Unit 9 Applications of Polarography, Amperometric Titrations and Voltammetry

UNIT 9 APPLICATIONS OF POLAROGRAPHY, AMPEROMETRIC TITRATIONS AND VOLTAMMETRY

Applications of Polarography, Amperometric Titrations and Voltammetry

Structure 9.1

Introduction Objectives

9.2 9.3 9.4

Applications of Polarography Applications of Amperometric titrations Polarography Experiments Determination of ascorbic acid in citrus fruits Determination of ascorbic acid (Vitamin C) in the citrus juice by the standard addition and calibration curve methods Other industrial important determinations for traces or minor constituents Determination of lead and copper in carbon steels Determination of the amount of Cd2+ present in the unknown solution Determination of the nature of the ion (E1/2)

9.5

Applications of voltammetry Voltammetry – Instrument Practical methods: steps involved in voltammetry

9.6 9.7 9.8 9.9

9.1

Application of Cyclic Voltammetry Summary Terminal Questions Answers

INTRODUCTION

While going through Unit 7 and Unit 8 of this course (Electroanalytical Methods), you have learnt about the different electroanalytical methods like Polarography, Voltammetry and Amperometric titrations. In this unit (Unit 9), we will discuss the applications of the previously discussed electroanalytical methods. In this unit we will start our discussion with the different applications of Polarography, followed by those of Amperometric titrations. A number of polarography experiments are then discussed. This is followed by the different applications of cyclic voltammetry.

Objectives After studying this unit you should be able to: •

discuss the elements or compounds determined with the help of polarography in different types of samples like food stuff, sea water, fuels etc.,

•

discuss the polarographic analysis of organic compounds,

•

give examples of the species determined with the help of amperometric titrations for different titrations and electrodes,

•

explain different polarography experiments using both the calibration curve method and standard addition method,

•

discuss other industrial important determinations for traces or minor constituents,

•

understand the application of cyclic voltammetry.

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9.2

APPLICATIONS OF POLAROGRAPHY

Most metal ions are reducible at DME, and multicomponent mixtures can often be analysed by selecting an appropriate supporting electrolyte so that the half-wave potentials of two ions are differed by about -0.2 V vs SCE or by using complexing agents by taking the advantage of complexing ability of the metal ions. Based on this, polarography is used predominantly for trace metal analysis of alloys, ultra-pure metals, minerals/metallurgy, environmental analysis (air, water, soil and sea water contaminants), foodstuffs, beverages and body-fluids, toxicology and clinical analysis. Reducible anions such as BrO 3− , IO3-, Cr2O72- and NO2- can also be determined using well buffered solutions.

9.2.1 Some applications of Polarography Table 9.1: Different samples and Element or Compound determined Element or Compound determined Cu, Pb, Sn, Zn Ga, Zn, Cd, Ni Cu, Pb, Ni, Co Sn, Pb Transition metals Free sulphur Antioxidants Riboflavin Vitamin C Oxygen

Type of sample Foodstuffs high purity aluminium Steels Beer and soft drinks High-purity salts Petroleum fractions Fuels Milk, pharmaceuticals Fruit and vegetables Sea water, gases

It is also useful in the analysis of biological systems to determine vitamins, alkaloids, hormones, terpenoid substances and natural colouring substance, analysis of drugs and pharmaceutical preparations, determination of pesticide or herbicide residues in foods, in the structure determination of many organic compounds etc. Polarographic analysis of organic compounds This technique is used in organic chemistry for qualitative and quantitative analysis and structure determinations. Most of the organic compounds are insoluble in pure aqueous medium and also in mercury to form amalgam. Therefore, the solvent in which the organic compound and its electrode product is soluble is added to the supporting electrolyte. These solvents include various alcohols or ketones, dimethyl formamide, acetonitrile, ethylene diamine and others. The commonly used supporting electrolytes which are easily mixed with organic solvents are various quaternary ammonium salts such as tetrabutyl ammonium iodide. Some of the organic functional groups that are reducible at DME are given in Table 9.2. Table 9.2: Reducible Organic Functional Groups > C=O

