Fast Determination of Vitamin A, Vitamin D and Vitamin E in Food by Online SPE Combined with Heart-Cutting Two Dimensional Liquid Chromatography

An automatic method combing online solid phase extraction (SPE) and heart-cutting two dimensional Liquid Chromatography (2DLC) was developed for the simultaneous determination of vitamins A, vitamin D and four vitamins E homologues in foodstuff. In this method, the target analytes were released from their coated state of lipoprotein after saponification. Then the saponified solution was directly injected into the constructed system combining online SPE and heart-cutting 2DLC for enrichment, purification, separation and quantification. Online dilution was incorporated into the online SPE process to weaken the solvent effect on the first-column separation. The analysis of vitamins A and four E homologues were carried out by using PFP as the first column. The analysis of vitamin D was performed by using PAH as the second column. The results showed good linearity (R-2 >0.9999) of the analytes and good reproducibility (RSD < 2 %, n = 5). The limit of quantification of vitamin A, D-2,D- D-3 and alpha-, beta-, gamma-, delta-vitamin E (calculated by S/N = 10:1) were 0.030, 0.013, 0.014, 0.51, 0.33, 0.31 and 0.33 ng, respectively. The spiked recoveries ranged from 93.29 % to 103.66 %. The proposed method greatly simplifies the analytical workflow and improves the efficiency.