Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2013
Publication Date: 10/18/2013
Citation: Byrdwell, W.C. 2013. Quadruple parallel mass Spectrometry for analysis of vitamin D and triacylglycerols in a dietary supplement. Journal of Chromatography. 1320:48-65.
Interpretive Summary: A method has been developed that eliminates all time-consuming, labor-intensive and resource-intensive sample preparation steps in the normal analysis of vitamin D3 in edible oil-filled dietary supplements. The fats that make up the majority of the gelcap are not broken down and destroyed, but instead are analyzed along with the vitamin nutrient, providing much more information with less effort than previous methods. Analysis of the triacylglycerols (TAGs) in the olive oil in the supplement is performed using four instruments, in parallel. A method of calculating response factors based on comparison to another independent detection technique is demonstrated.
Technical 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 25.0 ug (1000 International Units, IU) vitamin D3 in olive oil were diluted to 100 mL 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±.0044, 0.2870±.0059, and 0.2857±.0042 ug/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±.0055, 0.2885±.0090, and 0.2939±.0097' ug/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.