Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: December 15, 2007
Publication Date: February 1, 2008
Citation: Lin, L., Harnly, J.M. 2008. LC-MS profiling and quantification of food phenolic components using a standard analytical approach for all plants. In: Greco, L.V., Bruno, M.N., editors. Food Science and Technology: New Research. New York, NY: Nova Science Publishers, Inc. p. 1-103. Interpretive Summary: This book chapter summarizes research over the past 5 years on the development of an analytical profiling method for glycosylated flavonoids and other phenolic compounds. Because of the overwhelming number of phenolic compounds found in plants, the authors developed a standardized profiling method based on liquid chromatography with diode array and mass spectrometric detection that was used as the first step in the analysis of every material. The standardization of the approach allows the cross comparison of every sample with standards and materials that have been characterized in the literature. This standardized method allows positive or provisional identification of every phenolic compound. This chapter describes the development of the method, the use of the method for identifying compounds, and the application of the method for a wide variety of plant materials.
Technical Abstract: Phenolic compounds are secondary metabolites that are ubiquitous in the plant kingdom. The total number of chemically different phenolic acids, flavonoids, and polymeric flavonoids has been estimated to be as high as 8,000. Although the total count is high, usually only a few dozen are found in a specific plant. The types of phenolics tend to follow taxonomic lines, a trait shared by many of the secondary metabolites. Many of these compounds display a variety of biological activities and are purported to be beneficial to human health. Their impact on health has driven the need for databases and, in turn, a need for analytical methods. Their number and variety has presented a challenge to the analytical community. A standardized phenolic profiling method, based on liquid chromatography with photodiode array and electrospray ionization/mass spectrometric (LC-DAD-ESI/MS) detection, was developed specifically for glycosylated flavonoids and is applicable to phenolic compounds in general. This method is described as “standardized” because the same methodology is applied initially to all plant materials. The same extraction, separation, and detection scheme is used to provide the same overview of every sample or standard material. This enhances the capability for cross comparison of compounds in samples, standards, and results reported in the literature. Every sample analyzed contributes to a growing library of chromatographic and spectral data. The large volume of data furnished by the method and available in the literature make it possible to achieve positive identification of almost all of the common phenolics and provisional identification of many of the less common phenolics in a single chromatographic analysis using the standardized method. In this chapter, we describe the development and application of the standardized phenolic profiling method. To date we have analyzed more than 360 plant materials and over 200 standards. In the Experimental section, we describe the optimization of the method parameters. The first half of the Results Section describes the approach for identifying the structural characteristics of each compound. In the second half of the Results Section we present chromatographic profiles for a wide variety of fruits, vegetables, and herbal materials.