Ld. Spence et al., Characterization of document paper using elemental compositions determinedby inductively coupled plasma mass spectrometry, J ANAL ATOM, 15(7), 2000, pp. 813-819
Comparison of the origin of successive pages of a multiple page document ca
n provide important forensic evidence in cases of document fraud. The use o
f elemental compositions, determined by inductively coupled plasma mass spe
ctrometry (ICP-MS), to characterize paper is reported. Samples of commonly
used office document paper (white, A4, 80 gsm) from seventeen different sou
rces, were analysed for their elemental composition, after microwave digest
ion in nitric acid-hydrogen peroxide solution. The limits of detection, ins
trumental precision and potential matrix interferences were established for
the 23 most abundant elements found in paper. The variability of distribut
ion for these elements within a ream of paper was determined. Nine elements
(Na, Mg, Al, Mn, Sr, Y, Ba, La and Ce) were selected as suitable discrimin
ators because their concentrations were sufficiently high and uniform. All
seventeen papers could be distinguished by statistical t-tests (99% confide
nce) using only two of these elemental concentrations (Mn and Sr). The resu
lts are also presented using ternary plots which use three inter-element as
sociations to display the differences in paper composition. Four separate b
atches of a single product line from the same mill, manufactured at monthly
intervals, were also discriminated using elemental concentrations. Three u
nknown samples, chosen randomly from among the seventeen papers, were corre
ctly identified from their elemental composition; two unknown samples from
the four batches were similarly identified. The results show that elemental
analysis, using ICP-MS, provides an effective and robust technique for the
discrimination of document paper.