PVC membrane ion selective electrode for the determination of pentachlorophenol in water, wood and soil using tetrazolium pentachlorophenolate

A novel PVC membrane electrode selective for the determination of pentachlo rophenolate (PCP) ion based on 2,3,5-triphenyl-2H-tetrazolium (TPT) pentach lorophenolate ion pair as an electroactive material is described. The elect rode shows a linear response for PCP ion over the concentration range of 6 x 10(-5) to I X 10(-2) M with lower detection limit of 4 x 10(-5) M at 25 d egreesC. The electrode posses a Nernstian slope of -55.0 +/- 1.0 mV/decade and a fast potential response of 45 s, which is almost constant over a pH r ange of 5.5-10.5. Selectivity coefficient data for some common ions show ne gligible interference, however, 2,4,6-trichlorophenolate and cetylpyridiniu m ions interfere. An average recovery of 96.2% with relative standard devia tion of 2.3% has been achieved for the determination of 75.0 ppm PCP in was tewater samples. The determination of PCP in soil and wood samples gave res ults that compare favorably with those obtained by gas chromatography. The electrode has been utilized as an end point indicator electrode for the det ermination of PCP using potentiometric titration. (C) 2001 Elsevier Science B.V. All rights reserved.