Potentiometric sensor for sodium dodecyl sulfate based on an electrosynthesized polyaniline membrane

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±6 mV/decade, working concentration range of 3 × 10^-6 M to 1 × 10^-2 M SDS, correlation coefficient (r²) of 0.993 and with a limit of detection 1 × 10^-5 M DS^-. The sensor response is reproducible with a mean RSD of 8.08% from 3×10^-6 M to 3 × 10^-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^- 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 × 10^-4 M.