Steam Distillation
Definition
Passing live steam through a sample so that volatile organic compounds co-distil with water at a temperature below their own boiling point. The standard route for phenol, cresols, nicotine, aniline, salicylates and camphor that would char if heated directly.
- Core principle
- Volatile compounds co-distil with water vapor at temperatures below their boiling points
- Common applications
- Extraction of ethanol, methanol, phenol, chloroform, formaldehyde, and cyanide from viscera
- Key advantage
- Prevents heat-sensitive compounds from charring during extraction
Common questions
What is steam distillation used for in forensic toxicology?+
Steam distillation extracts volatile poisons like ethanol, methanol, phenol, and cyanide from tissue samples. The technique passes steam through the sample so volatile compounds evaporate below their normal boiling points, keeping them from being damaged by heat.
Why use steam distillation instead of heating directly?+
Some compounds like phenol, cresols, nicotine, and camphor will char or degrade if heated directly to their boiling point. Steam distillation keeps the temperature lower while still releasing the volatile compounds, so they survive the extraction intact.
Which forensic poisons can be extracted by steam distillation?+
Common targets include phenol, cresols, nicotine, aniline, salicylates, camphor, chloroform, nitrobenzene, and formaldehyde. Cyanide can also be extracted using steam distillation with sulfuric acid.
Related terms
- Conway Microdiffusion Cell
- A two-compartment glass or ceramic dish with a central well and an outer ring, sealed at the rim. The poison is released...
- ASE
- Accelerated solvent extraction (Dionex ASE). Pressurised solvent at elevated temperature pushes the analyte off the tissue matrix in minutes, replacing overnight Soxhlet.
- Dialysis
- Separation of small molecules from large ones across a semipermeable cellulose membrane. In forensic toxicology, used for clean-up of blood and plasma...
- Equilibrium Dialysis
- Variant in which the drug is allowed to redistribute across the membrane until the unbound concentration on both sides is equal. The...
- MWCO
- Molecular weight cut-off, the nominal size above which the membrane retains solutes. Forensic dialysis tubing typically uses 12 to 14 kDa MWCO,...
- QuEChERS
- Quick, Easy, Cheap, Effective, Rugged and Safe sample-prep protocol for pesticide residues. Acetonitrile extraction, MgSO4 + NaCl partition, dispersive SPE clean-up with...
- Simple Distillation
- Heating an aqueous sample in a round-bottom flask and collecting the condensed vapour. Used for volatiles that boil below 100 degrees C...
- SLE
- Supported liquid extraction. Diatomaceous earth columns absorb the aqueous sample as a thin film and a single pass of organic solvent elutes...
- SPE
- Solid-phase extraction. Sample is loaded onto a packed sorbent cartridge (C18, mixed-mode MCX/MAX, polymeric Oasis HLB), washed and selectively eluted. The dominant...
- SPME
- Solid-phase microextraction. A polymer-coated fused-silica fibre (typically PDMS or PDMS-DVB) is exposed to vial headspace, then thermally desorbed in the GC injector....
- Stas-Otto Procedure
- Classical 1851/1856 acid-base liquid-liquid fractionation. Acidify with tartaric acid and extract acidic and neutral organics into ether, then alkalise and extract bases...
- Viscera
- The standard set of organs and fluids collected at a suspected poisoning autopsy in India: stomach with contents, a length of upper...
Explained in these topics
- Distillation, Microdiffusion and Dialysis TechniquesPassing live steam through a sample so that volatile organic compounds co-distil with water at a temperature below their own boiling point. The standard route...
- Extraction, Isolation and Clean-up of Poisons from VisceraCo-distillation of volatile poisons with water vapour at temperatures below their pure boiling points. Used for ethanol, methanol, phenol, chloroform, nitroben...