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Thiol‐Functionalized Silica Thin Film Modified Electrode in Determination of Mercury Ions in Natural Water
Author(s) -
Cesarino Ivana,
Cavalheiro Éder Tadeu Gomes
Publication year - 2008
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200804325
Subject(s) - anodic stripping voltammetry , detection limit , thiol , chemistry , analytical chemistry (journal) , stripping (fiber) , mercury (programming language) , horizontal scan rate , glassy carbon , electrode , analyte , anode , electrochemistry , silica gel , mesoporous silica , ion , voltammetry , chromatography , materials science , cyclic voltammetry , mesoporous material , catalysis , organic chemistry , composite material , computer science , programming language
The use of a thin thiol‐functionalized silica film modified glassy carbon electrode in the determination of Hg(II) ions in a natural water sample is described. A typical measurement involves two successive steps: a glassy carbon electrode coated with a thin mesoporous silica film containing 10% of mercaptopropyl groups, according to the MPTMS/TEOS ratio in the starting sol‐gel, was first immersed into the accumulation medium for 15 min, then removed, and finally transferred into a detection solution containing KCl 1.0 mol L −1 where detection was performed by anodic stripping voltammetry. In this medium the previously accumulated Hg 2+ species complexed by the thiol groups in an open circuit preconcentration step is then directly reduced at −0.6 V during 60 s prior to be quantified by a differential pulse anodic scan from −0.6 to 0.3 V (vs. Ag/AgCl). A stripping peak appeared at about −0.01 V, which is directly proportional to the quantity of the analyte previously accumulated into the film. The best results were obtained under the following conditions: 100 mV pulse amplitude and 10 mV s −1 scan rate in 1.0 mol L −1 KCl solution pH 2.0. Using such parameters a linear dynamic range from 1.00 to 10.0×10 −8 mol L −1 Hg(II) was observed with a limit of detection of 4.3 nmol L −1 for an accumulation time of 15 min. Hg(II) spiked in a natural water sample was determined between 97.0 and 101.4% mean recovery at 10 −8 mol L −1 level. The results indicate that this electrode is sensitive and selective for the Hg(II)determination.