Forensic Science Ireland (FSI) has developed a method to extract commonly targeted drugs and drug metabolites from urine samples related to sexual assaults. Solid phase extraction methods are used before performing screening analysis via LCMSMS. The sample eluent is allowed to evaporate completely.
As part of its validation process, FSI assessed the application of the Genevac EZ-2 personal evaporator as an optional approach (Figure 1). In traditional blow down evaporation, gases like nitrogen are used. In contrast, Genevac’s EZ-2 system prevents the need for such gases, but also reduces reformatting stages and sample handling tasks.
Figure 1. Genevac EZ-2 Evaporator. Image credit: SP Scientific
Choice of Evaporation Procedure
Traditionally a nitrogen blow down system is used for evaporation of the analytes. However this method causes deposition on the tube sides and, with a reconstitution volume of only 200µl, all the analytes could not be resuspended. In order to realize maximum recovery, sequential evaporation in the MS analysis vial is required.
In the EZ-2 system, the solvent is boiled at low temperature under vacuum conditions. During evaporation, the samples are centrifuged at 500G, depositing the dried analyte at the bottom of the tube. Therefore, reconstitution is possible even in low volumes.
The experiments show that with the EZ-2 system, evaporation is simplified. Sample integrity is sustained with minimum time devoted to evaporation process. Better sensitivity without cross contamination is achieved, indicating the advantages of evaporation using the EZ-2 when compared to traditional evaporation techniques.
Produced from materials authored by Paula Clarke1 and Alison Wake2 from:
1 Forensic Science Ireland, Garda Headquarters, Dublin, Ireland
2 Genevac Ltd, Ipswich, UK
Genevac's high performance centrifugal solvent evaporator systems are designed for use in chemistry, biology and analytical science applications and are in use in laboratories worldwide.
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