These different inks were tested on nineteen different inkjet printers from three brands.
Samples were obtained from prints by reflection probe.
For both spectra obtained from square areas and lines reference, Principal Component Analysis (PCA) models were created.
Processed reflection spectra in the range 500-1000nm were used as samples in principal component analysis.
Variability between spectra of the same ink obtained from different prints, as well as between spectra of square areas and lines was examined.
By definition, a cash book has to be written by hand and the entries have to be made daily.
The questioned document was suspected to have been written within a short period (e.g., a few hours) and backdated.
In this paper we describe a case in which a cash book, dated of the year 2000, was sent to the Forensic Science Division, Document Laboratory, Zurich Canton Police in March 2003.
To answer these questions, the document was examined for latent elements by electrostatic detection device (ESDA).
The relative dating of the entries was performed by the quantification of the ballpoint pen ink dyes and their degradation products using HPLC.
Results show that it is possible to determine the relative age of entries written by ballpoint pen within a relatively short time scale, if storage and supporting material of the different samples are the same or at least similar.
ABSTRACT: Nineteen black inkjet inks of six different brands were examined by fibre optics reflection spectroscopy in Visible and Near Infrared Region (Vis-NIR FORS) directly on paper with a view to achieving good resolution between them.
The document lab was asked to determine the date of the entries of the questioned list.On one hand, we were asked, if the cash book had been kept on account consecutively during the period of one year, and on the other hand, the judges were interested in knowing, if the document could have been written in 2003 and back dated to 2000.