Saponification is most often used to hydrolyze glycerolipid interferences during carotenoid analysis. Ester bonds of other plant metabolites such as carotenoids are, however, also hydrolyzed during saponification, thus altering the natural carotenoid composition. A straightforward and selective cleanup procedure was therefore developed involving the enzymatic hydrolysis of matrix glycerolipids. The optimized procedure (100 μL of extracted vegetable or algal oil in 20 mL of 50:50 phosphate buffer/methanol with 25 μL of sodium n-octyl sulfate, 30 mg of bile salts, and 250 μL of NaCl solution (5 mM), magnetic stirring for 2 h at 40 °C with 1 mL of Lipozyme TL 100 L and 1 mL of Lipozyme CALB L) removed the greater part of triglycerides (94.8-100.0%) and diglycerides (88.2-99.8%) while preserving the natural carotenoid composition.
Keywords: carotenoid LC-MS analysis; esterified carotenoids; ionization suppression; lipase treatment; selective glycerolipid hydrolysis.