IDENTIFICATION OF TRIARYLMETHANE, PHTHALOCYANINE AND XANTHENE IN A MIXTURE OF DYES BY ELECTRON ABSORPTION SPECTROSCOPY

Abstract

In the work, the qualitative composition and differentiation of 43 samples of ballpoint pen pastes of different colors was investigated (blue-violet – 29 samples, pink-violet – 3 samples, blue – 3 samples, black – 5 samples, green – 1 sample and red –2 samples) by the method of electronic absorption spectroscopy. The results of the study showed that each paste can be distinguished by studying the nature of their absorption spectra, which arises due to the presence of different functional groups. It was established that most of the analyzed paste samples contain pigments based on triarylmethane, phthalocyanine, xanthene dyes or their mixture. Certain absorption maxima correspond to each type of dyes. The broad and most intense band at λ~590 nm, which was detected for all samples, corresponds to triarylmethane dyes. The band at λ~670 nm corresponds to phthalocyanine dyes. The presence of absorption bands in the green range (λ~520–560 nm) indicates the presence of xanthene dyes in the composition of the pastes. Using the method of photoluminescence spectroscopy upon exci­tation of IR luminescence in the green region of the spectrum (λ=530 nm) it is shown that 11 blue-violet, 5 black and one red pastes exhibit bright luminescence due to the presence of crystal violet and some other triarylmethane dyes in their composition. Weak luminescence was detected for three blue pastes. No luminescence response was observed for the other tes­ted pastes, which is due to the presence of phthalocyanine dyes in these pastes, the absorption of which overlaps with the luminescence spectra of triarylmethane dyes. The obtained data can be used to create a reference base for identifying and differentiating the composition of ballpoint pen pastes of modern manufacturers and establishing their classification and identification differences.