Determination of anionic surfactants in environmental waters by flow injection potentiometric analysis

An anionic surfactant selective electrode prepared by coating graphite rod with polyvinyl chloride (PVC) compound containing triheptyldodecyl ammonium and dodecylbenzene sulfonate (THDA-DBS) was developed. The optimum membrane composition is THDA-DBS 5 mg, dibutyl phthalate (DBP) 0.4 mL, nitrobenzene. (NB) 0.3 mL and PVC 0.2 g. The linear range for the electrode is 1.0 x 10(-3) similar to 1.0 x 10(-6) mol/L. The condition for the ion selective electrod-flow injection analysis (ISE-FIA) system is 0.01 mol/L KCl as carrier stream, 6.6 mL/min of flow rate, 200 muL sampling volume and 20 cm long of disperse coil. About 50 similar to 80 samples can be analysed per hour. The experimental results show that RSD is less than or equal to 3.1% (n = 7) for the determination of 10(-3) and 10(-4) DBS solution by the ISE-FIA system, the recovery is 88.0% similar to 105.0%. The electrode is easy to make, store, and inexpensive. The ISE-FIA system is characterized by good precision, easy operation and convenience.