| Abstract: | A new monitoring system for the adsorptive stripping‐indirect tensammetric technique has been developed. The system responded selectively to alkylphenol ethoxylates having 5–14 oxyethylene subunits (APE) (being a fraction of nonionic surfactants). It consists of 20 ppm of Mannoxol OT and 20 ppb of tetrabutylammonium bromide (TBAB). In the presence of APE a tensammetric peak of the monitoring mixture is growing. A calibration plot has a slightly sigmoidal shape; the dynamic response range is from 0.5 to 2.0 μg and the detection limit is 0.075 μg. APE determination is highly tolerant to alcohol ethoxylates (AE) having a C18 hydrophobic part, however, the tolerance of AE having a C12 hydrophobic part is small (the APE signal is only three times higher than that of AE having a C12 hydrophobic part). An analytical response to a mixture consisting different nonionic surfactants (NS) is approximately additive. The developed monitoring system was applied to the determination of an APE fraction in 14 river water samples. NS were separated from the water matrix by liquid‐liquid extraction with chloroform. The recovery of Triton X‐100 spike was 102% and the precision 6.5%. |
