Chemically surface-modified (tosyl-functionalized) carbon nanoparticles (Emperor 2000 from Cabot Corp.) are employed for the extraction and electrochemical determination of phenolic impurities such as benzophenone-3 (2-hydroxy-4-methoxybenzophenone) or triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol). The hydrophilic carbon nanoparticles are readily suspended and separated by centrifugation prior to deposition onto suitable electrode surfaces and voltammetric analysis. Voltammetric peaks provide concentration information over a 10-100 mu M range and an estimated limit of detection of ca. 10 mu M (or 2.3 ppm) for benzophenone-3 and ca. 20 mu M (or 5.8 ppm) for triclosan. Alternatively, analyte-free carbon nanoparticles immobilized at a graphite or glassy carbon electrode surface and directly immersed in analyte solution bind benzophenone-3 and triclosan (both with an estimated Langmuirian binding constants of K approximate to 6000 mol(-1) dm(3) at pH 9.5) and they also give characteristic voltammetric responses (anodic for triclosan and cathodic for benzophenone-3) with a linear range of ca. 1-120 mu M. The estimated limit of detection is improved to ca.5 mu M (or 1.2 ppm) for benzophenone-3 and ca. 10 mu M (or 2.3 ppm) for triclosan. Surface functionalization is discussed as the key to further improvements in extraction and detection efficiency.