A Novel Potentiometric Membrane Sensor Based on Aryl Palladium Complex for Selective Determination of Thiocyanate in the Saliva and Urine of Cigarette Smokers

Abstract

AbstractA highly selective potentiometric sensor for thiocyanate ion based on the use of a newly synthesized organo‐palladium ion exchanger complex dispersed in a plasticized poly(vinyl chloride) membrane is described. The sensor displays a Nernstian response (−57.8±0.2 mV decade−1) over a wide linear concentration range of thiocyanate (1.0×10−6–1.0×10−1 mol L−1 ), low detection limit (6.3×10−7 mol L−1), fast response (20 s), stable potential readings (±0.4 mV), good reproducibility (±0.9%), long term stability (8 weeks), high precision (±0.7%) and applicability over a wide pH range (4–10). Negligible interferences are caused by F−, Cl−, I−, Br−, NO3−, NO2−, CN−, SO42−, S2O32−, PO43−, citrate, acetate and oxalate ions. Under hydrodynamic mode of operation (FIA), the calibration slope is −51.1±0.1 mV decade−1, the linear response range is 1.0×10−5–1.0×10−1 mol L−1 SCN− and the sample throughput is 40–45 per hour. The sensor is satisfactory used for manual and flow injection potentiometric determination of SCN− in the saliva and urine of cigarette smokers and non smokers. The data agree fairly well with results obtained by the standard spectrophotometric technique. Direct potentiometry and potentiometric titration of SCN− with Ag+ are also monitored with the sensor.