Mixed polyelectrolyte coatings on glassy carbon electrodes: Ion-exchange, permselectivity properties and analytical application of poly- l-lysine–poly(sodium 4-styrenesulfonate)-coated mercury film electrodes for the detection of trace metals

• Published in: Talanta (Oxford) 2006-02, Vol.68 (5), p.1655-1662
• Main Authors: Monterroso, Sandra C.C., Carapuça, Helena M., Duarte, Armando C.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Anodic stripping voltammetry; Anti-fouling; Chemistry; Chromatographic methods and physical methods associated with chromatography; Electrochemical methods; Estuarine waters; Exact sciences and technology; Gas chromatographic methods; Poly(sodium 4-styrenesulfonate); Poly- l-lysine; Thin mercury film electrodes; Trace metals
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2005.08.029

The present work describes the preparation, optimization and characterization of mixed polyelectrolyte coatings of poly- l-lysine (PLL) and poly(sodium 4-styrenesulfonate) (PSS) for the modification of thin mercury film electrodes (MFEs). The novel-modified electrodes were applied in the direct analysis of trace metals in estuarine waters by square-wave anodic stripping voltammetry (SWASV). The effects of the coating morphology and thickness and also of the monomeric molar ratio PLL/PSS on the cation-exchange ability of the PLL–PSS polyelectrolyte coatings onto glassy carbon (GC) were evaluated using target cationic species such as dopamine (DA) or lead cation. Further, the semi-permeability of the PLL–PSS-coated electrodes based both on electrostatic interactions and on molecular size leads to an improved anti-fouling ability against several tensioactive species. The analytical usefulness of the PLL–PSS-mixed polyelectrolyte coatings on thin mercury film electrodes is demonstrated via SWASV measurements of trace metals (lead, copper and cadmium at the low nanomolar level; accumulation time of 180 s) in estuarine waters containing moderate levels of dissolved organic matter, resulting in a fast and direct methodology requiring no sample pretreatment.