spectrometry method for acrylic and polyester forensic fiber dye analysis

A critical point of comparison between a fiber collected from a crime scene and a fiber from a known source is the color. Fiber dye analysis using thin-layer chromatography or ultraviolet (UV)-visible (Vis) microspectrophotometry provides useful, although limited, data for comparison. High-performance liquid chromatography-electrospray ionization mass spectrometry (LC/MS) overcomes these limitations by integrating chromatography, ultraviolet-visible spectroscopy, and mass spectrometry into a single instrument. In order to evaluate the applicability of the LC/MS to forensic fiber dye analysis, a multi-stage chromatographic method using acidified water and acidified acetonitrile was developed that separated and identified a mixture of 15 basic and 13 disperse dye standards. The LC/MS also detected and analyzed dyes extracted from individual 0.5 cm acrylic and polyester fibers, demonstrating its applicability to this type of analysis. With regard to the analysis of disperse dyes in polyester fibers, the replacement of pyridine with acetonitrile in the extraction system allowed direct injection of the extracts into the LC/MS. The advantage of the LC/MS over other instrumental methods of textile dye analysis is demonstrated by the analysis and differentiation of three black acrylic fibers: two fibers had similar UV-Vis spectra but were differentiated with chromatography and two had similar UV-Vis spectra and chromatograms but were differentiated using the mass spectrometer.     

Raman spectroscopy and laser desorption mass spectrometry for minimal destructive forensic analysis of black and color inkjet printed documents

Inkjet ink analysis is the best way to discriminate between printed documents, or even though more difficult, to connect an inkjet printed document with a brand or model of printers. Raman spectroscopy and laser desorption mass spectrometry (LDMS) have been demonstrated as powerful tools for dyes and pigments analysis, which are ink components. The aim of this work is to evaluate the aforementioned techniques for inkjet inks analysis in terms of discriminating power, information quality, and nondestructive capability. So, we investigated 10 different inkjet ink cartridges (primary colors and black), 7 from the HP manufacturer and one each from Epson, Canon and Lexmark. This paper demonstrates the capabilities of three methods: Raman spectroscopy, LDMS and MALDI-MS. Raman spectroscopy, as it is preferable to try the nondestructive approach first, is successfully adapted to the analysis of color printed documents in most cases. For analysis of color inkjet inks by LDMS, we show that a MALDI matrix (9-aminoacridine, 9AA) is needed to desorb and to ionize dyes from most inkjet inks (except Epson inks). Therefore, a method was developed to apply the 9AA MALDI matrix directly onto the piece of paper while avoiding analyte spreading. The obtained mass spectra are very discriminating and lead to information about ink additives and paper compositions. Discrimination of black inkjet printed documents is more difficult because of the common use of carbon black as the principal pigment. We show for the first time the possibility to discriminate between two black-printed documents coming from different, as well as from the same, manufacturers. Mass spectra recorded from black inks in positive ion mode LDMS detect polyethylene glycol polymers which have characteristic mass distributions and end groups. Moreover, software has been developed for rapid and objective comparison of the low mass range of these positive mode LDMS spectra which have characteristic unknown peaks.     

Forensic analysis of black coral (Order Antipatharia)

Fourier-transform infrared spectroscopy (FTIR), discriminate analysis, X-ray fluorescence spectrometry (XRF), and stereoscopic microscopy were used to separate black coral forensic evidence items from similarly appearing items manufactured from plastics, bovid keratin, and mangrove wood. In addition, novel observations were made of bromine and iodine relationships in black coral that have not been previously reported.     

Identification of ascorbic acid and its degradation products in black powder substitutes

Low explosives such as smokeless powder, black powder, and black powder substitutes have been used in illicit pipe bombings throughout the United States. Some of the newer black powder substitutes are formulated with ascorbic acid, which gradually decomposes as the powder ages, making it difficult if not impossible for the forensic chemist to identify it by traditional bulk techniques. A sensitive method for the identification of residual levels of ascorbic acid in black powder substitutes is presented. Powder samples are extracted with a mixture of acetonitrile and bis(trimethylsilyl)acetamide (BSA), which converts carboxylic acid and alcohol functional groups to trimethylsilyl esters and ethers, respectively. Samples are then analyzed by gas chromatography-mass spectrometry (GC-MS). Results have shown that trace amounts of ascorbic acid can be identified at detection limits that are well below those for traditional bulk techniques. Degradation products for ascorbic acid (hydroxylated carboxylic acids, furanones, and lactones) can also be detected.     

Analysis of active ricin and castor bean proteins in a ricin preparation, castor bean extract, and surface swabs from a public health investigation

In late February 2008, law enforcement officials in Las Vegas, Nevada, discovered in a hotel room, a copy of The Anarchist Cookbook, suspected castor beans and a "white powder" thought to be a preparation of ricin. Ricin is a deadly toxin from the seed of the castor bean plant (Ricinus communis). The United States regulates the possession, use, and transfer of ricin and it is the only substance considered a warfare agent in both the Chemical and the Biological Weapons Conventions. Six samples obtained from the hotel room were analyzed by laboratories at the Centers for Disease Control and Prevention using a panel of biological and mass spectrometric assays. The biological assays (real time-PCR, time resolved fluorescence and cytotoxicity) provided presumptive evidence of active ricin in each of the samples. This initial screen was followed by an in-depth analysis using a novel, state-of-the-art mass spectrometry-based ricin functional assay and high sensitivity tandem mass spectrometry for protein identification. Mass spectrometric analysis positively identified ricin and confirmed that in each of the samples it was enzymatically active. The tandem mass spectrometry analysis used here is the most selective method available to detect ricin toxin. In each sample, ricin was unequivocally identified along with other R. communis plant proteins, including the highly homologous protein RCA120. Although database searches using tandem mass spectra acquired from the samples indicated that additional controlled substances were not present in these samples, the mass spectrometric results did provide extensive detail about the sample contents. To the best of our knowledge following a review of the available literature, this report describes the most detailed analysis of a white powder for a public health or forensic investigation involving ricin.     

Evaluation of Four Fingerprint Development Methods for Touch Chemistry Using Matrix‐Assisted Laser Desorption Ionization/Time‐of‐Flight Mass Spectrometry,

Four preparation techniques for MALDI/TOF mass spectrometry were compared to determine the ability to gather intelligence for investigations through the chemical analysis of latent fingerprints, defined as “touch chemistry.” Compatible fingerprint development processes used for identification along with new techniques are necessary to evaluate touch chemistry. Ten volunteers deposited fingerprints from solvent residues containing drugs and explosives onto microscope slides. The developers included (A) fingerprint powder, (B) MALDI matrix, (C) fingerprint powder and lifting, and (D) cyanoacrylate fuming with fingerprint powder. Qualitative identification was based on ion images and spectra. The highest average detection rates (88%) were found using methods A and B. Methods C (52%) or D (18%) had limited success. Results demonstrate the importance of imaging coupled to extracted mass spectral data in detecting analytes in deposited fingerprints. Overall, the results suggest continued development of touch chemistry applications could prove useful for gathering intelligence and forensically relevant information.