Separação e identificação de aditivos em tinta por TLC-IR/ UATR e extração seletiva

Abstract

ResumoVários aditivos são incorporados nas formulações de tintas para evitar defeitos no revestimento e melhorar o desempenho nas aplicações, constituindo, desse modo, um sistema complexo. A caracterização de uma composição pode ser realizada por separações física/ química e técnicas analíticas instrumentais. A análise de multicomponentes é utilizada no estudo de não conformidades, investigação forense e pesquisa e desenvolvimento de novos produtos. As pesquisas correlatas, em geral, utilizam metodologias convencionais, encontrando algumas limitações, o que motiva a utilização de técnicas alternativas, incluindo acoplamentos, para a análise de aditivos em tintas. Nesse contexto, foi avaliada a aplicabilidade do acoplamento (indireto ou off-line) das técnicas de cromatografia de camada fina (TLC) e espectroscopia no infravermelho com transformada de Fourier (FT-IR), denominado TLC-IR, e extração seletiva na análise de aditivos em tinta à base de resina poliuretânica (PU) e nitrocelulose (NC). Foi utilizada uma formulação, avaliados três sistemas de eluentes e um tipo de revelador, o de Gibbs. Os espectros FT-IR foram obtidos por Reflexão Total Atenuada Universal (UATR). Os principais resultados mostraram que o plastificante Acetil Tributil Citrato (ATBC), aditivo majoritário, foi facilmente identificado por TLC-IR. A metodologia permitiu detectar e diferenciar plastificantes do tipo ftalato, como dioctil ftalato (DOP) e dibutil ftalato (DBP), mesmo em pequena quantidade de amostra, e identificar a oleamida (aditivo promotor de deslize) por meio de extração seletiva e UATR. Palavras-chave: tintas, aditivos, TLC/IR, UATR, extração seletiva. AbstractVarious additives are incorporated into the paint formulations to prevent coating defects and improving the application performance, so it is a complex system. The characterization of the components present in this system can be performed by physical/ chemical separation and instrumental analytical techniques. Multi component analysis is used in the study of non-compliance, forensic investigation and research and development of new products. The related research generally uses conventional methodologies, finding some limitations, which motivates the use of alternative techniques, including couplings, for additive analysis in paints. In this context, has been reported the coupling (off-line) of thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FT-IR) (TLC-IR) and selective extraction in the analysis of additives in ink containing polyurethane (PU) and nitrocellulose (NC) resin. One formulation was evaluated, by using three eluting systems, and one type of developer, Gibbs. The FT-IR spectra were obtained by Universal Attenuated Total Reflection (UATR). The main results showed that the plasticizer Acetyl Tributyl Citrate (ATBC), as the majority additive was easily identified by TLC-IR. The methodology allowed even detect and differentiate phthalates like dioctyl phthalate (DOP) and dibutyl phthalate (DBP), even in small amount of sample, and iden...

Characterization of additives in NR formulations by TLC-IR (UATR)

“…FT-IR spectra were obtained, by reflection technique, using the UATR accessory. It was used 20 scans for UATR analysis, based on other papers that they have successfully published for paint [11] , rubber [12] and oil analysis [15] . This scan number is a suitable to smooth noises in the FT-IR reflection techniques, such as UATR, diffuse reflectance (DRIFT) and attenuated total reflection (ATR).…”

“…However, due to the wide variety of products in the extracts of rubbers and the small concentration of additives contained, it is necessary to perform a separation step by thin layer chromatography (TLC). The association of Infrared Spectroscopy Technique (TLC/IR) [10,11] is required for chemical structure characterization, although it is hardly used in the literature.…”

“…After solvent evaporation, this top is removed, scraped and pressed as a KBr disc for IR analysis. This technique was started in our laboratories, in the Brazilian Institute, Instituto de Aeronáutica e Espaço (IAE), in 1996 [10] and it was used for additives analysis, in rubbers [12] as in paints, with positive results [11] . Chauveau et al [13] separated and identified several vulcanization agents (CBS, MBT, TMTM, DPG, MBT and TMTM) and antioxidants (IPPD and 6PPD) present in hospital rubbers (synthetic polyisoprene-isoprene -IR and copolymer of butadiene and styrene -SBR), by means of the TLC technique.…”

“…Among them is the Rodrigues et al [11] publishing, where a painting formulation containing polyurethane (PU) and nitrocellulose (NC) was evaluated. In this study, three eluent systems were used: ethyl acetate/ethyl alcohol (70/35/30), pure toluene and toluene/ethyl acetate (70/30), applying Gibbs developer.…”

UATR and NIRA evaluation in the quantification of ATBC in NC blends

“…However, due to their potential to interfere negatively with the hormonal systems of animals and humans since belonging to endocrine disruptors, exogenous substances that alter the functions of the endocrine system and cause adverse effects on health [10] , special attention has been given to these compounds in recent years. The migration of these compounds into packaging materials has become an important source of contamination for food [11] .…”