FTIR-ATR imaging of TAED-detergent granules

Complete text of publication follows. The microstructure of detergents products for textile cleaning determines to a large extent their physical properties of these products. Release of a certain compound at a given time can improve the washing effect. Tetraacetylethylenediamine (TAED) is an important ingredient of washing powder/tablets. Its function is to enhance the bleaching effect to remove stains on clothing at lower temperatures. TAED granules are post-dosed to the formulation and consist of 4 compounds e.g.; TAED, sodium sulphate, a polymer and clay. To elucidate the microstructure of the detergents granules Fourier Transform Infrared (FTIR) microscopy using an Attenuated Total Reflection (ATR) crystal and Light Microscopy (LM) were used for characterization. FTIR-ATR-imaging was performed to elucidate the location of the different compounds. A Ge-crystal was brought in contact with the surface of interest. A principal component analysis was performed on the FTIR-ATR image, thus revealing the spatial distribution of the compounds (Figure 1) within the detergent granule. The full spectra obtained in a pixel can be used for identification. Figure 1 shows the distribution of the different compounds present in the TAED granule. The structure of the granule on the right is very porous. It shows large TAED particles partially encapsulated by sulphate and surrounded by the embedding material. The clay and copolymer compounds are mainly located around inner TAED particles. Combing techniques like FTIR-ATR imaging and LM results in useful information about the spatial distribution of chemical compounds within TAED granules. The FTIR spectra are used for positively identifying the chemical compounds.