PVC membrane electrode for the potentiometric determination of Ipratropium bromide using batch and flow injection techniques

Ipratropium (IP+) ion-selective electrode (ISE) has been constructed from poly(vinyl chloride) matrix membrane containing Ipratropium–tetraphenylborate (IP–TPB) as the electroactive component using 2-nitrophenyloctylether as plasticizer. The electrode exhibits near Nernstian response to Ipratropium bromide (IPBr) over the concentration range 10−5 to 10−2molL−1 and detection limit 5.1×10−6molL−1. The electrode offers significant advantages including long lifetime (>2 months), excellent stability and reproducibility, fast response time (<10s), wide pH working range (pH 2–9), high thermal stability (isothermal coefficient 0.37mV/°C) and superior selectivity for IPBr over a large number of inorganic and organic substances. The electrode was successfully used as indicator electrode in the potentiometric titration of IPBr versus sodium tetraphenylborate (NaTPB) and in the determination of IPBr in Atrovent® vials and spiked urine samples applying batch and flow injection techniques, with satisfactory results.