Ketone

-C=N

Nitrile

-NO2

Nitro

-CHO

Aldehyde

-N=N-

Azo

-NO

Nitroso

>C=C<

Alkene

-NO=N-

Azoxy

-NHOH

Hydroxylamine

-C

Aryl alkyne

-O-O-

Peroxy

-ONO-

Nitrite

Azomethine

-S-S-

Disulfide

-ONO2

Nitrate

C-

>C = C-

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In addition dibromides, aryl halides, alpha-halogenated ketone or aryl methane, and ketones, polynuclear aromatic ring systems, and heterocyclic double bond reduce at DME. -S-S-, -SH (mercaptones get oxidized at DME and give anodic currents).

Applications of Polarography, Amperometric Titrations and Voltammetry

It is also possible to convert the non-polarographic active groups into active polarographic groups and determine them. Table 9.3: Organic Functional Group Analysis of Non-polarographic active groups Functional Group Carbonyl

Girard T and D Semicarbazide Hydroxylamine

Active Polarographic Group Azomethine Carbazide Hydroxylamine

Primary amine

Peperonal CS2 Cu3(PO4)2 suspension

Azomethine Dithiocarbonate (anodic) Copper(II) amine

Secondary amine

HNO2

Nitrosoamine

Alcohols

Chromic acid

Aldehyde

1,2-Diols

Periodic acid

Aldehyde`

Carboxyl

(Transform to thiouranium salts)

- SH (anodic)

Phenyl

Nitration

- NO2

Reagent

SAQ 1 a)

Which compounds are used as supporting electrolytes in organic polarography?

…………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... b)

How can the non-polarographic active groups be determined polarographically? Give two examples.

…………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………...

9.3

APPLICATIONS OF AMPEROMETRIC TITRATIONS

Amperometric titrations have even wider range of applications than polarography because even electro-inactive substances can be determined using electro-active titrant. According to Ilkovic equation id is proportional to concentration keeping all other factors of the equation constant. So, if some of the electroactive material in the solution is removed by interaction with some other reagent (e.g.: EDTA reagent for

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Electroanalytical Methods-III

Zn2+ determination) the diffusion current will decrease. This is the fundamental principle of amperometric titrations or polarographic titrations. The diffusion current at an appropriate applied voltage is measured as a function of the volume of the titrating solution. The end point is the intersection of two lines giving the change of current before and after the equivalence point. Table 9.4: Examples of amperometric titrations Titrant

Electrode

Species determined

DME

many metallic ions

Dimethylglyoxime

DME

Ni2+

Lead nitrate

DME

SO42-, MoO42-, F −

Mercury (II) nitrate

DME

I-

Silver nitrate

Rotating Pt

Cl-, Br-, I-, CN-, Thiols

Thorium(IV) nitrate

DME

F-

Potassium dichromate

DME

Pb2+, Ba2+

Iodine

Rotating Pt

As(III), Na2 S2O3

Potassium bromate/KBr

Rotating Pt

As(III), Sb(III), N2H4

Additions

Rotating Pt

Alkenes

Substitutions

Rotating Pt

Some phenols, aromatic amines

Complexation reactions EDTA Precipitation reactions

Oxidation reactions

SAQ 2 What is the fundamental principle of amperometric or polarographic titration? …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………...

9.4

POLAROGRAPHY EXPERIMENTS

Different practical experiments have been given below:

9.4.1 Determination of the nature of the ion (E1/2) The half-wave potential of Tl+ solution. Procedure: Take 10 ml of 0.5 mM solution of TlNO3 in 0.1 M KNO3 supporting electrolyte and draw the polarogram. Determine E1/2 from the reduction wave of Tl+ i and compare with literature value. Also use E vs log plot for accurate E1/2. id −i

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9.4.2

Determination of the amount of Cd2+ present in the unknown solution

For the analytical determination use both the calibration curve method and standard addition method. i)

