Forensic Discrimination of Dyed Hair Color: II. Multivariate Statistical Analysis*,†

Abstract: This research is intended to assess the ability of UV–visible microspectrophotometry to successfully discriminate the color of dyed hair. Fifty‐five red hair dyes were analyzed and evaluated using multivariate statistical techniques including agglomerative hierarchical clustering (AHC), principal component analysis (PCA), and discriminant analysis (DA). The spectra were grouped into three classes, which were visually consistent with different shades of red. A two‐dimensional PCA observations plot was constructed, describing 78.6% of the overall variance. The wavelength regions associated with the absorbance of hair and dye were highly correlated. Principal components were selected to represent 95% of the overall variance for analysis with DA. A classification accuracy of 89% was observed for the comprehensive dye set, while external validation using 20 of the dyes resulted in a prediction accuracy of 75%. Significant color loss from successive washing of hair samples was estimated to occur within 3 weeks of dye application.     

Application of multivariate chemometrics in forensic soil discrimination based on the UV-Vis spectrum of the acid fraction of humus

Forty-four soil samples from five different areas were examined on the basis of the UV-Vis spectrum of the acid fraction of humus with a view to achieving good discrimination between them. Fulvic and humic acids were extracted from the samples into an alkaline aqueous solution and absorbance values, after appropriate transformations, were subjected to a K-mean cluster analysis (CA) over the objects (samples) for an initial feature reduction (20 variables retained). This was followed by principal component analysis (PCA) for the removal of outliers (four samples removed). The same statistical technique was used on the remaining samples to decide how many variables to enter into the linear discriminant function analysis (DA) and whether original variables or component scores should be used. It was found that the scree test was a good criterion for deciding on the number of components to extract (nine components extracted) and that the use of component scores instead of original variables led to a lower average redundancy (20.6%) of the variables in the discriminant model. From the components entered into the model and their loadings, it was concluded that the discrimination achieved was due to the relative concentration of aromatic groups and other fragments in the samples as well as the degree of soil humification. An overall 85% correct classification of the training dataset was observed (Wilks' lambda = 0.0420) and the method was judged satisfactory for supporting exclusionary forensic purposes.     

Estimation of postmortem interval based on the third component of complement (C3) cleavage

To estimate postmortem interval (PMI), the spontaneous conversion of the native third component of complement (C3) to its derived fragments in whole blood was studied by crossed immunoelectrophoresis. C3 cleavages in vitro at different temperatures showed that the incubation of whole blood at a higher temperature led to a faster conversion of beta 1C (native C3) to beta 1A (C3c). In cadaveric blood, we found a significant positive correlation between percentage of C3 cleavage and PMI. From these results, it is possible to estimate PMI from the ratios of C3 cleavage.     

Comparative Forensic Soil Analysis of New Jersey State Parks Using a Combination of Simple Techniques with Multivariate Statistics,

This study has shown that the combination of simple techniques with the use of multivariate statistics offers the potential for the comparative analysis of soil samples. Five samples were obtained from each of twelve state parks across New Jersey in both the summer and fall seasons. Each sample was examined using particle‐size distribution, pH analysis in both water and 1 M CaCl₂, and a loss on ignition technique. Data from each of the techniques were combined, and principal component analysis (PCA) and canonical discriminant analysis (CDA) were used for multivariate data transformation. Samples from different locations could be visually differentiated from one another using these multivariate plots. Hold‐one‐out cross‐validation analysis showed error rates as low as 3.33%. Ten blind study samples were analyzed resulting in no misclassifications using Mahalanobis distance calculations and visual examinations of multivariate plots. Seasonal variation was minimal between corresponding samples, suggesting potential success in forensic applications.     

