Volume 32, Issue 6 (November 1987)
Determining the Relative Age of Ballpoint Inks Using a Single-Solvent Extraction Technique
A new single-solvent extraction technique was developed to estimate the relative age of ballpoint inks. The procedure involves extracting the inks with weak solvents, spotting the ink extract onto a thin-layer chromatographic plate and measuring the amount of ink extracted densitometrically. By comparing the amount of questioned ink extracted with the amount extracted by known dated inks, it is possible to estimate the date the questioned ink was written. Success in using this technique depends on finding suitable weak solvents for extracting the ink. It also depends on the ability of the analyst to remove nearly equal amounts of ink from the document for each ink sample tested. This paper describes the results of several experiments for determining the relative age of ballpoint inks using a single extraction technique. Reproducibility measurements, experimental variations, and the limitations of the technique are also reported. Suggestions for further work are proposed.