The decrease in the total number of positive

Forensic-toxicology; Analysis; Formalin; Tissue; GC–MS; Sulfoxide
1. Introduction
In forensic toxicology, the investigation of drug from tissues, both before and after preservation in formalin solution, is a critical matter. Some research on drug analysis in formalin-fixed human VX689 has been published [1], [2], [3] and [4]. However, to our knowledge, few studies [5] and [6] have reported data from both before and after preservation of a given specimen, since analysis often is performed only after preservation. Notably, in cases where drug abuse or exposure is not suspected, specimens for toxicological analysis may not be collected at the time of autopsy. If toxicological analysis is subsequently required after months or years, only formalin-fixed tissues, which were preserved in fixative for histological examination, may be available for analysis.
It is known that some drugs are decomposed or converted into other compounds in formalin solution during preservation [7] and [8]. Therefore the interpretation of quantitative data of drugs obtained from tissues fixed in formalin solutions requires careful attention.