01 December 2007
Sirolimus measurement by LC-MS/MS without solid phase extraction – overcoming the obstacles
N. W. Brown, P. Arampatzis, C. E. Gonde, M. Pires, J. Tracey, M. TredgerAnn Transplant 2008; 13(1): 36-36 :: ID: 880193
Abstract
Background: Local clinical practice dictated the need for a 3-4 hour turn-around time for sirolimus (SRL) analysis. Of the many reported methods using LC-MS/MS, most proved unsuitable because they involved time consuming sold-phase extraction (SPE) or markedly over-estimated SRL in patient samples (by 1.5 to 2-fold) and spiked quality assurance samples (by 15-20%), showed poor (>15%) interassay precision or low sensitivity when evaluated in-house.
Material/Methods: Using stepwise optimisation of the pre-treatment, chromatography and tandem-mass spectrometry stages of the method we were able to successfully validate a method to FDA standards. Pretreatment with methanolic NH[sub]4[/sub] CO[sub]3[/sub]/ZnSO[sub]4[/sub] improved precipitation and optimised sirolimus extraction. Chromatography was enhanced using a C8 column and a column purge with 100% methanol reduced apparent ion-enhancement. Mass spectrometry with a low desolvation temperature removed a co-eluting peak.
Results: We identified a lower limit of quantification of 1.5 μg/L, inter-assay precision <12% from 2.9 to 40.0 μg/L and linearity to at least 50 μg/L. Recovery of spiked samples gave a median recovery of 107% and analysis of 27 stored quality assurance samples (patient pools and spiked samples) a median z value of +0.3 compared to the LC-MS/MS group mean. Comparison of results in 186 samples from liver, renal, pancreatic islet and bone marrow transplant recipients showed good agreement with a reference laboratory using LC-MS/MS and SPE: median (interquartile range) bias of +4.30% (-0.10 to 9.03%).
Conclusions: Timely analysis of SRL in patient samples is possible with satisfactory sensitivity and precision using LC-MS/MS without prior SPE.
Keywords: Sirolimus, Chromatography, analysis
Most Viewed Current Articles
26 Jan 2022 : Review article
Recurrence of Hepatocellular Carcinoma After Liver Transplantation: Risk Factors and Predictive ModelsDOI :10.12659/AOT.934924
Ann Transplant 2022; 27:e934924
24 Aug 2021 : Review article
Normothermic Machine Perfusion (NMP) of the Liver – Current Status and Future PerspectivesDOI :10.12659/AOT.931664
Ann Transplant 2021; 26:e931664
29 Dec 2021 : Original article
Efficacy and Safety of Tacrolimus-Based Maintenance Regimens in De Novo Kidney Transplant Recipients: A Sys...DOI :10.12659/AOT.933588
Ann Transplant 2021; 26:e933588
15 Mar 2022 : Case report
Combined Liver, Pancreas-Duodenum, and Kidney Transplantation for Patients with Hepatitis B Cirrhosis, Urem...DOI :10.12659/AOT.935860
Ann Transplant 2022; 27:e935860