Michael Vogeser, Ute Spöhrer
Automated processing of whole blood samples for the determination of immunosuppressants by liquid chromatography tandem-mass spectrometry
Background: Liquid chromatography tandem-mass spectrometry (LC-MS/MS) is an efficient technology for routine determination of immunosuppressants in whole blood; however, time-consuming manual sample preparation remains a significant limitation of this technique.
Methods: Using a commercially available robotic pipetting system (Tecan Freedom EVO), we developed an automated sample-preparation protocol for quantification of tacrolimus in whole blood by LC-MS/MS. Barcode reading, sample resuspension, transfer of whole blood aliquots into a deep-well plate, addition of internal standard solution, mixing, and protein precipitation by addition of an organic solvent is performed by the robotic system. After centrifugation of the plate, the deproteinized supernatants are submitted to on-line solid phase extraction, using column switching prior to LC-MS/MS analysis. The only manual actions within the entire process are decapping of the tubes, and transfer of the deep-well plate from the robotic system to a centrifuge and finally to the HPLC autosampler. Whole blood pools were used to assess the reproducibility of the entire analytical system for measuring tacrolimus concentrations.
Results: A total coefficient of variation of 1.7% was found for the entire automated analytical process (n=40; mean tacrolimus concentration, 5.3 ?g/L). Close agreement between tacrolimus results obtained after manual and automated sample preparation was observed.
Conclusions: The analytical system described here, comprising automated protein precipitation, on-line solid phase extraction and LC-MS/MS analysis, is convenient and precise, and minimizes hands-on time and the risk of mistakes in the quantification of whole blood immunosuppressant concentrations compared to conventional methods.
Clin Chem Lab Med 2006;44:1126–30.
Clinical Chemical Laboratory Medicine, Walter de Gruyter
Print ISSN: 1434-6621
Volume: 44, 09/2006
Pages: 1126 - 1130
Show full article (external site)
Show all available items of this journal
Search