Characterization and dating of blue ballpoint pen inks using principal component analysis of UV-Vis absorption spectra, IR spectroscopy, and HPTLC

The ink of pens and ink extracted from lines on white photocopier paper of 10 blue ballpoint pens were subjected to ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR), and high-performance thin-layer liquid chromatography (HPTLC). The R(f) values and color tones of the bands separated by thin-layer chromatography (TLC) analysis used to classify the writing inks into three groups. The principal component analysis (PCA) investigates the pen responsible for a piece of writing, and how time affects spectroscopy of written ink. PCA can differentiate between pen ink and ink line indicates the influence of solvent extraction process on the results. The PCA loadings are useful in individualization of a questioned ink from a database. The PCA of ink lines extracted at different times can be used to estimate the time at which a questioned document was written. The results proved that the UV-Vis spectra are effective tool to separate blue ballpoint pen ink in most cases rather than IR and HPTLC.     

In common batch searching of illicit heroin samples--evaluation of data by chemometrics methods

In this study three illicit heroin samples which belonged to three different batches were subdivided into eight samples each. To simulate the dealers' chain, and to check the influence (if any) of diluents on the analytical results, some of the samples were cut with the most frequently used cutting substances, whereas the others were left unchanged. Samples were analysed (within a 10-week period of time) by gas chromatography-mass spectrometry (GC-MS) and characterised by seven variables each. To recover batch links among investigated heroin samples three multivariate methods, i.e. hierarchical clustering (HCA), principal component analysis (PCA) and k-nearest neighbours (k-NN), were applied on to the normalised and scaled analytical dataset. The classification abilities of the HCA, PCA and k-NN were in the range from 95 to 100%. Disturbing effects due to the dilution of samples have not been observed.     

Linking the global to the national: an application of the international pathways model to examine the influence of international environmental agreements on Cameroon’s forest policy

Cameroon’s tropical forest cover is one of the largest in the world. It is home to some of the world’s rarest plant and animal species. However, the country has suffered extensive forest loss for many decades as a result of socioeconomic and political factors. The growing global concern for the health of the world’s forests and related global issues has placed pressure on Cameroon to sustainably manage its forests. The intricacies of domestic and international pressures on Cameroon’s forest sector means that policy makers have to take into consideration the dynamics of the domestic-international nexus in developing the country’s forest policies. The increasingly integrated global governance of the world’s forests—international agreements, protocols and treaties, international program, international institutions, international actors, and international norms—together constitute international policy regimes that have influenced the direction of Cameroon’s forest policy. Employing the international pathways framework model, an analytic model which describes how transnational actors and international institutions affect domestic policies and policy making, this paper examines the extent to which international environmental agreements have influenced the direction of Cameroon’s forest policy and policy making. The application of the international pathways model facilitated analytic review and allowed for a better understanding of how Cameroon has utilized the complex global forest governance arrangements to enhance its domestic forest policy.     

法庭科学中泥土物证XRF检验数据的分析研判

目的 对元素分析产生的大量数据进行统计,从而达到准确对样品进行区分和归类的目的.方法 利用X射线荧光光谱法对从北京郊区10个区县、辽宁沈阳、安徽泗县、四川泸州、山东威海和广西南宁提取的225个泥土样品进行元素定量分析.采用SPSS软件中欧氏距离计算泥土样品间的差异,利用主成分分析法进行样品归类.结果 确定了不同空间距离样品间差异的欧氏距离的阈值.主成分分析法可对225个泥土进行较为准确的分类.结论 欧氏距离值可为泥土样品的比对提供量化比对依据,利用主成分分析法可推断未知泥土样品的来源.     

