Structure elucidation and quantification of impurities formed between 6-aminocaproic acid and the excipients citric acid and sorbitol in an oral solution using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.

•6-aminocaproic acid, citric acid and sorbitol were investigated at 20 and 50–80°C.•An amide reaction product, dimer and caprolactam were identified with HR–MS and NMR.•Minor amounts of degradation products of 6-aminocaproic acid were also observed.•The stability study at 80°C represents normal storage conditions at 20°C.