Problems of Forensic Sciences 2016 Vol. 108 (CVIII) 605-622
EXAMINATION OF THE PEN-BALL WRITING USING LA-ICP-TOF-MS AND SEM TECHNIQUES AND A CHEMOMETRIC APPROACH
Paulina CHĘSY1, 2, Aleksandra PAWLACZYK1, Małgorzata Iwona SZYNKOWSKA1, Andrzej PARCZEWSKI1
1Institute of General and Ecological Chemistry, Faculty of Chemistry, Lodz University of Technology, Łódź, Poland
2Jagiellonian University, Kraków, Poland; a profesor emeritus
Streszczenie
Currently, more and more frequently laser ablation inductively coupled plasma mass spectrometry is being used in order to improve the discriminating power of various forensic examinations. In this type of study, estimation of the degree of randomness of the measurement results is of a great importance. One of the factors which may affect the randomness is the degree of homogeneity/heterogeneity of the tested material. The main purpose of this study was to answer the following questions: can different brands of inks be distinguished on the basis of LA-ICP-MS (Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry) measurements of writing made on different kinds of paper, are the inks homogenously spread along the drawn lines of writing and does the type of paper have an impact on the possibility of discrimination between inks and the degree of homogeneity of writing. In solving the above questions, an original chemometric approach was used and completed with DA (Discriminant Analysis) and PCA (Principal Component Analysis). The obtained results made it possible to discriminate between brands within each color of inks as well as to detect inhomogeneity of the amount of ink left along the written lines. The approach presented may be successfully applied in the examination of other kinds of samples.
Słowa kluczowe
Ink writings; Similarity; Homogeneity; Forensic chemistry; LA-ICP-TOF-MS.