Placing Indigenous Rights to Self-Determination in an Ecological Context

In this paper the author focuses on Australian land management and in particular on the environmental management issues that could have been prompted by the High Court recognition in 1996 (in Wik Peoples v. The State of Queensland ) that native title to land and pastoral leaseholdings can co-exist. Drawing on themes of self-determination and co-existence, the paper looks at more specific topics such as aboriginal title to land—what has been called land rights or native title in Australia—and some implications of that for land, sea and resource management. Central to this analysis are competing theories of Aboriginal land management and links between Aboriginal traditional knowledge and conservation of species. These are illustrated through the marine mammal, the dugong. The Australian debates lead to the Canadian debates and then to Scandinavia and the role of the Sami people in protection and management of the Arctic region. Issues of indigenous self determination inevitably provide an overall theme to these discussions. As a matter of global concern, the paper asks, but does not decide, whether indigenous peoples may manage fragile eco-systems more effectively than outsiders. It maintains that what is important in this context is a broader question. This concerns how culturally inclusive land and resource management can emerge from recognition of indigenous land and human rights and how comparative developments can provide crucial cross-jurisdictional information for future developments and opportunities in the interests of environmental conservation.     

Chemical fingerprinting of gasoline. 2. Comparison of unevaporated and evaporated automotive gasoline samples

Analysis of the C(0)- to C(2)-naphthalene compounds present in automotive gasoline using gas chromatography-mass spectrometry with selected ion monitoring (GC-MS (SIM)) and principal component analysis (PCA) was used to discriminate between different samples of gasoline. Phase one of this study explored the ability of this method to differentiate gasoline samples at different levels of evaporation. A total of 35 random samples of unevaporated gasoline, covering three different grades (regular unleaded, premium unleaded and lead replacement), were collected in Sydney, Australia and examined. The high-boiling C(0)- to C(2)-naphthalene compounds present in the gasoline were used to chemically fingerprint each sample at different levels of evaporation. Samples of 25, 50, 75 and 90% evaporated gasoline (by weight) were generated from the 35 samples of unevaporated gasoline. Analysis of the data by PCA followed by linear discriminant analysis (LDA) showed that the 35 samples formed 18 unique groups, irrespective of the level of evaporation. Good discrimination between gasoline samples that were collected on the same day was obtained. Phase two of this study examined the change in gasoline samples over time. The C(0)- to C(2)-naphthalene composition in 96 samples of gasoline collected from three service stations over a 16-week period was examined using the method described. In most cases, it was found that the C(0)- to C(2)-naphthalene profile changed from week to week, and from station to station. In a comparison of all 96 samples together it was found that the majority could be differentiated from one another. The application of the method to forensic casework is discussed.     

Identification of animal species by protein radioimmunoassay of bone fragments and bloodstained stone tools

In forensics and archaeology, it is important to distinguish human from animal remains and to identify animal species from fragmentary bones and bloodstains. We report blind tests in which a protein radioimmunoassay (pRIA) was used to identify the species of six bone fragments lacking morphological specificity and 43 bloodstained lithic tools, knapped experimentally and soaked in blood of known animal and human origin. The submitters of the bone fragments and the bloodstained tools each listed a number of possible species, from which the testers selected the best match with the pRIA results. All six bone fragments were correctly identified: three humans, a deer, a dog, and a cow. Forty-three tools were stained with blood from a wide variety of species including ungulates, carnivores, a fish, and a bird. On 40 of these 43, at least one species (or blood-free control) was identified correctly. Some of the tools were stained with blood of two different species. A mixture of sheep and musk ox blood was correctly identified; in several other mixtures, only a single species was detected. Two tools with human blood and one with human sweat were correctly reported as human. There was a single false positive (one of three controls reported as weakly bovine) and no false negatives. We conclude that the pRIA technique shows a high degree of accuracy in discriminating human from animal bone fragments and bloodstains and in identifying animal species.     

Application of MALDI‐TOF MS for Estimating the Postmortem Interval in Rat Muscle Samples

Estimating the postmortem interval (PMI) is very important in the forensic sciences. Although many approaches have been used for estimating the PMI, accurate PMI calculations are still difficult. In this study, four Sprague Dawley (SD) rats were sacrificed by suffocation, and muscle samples were collected by dissection at various time intervals (0, 48, 96, and 144 h) after death. All samples were probed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) to obtain molecular images and data for principal component analysis (PCA). The results showed that the peaks at m/z 1511, 1543, 1564, 1586 clearly decreased in intensity from 0 to 144 h postmortem and that the time groups were separated from each other on the PCA score plot. The prediction model showed high recognition capability (95.93%) and cross‐validation (83.72%). Our work suggests that MALDI‐TOF MS can be used to determine the PMI.     

