%0 Journal Article
%T Dried Blood Spot Sampling with LC-MS Analysis for Routine Therapeutic Caffeine Monitoring in Neonates
%A Graham Lawson
%A Parul Patel
%A Hussain Mulla
%A Sangeeta Tanna
%J ISRN Chromatography
%D 2012
%R 10.5402/2012/828719
%X A liquid chromatography-mass spectrometry (LC-MS) method was developed and validated for the determination of therapeutic levels of caffeine in dried blood spot (DBS) samples. Caffeine is used in the treatment of Apnoea of Prematurity (AoP) in newborn children. Calibration DBS samples were prepared by spotting 15£¿¦ÌL of whole blood spiked with the analyte onto specimen collection cards. 3£¿mm disks cut from the centre of the DBS were extracted in methanol containing the internal standard. The extract was separated using a Zorbax Eclipse Plus C18 column and the MS, operated in electrospray positive ion mode, used single ion monitoring at m/z 195 for caffeine and m/z 198 for the IS. The overall extraction recovery of caffeine from spiked blood spots was demonstrated to be 44¨C47%. Validation of the microanalytical method showed good precision (coefficient of variation) and accuracy (relative error) and specificity and was linear within the tested calibration range 500¨C25000£¿ng/mL for caffeine. Investigation of different specimen collection papers revealed different matrix effects with significant ion suppression from the FTA Elute paper itself. Requiring only a microvolume (15£¿¦ÌL) blood sample for analysis, the developed DBS based microanalytical method has the potential to facilitate the routine monitoring of caffeine in neonates. 1. Introduction The analysis of dried blood spots (DBS) is used routinely for newborn screening where the low volume blood sample is obtained from a simple heel prick procedure [1]. Advances in instrumental techniques [2] have enabled the analysis of DBS samples to be expanded to include therapeutic drug monitoring [3, 4], paediatric pharmacokinetic (PK) studies [5¨C8], and metabolite identification investigations [9, 10]. In this investigation a DBS analytical approach is developed for the routine monitoring of caffeine, used to treat Apnea of Prematurity (AoP) in neonates, that is, children less than 1 month old. Despite there being many references in the literature to the analysis of caffeine in blood, plasma, urine, and saliva there are only two citing the determination of caffeine in dried blood spots (DBS). The GC analysis reported by Brazier et al. [11] required solvent extraction followed by derivatisation with methyxanthine prior to measurement. More recently a DBS method without the need for several work-up steps and compound derivatisation has been established [12]. This method, based on LC-MS/MS analysis, has a lower limit of quantification (LLOQ) of 250£¿ng/mL based on a 15£¿¦ÌL DBS sample. The aim of this investigation
%U http://www.hindawi.com/journals/isrn.chromatography/2012/828719/