Formic acid is a popular eluent additive used to adjust eluent pH or protonate organic compounds for mass spectrometric detection. The buffering range of formic acid is between pH 2.77-4.77 and serves as an appropriate buffer for mild acidification over harsher options like phosphoric acid. Perhaps the most common concentration of formic acid-based eluent is 0.1% by volume and is sold commercially; although, methods have been reported with using elevated concentrations up to 0.3% (v/v) . However, in our experiments, a standard amount of dilute (0.1%) formic acid failed to fix the charge state of the analyte and resulted in characteristic twin peaks or poor separation. As well, more dilute formulations suffered from the same lack of resolution. For psilocybin, low buffering agent concentration avoids potential degradation of the analyte as is observed at more extreme pH levels using formic acid.