METHOD OF DATING HANDWRITTEN TEXTS AND OTHER WRITTEN MATERIALS Russian patent published in 2013 - IPC G01N21/17 

FIELD: chemistry.

SUBSTANCE: two samples of the analysed written material are obtained, one of which is extracted using a first solvent - acetonitrile, and other is heated first and then extracted under the same conditions and using the same solvent as the first sample. Both samples are then subjected to spectrometric analysis in the ultraviolet and visible range. The extracts are then quantitatively transferred to the same samples of the analysed written material from which they were taken, evaporated in a current of hot air or under normal conditions. Both samples are extracted with diemthyl formamide solvent and subjected to spectrometric analysis once more in the ultraviolet and visible range. Values of spectral criteria S1 and S2 are calculated using given formulae. The written texts are dated by comparing values of criteria S1 and S2 with the same criteria of written texts with a known date presented in graphic or table form.

EFFECT: high accuracy and reliability of dating analysed documents, accounting for errors in dating documents arising from non-uniformity when determining distribution of dye material per unit length of the mark.

3 cl, 2 tbl, 5 dwg