The literature reports citric acid concentrations of 499.8 mg/oz for bottled orange juices and 269.1 mg/oz for juiced oranges.5 Although in that particular experiment many juices were analyzed, only two different orange juices were sampled. The juices in this experiment ranged from 241.4 to 340.9 mg/oz for 100% orange juice drinks, 186.0 to 198.7 mg/oz for orange flavored drinks. The navel orange contained 426.8 mg/oz of citric acid, and the mixed fruit juice contained 36.01 mg/oz. Possible explanations for the variance in concentrations include the processing of the juice. The juices varied in actual juice percentage as well. Sunny D claimed 5% juice and there was no actual juice in Tang. The other juices claimed to be 100% juice, some being from concentrate. The navel orange had the highest citric acid concentration, but per serving it is actually much lower in comparison to the juices because the average orange contains approximately 2 oz. of juice, much less than the 6 to 12 oz. fruit juice servings. The Juicy Juice was expected to have a much lower concentration because it is not 100% orange juice, it also includes apple, pear, grape, and tangerine juices with orange juice listed fourth on the ingredients label. It was not possible to determine how much citric acid was natural verses synthetic because isotopically different compounds cannot be separated in HPLC. According to the ingredients labels on the juices only Juicy Juice, Sunny D, and Tang contain added citric acid. This is likely due to the lower percentages of actual orange juice in these samples. By adding citric acid to the juices the manufacturers are enhancing the flavor and improving the shelf li