Solid-phase reagents for the determination of anionic surfactants in water
Sorption–spectrometric methods for the determination of anionic surfactants (A Surf) in natural and waste water using silica gel (SG) loaded with ion-pair associates of high molecular weight quaternary ammonium salts (QAS) and anionic dyes were developed. For this purpose, the interaction of Methyl Orange (MO), sodium picrate (Picr) and fluorescein (Fl) with didecylaminoethyl-β-
tridecylammonium iodide (I) and N-methyl-N,N,N′,N′,N′-
pentadecylethyldiammonium diiodide (II) immobilized on the surface of SG was investigated. SG loaded with I-MO and I-Fl associates was used for the determination of sodium dodecyl sulfate (SDS) in natural and waste water using absorbance, diffuse reflectance spectrometric and luminescence methods. Detection limits were 0.05 and 0.01 ppm, respectively. Humic and fulvic acids at levels <0.5 ppm did not interfere with SDS determination. Water with higher acid contents was analysed using SG modified with the II-Picr associate at pH 2. Visual test scales for SDS determination in water at one fifth of the maximum admissible concentration (MAC) level was prepared.