Simple Distillation
Definition
Heating an aqueous sample in a round-bottom flask and collecting the condensed vapour. Used for volatiles that boil below 100 degrees C without decomposing, including ethanol, methanol, chloroform and acetone.
- Apparatus
- Round-bottom flask with condenser
- Applicable range
- Volatiles boiling below 100 degrees C, non-decomposing
- Typical analytes
- Ethanol, methanol, chloroform, acetone
- Field
- Forensic toxicology sample preparation
Common questions
When is simple distillation unsuitable for a toxicology sample?+
It fails for analytes that decompose near or below their boiling point, or for compounds with boiling points too close together to separate cleanly, in which case steam distillation or microdiffusion is used instead.
How does simple distillation differ from microdiffusion?+
Simple distillation collects a bulk condensed vapour fraction from heated liquid, while microdiffusion relies on a volatile analyte passively diffusing across a sealed chamber into a trapping reagent at room or gentle heat, which suits smaller or more delicate samples.
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...
- 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,...
- Steam Distillation
- Passing live steam through a sample so that volatile organic compounds co-distil with water at a temperature below their own boiling point....