Novel poly (vinyl chloride) matrix membrane electrodes for the determination of phenolic pollutants in waste water

The construction and electrochemical response characteristics of poly (vinyl chloride) matrix membrane sensors for seven phenolic compounds (phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, (alpha)-naphthol and (beta)-naphthol) are described. The membranes incorporate ion association complexes of these seven phenolic anions with phenanthroline-iron(II) as electroactive materials. These sensors show linear response for phenol, o-cresol, p-cresol, p-chlorophenol, o-nitrophenol, (alpha)-naphthol, and (beta)-naphthol over wide concentration ranges, with an average anionic slope 54.3 mV per concentration decade. The suggested sensors exhibit fast response time (1 min), low determination limits (1×105 M), good stability (2–3 weeks), reasonable selectivity to phenolic compounds in the presence of other water pollutants. The average percentage recovery was 99.78±0.088 for individual phenolates and 99.61±0.198 for phenolates in mixtures. The investigated sensors were successfully used for direct potentiometric determination of traces of these phenolic compounds in wastewater samples. Results with mean accuracy of 99.74±0.29%, 99.82±0.36%, 99.65±0.47%, 99.73± 0.37%, 99.77±0.30%, 99.86±0.31% and 99.91±0.22% was obtained for the seven sensors, respectively. These results were compared with data obtained using the British pharamacopial method (The British Pharmacopoeia, Her Majestyʹs Stationary Office, London, 1993) and others (Clarkeʹs Isolation and Identification of Drugs in Pharmaceuticals Body Fluids and Post-mortem Materials, 2nd Edition, The Pharmaceutical Press, London, 1998).