¹³C‐Isotope ratio mass spectrometry as a potential tool for the forensic analysis of white architectural paint: a preliminary study

Abstract

Paints have a dual role in society, to protect materials from environmental agents such as ultraviolet light, moisture and oxygen, and to make painted materials look more attractive. Variability in paint samples is often due to binder and pigment type within the sample. The most common resin used in decorative paints is drying oil alkyd resin, which incorporates soybean oil and vinyl acrylic based latexes. Traditional analytical methods used by forensic scientists may be able to say whether two paint samples are indistinguishable but cannot conclusively say that they both originate from the same source. To find out if isotopic composition can provide an added dimension of information, 28 different white architectural paints were analysed for (13)C abundance using isotope ratio mass spectrometry. In addition, variations in application, drying time and thickness were also investigated to assess the discriminatory power of (13)C data from white paints with an unknown history. Preliminary results indicate that this method could aid screening of paint samples.

Forensic utility of isotope ratio analysis of the explosive urea nitrate and its precursors

“…This approach has been applied in a forensic context to manufactured materials such as matches [7], paint [8], adhesive tapes [9], and plastic bags [10], as well as non-UN explosives [11][12][13][14][15]. Variations in the carbon or nitrogen isotope ratios have been used to show a possible link between starting reagents and the final explosive product molecules, such as RDX [14].…”

An initial evaluation of stable isotopic characterisation of post-blast plastic debris from improvised explosive devices

“…At present the major fields of interest are the geo-location of human beings, to counteract illegal immigration and people trafficking [4], and the association of controlled drugs, also including geolocation [5]. A limited number of authors has applied the technique to manufactured materials of forensic interest such as plastics [6,7], paints [8] and safety matches [9].…”

Stable isotope analysis of white paints and likelihood ratios

“…Two certified standards of known isotopic composition were used to quality control samples, coumarin (δ 18 O-VSMOW =15.83‰, δ 2 H VSMOW =62.56‰) and glucose penta-acetate (δ 18 O-VSMOW =23.94‰, δ 2 H VSMOW =−98.48‰), which have been calibrated against internationally recognised reference materials by Iso-Analytical (Sandbach, Cheshire, UK). Polyethylene (IAEA-CH-7) was also used for quality assurance purposes [9][10][11][12]. The principle was to use span standards which cover the range expected from the samples analysed.…”

“…Raw data obtained were blank corrected and calibrated against the REF samples by the proprietary instrument software. If necessary, δ-values were drift corrected according to the deviation of measured δ-values from known δ-values of the quality controls [9][10][11][12].…”

“…The makes are represented as ellipses corresponding to 95% of the empirical distribution for that make. 12 C isotope ratios are expressed in the δ notation [‰], relative to the international standard Vienna PeeDee Belemnite (VPDB).…”