Identification of necrophagous fly species using ISSR and SCAR markers

Necrophagous fly is the most common insect evidence collected during a death investigation. We analyzed the DNA polymorphism among the five forensically important fly species, namely, Lucilia sericata, Aldrichina grahami, Chrysomya megacephala, Parasarcophaga crassipalpis and Musca domestica using inter simple sequence repeat (ISSR) method. Nine ISSR primers selected from 18 primers could amplify 105 clear and stable bands, of which 95 bands were polymorphic. Some primers produced completely different band pattern in different species, indicating that they can be used to identify these species. Aiming at obtaining more reliable markers that might be universally used, we started an effort to convert species-specific ISSR fragments into the sequence-characterized amplified region (SCAR) markers that can be used for the molecular diagnosis of the five species.     

Differentiation of Cosmetic Foundation Creams Using Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy: A Rapid and NonDestructive Approach in Trace Evidence Analysis

Cosmetic foundation creams are encountered as evidentiary material in criminal investigations, particularly in cases related to sexual and physical assault against women. Analyzing foundation cream exhibit is a challenging task as the exhibit is recovered in trace quantity with similar hue. In the present study, ATR FTIR spectroscopy which is a rapid, nondestructive, sensitive, reliable, and safe alternative to other analytical techniques has been used to differentiate 31 cosmetic foundation creams belonging to 23 different brands supported by chemometric methods such as principal component analysis (PCA) and linear discriminant analysis (LDA). The discriminating power of visual analysis is found to be 98.0%, while PCA and LDA further increased the discriminating power to 99.3% and 100%, respectively. The blind test is conducted with three unknown samples (pretended to be unknown to the analyst), which were correctly linked with their respective source. Further, the effect of substrate such as tissue paper (dry and wet) and white cotton cloth during sample analysis are also examined to simulate the actual forensic casework conditions. The stains on substrates could be identified and linked to its parent product as well. The reported method provides significant results for the differentiation of cosmetic foundation creams.     

Discrimination of Geographical Origin of Asian Garlic Using Isotopic and Chemical Datasets under Stepwise Principal Component Analysis

Isotopic compositions of δ²H, δ¹⁸O, δ¹³C, and δ¹⁵N and concentrations of 22 trace elements from garlic samples were analyzed and processed with stepwise principal component analysis (PCA) to discriminate garlic's country of origin among Asian regions including South Korea, Vietnam, Taiwan, and China. Results indicate that there is no single trace‐element concentration or isotopic composition that can accomplish the study's purpose and the stepwise PCA approach proposed does allow for discrimination between countries on a regional basis. Sequentially, Step‐1 PCA distinguishes garlic's country of origin among Taiwanese, South Korean, and Vietnamese samples; Step‐2 PCA discriminates Chinese garlic from South Korean garlic; and Step‐3 and Step‐4 PCA, Chinese garlic from Vietnamese garlic. In model tests, countries of origin of all audit samples were correctly discriminated by stepwise PCA. Consequently, this study demonstrates that stepwise PCA as applied is a simple and effective approach to discriminating country of origin among Asian garlics.     

Rapid and non-destructive approach for characterization and differentiation of sealing wax using ATR-FTIR spectroscopy

