Abstract
Zn2+-selective sensor has been fabricated using poly(vinyl chloride) (PVC) matrix membranes containing a neutral carrier dithizone (1) as an ionophore. The sensor exhibited the best performance for the following membrane composition: (1): PVC-sodium tetraphenyl borate-1-chloronapthalene (5 : 150: 2: 150). This membrane worked well over a wide concentration range of Zn2+, i.e. 5.1 x 10(-6)-1.0 x 10(-1) mol L-1 and the corresponding calibration plots exhibited a Nernstian slope of 29.7 +/- 0.1 mV per decade of Zn2+ activity. The response time of the sensor was shorter than 8 s and the membrane could be used over a period of 6 months with good reproducibility. The proposed sensor could be operated over a wide pH range (3.1-6.5) and demonstrated good selectivity towards the analyte in the presence of several mono-, di- and trivalent cations. It could be also used in partially non-aqueous media containing up to 20% (v/v) of methanol, ethanol, or acetone and its Nerstian slope in the working concentration range remained almost unchanged. The proposed sensor has been used for determination of Zn2+ in human hair samples by direct potentiometry.