A new clean-up approach for stomach content toxicological analysis

Abstract

Stomach content is a matrix often applied in post-mortem cases. It is especially important in oral intoxication cases. The main advantages are the usually high concentration of analytes and the lack of biotransformation process. Still, even with extensive sample preparation, the final extract is not always suitable for analysis. The aim of this study was to develop an alternative method using QuEChERS for the extraction of drugs and pesticides from postmortem stomach content. Sample preparation started acetonitrile with 1% of acetic acid and QuEChERS salts. Later, the initial extract was cleaned-up using the EMR-Lipid sorbent. Residual water was withdrawn with MgSO4/NaCl in the third step and a final step with MgSO4. Vigorous shaken and centrifugation was performed after each step. The final supernatant was evaporated, re-suspended, and injected into GC–MS in full scan mode. This approach was successfully applied to stomach content, resulting in clean extracts, with low lipid levels. The method was able to detected target drugs and pesticides (cocaine, tramadol, diazepam, amytriptiline, phenobarbital, prochloraz, diazinon, heptachlor, permethrin, malathion and carbaryl) at the limit of detection of 0.1 mg/g or 0.1 mg/L. Recovery was over 70% for the majority of analytes, precision and accuracy was within acceptable range. The method was also applied to real forensic cases and carbofuran, terbuphos and fluoxetine was detected likewise. This work demonstrates that this method can provide an effective clean-up in high lipids samples such as stomach content, and can be used to analyze of pesticides and drugs in forensic cases.