Electrochemical Behavior and Detection of Sulfated Sucrose at a Liquid|Organogel Microinterface Array

The electrochemical behavior and detection of sulfated carbohydrates were investigated at an array of microinterfaces between two immiscible electrolyte solutions where the organic phase was gelled. It was found that the electrochemical signal was dependent on the organic phase electrolyte cation. Cyclic voltammetry (CV) of sucrose octasulfate (SOS) with bis(triphenylphosphoranylidene)ammonium BTPPA⁺ as the organic phase cation did not provide a response to a 10 μM SOS concentration. However, when the organic phase cation was tetradodecylammonium TDDA⁺, a distinct peak was present in the CV at ca. -0.47 V, indicative of a desorption process following adsorption during the preceding scan. This detection peak shifted to ca. -0.28 V when tridodecylmethylammonium TDMA⁺ was the organic phase cation, indicating an increased binding strength between this alkylammonium cation and SOS. By combining electroadsorption with TDMA⁺ as the organic phase electrolyte cation, detection limits of 0.064 μM SOS in 10 mM LiCl and 0.16 μM in a synthetic urine aqueous phase were achieved. The detection limit was improved to 0.036 μM SOS (10 mM LiCl) when the electroadsorption time was increased to 180 s, indicating the analytical capability for the detection of SOS and related sugars by ion-transfer adsorptive stripping voltammetry.