Question 21 5 Points a) Discuss in details the various methods that can be used to increase the selectivity factor of a chromatographic column.(2 points) b) Compare the external standard method with the internal standard method used in chromatographic quantitative analysis. Explain each method and list the advantages and the disadvantages of each (2 points) c) Explain the use of an eluent suppressor column in ion chromatography. (2 points) Use the editor to format your