Modified Screen-Printed Ion Selective Electrodes for Potentiometric Determination of Sodium Dodecylsulfate in Different Samples

Fabrication and general performance characteristics of novel screen-printed sensors for potentiometric determination of sodium dodecylsulfate (SDS) are described. The sensors are based on the use of ionassociation complexes of SDS with cetylpyridinium chloride (electrode I) and cetyltrimethylammonium bromide (electrode II) as exchange sites in a screen-printed electrode matrix. Electrodes (I) and (II) show fast, stable, and near-Nernstian response for the mono-charge anion of SDS over the concentration range of 1 x 10(-2) - 5.8 x 10(-7) and 1 x 10(-2) - 6.3x 10(-7) mol/L at 25 degrees C and the pH range of 2.0-9.0 and 2.0-8.0 with anionic slope of 57.32 +/- 0.81 and 56.58 +/- 0.65 mV/decade, respectively. Electrodes (I) and (II) have lower LODs of 5.8 x 10(-7) and 6.3 x 10(-7) mol/L and response times of about 8 and 13 s, respectively. Shelf life of 5 months for both electrodes is adequate. Selectivity coefficients of SDS related to a number of interfering cations, and some inorganic compounds were investigated. There were negligible interferences caused by most of the investigated species. The direct determination of 0.10-13.50 mg of SDS by electrodes (I) and (II) shows average recoveries of 99.96 and 99.85%, and mean RSDs of 0.83 and 1.04%, respectively. In the present investigation, both electrodes were used successfully as end point indicators for determination of SDS in pure pharmaceutical preparations and real spiked water samples. The results obtained using the proposed sensors to determine SDS in solution compared favorably