Preparation of ethambutol–copper(II) complex and fabrication of PVC based membrane potentiometric sensor for copper

Abstract

Copper(II) complex of ethambutol ( I) was prepared and used in the fabrication of Cu 2+ selective ISE membrane. The membrane having Cu(II)–ethambutol complex ( I) as electroactive material, along with sodium tetraphenylborate (NaTPB) as anion discriminator, dioctylphthalate (DOP) as plasticizer in poly(vinyl chloride) (PVC) matrix in the percentage ratio 6:2:190:200 ( I:NaTPB:DOP:PVC) (w/w) gave a linear response in the concentration range 7.94×10 −6 to 1.0×10 −1 M of Cu 2+ with a slope of 29.9±0.2 mV per decade of activity and a fast response time of 11±2 s. The sensor works well in the pH range 2.1–6.3 and could be satisfactorily used in presence of 40% (v/v) methanol, ethanol and acetone and is selective for copper over a large number of cations with slight interference from Na + and Co 2+ if present at a level ⩾1.5×10 −5 and 6.5×10 −5 M, respectively. It works well over a period of 6 months and can also be used as indicator electrode for the end point determination in the potentiometric titration of Cu 2+ against EDTA as well as in the determination of Cu 2+ in real samples.