Conversion of sertraline to N-methyl sertraline in embalming fluid: a forensic implication

Zoloft (sertraline hydrochloride) is one of the antidepressant medications used to treat depression, obsessive-compulsive disorder, and social anxiety disorder. The practice of embalming a cadaver is common, yet it may create problems for forensic toxicologists if the case was not previously suspected to involve drug overdose. According to the Eschweiler-Clarke reaction, drugs containing a secondary amine group react with formaldehyde to give N-methyl derivatives. Sertraline has a secondary amine group; therefore, we predicted that it may react with formalin to give N-methyl derivatives. The stability of sertraline in formalin solution was studied at three different concentrations (5%, 10%, and 20%) and at three different pHs (3.0, 7.0, and 9.5) for a period of 30 days. Setraline and its degraded products were extracted by liquid-liquid extraction using chloroform, and the concentrated extracts were analyzed by gas chromatography-mass spectrometry using electron impact ionization mode. The rate of conversion is rapid at higher pH. Sertraline was totally converted to the N-methyl derivative after 30 days in 10% and 20% formalin solutions at neutral and basic conditions. Therefore, forensic toxicologists should be cautious when performing a death investigation if formalin solution is the only sample available for analysis. This work shows that analysis for parent drug or its N-methyl derivative may provide data that will reduce the likelihood of false negatives.