Mass spectrometric and kinetics characterization of modified species of Growth Hormone Releasing Hexapeptide generated under thermal stress in different pH and buffers

•pH and thermal stress study (pH 3.0–8.0, 60 °C, 35 days) of GHRP-6 is presented.•Hydrolysis, cyclization and acylation as the main degradation pathways.•Formaldehyde derived from additives/elastomeric closures modifies the N-terminus.•Buffers “Generally Recognized as Safe” contribute to product heterogeneity.•Kinetic analyses for the generation of all modified species were determined.