Analytical scale supercritical fluid chromatography for the analysis of nine tocochromanols in 24 different cold-pressed plant oils : method development, validation, and isolation of tocotrienols and plastochromanol-8

In the present study, four tocotrienol (T3) homologues and plastochromanol-8 (PC-8) were isolated from plant oils; Linum usitatissimum (PC-8), Bixa orellana (γ-T3 and δ-T3), and Triticum spelta bran (α-T3 and β-T3) by analytical scale supercritical fluid chromatography (SFC). The optimized method of tocopherols, tocotrienols, and PC-8 separation via SFC with UV detection was validated on a biphenyl core-shell column. The sample preparation conditions of the plant oils involved a simple dilution in 2-propanol (1:9, v/v), followed by direct injection into the SFC. For the analysis of 24 different plant oils we recommended the following final analytical scale SFC method conditions: 5 µL for the injection volume and sample oil:2-propanol dilution ratio of 1:9. The final assay developed facilitated the rapid (<15 min) and sensitive (limit of detection within the range of 2.5–7.4 μg/mL and the limit of quantitation within the range of 7.7–22.6 μg/mL) analyses of tocochromanols in obtained cold-pressed oils from twenty-four different plant species. Furthermore, the method was repeatable and reproducible with % RSD values in the context of standard retention times which ranged within 0.10–0.31 intraday and 0.59–0.79 interday.