Direct Quantitative Analysis on Detergency of Soil Components Using ATR-FT/IR

To develop a novel spectroscopic method for quantitative evaluation of detergency, attenuated total reflection (ATR)-FT/IR spectroscopy was applied for quantitative analysis of oil- and protein-based soil components adhering to cotton fibres without precedent extraction procedure. In addition, influence of washing time and mechanical action on the detergency of soap (sodium salt of fatty acid) for soils on clothing was examined by using this method. In particular, oil- and protein-based soil contents can be separately estimated using relative intensities of their characteristic IR bands of CH2 and CH3 stretching (2930 and 2850 cm-1) and Amide I (1650 cm-1), respectively. In case of washing at a rotation rate of 60 rpm, no change was observed for the detergency of oil-based component between 1 and 15 min, whereas the detergency of proteinbased component slightly increased over 10 min. By contrast, in case of washing at 120 rpm, the detergency of two soil components remarkably increased with an increase of washing time. By using ATR-FT/IR method,oil- and protein-based soil components attached to the same surface of a wet-type artificially soiled fabric can be directly and separately quantified at the same time.