Simultaneous Determination of Sodium Tripolyphosphate, Sodium Sulfate and Linear Alkylbenzensulfonate in Washing Powder by Attenuated Total Reflectance: Fourier Transform Infrared Spectrometry

An analytical procedure has been developed for the simultaneous quantitative determination of sodium tripolyphosphate (STPP), sodium sulfate (SS) and Linear Alkyl Benzene Sulfonate (LABS) in a single washing powder sample. The method is based on the partial least squares treatment of data obtained by the Attenuated Total Reflectance Fourier Transform Infrared (ATR‐FTIR) spectrometric method in the wavenumber range of 800–1,290 cm−1. Absorbance spectra were employed for measurement using 29 aqueous standard solutions of STPP, SS and LABS. The method is simple, rapid and accurate and has been applied to commercial washing powders analysis performing the STPP, SS and LABS determination with a simplified sample preparation step consisting only of powder dissolution in distilled water. The other advantage of this method is its minimal time consumption (about 15 min), in comparison with previously introduced methods based on the determination of separated analytes (more than 4 h). The relative standard deviations of the proposed method for analyzing these real samples were 0.99, 0.56 and 0.91% for STPP, SS and LABS, respectively.