Principle of Sample Preparation for Lindane

In view of the problems described above, various carrier materials for solid phase extraction were tested. Criteria used included the injection of the sample, the distribution on the carrier and the consequent reproducibility of the results. The following carrier materials were tested  

The first three carrier materials were found to be unsuitable. The grain size of the commercially available materials was too small. The material adhered to the blood, so that separation became impossible. The small surface area of the materials prevented distribution on the carrier from occurring. Both whole blood and hemolyzed blood were tested. 

Extrelute consists of coarsely porous diatomite with a granular structure and a high pore volume. This material is supplied in pre-packed columns containing various amounts of material. 

The sample is applied to the carrier material and becomes distributed on the inert carrier matrix as a thin film, so acting as the stationary phase . It is then eluted with an organic solvent immiscible with water. AH lipophilic substances such as lindane are extracted from Hie aqueous phase by the organic phase. The matrix remains on the carrier. 

This sample preparation scheme is the result of a number of experiments, in which, for example, the amount and nature of the solvent was varied. The criterion of quality was the recovery rate. The investigation was also carried out using whole blood and hemolyzed whole blood. The use of hemolyzed blood led to problems in the sample preparation. Here, recovery rates of only 20% could be achieved. In the following discussion, only EDTA (ethylenediamine-tetraacetic acid)-whole blood was used. 

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