Analysis of thin-layer chromatograms of paint pigments and dyes by direct microspectrophotometry

The Nanospec 10S microspectrophotometer has been used to produce reflectance spectra over the 380–900 nm range from coloured thin-layer chromatography spots. The method has been applied to extracted paint pigments and to dyes from other materials examined in forensic science.     

The variation in the colour of paint on individual vehicles

The Nanospec 10S microspectrophotometer has been used to study the variations in topcoat colour over the external painted surface of a number of vehicles. The colour differences observed between samples of the manufacturers' original finish topcoats from different points on the vehicles were relatively small. Visual inspection of the reflectance spectra obtained from individual paint layers is a satisfactory method for showing that two layers have the same pigment composition.     

Analysis of some commonly found inhalants using gas chromatography-mass spectrometry (GC MS) – Effect of substrates on the identification of inhalants

Inhalant abuse is a serious and ever-evolving problem for our society. Inhalants are abused more commonly by teenagers and adolescents. Inhalants such as glue, paint thinners, correction fluid, and nail paint remover are easily available in the market which makes them readily abused. Out of various methods of abuse, huffing (placing a piece of cloth soaked with inhalant is placed in the mouth), bagging (placing head in a polythene bag containing inhalant), and ballooning (balloons filled with inhalant are used for inhaling vapors through the mouth) are most common. Inhalant abuse results in multiple target organ dysfunction with neuritis and brain damage due to the dissolution of the myelin sheath. In acute poisoning cases, it might cause death due to asphyxia and sudden sniffing syndrome. In such cases, various articles containing traces of inhalants could be retrieved from the scene of incidence and to detect these traces become an important facet of the investigation. However, it might be difficult due to the rapid evaporation of inhalants and the formation of reaction product species. In the present study, an attempt has been made to study the effect of three substrates (balloon, cloth, polythene) on component profiles of four paint thinners and four nail paint removers. The study suggests that although some components are retained, there is the formation of a large number of reaction product species and these must be taken into consideration before furnishing the opinion. These reaction product species might also be inhalant specific which must be further explored.     

Note on fabric marks in motor vehicle collisions

Two cases are described where motor vehicle accidents lead to fabric weave impressions and fibres being transferred to the paintwork of vehicles from the clothes of the victims.     

Chinese Contemporary Artists(8) Ji Dachun:Imagine It,Paint It

正"There is nothing that can’t be painted;if I can imagine it,I can paint it,and I can imagine a lot."WHEN I think of Ji Dachun,I can imagine him sitting down with Rene Magritte over tea and discussing theories on painting or playing chess with Marcel Duchamp and Man Ray.Dachun is a true surrealist and there are simply not that many contemporary Chinese surrealist painters.He is as unique as the subjects of his paintings that,for all their diversity,are consistently whimsical,irreverent,absurd,and always minimal like the workspace in which they are created.     

PRAXIS—combined μ-Raman and μ-XRF spectrometers in the examination of forensic samples

Recently, two analytical techniques – Raman and XRF spectroscopy – have been often applied in criminalistic examinations of different kinds of trace evidences. In this paper, the application of the new combined μ-Raman and μ-XRF spectrometer in analysis of multilayer paint chips, modern inks, plastics and fibres was evaluated. It was ascertained that the apparatus possesses real advantages and could be helpful in the identification of examined materials after some modifications, i.e. by adding an extra laser and decreasing the spot size of the X-ray beam.     

The use of microspectrophotometry for the identification of pigments in small paint samples

The visible reflectance spectra of a number of common pigments are presented. These were measured between 380 nm and 900 nm in paint films using the Nanospec 10S Microspectrophotometer. This data can be used in combination with a computer program based upon simple Kubelka-Munk theory to identify the pigments in paint samples. The use of this approach in forensic science is illustrated by examples from recent cases.     

Author index : Volume 26 (1984)

A survey of 100 case-openers received in the Metropolitan Police Forensic Science Laboratory showed the wide variations that exist in blade tip shapes, dimensions and paint formulations.     

Stable isotope analysis of white paints and likelihood ratios

Architectural paints are commonly found as trace evidence at scenes of crime. Currently the most widely used technique for the analysis of architectural paints is Fourier Transformed Infra-Red Spectroscopy (FTIR). There are, however, limitations to the forensic analysis of white paints, and the ability to discriminate between samples.Isotope ratio mass spectrometry (IRMS) has been investigated as a potential tool for the analysis of architectural white paints, where no preparation of samples prior to analysis is required. When stable isotope profiles (SIPs) are compared, there appears to be no relationship between paints from the same manufacturer, or between paints of the same type. Unlike existing techniques, IRMS does not differentiate resin samples solely on the basis of modifier or oil-type, but exploits additional factors linked to samples such as geo-location where oils added to alkyd formulations were grown. In combination with the use of likelihood ratios, IRMS shows potential, with a false positive rate of 2.6% from a total of 1275 comparisons.