What is the pH at the end of an enzyme-catalyzed reaction if it were carried out in a 0.1 M buffer initially at pH 2.12, and 0.004 M of acid (H⁺) was produced during the reaction?

(The buffer used was a polyprotic acid of the general form: H₃A; the 3 pK_as of this polyprotic acid are 2.12, 6.54, and 11.32.) Please answer to the nearest hundredths.