Applications of Polarography, Amperometric Titrations and Voltammetry

Wave height – concentration plots (calibration): Prepare stock solutions of Cd2+ ion by dissolving 1.0 g of Cd2+ per dm3. From this take 1.0, 2.5, 5.0 and 10 cm3 into 100 cm3 volumetric flask, add 50 cm3 of 2M KCl solution and 2.5 cm3 of 0.2% gelatin solution to each flask and then dilute to the mark with distilled water. Take 10 cm3 of unknown solution (of about 0.04 g of Cd2+ per dm3) in a volumetric flask, add 50 cm3 2M KCl and 2.5 cm3 of 0.2% gelatin solution and dilute to the mark with distilled water. Record the polarograms of four standard solutions and unknown after deaeration. Draw calibration curve taking wave heights of all four standard solutions as ordinates and concentrations as abscissa. From this the concentration corresponding to wave height of unknown is noted.

ii)

Method of standard addition Polarograms of unknown solution is first recorded as under (i) and a second polarogram is recorded by adding a known amount of the same ion.

iii)

Second polarogram Place 10 cm3 of unknown solution, 5 cm3 of known stock solution [of method (i)], 50 cm3 of 2M KCl and 2.5 cm3 of 0.2% gelatin solution in a volumetric flask and dilute to the mark with distilled water and record the polarogram of this solution in a polarographic cell after removing dissolved oxygen with nitrogen. Determine its wave height and calculate the concentration of unknown solution as described under Unit 8 (polarography).

9.4.3

Determination of lead and copper in carbon steels

In the application of the polarographic method of analysis to steel, ferric ion interferes due to its reduction near zero potential in sodium tartrate supporting electrolyte. Fe(III) has to be reduced to Fe(II) with hydrazinium chloride in a hydrochloric acid medium so that Fe(II) is reduced at much negative potential of -1.4 V vs SCE which is more negative than lead and copper. Procedure: Dissolve accurately weighed 5.0 g of the steel in a mixture of 25 cm3 of water and 25 cm3 of concentrated hydrochloric acid and heat gently. Add few drops of standard potassium chlorate solution to dissolve carbides and boil the mixture until the solution is clear. Cool and dilute to 50 ml with water in a volumetric flask. Pipette 2 ml of this solution into a polarographic cell and add 1.0 cm3 of 20% hydrazine hydrochloric solution to reduce Fe(III) to Fe(II) ion, 1.0 cm3 of 0.2% methyl cellulose to act as maximum suppressor and 5.5 cm3 of 2.0 M sodium formate solution. Keep the cell in a nearly boiling water bath for 10 minutes in order to complete the reduction. Cool and take the polarogram using SCE. The polarogram will have two steps. The first one at E1/2 of - 0.25 V vs SCE is due to the reduction of cuprous to copper metal. The second step at E1/2 of - 0.45 V vs SCE is due to lead. Use standard addition method for determination. For this carry out a calibration by adding known amounts of copper and lead ions to a solution of steel of low copper and lead content and determine the increase in wave heights due to addition. Calculate the percentage of copper and lead in the sample.

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9.4.4 Other industrial important determinations for traces or minor constituents i)

Analysis of steel and ferro-alloys for minor constituents (Cu, Ni, Co, Mn, Cr, Mo, W, V, Ti, Sn, Pb, and Al).

ii)

Analysis of Copper base alloys (Pb, Sn, Ni, Zn).

iii)

Analysis of high purity zinc and of zinc alloys (Cu, Pb, Cd, Sn, Mn, Al).

iv)

Analysis of ferrous sulphate (Zn, Pb, Cu).

v)

Analysis of aluminium alloys (Zn, Pb, Cu, Ni, Fe, Mn).

vi)

Analysis of pure aluminium (Cu, Cd, Ni, Zn, Fe, Pb).

vii)

Analysis of magnesium alloys (Al, Zn, Pb, Mn).

