Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Review Article
Publication Acceptance Date: January 31, 2003
Publication Date: June 30, 2003
Citation: Robbins, R.J. 2003. Phenolic acids-an overview of analytic methodology. Journal of Agricultural and Food Chemistry. 51:10:2866-2887. Interpretive Summary: Phenolic acids are molecules synthesized by plants and hence are present in all plant-based foods. Analytical measurements systems for phenolic acids have developed to learn about where they are located in plants and their biological roles as well as their effect on food quality and flavor. Recently, interest in phenolic acids has stemmed from their potential protective role -through a diet of fruits and vegetables- against certain diseases (coronary heart disease, stroke and cancers). A literature search on these measurement systems was performed and the results summarized in this review article. Two major separation techniques High Performance Liquid Chromatography (HPLC) as well as Gas Chromatography (GC) were examined. Sample preparation techniques including sample stability and extraction from plant are summarized in tabular form. The common detection systems are discussed as well.
Technical Abstract: Phenolic acids are aromatic secondary plant metabolites, widely spread through out the plant kingdom. These compounds are a subclass of a larger category referred to as `phenolics¿- a term which describes approximately 8000 naturally occurring compounds all of which possess one common structural feature: an aromatic ring bearing at least one hydroxyl substituent. Existing analytical measurements systems for phenolic acids originated from interest in their biological roles as secondary metabolites, markers for taxonomic studies and for their roles in food quality and organleptic properties. Recent interest in phenolic acids stems from their potential protective role - through ingestion of fruits and vegetables - against oxidative damage diseases (coronary heart disease, stroke and cancers). High Performance Liquid Chromatography (HPLC) as well as Gas Chromatography (GC) are the two separation techniques reviewed. The varied sample preparation steps, including, extraction from plant materials and hydrolysis (acidic, basic and enzymatic) are summarized and discussed as are the derivatization reagents, used in sample preparation for GC. Detection systems discussed include UV-Vis spectroscopy, mass spectrometry, electrochemical and fluorometric detection. The most common tandem techniques are HPLC-UV and GC/MS yet LC/MS is becoming more common. The masses and fragmentation patterns of phenolic acids are discussed and tabulated as are the absorption maxima.