Determination of Sterols and Fatty Acids in Prostate Health Dietary Supplements by Silica Gel High Performance Thin Layer Chromatography with Visible Mode Densitometry

Abstract

A quantitative method using silica gel high performance thin layer chromatography plates, semiautomated bandwise sample application, and automated visible mode densitometry has been developed for the determination of the steroids and fatty acids in two nutritional supplements consumed to aid prostate and urinary health. The mobile phase was petroleum ether‐diethyl ether‐glacial acetic acid (80:20:1), and lipids were detected with phosphomolybdic acid reagent. A softgel containing 320 mg of saw palmetto extract with 85–95% of sterols plus fatty acids and a caplet product containing 300 mg of mixed sterols were analyzed. By comparison to a mixed neutral lipids standard, results averaged 32.1% of free fatty acids plus free sterols for the softgels and 141% recovery of mixed sterols for the caplets relative to these stated label values. Other neutral lipids were found in the samples, including triacylglycerols, steryl esters, and two unidentified fractions.

Keywords:

• Thin layer chromatography
• Sterols
• Fatty acids
• Nutraceuticals
• Prostate medications

Acknowledgments

Tamara Halkina was supported by the Lafayette College EXCEL Scholar program. The authors thank the AR2i Company for the ChromImage densitometer and EMD Chemicals, Inc. for the HPTLC plates used in our experiments.