viii) Analysis of refined metallic tin and of tin base alloys (Cu, Bi, Pb, Cd, Zn, Fe). ix)

Analysis of metallic cobalt and cobalt salts (Cu, Pb, Ni).

x)

Analysis of refined metallic lead and of lead base alloys (Bi, Fe, Cu, Cd, Zn, Sb).

xi)

Analysis of nickel alloys and nickel compounds (Cu, Pb, Fe).

xii)

Analysis of metallic cadmium (Cu, Pb, Zn).

xiii) Analysis of high purity zinc and zinc base alloys (Cu, Pb, Cd, Sn, Bi, Mn). xiv) Analysis of pure strontium salts (Ba).

9.4.5 Determination of ascorbic acid (Vitamin C) in the citrus juice by the standard addition and calibration curve methods Principle: Ascorbic acid gives a well defined polarographic oxidation wave. HO

HO

O

O

O

HO HO

OH

HO -

-2e →

Ascorbic acid

O

+ 2 H+ Dihydro ascorbic acid O

Use freshly prepared diluted juice Calibration curve method

Prepare a fresh stock solution of 50 cm3 of 0.2% ascorbic acid. Prepare 5 standard solutions of ascorbic acid in volumetric flasks of 25 cm3. To each one add 0.5 cm3 of 0.5 M acetate buffer and different volumes of 0.2% ascorbic acid, 0, 200, 400, 600 and 800 µdm3 . Dilute to the mark with distilled water. For each solution record polarograms over the potential range -150 to + 200 mV vs Ag/AgCl/1M KCl reference electrode. Plot id vs c of ascorbic acid (calibration curve). Standard addition methods

Squeeze an orange, grape fruit or lemon until about 10 cm3 of juice is obtained. Filter the juice through a porous funnel (pore size about 1 mm). Prepare four 25 cm3 volumetric flasks. Add to each 0.5 cm3 of 0.5M acetate buffer, 2.0 cm3 of the juice and standard addition of 0, 200, 400, and 600 µdm3 of 0.2% ascorbic

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acid. Dilute to mark with distilled water. Record polarograms under the same conditions as in the calibration step. Draw the standard additions plot and determine the concentration of ascorbic acid. Report the concentration of ascorbic acid (Vitamin C) in the original sample (juice) in mol/l and also ppm.

Applications of Polarography, Amperometric Titrations and Voltammetry

SAQ 3 Complete the sentence by selecting the correct alternatives: a)

Polarography is used for organic/inorganic/both organic and inorganic analysis.

…………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... b)

How can the ferric ion interfere in the polarographic analysis of steel and how is its interference prevented?

…………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………...

9.5

APPLICATIONS OF VOLTAMMETRY

All these techniques can be applied quantitatively for the analysis of large variety of samples (environmental samples, steels, clinical samples etc). The choice of a particular technique will depend on the analyte's characteristics, expected concentration, other constituents present and location of the sample. Pulse polarography is better for analyzing a wide range of inorganic/organic analytes. While in the case of stripping methods the analyte is to be preconcentrated at the electrode surface. Further the concentration of the analyte in the sample, the accuracy and precision required will decide the technique to be selected. The analysis of a sample component is quite simple and any of the methods can be used and from the linear relationship between the current and concentration, the unknown concentration in the sample can be obtained. In case of samples containing more than one analyte; if the components behave independently, the analysis will be a simple addition of the respective individual separation voltammograms. However if the id or ip is sufficient they can be determined independently as if they were only a single component. The amount of separation between these potentials will depend on the type of the potential, technique used, concentration of the components. If the difference is less than minimum separation and there is overlap between the voltammograms of the two components, independent analysis is not possible and a simultaneous analysis method is to be followed by taking the sample and simultaneous equations for the current at two potential be formed and by solving these equations, the concentrations of both the analytes can be obtained. The analysis has been explained in detail in the numericals given in the terminal questions.

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Electroanalytical Methods-III

9.5.1 Voltammetry – Instrument The basic instrument consist of two important components:

Fig.9.1: Basic instrument for voltammetry

1.

