Document Type

Thesis - University Access Only

Award Date

2004

Degree Name

Master of Science (MS)

Department / School

Chemistry and Biochemistry

First Advisor

Duane Matthees

Abstract

Phytosterols, which are the sterols occurring in plants, iv are considered to be beneficial for health. They have different forms: free phytosterols and phytosterol esters. It 1 s possible that these different phytosterols may function in different ways. Therefore, it would be desirable to measure individual sterols as well as total phytosterols as part of nutrient composition information in food products. Phytosterols have been studied using both gas chromatography (GC) and high performance liquid chromatography (HPLC). In GC analysis which internal standard to use often is a difficult choice. Also, phytosterols are not very thermostable at the high temperature which GC analysis requires. Some studies have employed HPLC with different detectors, mobile phases, and columns, but only partial separation of phytosterols was accomplished. The original goal of this research was to develop a HPLC method to separate and identify both free phytosterols and phytosterol esters in corn completely. This objective could not be met in this research because of serious overlap of lipid components. Thus saponification was used to convert all combined sterols to free sterols in this method. The following work has been done: {a) Evaporative light scattering detector (ELSD) conditions and HPLC conditions were tested, V (b) Extraction efficiency for different solvents was tested. We found that hexane is the most efficient solvent for extraction of phytosterols in corn, (c) It was found that the choice of solvent for dissolving the sample extract was important for quantification of sterols. Several solvents were tested to determine the best choice of solvent for the sample extract. Hexane was the most efficient one in those tested solvents, and (d) The precision and recovery of this method were determined. The good precision and recovery presents that the saponification method was successful. It initially seemed that the stigmasterol was lost after saponification. However GC-MS showed that the stigmasterol is not lost but an extra peak (ergostanol) between stigmasterol and campesterol is produced after saponification, causing a resulting loss of resolution. It became obvious that successful HPLC analysis of sterols will depend on increased resolution of these compounds. Different methods were tried in order to increase the resolution but neither approach worked. The future work should focus on how to improve the resolution between campesterol, ergostanol and stigmasterol.

Library of Congress Subject Headings

Corn products
Sterols
High performance liquid chromatography

Publisher

South Dakota State University

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Rights Statement

In Copyright