The production of amitriptyline from nortriptyline in formaldehyde-containing solutions

J Anal Toxicol. 1990 Sep-Oct;14(5):325-6. doi: 10.1093/jat/14.5.325.


The stability of nortriptyline in aqueous solutions containing various concentrations of formaldehyde was investigated. Amitriptyline, as a reaction product, was determined by gas chromatography/mass spectrometry (GC/MS) in these experiments. Factors that may contribute to this phenomenon, including pH, formaldehyde concentration, and incubation time were evaluated. At 40% (v/v) formaldehyde concentration and pH 4, there was a 68% decrease in nortriptyline concentration along with a concomitant formation of amitriptyline after 24 h. The N-methylated product was responsible for 48% of the total tricyclic drug present. The data also clearly indicate that the formation of amitriptyline is favored at elevated pH.

MeSH terms

  • Amitriptyline / analysis
  • Amitriptyline / chemistry*
  • Embalming
  • Formaldehyde / chemistry*
  • Gas Chromatography-Mass Spectrometry
  • Hydrogen-Ion Concentration
  • Nortriptyline / analysis
  • Nortriptyline / chemistry*


  • Amitriptyline
  • Formaldehyde
  • Nortriptyline