Background: Promising results in animals have shown the diagnostic potential of polypyrrole coated SPME fibres introduced directly into the blood stream. This study was intended to extend this technique to a clinically relevant antibiotic drug under close to physiological conditions in human blood.
Methods: An artificial vein system was built up from heart and lung machine components. Determination of Linezolid (0-15 mug/mL) was performed by SPME from the flowing system ("online", flow velocities 2-50 cm/s), from blood withdrawn from the system ("offline") and by means of a SPE/HPLC method. SPME was done using new fibres ("new") for each analysis, and in the way that one fibre was reused ("re") for one series of measurements.
Results: Drug SPME did not depend on blood flow velocities. Linear regression of data (concentration vs. amount extracted) yielded R(2)=0.998 for SPE/HPLC, R(2)=0.955 for SPME(online_new), 0.929 for SPME(online_re), 0.929 SPME(offline_new), 0.973 for SPME(offline_re), RSD were 52% (SPME(online_new)), 10% (SPME(online_re)), 47% (SPME(offline_new)), 18% (SPME(offline_re)), 8% (SPE/HPLC).
Conclusions: In-vein SPME has the potential to minimize blood requirement for diagnostic purposes and to speed up analysis of clinically relevant drugs, if inter-fibre variation can be reduced through standardized manufacturing.