Comparative study of polymer‐coated mercury film electrodes for voltammetric analysis of lead and cadmium in the presence of surfactants

Abstract

Four different polymer-modified mercury film electrodes (MFEs) on a glassy carbon substrate were tested for their ability to determine lead and cadmium in the presence of surfactants. The polymers used for electrode modification were: Nafion, polyaniline, base-hydrolyzed cellulose acetate, and base-hydrolyzed poly(ethyl3-thiophene acetate). Triton X-100, sodium dodecyl sulfate, dodecyl pyridinium chloride, and bovine serum albumin were chosen as representatives of surface active compounds. It is shown that polymer-covered electrodes are useful in surfactant-containing media ,in some instances, but none of them remained unaffected by any of the four surfactants. The cellulose acetate electrodes seem to be less affected by proteins than the bare MFE and other modified electrodes. The Nafion and cellulose acetatecoated electrodes were used for the determination of lead in filtered and acidified, but otherwise untreated, water samples from a sewage treatment plant. The results obtained with the cellulose acetate-coated electrode were in good agreement with those from atomic absorption spectroscopy.

Modified electrode voltammetric sensors for trace metals in environmental samples

“…This rather remarkable fact may be an artefact due to specific interactions of lead cations with detergent-type surfactants in the zone of the electrode surface at neutral pH values and demonstrates the extra care that may need to be taken for measuring lead levels. This interaction can give rise to an increase in lead stripping currents, as has been previously shown 8,11 . Two situations can be envisaged.…”

“…Secondly, the evident difference in sensitivity for lead and cadmium found at the bare MTFE is further enhanced at the NCMTFE and at the RAM-NCMTFE. The microelectrode characteristics of RAM electrodes led to a decrease by a factor of at least 1.5 in detection limit, according to the metal ion, and sensitivity as a function of normalised area was higher compared with larger An additional potential problem which could arise in applications is due to variations in stripping signal between different coated electrodes 11 , which may reach 10%. However, since the standard addition technique is used to determine the levels of these trace metal ions, such differences are unimportant.…”

Nafion-Coated Mercury Film Electrodes for Square Wave Stripping Voltammetry Determination of Lead and Cadmium in Continuous Flow

“…Although it has been reported [10,34] that the anodic stripping determination of lead at Nafion coated electrodes is rather problematic in the presence of Triton X-100, it should be emphasized that in the experimental conditions presented here the interference can be largely mmimized through the use of the NCMFE. The obtained results basically agree with data found previously by other authors at mercury film electrodes modified with cellulose acetate [16] and Nafion [13,[31][32][33].…”

“…These effects can be prevented by time-consuming sample pretreatment (e.g., mineralization) [6], that considerably lenghtens the analytical procedure and introduces risks of contamination and losses; furthermore such extended pretreatments are not possible in many situations, namely in continuous flow applications. Chemical modification of electrode surfaces with permselective membrane coatings has received considerable attention [7][8][9][10][11][12][13][14][15][16][17][18][19][20] in order to improve electrode response, protecting its surface from adsorptive interferences. For this purpose, Nation [7][8][9][10][11][12][13][14][15], cellulose acetate [10,16], other polymers [17,18] and dyalisis membranes [19,20] have been employed in voltammetric sensors.…”

Eletrodos modificados com polímeros perfluorados e sulfonados: aplicações em análises ambientais

“…O efeito de surfactantes na faixa de 1 a 100 mg L -1 foi observado e obteve-se os mesmos resultados dos estudos anteriores 6 . Um estudo comparativo entre eletrodos de filme fino de mercúrio cobertos com diversos polímeros usados para análise voltamétrica de Pb e Cd na presença de surfactantes foi realizado 32 . Entre os eletrodos, o NCTMFE mostrou bom desempenho frente ao dodecil sulfato de sódio e proteína.…”