Bone provides an important source of forensic evidence. The storage conditions of bone have been recognised as a factor in
maintaining the integrity of such evidence. Thermogravimetric analysis (TG) has been employed to examine the effects of storage
environments and preparation methods on the structural properties of pig bones. A comparison of oven and freeze drying has
been made to study the effect of storage conditions. A comparison has also been made of ground bone specimens with cut specimens.
Freeze-dried hand ground specimens provided the most consistent results and, thus, this is the recommended method of preparation
of bone specimens for TG analysis.
Thermal analysis has been employed in a study of the degradation of heritage Sydney sandstone used in St Mary’s Cathedral
in Sydney, Australia. TG and DSC have been used to characterise the clay components removed from weathered and unweathered
sandstone. Two types of kaolin clays — kaolinite and its polymorph, dickite — have been identified. A higher amount of dickite
present in the clay of weathered sandstone indicates that a kaolinite-to-dickite transformation occurs upon weathering. XRD
hot stage analysis was also used to demonstrate the presence of a more thermally stable polymorph of the kaolinite.
Authors:A. Onishi, P. Thomas, B. Stuart, J. Guerbois, and S. Forbes
A challenge for forensic examiners is the
ageing and characterisation of bone fragments or decomposed skeletal remains.
Due to the sensitivity of thermal methods to morphological states, thermal
analysis has been selected as a technique which could overcome the difficulties.
In this preliminary study, TG-MS was applied to the characterisation of bone
fragments derived from the compact bone of pig rib specimens. TG-MS curves
were collected by heating bone samples to 1000C in an argon atmosphere.
Under these conditions, both the organic and inorganic phases decomposed,
producing a variety of organic fragments and carbon dioxide. Pyrolysis of
the organic phase, which is composed predominantly of collagen, occurred resulting
in the observation of ion fragments up to 110 amu. Selected fragments were
monitored and their observation is discussed in terms of the decomposition
of both the collagen phase and the inorganic carbonated hydroxyapatite phase.
Authors:T. Devièse, M. Colombini, M. Regert, B. Stuart, and J. Guerbois
The use of thermogravimetric analysis–mass spectrometry (TGMS) to study the state of preservation of archaeological bones
has been investigated. As part of a collaborative multi-analytical study, bones exhumed from graves of the late Roman period
in France and Italy were examined. A decrease in organic matter for the archaeological bones compared to that for new bone
was confirmed, demonstrating that diagenesis of aged bones can be detected using TGMS. Different amounts of collagen were
determined for bones from different graves and could, for the majority of specimens, be correlated with the visually observed
Authors:A. Onishi, P. Thomas, B. Stuart, J. Guerbois, and S. Forbes
In order to investigate the potential of thermal analysis for the determination of post-mortem age, rib bone specimens were
collected from the remains of a number of slaughtered pigs that were allowed to decompose in the Australian bush in a controlled
site under a range of conditions for time periods ranging from 1 to 5 years. The bone specimens were cut in cross-section
with the compact bone collected for analysis. TG-MS curves were collected by heating bone samples to 1100°C in an argon atmosphere.
The TG-MS data showed significant differences for the pig bone specimens derived from the different environments and showed
trends in peak size correlating with age. The reported data suggest that TG-MS has significant potential for the identification
of origin as well as the ageing of skeletal remains in a forensic context.
Authors:P. S. Thomas, B. H. Stuart, N. McGowan, J. P. Guerbois, M. Berkahn, and V. Daniel
The potential of thermogravimetric analysis (TG) as a tool for the characterisation of ochre paint used in indigenous Australian bark paintings has been investigated. TG has been combined with differential scanning calorimetry (DSC) and mass spectrometry (MS) to identify and quantify the main inorganic and organic components present in the paints. The results obtained were supported by comparison with infrared spectra and XRD data obtained for the same specimens. The potential of thermal methods for the characterisation ochres has been demonstrated, with subtle differences between small samples being able to be identified.
Authors:K. H. Friolo, A. S. Ray, B. H. Stuart, and P. S. Thomas
Summary Many of Sydney’s heritage buildings and monuments were built as a result of the first European settlement in the 1800s. These buildings not only display the richness of the Australian culture, but also capture the architectural and historical values of its past. Although many of these buildings still appear to be strong and sound, many signs of deterioration have been detected in recent years. Conservators from various disciplines such as science, architecture and engineering are working closely together to develop suitable solutions to stop or at least slow down the degradation process of these precious buildings. This study demonstrates the usefulness of thermal analysis in determining the weathering mechanisms of marble and sandstone taken from two of Sydney’s landmarks, the Captain Arthur Phillips Monument at Sydney’s Botanic Gardens and Sydney’s St Mary’s Cathedral. This paper reports the findings of the weathering behaviours of both marble and sandstone samples determined using thermal analysis techniques.
Authors:S. Raja, P. Thomas, B. Stuart, J. Guerbois, and C. O’Brien
An accurate means of determining bone age is a goal for forensic scientists. In this study, thermogravimetric analysis (TGA)
has been used to examine pig bone specimens of different post-mortem age. Analysis of bone in both air and nitrogen atmospheres
reveals a decrease in total mass loss as the bones age. Two mass loss steps due to the decomposition of the organic bone components
were observed and show decreasing trends with age for decomposition in an air atmosphere. In a nitrogen atmosphere the decomposition
was observed to be more complex and age dependence of the mass loss for each step was not identified. The TGA data, however,
demonstrates the potential of the technique as a means of estimating post-mortem age of forensic bone specimens.
Authors:T. Fukumoto, P. S. Thomas, B. H. Stuart, P. Simon, G. Adam, R. Shimmon, and J.-P. Guerbois
The mechanism and stability of dimethylol urea (DMU) to polycondensation were investigated using thermogravimetric analysis coupled with mass spectroscopy (TG-MS) for evolved gas analysis and a non-isothermal model-free induction period kinetic analysis using three temperature functions; the Arrhenius function and two non-Arrhenian functions. The polycondensation was observed to occur through a two-step process of condensation followed by elimination of formaldehyde during structural rearrangement as has been reported in the literature. The rate equations for each temperature function were evaluated and extrapolated to room (23 °C) and refrigerator (4 °C) temperature to estimate the length of the induction period for the onset of polycondensation for storage life prediction. Based on experience, estimates of the length of the induction periods and, hence, storage life, were most realistically predicted by the non-Arrhenian temperature functions.