Determination of Manganese(II) using Catalytic Hydrogen Wave (CHW) Technique in Environmental and Biological Samples
Authors: Thondavada Niranjan , Chokkareddy Rajasekhar , Redhi Gan G. , Nuthalapati Venkatasubba N. 
Published: January 2020

Background:

A simple, low cost and highly sensitive catalytic hydrogen wave (CHW)
method has developed for the investigation of Manganese(II) in ammonium 4-phenylpiperazine-1-
dithiocarbamate and ammonium 4-benzylpiperidine-1-dithiocarbamate in various environmental and
biological samples using D.C. polarography. This procedure was based on the reaction of Mn(II) in
APP-DTC/ABP-DTC in the presences of NH4Cl-NH4OH medium at pH 6.6 and 7.2 respectively.
The resulting oxidation signals were obtained at -0.78 V and -0.64 V vs SCE, owing to the CHWs.
Different experimental conditions such as pH effects, background electrolyte (NH4Cl-NH4OH) effects
and DTCs and Mn(II) ion effects have been studied. The current method was effectively employed
for the testing of Mn(II) in different environmental and biological samples and attained recovery
percentages (95-99%) are comparable to the Atomic Absorption Spectrophotometry (AAS)
method.

Methods:

Direct current polarography, model CL-357 and CL-25 (Elico Private Ltd, Hyderabad, India),
Shimadzu AA 6300 spectrometer furnished thru a deuterium background corrector and hollow
cathode lamp, at corresponding wavelengths (resonance line) with an air acetylene flame. The experimental
guidelines remained those suggested by the makers.

Results:

The effect of NH4Cl between 0.1 to 0.7 M on the nature of CHW at DME, maintaining the
concentrations of Mn(II) at 4.0 ppm and DTC at 3.0 mM (APP-DTC/ABP-DTC) then adjusting the
pH to 6.6/7.2 (APP-DTC/ABP-DTC). The polarograms were well-defined in NH4Cl of 0.4/0.5 M for
APP-DTC/ABP-DTC. The peak height decreased beyond this concentration and therefore 0.4/0.5 M
(APP-DTC/ABP-DTC) concentrations was kept for more analysis. At fixed concentration of DTC,
(3.0 mM APP-DTC/ABP-DTC) and (0.4/0.5 M for APP-DTC/ ABP-DTC) NH4Cl adjusting the pH
to 6.6/7.2 respectively the metal ion concentration of the Mn(II) was adjusted between 0.05 to 7.0
ppm and results of CHWs were studied. The peak current increased linearly with Mn(II) concentration
in the range 0.05 to 4.0 ppm for both DTCs. However, the sensitivity of the method was more
with APP-DTC/ABP-DTC because of strong complex of Mn(II) and increased catalytic activity.

Conclusion:

The developed CHW method is highly sensitive, simple and spontaneous for the analysis
of Mn(II) in environmental and biological samples. The polarographic reduction of Mn(II) in
aqueous solutions in the attendance of DTC displays a catalytic wave as a role of pH, concentration
of supporting electrolyte and metal ion. The graphs of catalytic signals as a role of the concentration
of dithiocarbamate shows that the signals do not vary linearly with the concentration of dithiocarbamate
which the characteristic of Brdicka CHWs. It is presumed that the dithiocarbamate complexes
with metal ions involve adsorption process and can be described by a Langmuir adsorption isotherm
and the plot of CL/ip Vs CL should be linear. The CHW method is free from interference effect avoiding
the removal stages which made towards placing among utmost sensitive methods for the analysis
of Mn(II) in different Environmental and Biological samples.