What is pulse polarography?
What is pulse polarography?
Definition: An electrochemical technique where the cell current is measured as a function of time and as a function of the potential between the indicator and reference electrodes.
What is polarography used for?
The majority of the chemical elements can be identified by polarographic analysis, and the method is applicable to the analysis of alloys and to various inorganic compounds. Polarography is also used to identify numerous types of organic compounds and to study chemical equilibria and rates of reactions in solutions.
Why DME is used in polarography?
Explanation: A major advantage of the DME is that each drop has a smooth and uncontaminated surface free from any adsorbed analyte or impurity. The self-renewing electrode does not need to be cleaned or polished like a solid electrode.
How does differential pulse voltammetry work?
The basis of the differential pulse voltammetry technique is to measure the differences in the rate of the decay of charging and Faradaic current when a potential pulse is applied. The potential is scanned with a series of pulses, while the current is monitored at the beginning and the end of each.
How differential pulse polarography is used in analysis?
Differential pulse polarography (DPP) is used to measure chromium in water and biological materials (including foods). Chromium is only detectable as Cr(VI). A reduction peak is observed at − 0.80 V, when sodium citrate is used as a buffer (pH 9–10.5) and ammonia (ammonium chloride) as a support electrolyte.
How differential pulse polarography technique is used in analysis?
Differential pulse voltammetry (DPV) (also differential pulse polarography, DPP) is a voltammetry method used to make electrochemical measurements and a derivative of linear sweep voltammetry or staircase voltammetry, with a series of regular voltage pulses superimposed on the potential linear sweep or stairsteps.
Which supporting electrolyte is used in polarography?
BUFFER solutions containing ammonia and an ammonium salt have been widely used as supporting electrolytes in polarographic analysis.
Why supporting electrolyte is used in polarography?
This is done to increase the conductivity of the solution (to practically eliminate the so-called IR drop), to eliminate the transport of electroactive species by ion migration in the electric field, to maintain constant ionic strength, to maintain constant pH, etc.
What are the advantages of the polarography?
The major advantages using polarography for inorganic analysis may be summarized: (1) comparatively inexpensive equipment is required, (2) ability of the technique to distinguish between elemental oxidation states (i.e., Cr, As), (3) ability of the technique to establish the chemical form of elements (e.g..
What type of working electrode is used in polarography?
mercury
In polarography, mercury is used as a working electrode, because mercury is a liquid metal and thus the electrode can be renewed after each droplet.
How does differential pulse polarography work?
Differential Pulse Polarography is a polarographic technique that uses a series of discrete potential steps rather than a linear potential ramp to obtain the experimental polarogram. In this manner, the total waveform applied to the DME is very much like a combination of a linear ramp with a superimposed square wave.
What is polarography recorded?
Polarography is a voltammetric technique in which chemical species (ions or molecules) undergo oxidation (lose electrons) or reduction (gain electrons) at the surface of a dropping mercury electrode (DME) at an applied potential. Polarography only applies to the DME.
When did polarography become used in pharmaceutical analysis?
PHARMACEUTICAL ANALYSIS BY J. E. PAGE, B.Sc., Ph.D., F.R.I.C. Glaxo Laboratories, Ltd., Greenford, MiddIesex INTRODUCTION THE polarographic method of analysis was devised by Professor J. Heyrovskjr in Prague about 25 years ago, but it is only during the last ten years that polarography has been accepted for pharmaceutical analysis.
What are the characteristics of a polarography sample?
CHARACTERISTICS OF POLAROGRAPHY In polarography the sample to be examined is dissolved in a base solution containing an excess of a base or supporting electrolyte and is placed in a special electrolytic cell, which has a pool of mercury as anode. and mercury dropping from a capillary at the rate of one drop every 2 to
How are current voltage curves plotted in a polarogram?
The current-voltage curves, or polarograms, as they are usually called, may be plotted manually or recorded, either photographically or by means of a pen-recorder. A recording instrument is recommended for pharmaceutical investigations.