Exercises for HPLC1)Haddad and associates report the following capacity factors for the reverse-phase separation of salicylamide (k sal) and caffeine (k caff). %v/v methanol 30% 35% 40% 45% 50% 55% 2.4 1.6 1.6 1.0 0.7 0.7 4.3 2.8 2.3 1.4 1.1 0.9Explain the changes in capacity factor. What is the advantage of using a mobile phase with a smaller %v/v methanol? Are there any disadvantages?2) Suppose that you are to separate a mixture of benzoic acid, aspartame, and caffeine in a diet soda. The following information is available to you.in Aqueous Mobile Phase Buffered to a pH ofCompound 3.0 3.5 4.0 4.5benzoic acid 7.4 7.0 6.9 4.4aspartame 5.9 6.0 7.1 8.1caffeine 3.6 3.7 4.1 4.4(a) Explain the change in retention time for each compound.(b) Plot retention time versus pH for each compound on the same graph, and identify a pH level that will yield an acceptable separation.3) The composition of a multivitamin tablet is conveniently determined using an HPLC with...