Sealing wax is used for maintaining the integrity and authenticity of a document or physical evidence. Any tampering with the seal calls into question the overall integrity and authenticity of the tangible evidence or document. In these circumstances, determining the authenticity of the sealing material (physical and chemical) becomes imperative. In this study, ATR-FTIR spectroscopy supported by chemometrics has been used to differentiate sealing wax samples belonging to 12 different brands available across India. All the samples were first melted, cooled, and then analyzed using ATR-FTIR spectroscopy in the mid-infrared region (4000–600 cm⁻¹). The obtained spectra were first examined visually for the presence of different functional groups. Principal component analysis (PCA) and principal component analysis-linear discriminant analysis (PCA-LDA) were employed to analyze the sample clustering patterns and to categorize them into their respective groups, respectively. For classification, a PCA-LDA training model was applied, and it demonstrated 95.83% accuracy. The validation test resulted in an accuracy of 83.33%. PCA-LDA model offered 100% accurate prediction for samples on various substrates, including cloth, cardboard, and paper. A blind study was also performed using five unknown samples, which were accurately classified into their respective groups. PCA-LDA model will be helpful in providing investigative leads by linking a questioned sealing wax sample with its respective group.     

Spontaneous formation of γ-hydroxybutyric acid from γ-butyrolactone in tap water solutions

The spontaneous conversion of γ-butyrolactone (GBL) to γ-hydroxybutyric acid (GHB) in seven different Swedish tap waters was investigated. The waters used in the study were selected to represent the diversity among Swedish tap waters as well as possible, which was enabled by principal component analysis (PCA) of a number of water quality parameters. GBL solutions (5, 25 and 50% v/v) were prepared in each of the tap waters and in deionized water and the formation of GHB was followed over time. The GHB quantifications were made using a CZE method, employing a carrier electrolyte consisting of 25mM benzoic acid, 54mM tris(hydroxymethyl)aminomethane (Tris) and 1.7mM tetradecyltrimethylammonium bromide (TTAB), which was developed as a part of the current study. Data evaluation showed that the formation of GHB was largely dependent on the type of tap water. For example, there was a negative correlation between the kinetics of the GHB formation and the alkalinity of the tap waters (r(2)=0.990). This could be explained by a faster decrease in pH in the waters with low buffering capacity (i.e. low alkalinity), which catalysed the hydrolysis of GBL. Equilibrium was reached after 40-250 days depending on the initial GBL concentration and the type of tap water. The level of the equilibrium appeared to be dependent on the initial GBL concentration and ranged from 26 to 37%. Gained knowledge on the levels of the GHB/GBL equilibrium and the kinetics of the formation of GHB in tap water solutions of GBL, including the influence of the tap water quality, may be useful information for casework with the GHB/GBL problem in focus.     

Provenance Establishment of Stingless Bee Honey Using Multi‐element Analysis in Combination with Chemometrics Techniques

As consumption of stingless bee honey has been gaining popularity in many countries including Malaysia, ability to identify accurately its geographical origin proves pertinent for investigating fraudulent activities for consumer protection. Because a chemical signature can be location‐specific, multi‐element distribution patterns may prove useful for provenancing such product. Using the inductively coupled‐plasma optical emission spectrometer as well as principal component analysis (PCA) and linear discriminant analysis (LDA), the distributions of multi‐elements in stingless bee honey collected at four different geographical locations (North, West, East, and South) in Johor, Malaysia, were investigated. While cross‐validation using PCA demonstrated 87.0% correct classification rate, the same was improved (96.2%) with the use of LDA, indicating that discrimination was possible for the different geographical regions. Therefore, utilization of multi‐element analysis coupled with chemometrics techniques for assigning the provenance of stingless bee honeys for forensic applications is supported.     

超快速气相色谱电子鼻分析技术在汽油标号判定中的应用研究

目的采用电子鼻（超快速气相色谱仪）对汽油样品分析。方法用主成分分析法（PCA）对样品中的色谱峰进行数据处理并建立模型,对不同汽油标号（90#、93#、97#）进行归类和判定。气体顶空进样/快速气相色谱法主要条件：进样体积500μL;进样口温度250℃;进样时间5s;数据采集时间5min;热脱附温度280℃;程序温度40℃（30s）-1℃/s-280℃（30s）;FID温度280℃。结论利用超快速气相色谱和电子鼻指纹分析技术,可以用于未知汽油样本的定性和汽油标号判定。