Optima grade water, methanol (MeOH) and acetonitrile (MeCN) were purchased from Fisher Scientific (Fair Lawn, NJ, USA). Ammonium acetate (NH4Ac) (>98%) was obtained from Anedra (Argentina), and formic acid (96%) was obtained from Tedia (Fairfield, OH, USA). Immunoaffinity columns (AFLAPREP M) were supplied by R-Biopharm Rh one (Glasgow, Scotland).