dc.description.abstract |
The aim of present study is to develop simpler high sensitive, selective, and rapid direct
spectrophotometric methods to the determination of trace metal ions. The method is based on the
metal complex formation with chelating agents. The insoluble metal complexes were extracted in
organic solvent then were determined spectrophotometrically for the determination of metal ions.
Developed methods do not require tedious solvent-extraction steps; hence the use of
carcinogenic carbon tetrachloride or chloroform is replaced by the micellar method. Proposed
methods are more selective, non-extractive, simple and rapid than all existing spectrophotometric
methods. In the field of metal ion complexation, the ability of micellar system to solubilize
insoluble metal-complex has been investigated to enhance the analytical merits of proposed
method. Use of surfactants showed increase in the molar absorptivity and bathochromic shifts in
the wavelength of maximum absorbance.
In the present study rapid and sensitive methods have been developed by using
chromogenic complexing reagents in anionic sodium dodecyl sulphate (SDS) and cationic
cetyltrimethylammoniumbromide (CTAB) surfactants by improving the sensitivity, selectivity,
detection limits, Beer’s law range, cause a change in the pH, red-shifts in the absorption bands
and reducing the interferences of the analytes by using normal mode and first derivative mode
spectroscopy.
The present research is continuation and extension work of G.A. Shar Ph.D thesis 2003,
By exploring in various surfactants and development of methods by optimizing various
parameters.
Metal ions studied are: cobalt (II), iron(II), nickel (II), copper (II) and cadmium (II). The
chelating
agents
used
were
1-(2-pyridylazo)-2-naphthol
(PAN),
ammonium
pyrollidinedithiocarbamate (APDC) and 1-nitroso-2-naphthol (NNPh). The characterizations of
metal complexes were investigated by infrared IR spectroscopy. Different experimental
conditions were optimized the include pH, amount of the complexing reagent and the stability of
the metal complex. The interfering effects were studied and interferences were lowered by
adjusting the pH/ the masking agents and by the use of first derivative mode spectroscopy. The
detection limits for these metal ions were obtained up to 1.7 ngmL-1 in first derivative mode
spectroscopy.
The use of derivate mode spectroscopy has removed the interferences of the analytes and
lowered the detection limit upto trace ng level which showed improved sensitivity and selectivity
of the methods than reported normal mode spectroscopy. The results of the metal ions
determination were compared with official methods and showed good agreement in both
methods. No significant difference was found between two methods by applying t-test. The
precision and accuracy of measurements have been evaluated using elemental comparator
standards and certified reference materials, respectively. The methods have been applied to the
determination of the metal ions in biological, pharmaceutical and environmental samples. |
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