We have succeeded in extracting a large amount of expensive limonoids and the high total antioxidant capability yuzu seed oil from waste yuzu seed by simple methods. Yuzu seeds contain higher amounts of fat-soluble limonoid aglycone (330.6 mg g(-1) of dry seed), water-soluble limonoid glycoside (452.0 mg g(-1) of dry seed), and oil (40 mg g(-1) of green seed) than other citrus fruits. The antioxidant activities of yuzu seed aglycone, glycoside, and seed oil were evaluated in vitro. The potential antioxidant activity in oil solution, diphenylpicrylhydrazyl radical-scavenging activity, and hydrogen peroxide-scavenging activity effects of the seed extracts were also investigated. The antioxidant activity of yuzu seed oil was two times that of grapefruit seed oil, which has high activity. Yuzu glycoside produced the same high antioxidant activity as Luo Han Guo glycoside.
A simple and rapid determination method for trace amounts of copper and lead in water and rock samples by tungsten metal furnace atomic absorption spectrometry was investigated. Copper and lead were quantitatively collected on activated carbon impregnated with 1,2-cyclohexanediondioxime (AC-Dox) at pH 5.0 for copper and pH 8.0 for lead. The copper and lead collected on an AC-Dox were eluted with 1 mol dm -3 hydrochloric acid, and the absorbances of the eluents were measured at 324.8 nm for copper and 283.3 nm for lead, respectively. The detection limit (S/N=3) for copper was 0.013 mg/5.0 cm 3 and that for lead was 0.075 mg/5.0 cm 3 . The relative standard deviations (n=5) were 2.0 -4.0% for each metal.
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