Identification of N,N-dimethylamphetamine formed by methylation of methamphetamine in formalin-fixed liver tissue by multistage mass spectrometry

Analysis, Stability and Distribution of Pharmaceuticals and Drugs of Abuse over a Period of One Year in Formalin-Fixed Liver and Formalin Solutions

The present study reports a thorough research on the stability of drugs of abuse and pharmaceuticals over a time period of 12 months. Fixed-liver tissues and formalin solutions where the tissues were preserved were analyzed using an ultra high performance liquid chromatography--tandem mass spectrometry method that has been developed and validated for this purpose. The method monitors 84 drugs in a 13-minute run. The concentrations of the drugs found were compared with their concentrations determined in the fresh liver tissues in a previous study. In the study, 14 cases with forensic interest were included with the main objective of the analysis and the study of the stability and the distribution of drugs of abuse and pharmaceuticals in the human liver and the formalin solution during preservation. The results showed that the number of detected compounds in the first month was significantly lower than the compounds found in fresh tissues. The effect of formalin was catalytic, and few substances could be detected. Specifically, out of the 86 positive detections of the monitored substances in the fresh tissues (in which 25 different substances were found), only 32 (37%) remained detectable 3 months after, 20 (23%) 6 months after and 15 (17%) 12 months after.

Forensic toxicological analyses of drugs in tissues in formalin solutions and in fixatives

Forensic toxicological drug analyses of human specimens are usually performed immediately after autopsy or on frozen preserved tissues. Occasionally, cases require analysis of drugs from tissues fixed in formalin solution. To improve the estimation of the level of drug in tissues following formalin fixation, we studied drug concentrations in human tissues, liver and kidney, that were collected from a drug-positive autopsy case. Parts of tissues were preserved in formalin solution for 1, 3, 6 and 13 months. Tissues obtained before and after preservation, along with tissue-exposed fixatives, were assayed using gas chromatography-mass spectrometry; all of the samples were assayed for the presence of drugs and changes in the drug concentrations both before and after preservation in formalin. Concentrations of assayed drugs decreased upon fixation in formalin; levels of these drugs did not necessarily show further decreases during subsequent storage in fixative, up to 13 months. Distinct trends in drug levels were found in liver and kidney. In liver, the levels of chlorpromazine, levomepromazine, and promethazine decreased to 23-39% at 1 month after preservation; all 3 of these drugs were detected at all tested time points of preservation. Bromazepam was not detected at 13 months after preservation. Milnacipran was the most unstable after preservation in formalin solution among all of the assayed drugs. In kidney, all assayed drugs exhibited reduced stability during preservation compared to levels in liver. Methamphetamine and methylenedioxymethamphetamine were not detected in any time points of tissues. The proportions of the drugs that remained within the tissues differed between liver and kidney. Also, S-oxide compounds of chlorpromazine and levomepromazine, which were not observed before preservation, were detected in fixed liver tissues and their fixatives at 3, 6 and 13 months of preservation. These results suggest that analyses in formalin-fixed tissues need to include analysis of various organ-tissues and their fixatives at multiple time points for the duration of preservation. These analyses should include detection of chemical degradation/denaturation products, such as S-oxides of chlorpromazine and levomepromazine.

Stability of cocaine in formalin solution and fixed tissues

Embalming and formalin fixation are common, and yet they can create problems for the forensic scientist if a drug has been the cause of death and if the only available specimens to be analyzed are formalin-fixed tissues. Previous studies have demonstrated that during fixation xenobiotics are extracted into formalin according to tissue and fixing solution characteristics. In some cases formalin can react with the analyte resulting in the production of new chemical entities. Regarding cocaine and its metabolites, Cingolani et al. have reported that formalin-fixation extracts benzoylecgonine (BE) from tissues and that BE is stable in the fixing solution. However, the stability and kinetic properties of cocaine remain so far unexplored. Our data show that in buffered formalin (pH 7.4) cocaine is hydrolyzed to BE in agreement with a pseudo first-order reaction kinetic (half-life time approximately 7 days), whereas in unbuffered formalin (pH approximately 3.5) it is relatively stable over a period of 30 days. The analysis of brain and liver samples at different fixation times indicates that during fixation an extraction process occurs for both analytes and that the extraction is more efficient in the liver than in the brain, probably because of a greater lipophilicity of the brain tissue. In conclusion, our study demonstrates that formalin-fixed tissues and their fixing solutions can be used for cocaine analysis only if a short time period has passed since the fixation beginning. The rapid extraction process of cocaine into formalin and the concomitant hydrolysis to BE occurring in buffered formalin may prevent the identification of cocaine in both tissues and formalin solution already at 15-30 days after fixation. Moreover, the unpredictable extraction rate of both analytes, along with the hydrolysis of cocaine into BE significantly affects tissue concentrations, thus complicating the interpretation of quantitative results.