The HILIC method was adapted from Want et al. , employing a simple and reliable unbonded ethylene bridged hybrid (BEH) particle (Waters Corp., Milford MA, USA) as the stationary phase. The mobile phase composition was adapted to use a pair of unblended solvents, eliminating the need for accurate volumetric preparation of a disproportionate (95:5 organic solvent-to-water) mix sensitive to even minor compositional variation. The ultra-high performance liquid chromatography (UHPLC) instrument is instead used to mix the solvent pair during use in an accurate and reproducible manner, achieving the desired initial conditions for maximal analyte retention. The aqueous solvent is prepared with 20mM ammonium formate and both solvents are prepared with 0.1% formic acid, resulting in an ionic strength gradient across the separation. Importantly, this precludes the need to force volatile buffer salts into bulk solution with a mostly organic solvent which in our experience is an unreliable practice. The result is easy and efficient solvent preparation that yields exceptional separation reproducibility among solvent batches and experiments. The gradient used follows the same principle employed in the RPC method of higher flowrate and longer column, the latter being especially useful for HILIC because of the near-isocratic conditions used. The method is used with positive mode ion detection only.