Automated, fast and sensitive quantification of drugs in blood by liquid chromatography-mass spectrometry with on-line extraction: immunosuppressants

J Chromatogr B Biomed Sci Appl. 2000 Oct 1;748(1):41-53. doi: 10.1016/s0378-4347(00)00380-7.


We developed a universal LC-mass spectrometry assay with automated online extraction (LC/LC-MS) to quantify the immunosuppressants cyclosporine, tacrolimus, sirolimus and SDZ-RAD alone or in combination in whole blood. After protein precipitation, samples were loaded on a C18 extraction column, were washed and, after activation of the column-switching valve, were backflushed onto the C8 analytical column. [M+Na]+ ions were detected in the selected ion mode. For tacrolimus, sirolimus and SDZ-RAD, the assay was linear from 0.25 to 100 microg/l and for cyclosporine from 7.5 to 1250 microg/l (all r2>0.99). Analytical recovery was >85% and, in general, inter-day, intra-day variability for precision and accuracy were <10%.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Automation
  • Calibration
  • Chromatography, Liquid / methods*
  • Immunosuppressive Agents / blood*
  • Mass Spectrometry / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity


  • Immunosuppressive Agents