Polymeric Membrane Lanthanum(III)‐Selective Electrode Based on N,N ′‐Adipylbis(5‐phenylazo salicylaldehyde hydrazone)

A recently synthesized azao‐containing Schiff's base N , N ′‐adipylbis(5‐phenylazo salicylaldehyde hydrazone) was used as a suitable neutral ion carrier in construction of a highly selective La 3+ ‐PVC membrane electrode. The electrode exhibits a Nernstian response with a slope of 19.4 mV decade −1 over a wide concentration range (1.0×10 −6 –1.0×10 −2  M) and a limit of detection of 4.0×10 −7 M (0.05 ppm). The electrode possesses a fast response time of ca. 10 s and can be used for at least 3 months without observing any deviation. The proposed electrode revealed excellent selectivity for La 3+ over a wide variety of alkali, alkaline earth, transition and heavy metal ions and could be used in a pH range of 4.0–8.0. The practical utility of the electrode has been demonstrated by its use as an indicator electrode in the potentiometric titration of La 3+ ions with EDTA and in determination of F − ion in some pharmaceutical preparations.