Metformin HCl — analytical method note
Working notes for using the Metformin HCl reference standard (CAS 1115-70-4, C4H12ClN5, 165.62 g/mol) in HPLC-UV assay, system-suitability and impurity-profiling work.
Purpose of the standard
The Metformin HCl standard is released against a written specification of ≥ 99.9% (HPLC verified) and is intended for retention-time confirmation, response-factor determination, system-suitability checks and impurity profiling.
It is not a certified reference material: purity is reported as a chromatographic value rather than an assigned value with an uncertainty budget.
Standard preparation
Reported solubility: Water ≥ 50 mg/mL. Prepare stock solutions in the solvent that matches your mobile-phase composition to avoid injection-peak distortion.
Allow the vial to equilibrate to room temperature before opening to prevent moisture uptake, weigh on a calibrated balance, and record the lot number of the standard against the prepared solution.
Chromatographic conditions
A C18 reversed-phase column with a gradient of acidified aqueous phase and acetonitrile, UV detection at 254 nm, is the usual starting point for this class of standard. Confirm wavelength against the compound's own absorbance maximum before quantifying.
Identity is confirmed orthogonally by LC-MS in positive electrospray, with the observed molecular ion consistent with a molecular weight of 165.62 g/mol.
Storage, stability and documentation
Storage condition for this lot: Store at 2–8 °C, desiccated.. Stock solutions should be requalified rather than assumed stable across storage intervals.
Retain the certificate of analysis with the lot number, manufacture date and retest date so every assay result can be traced back to the lot that produced it.
Method notes are supplied as analytical guidance for in-vitro laboratory research and analytical testing only. They are not a validated method and not a recommendation for any use in humans or animals.