title: Quantitative determination of total L-carnitine in infant formula, follow-up formula, and raw materials by liquid chromatography with tandem mass spectrometry.
abstract: We developed a rapid and useful routine screening assay for total L-carnitine content in various infant formulas and materials by liquid chromatography coupled with a tandem mass spectrometric method (LC-MS/MS) and alkaline hydrolysis. For separation of L-carnitine, a multi-mode octadecylsilane (ODS) column was used that contained ODS ligands, anion ligands, and cation ligands to avoid using ion-pairing agents. The stable isotope L-carnitine-d3 (m/z 165 → 103/85) was used in electrospray MS/MS in the multiple reaction monitoring mode with the ion transitions of m/z 162 → 103/85 for detection and quantitation of L-carnitine. Alkaline hydrolysis of short/medium chain (C2 - C15) acyl-L-carnitines in infant formula was analyzed by LC with quadrupole time-of-flight mass spectrometry (QTOF-MS). The majority of short/medium chain acyl-L-carnitines were hydrolyzed to free L-carnitine. The overall standard deviations for L-carnitine in infant formula, follow-up formula and raw materials ranged from 2.1 to 4.0. The overall mean recoveries ranged from 90.2 to 94.2%.
authors.affiliation: Department of Infant Milk and Analytical Technology, Research and Development Center, Wakodo Co., Ltd.
authors.forename: Isao
authors.initials: I
authors.lastname: Nadaoka
authors.forename: Emi
authors.initials: E
authors.lastname: Hatakeyama
authors.forename: Chihiro
authors.initials: C
authors.lastname: Tanada
authors.forename: Tasuku
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Shinichi
authors.initials: S
authors.lastname: Fukaya
authors.forename: Takashi
authors.initials: T
authors.lastname: Akiba
authors.forename: Koichi
authors.initials: K
authors.lastname: Inoue
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yamano
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Toyo'oka
mesh_terms: D002331:Carnitine / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods*; D007225:Infant Food / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D002331:Carnitine