A novel method for the determination of fatty acid esters in aqueous emulsion on Ti6Al4V surface with IRRAS and carbon quantification

A novel direct method based on infrared reflection absorption spectroscopy (IRRAS) and carbon elemental analysis has been developed for the quantitative determination of fatty acid ester on Ti6Al4V surface. The new approach involves the IR spectra and carbon analysis of a Ti6Al4V strip treated with a surfactant and ester emulsion adjusted to pH 9.2 with 2-aminoethanol. The results are dependent on the ester and surfactant concentration. The analytical signals are the integral value of the CH2 and CO signals of the IR spectra and the carbon content. The main advantage of the proposed method is that the analysis made directly on the metal surface allows knowing the film forming ability of the emulsion. The method may be useful for research and development of more environmentally friendly water-based metalworking fluids for the metal industry.