Polytetrafluorethylene Membrane–Based Liquid Three–Phase Micro Extraction Combined with in–Situ Differential Pulse Anodic Stripping Voltammetry for the Determination of Cadmium Ions Using Au–Nanoparticles Sol–Gel Modified Pt–Wire, Ali A. Ensafi,et al.

In this study, one particular application of in situ pulse anodic stripping voltammetry and
polytetrafluoroethylene  membrane-based  liquid  three-phase  micro  extraction  is  presented  for
the  micro  extraction  and  quantification  of  cadmium(II)  ions  in  trace  levels. The  main  factors
influencing on preconcentration and micro extraction of cadmium ions such as organic solvent,
aqueous feed solution pH and acceptor phases, complexing agent concentration, time of extraction
and stirring were examined and discussed in details. The design voltammetric cell was made of
three microelectrodes inserted into an extraction cell, containing acceptor solution and then the
voltammetric analysis was performed in situ during the extraction time. The enrichment factor
and the relative standard deviation, under the optimized conditions, were 15 and 1.7% (n = 5),
respectively. The obtained calibration curve was in the range of 1.0-250 nmol L -1  Cd II  with a
regression coefficient of 0.9980. The limit of detection was found 0.1 nmol L –1 . Due to the high
total effective area of the gold nanoparticles and the low analyte concentration, the anodic stripping
voltammetric method relies exclusively on the underpotential deposition and stripping process
of Cd II  on gold, with little hydrogen evolution during deposition at -0.40 V and no gassing at the
stripping peak near 0.0 V vs. Ag/AgCl. The good selectivity for the underpotential deposition/
stripping method is one of advantages of the proposed method. The efficiency of the method for
determination of cadmium(II) for real samples was checked using fish and rice samples.

J. Brazilian Chem. Soc., 2015, 26(7), 1482-1490.