ホウ酸錯塩のケイ光(第3報) : 食品中のデヒドロ酢酸(DHA)のケイ光定量

抄録

In order to determine the trace of dehydroacetic acid added to various kinds of foodstuff, the fluorescence determination of dehydroacetic acid reported earlier³⁾ was modified. Dehydroacetic acid reacts with boric acid in 88-77% (v/v) sulfuric acid to form a fluorescent complex salt. The maximum excitation wave length (fluorescence wave length set at 370 mμ) of this complex salt solution is at 325 mμ (corr.) and the maximum wave length of the fluorescence is at 368 mμ (corr.). For this determination, the sample is submitted to steam distillation, 1.0 ml of the distillate (containing 0.03-3 μg/ml of dehydroacetic acid) is placed in a 30 ml glass-stoppered test tube, 8.0 ml of sulfuric acid is added dropwise while cooling the test tube in an ice-water bath, and 1.0 ml of sulfuric acid solution of boric acid is added. The mixture is allowed to stand at 30-35° for 20 minutes, and intensity of fluorescence of this solution is measured. Calibration curve of this solution showed a good lineality in a concentration range of 0.0004-0.7 μg/ml of dehydroacetic acid at the time of fluorescence measurement, and the fluorescence was stable. It was found that sodium dehydroacetate contained in foodstuff (such as fruit juice, Miso, bean paste, fermented milk, and butter) can be determined satisfactorily by this fluorescence method by using the partially modified steam distillation.