The clinical samples have been withdrawn from patients in the context of the clinical trial EPOC-MS-001 (EudraCT Nr: 2009-011454-17, ClinicalTrials.gov Identifier: NCT01095926) in order to run pharmacokinetic modelling in the pediatric population . The re-use of remaining material to further develop and establish a point-of-care analytical procedure has independently been approved by the local ethics committee of the sponsor (ethics committee of the medical association Westfalen-Lippe and the University of Münster; reference number 2016 154-f-S).