Comprehensive Dual Liquid Chromatography with Quadruple Mass Spectrometry (LC1MS2 × LC1MS2 = LC2MS4) for Analysis of Parinari Curatellifolia and Other Seed Oil Triacylglycerols.

Online two-dimensional (2D) comprehensive liquid chromatography (LC × LC) has become increasingly popular. Most LC × LC separations employ one or more detectors at the outlet of the second dimension, D, with very short runs to avoid undersampling. We used six detectors, including dual parallel mass spectrometry (LC1MS2), for detection of the first dimension, D. We made an argentation (silver-ion) UHPLC column from a strong cation exchange column for D, coupled with UV and LC1MS2 detection. LC1MS2 in D combined with LC1MS2 in D, plus five other detectors, constituted LC2MS4 in a comprehensive LC1MS2 × LC1MS2 2D-LC separation. Electrospray ionization (ESI) high resolution accurate mass (HRAM) mass spectrometry (MS) and atmospheric pressure chemical ionization (APCI) MS were used in parallel for D detection, while atmospheric pressure photoionization (APPI) MS and ESI-MS were used for detection of D. The LC1MS2 used for D allowed quantification of triacylglycerol (TAG) molecular species of Parinari curatellifolia and other seed oils, while the D allowed isomers of TAG containing 18:3 fatty acyl chains as well as TAG regioisomers to be separated and identified. The LC1MS2 in D allowed identification of oxo-TAG species by HRAM MS and quantification of 806.3 ± 1.3 and 1101 ± 22 μg/g of α- and γ- tocopherols, respectively, in P. curatellifolia by APCI-MS. It is now feasible to use silver-ion UHPLC as the D separation in LC × LC and to use multiple mass spectrometers across both dimensions to perform conventional quantitative analysis and to take advantage of the newest LC × LC separation technology to identify isomers that are otherwise difficult to separate.