Potentiometric Sensor for Sodium Dodecyl Sulfate Based on an Electrosynthesized Polyaniline Membrane

Abstract

Sodium dodecyl sulfate (SDS) sensor was prepared by potentiostatic polymerization of aniline onto graphite/epoxy composite electrode. The optimized electropolymerization parameters obtained were 0.1 M aniline in 0.2 M SDS, pH 5 acetate buffer solution, 30 minutes electropolymerization time, and applied voltage 0.8 V. The optimized potentiometric measurement parameter provided a sensor with sensitivity of 45.54/spl plusmn/6 mV/decade, working concentration range of 3 /spl times/ 10/sup -6/ M to 1 /spl times/ 10/sup -2/ M SDS, correlation coefficient (r/sup 2/) of 0.993 and with a limit of detection 1 /spl times/ 10/sup -5/ M DS/sup -/. The sensor response is reproducible with a mean RSD of 8.08% from 3/spl times/10/sup -6/ M to 3 /spl times/ 10/sup -3/ M SDS. The response time of the sensor is 20 s and the lifetime of about one week during which it could be used without measurable divergence. The selectivity coefficient values indicate that the electrode is highly selective for DS/sup -/ over a number of other anions except DBS-. Although DBS- is likely to cause some interference, it would not interfere at the concentration of < 3 /spl times/ 10/sup -4/ M.