Use of sodium dodecyl sulfate for suppression of electrode fouling in the voltammetric detection of biologically relevant compounds

An investigation is reported on whether the anionic surfactant sodium dodecyl sulfate (SDS) was effective in suppressing electrode fouling by proteins and phospholipids in the square wave voltammetric detection of a range of bioorganic compounds (dopamine, epinephrine, catechol, NADH, uric acid, guanine, and acetaminophen) at a glassy carbon electrode. Albumin, globulin, and phosphatidylethanolamine served as test interferents. For most of the analytes, the interferents caused a significant decrease as well as an anodic shift of the signal. When SDS was added to the measuring solution prior to the interferent, these effects were markedly reduced or eliminated. In contrast, addition of SDS subsequent to the interferent did not always fully reverse the interference effects, and therefore the fouling of the electrode can be irreversible. Depending on the analyte, SDS alone caused either a moderate decrease or an enhancement of the signal, and positive as well as negative peak shifts were seen. However, these effects were generally much smaller in magnitude than those caused by the interferents. SDS is therefore useful as suppressor of adsorption interferences in the voltammetric detection of bioorganic analytes, and matrix effects from surface-active constituents of the sample are minimized.