Determination of Rhodamine B and Rhodamine 6G dyes in Various Ink Samples by Zero Crossing Method: First Derivative Spectrophotometry

A simple spectrophotometric method has been developed for resolving binary mixtures of Rhodamine B and Rhodamine 6G dyes of red ballpoint pen ink using the first-derivative spectra with measurements at zero-crossing wavelengths. Calibration graphs were linear up to 8 mg L-1 for Rhodamine B and 10 mg L-1 for Rhodamine 6G. This method was successfully applied for the quantitative determination of dyes having overlapping spectra in their bi-component mixtures. The applied derivative method is practical, simple, rapid, inexpensive and suitable for quantitative analysis of bi-component dye solutions in the ballpoint pen ink.

Manuscripts from Different Brands of Ballpoint Pens – GC/MS Ageing Profile in Brazilian Tropical Weather

Background: Dating of ballpoint pen manuscripts in forensic documents is still a challenge for experts. Methods of ink dating consider solvent evaporation through time, especially 2- phenoxyethanol (2-PE). Objective: The objective of the researchers was to perform a continued study with pen ink strokes of ballpoint pens commercialized in Brazil, to characterize the ageing profile of 15 brands of blue and black pens. Methods: Solvent composition analysis of ballpoint pen ink lines written in white and recycled paper was performed by gas chromatography/mass spectrometry, to quantify 2-PE, in recently written lines and in lines aged 4, 18, 27 and 36 months. Results: The results showed that the pens had initial quantities of 2-PE smaller than in the Europe despite of having similar ageing behavior. Such kind of paper had more influence on aged pen strokes than in the recently applied pen strokes. Light and heat accelerated ageing. Some pens stopped ageing at 18, 27 and 36 months. Conclusion: The results obtained were promising for elucidation of the ageing behavior of pen ink lines in tropical weather, but further statistical treatments could be done to adequate interpretation in real cases.