Michael Deters, Gabriele Kirchner, Klaus Resch, Volkhard Kaever
Simultaneous Quantification of Sirolimus, Everolimus, Tacrolimus and Cyclosporine by Liquid Chromatography-Mass Spectrometry (LC-MS)
We developed a universal liquid chromatographymass
spectrometry (LC-MS) assay with automated online
extraction to quantify simultaneously the immunosuppressants
sirolimus, everolimus, tacrolimus,
and cyclosporine. Whole blood (300 ?l) plus 6 ?l 32-desmethoxyrapamycin (1 ng/?l) as internal standard
was treated with 600 ?l methanol/0.2 M ZnSO4 (80/20
v/v). After vortexing (30 s) and centrifugation (20000 g,
5 min) 50 ?l of the supernatant were loaded on an extraction
column, were washed by 0.35 ml/min water
for 3 min and, after activation of a column-switching
valve, were back-flushed by 0.25 ml/min methanol/
water (90/10 v/v) onto a C18 analytical column. After 22
min the extraction column was washed for 2 min with
methanol and for 3 min with water before starting the
next run. Column temperatures were kept at 33 °C.
Sodium adduct ions [M+Na]+ ions were detected in the
selected ion mode. For sirolimus, everolimus and
tacrolimus the assay was linear from 0.3 to 200 ?g/l
and for cyclosporine from 5 to 1000 ?g/l (all r2>0.999).
Recovery of all immunosuppressants and the internal
standard was >90% and in general, inter-day and intra-day
precision was <10%. The simultaneous quantification
of blood levels by LC-MS seems to be the method
of choice in transplanted patients receiving multiple
immunosuppressants.
Clinical Chemical Laboratory Medicine, Walter de Gruyter
Print ISSN: 1434-6621
Volume: 40, 04/2002
Pages: 285 - 292
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