What is the Construction and working of Dropping Mercury Electrode
Introduction:
In the electrochemical processes, an Electrode plays a crucial role by allowing the transfer of electrons between the solution under investigation and the external circuit. This electron transfer makes it possible to detect and analyze electrochemical reactions which have several uses in different industries like pharmaceuticals.
The dropping mercury electrode (DME) is a precise electrode that is used in electrochemical analysis which provides the continuous dropping of mercury onto a working electrode surface. Due to the continuous dropping of mercury, the surface remains fresh for electrochemical reactions and provides a highly sensitive and accurate analysis of the substance in the solution.
Construction of Dropping Mercury Electrode
- A Capillary ( Dimensions; Dia-0.05 to 0.08 mm, Length- 5 to 9 mm)
- The Reservoir Vessel ( Dimensions; 03 to 0.05mm internal dia)
- Standing tube with a stopcock nearby. 5.5 centimeters of Corning marine barometer tube and 6 millimeters of soft glass are combined to form the capillary tube. The tungsten contact mercury wells in this reservoir vessel are used to link the mercury inside to an electrical system.
A Step-by-step guide to constructing a Dropping Mercury Electrode
Preparation of Mercury
- Take a clean and dry glass container and fill the container with mercury.
- Add slowly 1% v/v Hydrochloric Acid to the container, and stir it to mix.
- Allow the mixture to settle down for a few minutes.
- Then remove the HCL layer from the top of the container. It removes the impurities in the mercury.
- Repeat step 4, for 2 to 3 times to ensure that all impurities have been removed from the mercury filled in the container.
Assembly of the Electrode
- First of all, attach the electrode holder to the electrical supply.
- Then connect the electrode wire to the holder.
- Connect the rubber tubing to the dropping funnel and glass tube
- Connect the dropping funnel to the electrode holder using the rubber tubing.
- Pour the prepared mercury into the dropping funnel.
Working of Dropping Mercury Electrode
Polarography technique
Advantages and Disadvantages of Dropping Mercury Electrode
Advantages:
- In DME, High sensitivity to changes in concentration
- Possibility of High Accuracy and Precision
- In DME Process, it has the ability to measure trace amounts of analytes.
- There is low resistance to mass transport
Disadvantages
- The handling of Mercury is not safe due to its toxic and hazardous nature.
- The cost of DME electrodes is high
- It requires special precautions for handling and storage of DME.
Conclusion
References:
Bard, A.J., Faulkner, L.R. (2001). Electrochemical Methods: Fundamentals and Applications, 2nd Edition. Wiley.
Kissinger, P.T., Heineman, W.R. (1983). Laboratory Techniques in Electroanalytical Chemistry, 2nd Edition. CRC Press.
Sawyer, D.T., Sobkowiak, A., Roberts, J.L. (1995). Electrochemistry for Chemists, 2nd Edition. Wiley.
Bullock, J.N. (2005). "Dropping Mercury Electrode", in Encyclopedia of Electrochemistry, edited by Allen J. Bard and Martin Stratmann. Wiley.
Bond, A.M. (1982). "The Dropping Mercury Electrode: Theory and Practice". Elsevier Science Publishers.
Compton, R.G. (2006). "Dropping Mercury Electrode", in Analytical Electrochemistry, edited by Joseph Wang. Wiley.
Mikkelsen, S.R. (1981). "Dropping Mercury Electrode Techniques: A Review". Analytical Chemistry, vol. 53, no. 14, pp. 1927-1932.
Delgado-Charro, M.B., Guy, R.H. (1995). "Determination of Drug Diffusion Coefficients in Stratum Corneum from Maximum Flux Measurements with the Dropping Mercury Electrode". Journal of Pharmaceutical Sciences, vol. 84, no. 6, pp. 677-683.
Osteryoung, J.G., House, D.A. (1963). "Determination of Solute Diffusion Coefficients by Dropping Electrode Techniques". Analytical Chemistry, vol. 35, no. 9, pp. 1172-1176.
Pierson, J.F., Simons, K.J. (1983). "Dropping Electrode Studies of the Electrodeposition of Copper from Acid Sulfate Solutions". Journal of the Electrochemical Society, vol. 130, no. 9, pp. 1824-1831.
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