A normal phase high performance liquid chromatography method for the separation of hydroxy and non-hydroxy neutral lipid classes compatible with ultraviolet and in-line liquid scintillation detection of radioisotopes.

In this paper, we report a method for the separation of hydroxy fatty acid and non-hydroxy fatty acid containing neutral lipid classes via normal phase HPLC with UV detection on a PVA-Sil column. The hexane/isopropanol/methanol/water based method separates all the neutral lipids in 21 min, and subsequently flushes through the polar lipids by 27 min such that prefractionation of neutral and polar lipids are not required, and the column is re-equilibrated for the next run in 15 min, for a total run time of 45 min per sample. The separation was demonstrated at both 1.0 mL/min and 1.5 mL/min for added applicability for fraction collection or inline analysis. Separation of various hydroxy fatty acid containing lipids was demonstrated from three different plant species Ricinus communis, Physaria fendleri, and engineered Arabidopsis thaliana. Additionally, we have combined this method with an in-line liquid scintillation counter for the separation and quantification of ¹⁴ C labeled lipids obtained from in vivo metabolic flux experiments conducted in the developing seeds of Arabidopsis thaliana.
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