Identifying chloroform at trace levels in biological postmortem samples and other suspect items associated with criminal activities is a critical factor in toxicology.
This observation was made in an article on “A novel technique to detect chloroform at trace levels in biological specimens and other items” which was authored by L.S. Hathurusinghe, A. Welianga, W.D.V. Karunaratne and T.R.M.C.D. Menike (all four attached to the Government Analyst's Department) and published in the Sri Lanka Journal of Forensic Medicine, Science and Law's 11th Volume's Second Issue in December 2020.
Chloroform (Trichloromethane, CHCI 3) is used in the chemical industry for synthetic purposes and laboratories as an extraction solvent. Hence, people have free access to chloroform which can be used for criminal activities. Chloroform, as mentioned in Y. Gaillard, M.F. Masson-Seyer, M. Giroud, J.F. Roussot, and J.M. Pervosto's “A case of drug facilitated sexual assault to death by chloroform poisoning”, C. Richeval, D. Allorge, V. Lopez, B. Boyer and J. Gaulier's “Unusual case of drug facilitated sexual assault using chloroform”, N. Sridhar, C. Krishnakishore, Y. Sandeep, P. Sriramnaveen, Y. Manjusha and V. Sivakumar's “Chloroform poisoning- A case report”, and F. Huq's “Molecular modelling analysis of the metabolism of chloroform”, is commonly known as a knockout drug as it has a sedative property that causes instantaneous central nervous and respiratory system depression. Historically, chloroform had been used as a surgical anaesthetic. However, its use has become obsolete, per C. Lionte's “Lethal complications after poisoning with chloroform – Case report and literature review”, due to adverse side effects such as hepatic (liver) and renal (kidneys) cancer. Chloroform induced toxicity is due to the production of reactive metabolites during the metabolism of chloroform in the liver and the kidneys. As noted in Y. Seto, N. Tsunoda, H. Ohta and T. Shinohara's “Determination of chloroform levels in blood using a headspace capillary gas chromatographic method (a sampling and/or injection technique involving the indirect determination of volatile constituents in liquid or solid samples by analysing the associated vapour phase)”, J.P. Payne's “The criminal use of chloroform”, M. Riße, F. Erdmann, H. Schutz and G. Weiler's “Multiple homicides as a result of chloroform poisoning: Case report and experimental study” and R.J. Flanagan and D.J. Pounder's “A chloroform related death: Analytical and forensic aspects”, there have been several cases reported on chloroform poisoning by forced inhalation during criminal activities such as homicide, suicide and sexual assault.
In the early days, as pointed out in C.R. Vogt, J.C. Liao and A.Y. Sun's “Extraction and determination of chloroform in rat blood and tissues by gas chromatography – Electron capture detection: Distribution of chloroform in the animal body”, steam distillation or organic solvent extraction methods were used to extract chloroform from blood and gas chromatograph with electron capture detector or colourimetric methods were used for its detection. Later, a few methods using the headspace gas chromatograph coupled with a mass spectrophotometer (an instrument that measures the amount of photons [the intensity of light] absorbed after it passes through a sample solution where the amount of a known chemical substance [concentrations] can also be determined by measuring the intensity of light detected) detector have been reported for the determination of chloroform in trace levels. Only a single method acquired more sensitive single ion monitoring mode for the quantitative analysis.
Hathurusinghe et al. describe a more reliable method for the detection of chloroform in post-mortem specimens and related items where a sensitive and selective headspace gas chromatography - mass spectrometric method (HS-GC/MS) for the detection of chloroform at trace levels in biological specimens and other items was developed.
Case one
A woman declared that her former boyfriend smothered her with a cloth soaked in some chemical. She had fallen asleep with intermittent spells of wakefulness during which she had screamed for help. Neighbours had heard her screams and entered the house with others. The victim had been lying naked with her hands and legs tied to a bed. The Police was informed immediately. The investigation revealed a piece of cloth on one of the pillows, a screw capped bottle containing a colourless liquid and used condoms. The piece of cloth and the bottle were sent to the Forensic Toxicology Laboratory of the Government Analyst’s Department for toxicological investigation. During this time, the suspect was apprehended.
Case two
A 30-year-old male was found hanging in his residence. His nose and mouth were said to have been covered with a face mask with a plastic cup inserted. Post-mortem blood and an empty bottle found at the scene were sent to the Laboratory for toxicological investigations.
The developed technique was applied to these two cases and was found to be acceptable with respect to all the validation parameters.
On the toxicological analysis of the samples in the first case, 422 milligrams per litre (mg/L) of chloroform was identified in the liquid in the suspected bottle and traces of chloroform were detected on the piece of cloth. Analysis of the samples in the second case revealed the presence of chloroform. The post-mortem blood contained 72 mg/L of chloroform and traces in the empty bottle. R.C. Baselt and R.H. Cravey's “Disposition of toxic drugs and chemicals in man” reported that concentrations of chloroform ranging from 10-194 mg/L with an average of 64 mg/L have been found in fatal cases. Chloroform levels of 73 to 115 mg/L have been reported in the post-mortem blood of homicides. Further, K. Meichsner, R. Lessig, K. Müller and H.J. Wehran's “Suicidal chloroform poisoning” reported that 47 mg/L of chloroform was found in the post-mortem blood of suicidal poisoning by chloroform inhalation. Chloroform exposure was lethal for the victim of suicidal hanging in the second case.
The reported cases were the first cases where trace levels of chloroform were identified in blood and objects in Sri Lanka using headspace gas chromatography mass spectrometry.
The study illustrates that chloroform can be detected and quantified at trace levels from blood. Further, the analytical findings provide corroborative evidence as to the criminal intent.