title: A new approach for the determination of immunosuppressive drugs using HPLC-MS/MS and Cs+ adducts.
abstract: In this study a new principle of measurement in LC-MS/MS (liquid chromatography mass spectrometry) for determination of the immunosuppressive drugs sirolimus, everolimus, tacrolimus, and cyclosporin A has been introduced by using the Cs(+) ion as the product ion in the multiple reaction monitoring mode (MRM). Separation of the immunosuppressive agents was achieved using a phenyl-hexyl-RP column together with a ternary gradient elution profile, consisting of water, methanol and acetonitrile combined with 0.1% v/v formic acid and 0.1 mmol/l Cs+. Quantification was performed using cyclosporin D, ascomycin and 32-desmethoxy-rapamycin as internal standards. The inter-run precision of this new method, expressed as the coefficient of variation, was 2.57% for sirolimus, 2.11% for everolimus, 2.31% for tacrolimus and 2.11% for cyclosporin A.
authors.affiliation: Reference Laboratory, Instand e.V., Düsseldorf, Germany. kaiser@instand-ev.de
authors.forename: Patricia
authors.initials: P
authors.lastname: Kaiser
authors.forename: Theodorus
authors.initials: T
authors.lastname: Akerboom
authors.forename: William Graham
authors.initials: WG
authors.lastname: Wood
authors.forename: Hans
authors.initials: H
authors.lastname: Reinauer
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