Toxicological analyses of medications and chemicals in formalin-fixed tissues and formalin solutions: a review.

Toxicological analyses of medicines and chemicals in formaldehyde-treated specimens are a component of forensic toxicology. This review involves two parts: (i) reactions of formaldehyde with substances in tissues fixed with formalin (aqueous formaldehyde solution) and (ii) the stability of substances in formalin-treated tissues and formalin solutions. Because it was well known that formaldehyde reacts with amines to form Schiff bases, it was additionally suggested in 1998 that formaldehyde reacts with primary and secondary amines together with formic acid to form N-methyl substances via the Eschweiler-Clarke conversion, which proceeds at room temperature. The reaction increases with pH and the concentration of formaldehyde. In addition, this report includes both experimental studies and practical cases involving embalmed bodies.