2. Analysis and Chromatography

Question 1

What is coulometry?

Answer 1

Coulometry is macro-electrochemistry, and it is based on counting the electrodes of a redox reaction.
This is a very precise and sensitive method.

Question 2

What is amperometry?

Answer 2

Amperometry uses two electrodes. The amperiometric biosensors are classied as one of the
following two: mediated electron transfer and direct electron transfer.

Question 3

What are the 3 electrodes in the 3 electrode cel?

Answer 3

Working electrode: polarizable metal electrode.
Reference electrode: non-polarizable for small currents - constant potential.
Auxiliary electrode: current flows between WE and AE.

Question 4

What are the advantages of ion selective electrodes?

Answer 4

• 4 to 6 orders of magnitude
• Does not consume unknowns
• Negligible contamination
• Fast response and automization
• Color and turbidity do not interfere
• Low price

Question 5

What are the disadvantages of ion selective electrodes?

Answer 5

• Electrodes can be fouled
• Interference problems (important to know selectivity coefficients)
• Some electrodes have short life
• High ionic strength needed to use conc. instead of activities