title: Determination of misoprostol free acid in human breast milk and serum by gas chromatography/negative ion chemical ionization tandem mass spectrometry.
abstract: To study an expected transition of misoprostol from human blood into breast milk, a novel method for the determination of its active metabolite misoprostol acid (MPA) was developed. MPA was determined in serum and breast milk samples by an isotope dilution assay using gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS). After addition of (15S)-15-methylprostaglandin E(2) (15-methyl-PGE(2)) as an internal standard, MPA was extracted from both matrices using a reversed-phase cartridge. The prostanoids were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride (PFBHA) and 2,3,4,5,6-pentafluorobenzyl bromide (PFBB) to the pentafluorobenzyl oxime (PFBO)-pentafluorobenzyl ester (PFB) derivatives. The sample was subjected to thin-layer chromatography with ethyl acetate-hexane (1 : 1 (v/v)) as the developing solvent. The corresponding zone was extracted. After derivatization to the trimethylsilyl ether, MPA was determined by GC/NICI-MS/MS using the [molecule (M) - pentafluorobenzyl (PFB)](-) ([P](-)) ions as precursor in the negative ion chemical ionization mode. The product ions used for quantification were [P - 2TMSOH - C(6)F(5)CH(2)OH](-) (MPA) and [P - 2TMSOH - C(6)F(5)CH(2)OH - CO(2)](-)(15-methyl-PGE(2)), respectively. The limit of quantification for MPA was approximately 1 pg ml(-1) in breast milk and serum samples. The correlation coefficients of the calibration curves for MPA were r > 0.997 in the 0.5-2000 pg ml(-1) range for both tested matrices.
authors.affiliation: Department of Pediatrics, Philipps University Marburg, Deutschhausstrasse 12, D-35033 Marburg, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Watzer
authors.forename: Hannsjörg W
authors.initials: HW
authors.lastname: Seyberth
authors.forename: Horst
authors.initials: H
authors.lastname: Schweer
mesh_terms: D000328:Adult; D002138:Calibration; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D016595:Misoprostol / Q000032:analysis* / Q000097:blood; D010120:Oxytocics / Q000032:analysis* / Q000097:blood; D015203:Reproducibility of Results; D012997:Solvents
chemical_list: D010120:Oxytocics; D012997:Solvents; D016595:Misoprostol