Application Notes

Application Notes

AppNote 5/2006: Stir Bar Sorptive Extraction Based on Restricted Access Material for the Direct Extraction of Drugs and Metabolites in Biological Fluids


An experimental biocompatible stir bar sorptive extraction (SBSE) device was prepared using a restricted access material (RAM) as the SBSE coating. The biocompatible SBSE approach was advantageous in terms of simplifying the sample preparation procedure. The RAM-SBSE bar was able to simultaneously fractionate the protein component from a biological sample, while directly extracting caffeine and its metabolites;
overcoming the present disadvantages of direct sampling in biological matrices by SBSE, such as fouling of the extraction coating by proteins. Analytical Figures of Merit for Caffeine Determination in Plasma:
– Limit of detection (s/n = 3) for caffeine = 25 ng/mL
– Linear over the range of 0.5-100 μg/mL (R2 = 0.9981)
– Injection repeatability and intra-assay precision % R.S.D.
< 8% The RAM-SBSE device was simple to use, robust and reuseable with over 50 direct extractions of caffeine and its metabolites in biological fluids without significant signal loss.


SBSE, Drugs, Metabolites, Biological Fluids