HPLC-grade deionized water and acetonitrile were purchased from Thermo Fisher Scientific and used as eluents without further purification. The aqueous eluent was prepared, as needed, with a concentration of 0.143 mM ammonium formate (Sigma Aldrich, reagent grade, 97%,). Analytical grade formic acid was used for eluents in initial eluent composition experiments (Fisher 99.0+%, Optima™ LC/MS Grade). Psilocybin (99.977%) was purchased from Psygen Labs and used without further purification. Blanks analyzed in-between replicates ensured the column was free from impurities for backto-back injections.