title: Qualitative and quantitative analysis of pharmaceutical compounds by MALDI-TOF mass spectrometry.
abstract: In this report, we discuss key issues for the successful application of MALDI-TOF mass spectrometry to quantify drugs. These include choice and preparation of matrix, nature of cationization agent, automation, and data analysis procedures. The high molecular weight matrix meso-tetrakis(pentafluorophenyl)porphyrin eliminates chemical noise in the low-mass range, a "brushing" spotting technique in combination with prestructured target plates enables fast preparation of homogeneous matrix crystals, and addition of Li+ leads to intense cationized drug species. Complex biological samples were cleaned up using a 96-well solid-phase extraction plate, and the purified samples were automatically spotted by a pipetting robot. To obtain a suitable data analysis procedure for the quantitative analysis of drugs by MALDI-TOF mass spectrometry, various data processing parameters were evaluated on our two model drugs lopinavir and ritonavir. Finally, and most importantly, it is shown that the above-described procedure can be successfully applied to quantify clinically relevant concentrations of lopinavir, an HIV protease inhibitor, in extracts of small numbers of peripheral blood mononuclear cells (1 x 10(6)).
authors.affiliation: Department of Neurology, Laboratory of Neuro-Oncology, and Department of Pediatrics, Division of Pediatric Infectious Diseases & Immunology, Sophia Children's Hospital, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Jeroen J A
authors.initials: JJ
authors.lastname: van Kampen
authors.forename: Peter C
authors.initials: PC
authors.lastname: Burgers
authors.forename: Ronald
authors.initials: R
authors.lastname: de Groot
authors.forename: Theo M
authors.initials: TM
authors.lastname: Luider
mesh_terms: D000328:Adult; D017320:HIV Protease Inhibitors / Q000032:analysis* / Q000493:pharmacokinetics; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000378:metabolism; D061466:Lopinavir; D011744:Pyrimidinones / Q000032:analysis / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D019438:Ritonavir / Q000032:analysis / Q000493:pharmacokinetics; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D061466:Lopinavir; D019438:Ritonavir