XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
176
T1: P–43
The use of UV/VIS and FTIR spectrometry in differentiation samples of
degraded papers with application of PCA method for forensic purposes
Janina Zięba-Palus
1
, Beata Trzcińska
1
, Rafał Kowalski
1
,
Aleksandra Wesełucha-Birczyńska
2
, and Paulina Moskal
2
1
Institute of Forensic Research, Kraków, Poland, e-mail: jzieba@ies.krakow.pl
2
Faculty of Chemistry, Jagiellonian University, Kraków, Poland
The subject of forensic examination is often paper being the basis of bogus or in other
manner fraudulently alternated documents. Paper owes its properties to cellulose – a structural
biopolymer. Its properties are highly dependent on the interactions between and within the
cellulose chains mainly regarded to inter-and intramolecular hydrogen bonds. During paper
degradation the degree of polymerization of cellulose chain changes. Cellulose degradation
should be regarded in terms of mixed oxidative and hydrolytic mechanisms. Spectroscopic
methods are of major importance in paper characterization. Vibrational spectroscopy has already
been widely applied to resolve cellulose structure, crystalline phases and hydrogen bonds
network [1-4]. The aim of the present research was to analyse degraded papers by spectroscopic
techniques and to evaluate the possibility of differentiation between them.
Six paper samples were artificially aged in a climatic chamber under 100% relative humidity
in air at 90°C for various periods up to 35 days. The samples were also aged in normal
conditions, i.e. in room temperature in darkness and in sun light for various periods up 24
months. The conditioned samples differing in ageing time were subjected to further analyses.
FTIR spectra were collected on IS50 Thermo Scientific spectrometer at an optical resolution of
4 cm-1 using ATR technique. VIS spectra were recorded using spectrophotometer 20/20 PV TM
CRAIC in the range 200–800 nm.
It was observed that the paper samples differ slightly in the range 1000–1120, 2860–2950
and 1300–1380 cm
–1
in infrared in the function of time. The differences were also found in
UV/VIS spectra and concerned intensity of ca. 280 and 350 nm bands. 2D correlation
spectroscopy clearly differentiated impact of aging process on the tested cards.
Fig. 1. 2D correlation asynchronous map.
The asynchronous maps show different cross-peaks patterns +(289, 359), -(354, 428), -(272,
427); +(311, 422), +(293, 319), +(281, 317), -(316, 354); +(257, 385), +(233, 383) and -(343,
411), -(293, 405) for the 1st, 2nd, 4th and 5th card respectively. So, it was possible to
differentiate between examined degraded paper samples.
Keywords: paper; infrared spectroscopy; UV-VIS spectroscopy
References
[1] M. Manso, M.L. Carvalho, Spectrochim. Acta B 64 (2009) 482.
[2] M. Bicchieri, A. Sodo, G. Piantanida, C. Coluzza, J. Raman Spectroscopy 37 (2006) 1186.
[3] M. Ali, A.M. Emsley, H. Herman, R.J. Heywood, Polymer 42 (2001) 2893.
[4] J. Zięba-Palus, A. Wesełucha-Birczyńska, B. Trzcińska, R. Kowalski, P. Moskal, J. Mol. Struct. 1140
(2017) 154.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
177
T1: P–44
The influence of the type of substrate on the possibility of spray paint
identification for forensic purposes
Rafał Kowalski
1
, and Janina Zięba-Palus
1
1
Institute of Forensic Research, Krakow, Poland, e-mail: jzieba@ies.krakow.pl
Graffiti or other daubs made by the use of spray paints destroy elevation of many buildings
and are often a subject of forensic examinations [1–4]. Sometimes spray paints are used to
destroy traces left by perpetrator on the crime scene. The layer of paint, which creates an
inscription, smudge or a drawing, is thin and difficult to be separated from the base. Moreover,
the small droplets of paint are also left on the clothing of the perpetrator. They point at his
presence on crime scene. The aim of this paper was to apply infrared spectrometry (IR) and
Raman spectroscopy in examination of spray paints for forensic purposes.
Model examinations using spectroscopic methods (FTIR, Raman) were performed for the
identification of spray paints on different substrates (glass, paper, fabrics). Seven red spray
paints, available on the Polish market were placed on the surface of glass plate, paper and
fabrics (cotton, polyamide, polyester). The IR spectra were recorded on Nicolet iN10
spectrometer (Thermo Scientific) with Omnic Picta program, in transmission mode, in the range
600–4000 cm
–1
. Raman spectra were obtained by means of InVia Raman Microscope,
(Renishaw UK), lasers: 514, 633 and 785 nm, spectra recorded in the range 200–2000 cm
–1
.
Raman shift [cm
-1
] Wavenumber [cm
-1
]
Fig. 1. Raman (a) and infrared (b) spectra of spray paint placed on different substrates.
It was found that it is possible to differentiate spray paints using both IR and Raman
spectroscopy. FT-IR technique allows to identify the main polymers and fillers in spite of the
influence of the substrate. Raman spectroscopy provides information about pigment composition
but sometimes results are influenced by inhomogeneity in pigment distribution in paint.
Keywords: spray paint; infrared spectroscopy; Raman spectroscopy
References
[1] J. Zięba-Palus, J. Mol. Stuct. 744–747 (2005) 229.
[2] J. Milczarek, J. Zięba-Palus, Anal. Appl. Pyrol. 86 (2009) 252.
[3] C. Muehlethaler, G. Massonnet, P. Buzzini, Forensic Sci. Int. 237 (2014) 78.
[4] C. Muehlethaler, G. Massonnet, P. Esseiva, Forensic Sci. Int. 244 (2014) 170.
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