RESUMEN
A novel PVC membrane electrode selective for the determination of pentachlorophenolate (PCP) ion based on 2,3,5-triphenyl-2H-tetrazolium (TPT) pentachlorophenolate ion pair as an electroactive material is described. The electrode shows a linear response for PCP ion over the concentration range of 6x10(-5) to 1x10(-2) M with lower detection limit of 4x10(-5) M at 25 degrees C. 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 range of 5.5-10.5. Selectivity coefficient data for some common ions show negligible interference, however, 2,4,6-trichlorophenolate and cetylpyridinium ions interfere. An average recovery of 96.2% with relative standard deviation of 2.3% has been achieved for the determination of 75.0 ppm PCP in wastewater samples. The determination of PCP in soil and wood samples gave results that compare favorably with those obtained by gas chromatography. The electrode has been utilized as an end point indicator electrode for the determination of PCP using potentiometric titration.
RESUMEN
A potentiometric method is described for the determination of cetylpyridinium (CP) cation using a polyvinyl chloride powder (PVC) membrane sensor based on CP-iodomercurate ion pair as an electroactive material. The sensor shows a linear response for CP ion over the concentration range of 2x10(-6)-1x10(-3) M at 25 degrees C. The electrode posses a sub-Nernstian slope of 29.0+/-0.4 mV decade(-1), which has been thoroughly discussed.The electrode shows a fast potential response of approximately 50 s, which is almost constant over a pH range of 3.0-6.0. Selectivity coefficient data for some common ions show negligible interference, however, cetyltrimethylammonium bromide (CTMAB) interferes significantly. An average recovery of 98.8% for CP with an average relative standard deviation (R.S.D.) of 1.2% has been achieved. The determination of CPC in Ezafluor mouth wash gave result that compare favorably with those obtained by the British Pharmacopoeia method. The CP electrode has been utilized as an end point indicator electrode in potentiometric titration of some anions, and applied for the determination of anionic surfactants in some commercial detergents and waste water.