Employment of electrostatic interactions for amperometric detection of carbon nanoparticles in a FIA system

The development of methods for nanoparticle detection is highly desirable due to their increasing presence in the environment. Recently, we have shown that the electrochemical detection in flow is one of the possible solutions. Here we demonstrate a dramatic improvement of analytical parameters of such detection. The significant enhancement of an amperometric signal resulting from the electrocatalytic oxidation of ascorbic acid (AA) in a negatively charged phenylsulphonated carbon nanoparticle suspension in the millifluidic flow injection analysis system as compared to earlier results (D. Ogończyk, et al., Electrochem. Commun., 2014, 43, 40) is presented. This effect results from the tailoring of electrostatic interactions, e.g. optimization of the supporting electrolyte and AA concentration and/or immobilization of positively charged functionalities at the electrode surface. The sensitivity is improved by almost three orders of magnitude and the limit of detection of carbon nanoparticles is decreased by two orders of magnitude down to 0.001 mg mL−1.