title: Small molecule adduct formation with the components of the mobile phase as a way to analyse valproic acid in human serum with liquid chromatography-tandem mass spectrometry.
abstract: A valproic acid (VPA) LC-MS/MS analytical method using analyte adduct formation was developed and validated in human serum. The fragmentation of the sodium acetate adduct (mass transition: 225/143) and acetic acid adduct (mass transition: 203/143) were used as the target and qualifier mass transition, respectively. A Luna 5 μm C18 (2) 100 A, 150 mm×2 mm analytical column and a mobile phase consisting of A (H2O/methanol=95/5, v/v) and B (H2O/methanol=3/97, v/v), both with 10mM ammonium acetate and 0.1% acetic acid (pH=3.2) were used. A binary flow pumping mode with a total flow rate of 0.4 mL/min was applied. Protein precipitation with 1 mL of the mobile phase B was used as sample preparation. The calculated limit of detection/quantification was 0.45/1.0 μg/mL and the inter-/intra-day precision was <6%. The application of a deuterated internal standard resulted in a good adduct formation reproducibility. The strategy applied made the VPA LC-MS/MS analysis in human serum on the basis of two mass transitions possible. Therefore, it is an interesting alternative for the VPA pseudo multiple reaction monitoring methods (mass transition 143/143) and a proof that the developed strategy is also useful for the analysis of compounds which do not produce any stable ion fragments detectable by tandem mass spectrometry.
authors.affiliation: Institute of Legal Medicine, Hannover Medical School (MHH), Carl-Neuberg-Str. 1, D-30625 Hannover, Germany. Electronic address: Dziadosz.Marek@mh-hannover.de.
authors.forename: Marek
authors.initials: M
authors.lastname: Dziadosz
authors.affiliation: Institute of Legal Medicine, Hannover Medical School (MHH), Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Klintschar
authors.affiliation: Institute of Legal Medicine, Hannover Medical School (MHH), Carl-Neuberg-Str. 1, D-30625 Hannover, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Teske
mesh_terms: D000927:Anticonvulsants / Q000097:blood* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D015394:Molecular Structure; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014635:Valproic Acid / Q000097:blood* / Q000737:chemistry
chemical_list: D000927:Anticonvulsants; D014635:Valproic Acid
keywords: Adduct formation; Liquid chromatography; Mass spectrometry; Valproic acid