Normal three electrode polarograph.

2.

Linear scan voltage generator to give different type of signals. The polarographic cell is made up of a three electrodes dipped in a solution containing the electroactive species and excess of inert electrolyte usually called supporting electrolyte. i)

Working electrode, usually a microelectrode whose potential is varied linearly with time.

ii)

Reference electrode: Normally a standard electrode is used whose potential is constant throughout the experiment (saturated calomel electrode or Ag/AgCl electrode).

iii)

Counter electrode, which is a coil of platinum wire or a pool of mercury that simply serves to conduct electricity from the signal source through the solution to the micro electrode.

The potentiostat allow to impose the potential scanning between the working and reference electrodes while the current flowing through the circuit is recorded between the working and auxiliary electrodes. The computer CVA Trace analyzer from Metrohm Ltd. can be used as an intergrated instrument with keyboard or a commercially available personal computer interface to measuring system (with software): i)

to send the scanning parameters to the potentiostatic analyzer and check its correctness and accuracy.

ii)

handle the current potential output data.

9.5.2 Practical methods: steps involved in voltammetry

74

1.

Sample treatment: For this analysis the sample must be in a solution form. If solid, it has to be brought into solution by dissolving in a suitable solvent. Liquids or solids with low solubility are to be digested or extracted.

2.

Addition of supporting electrolyte: Every analysis has to be performed using a suitable supporting electrolyte, of appropriate concentration normally at least 10 times the concentration of the analyte.

3.

Bubbling of the solution with N2.

4.

Electrode cleaning.

5.

Addition of the standard analyte.

6.

Scanning/registration of voltammograms.

7.

Measurement of peak height.

8.

Drawing of the graphs.

9.

Calculation of the unknown concentration.

Applications of Polarography, Amperometric Titrations and Voltammetry

SAQ 4 Give the schematic diagram of the basic instrument for voltammetry. …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………...

9.6

APPLICATION OF CYCLIC VOLTAMMETRY

Coupled chemical Reactions

There are inorganic ions, metal complexes and a few organic compounds which undergo electron transfer reactions without the making or breaking of covalent bonds. The vast majority of electrochemical reactions involve an electron transfer step which leads to a species which rapidly reacts with components of the medium via so called coupled chemical reactions. One of the most useful aspects of CV is its applications to the qualitative diagnosis of these homogeneous chemical reactions that are coupled to the electrode surface provides the capability for generating a species during the forward scan and then probing its fate with the reverse scan and subsequent cycles, all in a matter of seconds or less. In addition, the time scale of the experiment is adjustable over several order of magnitude by changing the potential scan rate, enabling some assessment of the rates of various reactions. There are several examples of the coupled chemical reactions, however two are given below. A cyclic voltammogram for the popular antibiotic chlor-amphenicol is illustrated in Fig. 9.2. The scan was started in a negative direction from 0.0 V. Three peaks are observed, peak A for the initial reduction, peak B for oxidation of a product of this reduction and peak C for oxidation of a product resulting from the events accounting for peak B. All three “peaks” or “waves” involve more than a simple electron transfer reaction. peak A peak B peak C

RφNO 2 + 4e + 4 H + → RφNHOH + H 2 O

RφNHOH → RφNO + 2H + + 2e RφNO + 2e + 2H + → RφNHOH

To assist in “proving” the diagnosis, authentic samples of the hydroxylamine and nitroso derivative can be used to confirm the assignment of peak B and C.

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Electroanalytical Methods-III

Thyronine is an ether which may conveniently be thought of as representing the combination of the amino of the amino acid tyrosine with hydroquinone.

