High-performance liquid chromatography functional foods

The reaction of sulfite with formaldehyde to form hydroxymethylsulfonate (HMS), which is very stable under the controlled conditions of this assay, was used as the first step in an analytical procedure to determine food-borne sulfite. The effect of mobile-phase pH on the stability of HMS during high-performance liquid chromatography was studied. It was found that on-column HMS dissociation to formaldehyde and bisulfite increased with the pH of the mobile phase therefore the relatively low pH 4.7, at which the dissociation of HMS was approximately 2%, was selected for the analysis. In addition, the release of sulfite from its reversibly bound forms in wine and other foods was examined as a function of the pH of the extraction medium by following the appearance of HMS formed from the reaction of the freed sulfite with formaldehyde. The rate of dissociation of the reversibly bound sulfite was relatively slow at pH 3 but very rapid at pH 7. 

In most respects, the standard approach taken to analyze the fatty acids of functional foods is similar to that for conventional foods. The steps are to extract the total lipids or fatty acids, convert the fatty acids to a suitable derivative (often to fatty acid methyl esters (FAME)), and analyze the derivatized fatty acids by a suitable chromatographic technique, usually GC with flame ionization detection (FID), Other chromatographic techniques, including gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC), may be required. Nonchromatographic techniques such as infrared (IR) spectroscopy may be used in some simations, perhaps because of the speed of analysis. 

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