title: Quadruple parallel mass spectrometry for analysis of vitamin D and triacylglycerols in a dietary supplement.
abstract: A "dilute-and-shoot" method for vitamin D and triacylglycerols is demonstrated that employed four mass spectrometers, operating in different ionization modes, for a "quadruple parallel mass spectrometry" analysis, plus three other detectors, for seven detectors overall. Sets of five samples of dietary supplement gelcaps labeled to contain 25.0μg (1000 International Units, IU) vitamin D3 in olive oil were diluted to 100mL and analyzed in triplicate by atmospheric pressure chemical ionization (APCI) mass spectrometry (MS), atmospheric pressure photoionization (APPI) MS and electrospray ionization (ESI) MS, along with an ultraviolet (UV) detector, corona charged aerosol detector (CAD), and an evaporative light scattering detector (ELSD), simultaneously in parallel. UV detection allowed calculation by internal standard (IS), external standard (ES), and response factor (RF) approaches, which gave values of 0.2861±0.0044, 0.2870±0.0059, and 0.2857±0.0042μg/mL, respectively, which were not statistically significantly different. This indicated an average amount of vitamin D3 of 14.5% over the label amount. APCI-MS analysis by selected ion monitoring (SIM) and two transitions of selected reaction monitoring (SRM) provided values of 0.2849±0.0055, 0.2885±0.0090, and 0.2939±0.0097μg/mL, respectively, relative to vitamin D2 as the IS. The triacylglycerol (TAG) composition was determined by APCI-MS, APPI-MS and ESI-MS, and the fatty acid (FA) compositions calculated from the TAG compositions were compared to the FA composition determined by gas chromatography (GC) with flame ionization detection (FID) of the FA methyl esters (FAME). APCI-MS provided the FA composition closest to that determined by GC-FID of the FAME. A previously reported approach to TAG response factor calculation was employed, which brought all TAG compositions into good agreement with each other, and the calculated FA compositions into excellent agreement with the FA composition determined from GC-FID of the FAME.
authors.affiliation: USDA, Agricultural Research Service, Beltsville Human Nutrition Research Center, Food Composition and Methods Development Laboratory, USA. Electronic address: C.Byrdwell@ars.usda.gov.
authors.forename: William Craig
authors.initials: WC
authors.lastname: Byrdwell
mesh_terms: D000336:Aerosols; D002849:Chromatography, Gas / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D019587:Dietary Supplements / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet; D014280:Triglycerides / Q000032:analysis*; D014807:Vitamin D / Q000032:analysis*
chemical_list: D000336:Aerosols; D014280:Triglycerides; D014807:Vitamin D
keywords: APCI-MS; APPI-MS; Cholecalciferol; ESI-MS; Triacylglycerols; Vitamin D