Fig. 9.2: Cyclic voltammogram of 3.3 mg/25 cm3 chloramphenicol in 0.1 M acetate buffer, pH 4.62. Carbon paste electrode. Scan rate = 350 mV/s

Its oxidative CV on a carbon paste electrode is illustrated in Fig. 9.3. In this case the scan is initiated in a positive direction from 0.0 volts. The initial two-electron oxidation (peak A) generates a proton and an organic cation which is readily hydrolyzed to benzoquinone and tyrosine. OH

OH

O

O

+

H2N

COOH

H2N

+

2e + H

+

COOH OH2

OH

O + O Peak A

H2N

COOH

The tyrosine thus produced is subsequently oxidized at peak B (no product from peak B is detected on the reverse scan).

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OH

Applications of Polarography, Amperometric Titrations and Voltammetry

O H + 1e

H2N

H2N

COOH

COOH Coupling Products

Peak B

The benzoquinone is reduced on the reverse scan at peak C to produce hydroquinone,

Fig. 9.3 Cyclic voltammogram of 5 mg/25 cm3 L–thyronine in 1 M H2 SO4. Carbon paste electrode, scan rate = 200 mV/s

which is then oxidized back to benzoquinone at peak D on the second positive-going half-cycle. OH O +

+ 2e + 2 H O Peak C

OH

Standard solutions of benzoquinone, hydroquinone, and tyrosine can be used to verify these assignments.

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Electroanalytical Methods-III

O

OH

+ 2H+ + 2e

O

OH Peak D

Interpreting complex cyclic voltammograms is often a challenge best met by the combination of chemical intuition with the study of model compounds, exactly in the same manner used by many spectroscopists to interpret optical, magnetic resonance, or mass spectra.

SAQ 5 What are Coupled chemical Reactions? …………………………………………………………………………………………... …………………………………………………………………………………………...

9.7

SUMMARY

In this unit we have discussed about the elements or compounds determined with the help of polarography in different types of samples like food stuff, sea water, fuels etc. We discussed the polarographic analysis of organic compounds. We studied the given examples of the species determined with the help of amperometric titrations for different titrations and electrodes. We discussed the different polarography experiments using both the calibration curve method and standard addition method. We discussed other industrial important determinations for traces or minor constituents. Lastly we discussed about the application of cyclic voltammetry.

9.8

TERMINAL QUESTIONS

1.

What is the purpose of Polarographic analysis in the case of organic chemistry?

2.

Why is solvent required to first dissolve the organic compounds in case of Polarographic analysis?

3.

Give two examples of amperometric titrations involving precipitation reactions.

4.

Give the details of the polarography experiment for determination of the amount of Cd2+ present in the unknown solution by method of standard addition.

5.

Give briefly the steps involved in voltammetry.

9.9

ANSWERS

Self Assessment Question 1.

78

a)

The commonly used supporting electrolytes which are easily mixed with organic solvents are various quaternary ammonium salts such as tetrabutyl ammonium iodide.

b)

It is also possible to convert the non-polarographic active groups into active polarographic groups and determine them. Refer to Table 9.3.

2.

According to Ilkovic equation id is proportional to concentration keeping all other factors of the equation constant. So, if some of the electroactive material in the solution is removed by interaction with some other reagent (e.g.: EDTA reagent for Zn2+ determination) the diffusion current will decrease. This is the fundamental principle of amperometric titrations or polarographic titrations.

3.

a)

Polarography is used for both organic and inorganic analysis.

b)

In the application of the polarographic method of analysis to steel ferric ion interferes due to its reduction near zero potential in sodium tartrate supporting electrolyte. Fe (III) has to be reduced to Fe (II) with hydrazinium chloride in a hydrochloric acid medium so that Fe (II) is reduced at much negative potential of –1.4 V vs. SCE which is more negative than lead and copper. This is how the interference of ferric ions is prevented.

4.

Fig. 9.1

5.

There are inorganic ions, metal complexes and a few organic compounds which undergo electron transfer reactions without the making or breaking of covalent bonds. The vast majority of electrochemical reactions involve an electron transfer step which leads to a species which rapidly reacts with components of the medium via so called coupled chemical reactions.

Applications of Polarography, Amperometric Titrations and Voltammetry

Terminal Questions 1.

This technique is used in organic chemistry for qualitative and quantitative analysis and structure determinations.

