Citric chelating function

Antioxidants (qv) have a positive effect on oils when present in the proper concentration. Sterols and tocopherols, which are natural antioxidants, may be analy2ed by gas-Hquid chromatography (glc), high performance Hquid chromatography (hplc), or thin-layer chromatography (tic). Synthetic antioxidants maybe added by processors to improve the performance or shelf life of products. These compounds include butylatedhydroxyanisole (BHA), butylated hydroxytoluene (BHT), / fZ-butyUiydroquinone (TBHQ), and propyl gallate. These materials may likewise be analy2ed by glc, hplc, or tic. Citric acid (qv), which functions as a metal chelator, may also be deterrnined by glc. 

Certain compounds, known as chelating agents (qv), react synergisticaHy with many antioxidants. It is beheved that these compounds improve the functional abiUties of antioxidants by complexing the metal ions that often initiate free-radical formation. Citric acid and ethylenediaminetetraacetic acid [60-00-4] (EDTA), C2QH2gN20g, are the most common chelating agents used (22). 

Vitamin K status can be assessed by a functional test, called the "prothrombin time test," which involves measuring the lime required to form a blood clot. The test is performed as follows. A blood sample is withdrawn from a subject and immediately mixed with citric acid. Citric acid is a chelator, which means that it can form a tight complex with ions, such as calcium ions. The chelator prevents the interaction of calcium ions with the blood-clotting proteins and thus prevents these proteins from forming a blood clot in the sample. Calcium ions, it should be noted, are required for supporting the activity of several blood clotting proteins. The "citrated blood" is placed in a machine called a fibrometer. The fibrometer is used to detect increases in the viscosity of the blood over a period. 

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