Different sample preparation techniques commonly used for the analyses at the Toxicological centre are described below.

Soxhlet Extraction

In Soxhlet extraction, a solid sample is extracted at a high temperature with an organic solvent. By including a reflux cooler the organic solvent continuously evaporates from a solvent container and condenses to flow into the extraction chamber (where the sample and the analytes remain). This cycling process creates a “fresh/clean” extraction solvent throughout the whole procedure. The extraction takes 2 hours (if extraction is used in hot Soxhlet mode) and is usually followed by concentration and clean-up (e.g. Solid Phase Extraction).

Solid Phase Extraction

In Solid Phase Extraction, a solution containing the target compound is loaded onto a sorbent in a cartridge. Target compounds are retained on the sorbent if their affinity for the sorbent is higher than for the solution. This technique can be applied both for extraction of drugs, drugs of abuse, and contaminants from fluids and for clean-up of extracts (after Soxhlet or liquid-liquid extraction). 

Micro Solid Phase Extraction


Liquid-liquid extraction

Liquid-liquid extraction employs differences in affinity of a specific compound for two immiscible solutions. Many drugs, drugs of abuse, and contaminants have a higher affinity for an organic solvent than for water and are easily extracted from blood for instance by adding a solvent. It is a quick approach for sample preparation, but can make part of a longer sample preparation protocol.