1. Electroanalytical Chemistry Chapter 3

2. Best seen broken into four categories Part 1: Ion Selective Electrodes Part 3: Step Voltammetry Part 2: Amperometric Sensors Part 4: Cyclic Voltammetry

3. Electroanalytical devices that measure concentration of a selected ion in a sample by virtue of electric potential difference due to concentration of that ion. There are many applications (cba to list) And many analytical advantages! (again cba to list) Naming is Trivial!!!!!! ISE to detect F - Fluoride selective electrodes ISE to detect Ca 2+ Calcium selective electrodes etc Note ISE to detect H + pH electrodes (1) Ion Selective Electrodes

4. General Outline of an ISE Morgan. T. 2014, Summary of Electrodes, www.che-revision.weebly.com

5. Click button below to visit the ‘Summary of Electrodes’ page on the revision website. Just re-open the presentation afterwards. If you are confident enough on this topic (AS IF!!!!!) then alternatively continue through the presentation. The different types of ISE Summary of Electrodes at CHE- Revision Highly Recommended! Documentary on The Crazy Nastyass Honey Badger Not Recommended! May result in procrastination

6. How do ISEs Work? Nernst Equation

7. Prediction of Nernstian Responses E ISE Log 10 [X] E ISE Log 10 [X] For a Uni-Cation (ie Na + ) at 25’C For a Di-Anion (ie O 2- ) at 25’C Gradient = 0.059 V per log 10 [X] Gradient = - (0.059/2) V per log 10 [X]

8. A Ca 2+ selective electrode reads an E ISE value of 0.473 V in a sample containing 3 x 10 -3 M Ca 2+ at 25’C. Calculate Cell constant for this electrode. Example Questions

9. Calculate E ISE for this electrode in a sample containing 30 x 10 -2 M Ca 2+ at 25’C. Note Cell constant was calculated to be 0.547 V Example Questions

10. What is the Ca 2+ concentration when E ISE reads 0.347 V at 25’C? Note Cell constant was calculated to be 0.547 V Example Questions

11. Can you describe what an ISE is to someone who knows nothing about chemistry? How do you name them? Can you illustrate a simple design of an ISE? Can you recall all the different types of ISE with illustrations? Do you remember and can you use the Nernst Equation? Can you predict graphical responses of Nernst relationships? What do you need to know Best go back and revise it again then!

12. Best seen broken into four categories Part 1: Ion Selective Electrodes Part 3: Step Voltammetry Part 2: Amperometric Sensors Part 4: Cyclic Voltammetry

13. Electroanalytical devices that measure the concentration of a selected redox active species in a sample. Concentration determined by virtue of flow of electrical current due to oxidation or reduction. There are many applications of Amperometric Sensors Dissolved Oxygen Glucose Neurotransmitters They also have many analytical advantages (same as ISE) BUT MORE EFFECTED BY SURFACE DETERMINATION (revisit later) (2) Amperometric Sensors

14. Really? If you want me to go through this, I don’t even think you should be here :L But ill explain briefly: Remember GCSE: OILRIG Lets try some questions! Is species A reduced or oxidised? A - + B  A + B - Its OXIDISED AS ITS LOST AN ELECTRON! That is it! Oxidation and Reduction

15. Oxidation / Reduction in Solution and at electrode surface Can you spot the mistake? Solution No net direction of electron transfer Electrode All electron transfer in same direction to give a flow of electrical current! TADA!

16. Click button below to visit the ‘Summary of Electrodes’ page on the revision website. Just re-open the presentation afterwards. If you are confident enough on this topic (AS IF!!!!!) then alternatively continue through the presentation. The different types of Amperometric Sensors Summary of Electrodes at CHE- Revision Highly Recommended! Documentary on The Crazy Nastyass Honey Badger Not Recommended! May result in procrastination

17. Direction of Current

18. Equation on Amperometrics

19. Dopamine is oxidised in a two-electron process that has a reduction potential E 0 of 0.2 V vs SHE. Which of the potentials below would be best applied to a sample to induce dopamine oxidation at 25’C? Questions on Amperometrics

20. Calculate the percentage of dopamine at the electrode surface when it has equilibrated at the potential given to your answer above. Questions on Amperometrics

21. Relationships between Current and Concentration

22. A clark electrode with a sensor electrode area of 0.2 cm 2 measured a current magnitude of 10 x 10 -8 Amps in a stirred solution containing 10x10 -6 M dissolved oxygen. What is the dissolved oxygen concentration in a stirred solution for which the same clark electrode measured a current magnitude of 3 x 10 -8 Amps? Questions on Amperometrics

23. A clark electrode with a sensor electrode area of 0.2 cm 2 measured a current magnitude of 10 x 10 -8 Amps in a stirred solution containing 10x10 -6 M dissolved oxygen. What current magnitude is predicted to be measured in a stirred solution containing 10x10 -6 M dissolved oxygen with a clark electrode having sensor electrode area of 0.05 cm 2 ? Questions on Amperometrics

24. A clark electrode with a sensor electrode area of 0.2 cm 2 measured a current magnitude of 10 x 10 -8 Amps in a stirred solution containing 10x10 -6 M dissolved oxygen. What is the sign (positive or negative) of the current measured during the detection of oxygen with a clark electrode? Questions on Amperometrics

25.  Can you describe an amperometric sensor to someone who doesn’t do chemistry?  Do you know the principals of oxidation and reduction?  Do you know the direction of current and their signs?  Can you illustrate the basic design of an amperometric sensor and recall different types?  Can you recall and use equations of relationships between sensor response and concentrations? What do you need to know? Best go back and revise it again then!