2.

Most of the organic compounds are insoluble in pure aqueous medium and also in mercury to form amalgam. Therefore, the solvent in which the organic compound and its electrode product is soluble is added to the supporting electrolyte.

3.

Examples of amperometric titrations: Titrant Electrode Precipitation reactions Dimethylglyoxime DME Lead nitrate DME

4.

Refer to Section 9.4.2.

5.

Refer to Section 9.5.2.

Species determined

Ni2+ SO42-, MoO42-, F-

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Electroanalytical Methods-III

Further Reading Websites S.No.

Topic An article in Resonance on Polarography by the eminent scientist V. Lakshminarayanan

http://dspace.rri.res.in/bitstream/2289/856/1/2004 %20RES%209%20p51-61.pdf

2.

Anodic Stripping voltammetry

http://www2.chemistry.msu.edu/courses/cem837/ Anodic%20Stripping%20Voltammetry.pdf

3.

Anodic Stripping voltammetry, a very detailed presentation

http://ocw.kfupm.edu.sa/user/CHEM54201/Anodi c%20stripping%20good.pdf

4.

Cyclic Voltammetry

http://www.chemistry.nmsu.edu/studntres/chem43 5/Lab13/

5.

Cyclic Voltammetry

http://www.biol.paisley.ac.uk/marco/Enzyme_Ele ctrode/Chapter1/Cyclic_Voltammetry1.

6.

Details of http://faculty.uml.edu/david_ryan/84.514/Electroc hemLecture11.pdf polarography, pulse polarography and cyclic voltammetry

7.

Linear sweep voltammetry

http://www.chemistry.adelaide.edu.au/external/so c-rel/content/linsweep.htm

8.

Polarography

http://electrochem.cwru.edu/ed/encycl/art-p03polarography.htm

9.

Polarography

http://www.drhuang.com/science/chemistry/electr ochemistry/polar.doc.htm#_Toc172448509

10.

Polarography

http://www.drhuang.com/science/chemistry/electr ochemistry/polar.doc.htm#_Toc172448509

11.

Voltammetry

http://www.amelchem.com/download/items/volta mmetry/manuals/eng/manual_eng.pdf

12.

Voltammetry

http://new.ametek.com/contentmanager/files/PAR/App%20Note%20E-4%20%20Electrochemical%20Analysis%20Techniques 1.pdf

1.

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Web Sites/Books

Books 1.

Polarography and other voltammetric methods by Tom Riley and Arthur Watson, by ACOL, Wiley.

2.

Vogel’s Textbook of Quantitative Chemical Analysis by J. Menham, R.C. Denney, J.D. Barnes and M.J.K. Thomas, 6th Edn, Low Price Edition, Pearson Education Ltd, New Delhi (2000).

3.

Instrumental Analysis, Editors, H.H. Bauer, G.D. Christian and J.E.O’ Reilly, 2nd Edn, Allyn and Bacon, Inc., Boston (1991).

4.

Analytical Chemistry by G.D. Christian, 6th Edn, Wiley-India.

5.

Principles and Practice of Analytical Chemistry by F.W. Fifield and D. Kealey, 5th Edn, Blackwell Science Ltd, New Delhi (2004).

6.

Instrumental Methods of Chemical Analysis by G.W. Ewing, 5th Edn, Mc-Graw Hill, Singapore (1985).

7.

Instrumental Methods of Analysis by Willard Merritt, Dean Sattle, 7e, Cbs Publishers & Distributors.

8.

Polarographic techniques by Louis Meites, Interscience publishers.

9.

Principles of Instrumental Analysis 5th Edition, by Skoog, Holler, Nieman, Thomson Brooks/Cole.

10.

Fundamentals of Analytical Chemistry by Skoog, West, Holler and Crouch, Thomson Brooks/Cole.

11.

Modern Analytical Chemistry by David Harvey, Mcgraw-Hill Education.

Applications of Polarography, Amperometric Titrations and Voltammetry

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