Deproteination of serum samples for LC–MS/MS analyses by applying magnetic micro-particles

ObjectivesInvestigation of the practicability and performance of a magnetic micro-particle based method for protein depletion of serum samples, preceding the quantitative analysis of small molecules by LC–MS/MS.Design and methodsA commercially available kit including a protein denaturation reagent and functionalized magnetic particles together with a magnetic separator device was tested by addressing the quantification of amiodarone in serum as an exemplary analyte by LC–MS/MS with on-line SPE. A standard method validation protocol was applied.ResultsThe sample preparation protocol was found to be convenient, straightforward and robust. Validation data characterized the entire analytical method – combining particle-based protein depletion and two-dimensional chromatography – as compatible with the analytical needs regarding selectivity, accuracy (102–106%), linearity (r2 ≥ 0.99), reproducibility (CV < 7%), and control of ion suppression.ConclusionsSince this novel approach of sample preparation does neither require centrifugation nor the technically demanding application of positive or negative pressure, as in conventional solid phase extraction protocols, it seems highly attractive for developing fully automatized preparation systems for LC–MS/MS analyzers.

► A magnetic particle based protocol for deproteination of serum samples is described.
► This approach allows straightforward sample preparation for LC/LC–MS/MS.
► The protocol was tested for amiodarone as a representative small molecule analyte.
► Performance and practicability of this novel technology was found good.
► The technology seems promising for the development of fully automated MS-analyzers.