Authors: Christina Moser Andreas Gschließer Verena Mattle Ludwig Wildt Andrea Griesmacher Christoph Seger
Publish Date: 2011/02/26
Volume: 400, Issue: 8, Pages: 2655-2662
Abstract
A selective and sensitive liquid chromatographytandem mass spectrometry method for the determination of very low levonorgestrel d−norgestrel serum levels such as those found in patients using levonorgestrelreleasing intrauterine devices IUDs was developed To achieve the subnanomolar sensitivity needed to measure such serum levels a diethyl ether extraction sample preparation protocol was applied prior to the online solidphase extractionliquid chromatographytandem mass spectrometry SPELCMS/MS assay Analyte quantification from the selected reaction monitoring experiments relied on the use of sixfold deuterated norgestrel as internal standard The final method was linear up to 150 ng/ml with a lower limit of quantification LLOQ of 005 ng/ml It was found to be precise and accurate with imprecision 8 and bias 6 assessed at three control levels Total analyte recovery measured in patient pools at three concentration levels was found to exceed 92 Matrix interferences were excluded by postcolumn analyte infusion experiments As a proof of concept a set of IUD patient serum samples was screened for their levonorgestrel content A total of 975 n = 94 of the samples did show serum levels exceeding the LLOQ proving the applicability of the assay in relevant clinical cohorts This method must not be used for diagnostic or therapeutic purposes since it did not undergo formal performance evaluation in the sense of the in vitro diagnostic directive 98/79/EG of the European community
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