Question

Which of the following is the detection limit of the coulometric method used for measurement of sulphur dioxide?

(a) 0.1 ppm

(b) 1 ppm

(c) 2 ppm

(d) 0.01 ppm

The question was posed to me in an international level competition.

My question comes from Sulphur Di-oxide Monitoring in section Pollution Monitoring Instruments of Analytical Instrumentation

Answer 1

Right option is (d) 0.01 ppm

To explain I would say: The detection limit of the coulometric method is 0.01 ppm. The shift in anode cathode potential is detected by a third electrode.