Methyl Orange Paired Microextraction and Diffuse Reflectance‐Fourier Transform Infrared Spectral Monitoring for Improved Signal Strength of Total Mixed Cationic Surfactants

We report a novel methyl orange paired microextraction (MOP‐ME) and diffuse reflectance‐Fourier transform infrared (DRS‐FTIR) spectral monitoring for improved signal strength of total mixed cationic surfactants (CS + ) for its quantification in real water samples. To the best of our knowledge, this is the first report that describes the rapid quantitative determination of total mixed CS + using MOP‐ME/DRS‐FTIR. The method is based on separation and preconcentration of CS + using chloroform as the extracting solvent by the formation of ion‐pair complex with anionic methyl orange (MO − ) followed by DRS‐FTIR analysis. The intense vibration peak obtained at 2919 cm −1 in the FTIR spectra was used for the optimization of all analytical parameters and for the determination of mixed CS + . The best extraction efficiency of CS + from the aqueous solution was obtained at pH 4.0 when extracted for 3 min in chloroform at a stirring rate of 250 rpm. The linearity range obtained for the determination of total mixed CS + in water sample was 0.150–300 μg L −1 with the limit of detection and limit of quantification as 0.05 and 0.150 μg L −1 , respectively. The good recovery percentage (97.1–109.5%) from wastewater showed that the method is very selective for the determination of total CS + in complex sample matrices. The advantages of the MOP‐ME/DRS‐FTIR method are its simplicity, selectivity, and sensitivity toward the analysis of total mixed CS + in wastewater samples.