title: Automated, fast and sensitive quantification of drugs in blood by liquid chromatography-mass spectrometry with on-line extraction: immunosuppressants.
abstract: 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%.
authors.affiliation: Department of Biopharmaceutical Sciences, University of California, San Francisco 94143-0446, USA. uwec@itsa.ucsf.edu
authors.forename: U
authors.initials: U
authors.lastname: Christians
authors.forename: W
authors.initials: W
authors.lastname: Jacobsen
authors.forename: N
authors.initials: N
authors.lastname: Serkova
authors.forename: L Z
authors.initials: LZ
authors.lastname: Benet
authors.forename: C
authors.initials: C
authors.lastname: Vidal
authors.forename: K F
authors.initials: KF
authors.lastname: Sewing
authors.forename: M P
authors.initials: MP
authors.lastname: Manns
authors.forename: G I
authors.initials: GI
authors.lastname: Kirchner
mesh_terms: D001331:Automation; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D007166:Immunosuppressive Agents / Q000097:blood*; D013058:Mass Spectrometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007166:Immunosuppressive Agents