Selenium and selenium speciation in gingko leaf is different in different vegetal period. Each kind of dissolved selenium varies with the seasons. The total selenium content in gingko leaf picked in different season was studied and the various dissolved selenium content distribution was discussed. The selenium content in July, September and after the first frost is respectively 1.875, 2. 136 and 0. 815 mg · kg-1. The selenium exists in gingko leaf primarily as a water-soluble speciation. According to the experiment, the thick polysaccharide content in the gingko leaf is in the order: July＜September＜November. The thick polysaccharide in July is the sepia solid powder 25. 64 g · kg-1 and purity is 20. 20％ ; In September the condition is the faint yellow solid powder 31.60 g · kg-1 and purity is 8. 68％; In November is in turn the cream color solid powder 83. 57 g · kg-1, and purity is 17. 60％. Their deproteinised solution have no absorption peaks at 260 and 280 nm by UV-Vis, which further demonstrates that the solid powder is exactly the thick polysaccharide by IR. Determination of trace element content in the gingko leaf and the thick polysaccharide was carried out by ICP-MS, and the trace element content also changes along with the seasons.%银杏叶中总硒和各种溶解形态硒含量随着季节而变化,实验研究了不同采摘期银杏叶中总硒及不同溶解态硒含量分布.7月、9月和霜降之后采摘的银杏叶总硒的含量分别为1.873,2.136,0.815 mg·kg-1,硒的形态以水溶态硒为主.银杏叶粗多糖含量分布依次为9月＞7月＞11月.7月份采集的银杏叶中得到粗多糖为棕褐色固体粉末,粗多糖质量为25.64 g·kg-1的,纯度为20.20%;9月粗多糖为淡黄色固体粉末,质量为31.60 g·kg-1,纯度8.68%;11月份粗多糖为乳白色固体粉末,质量为83.57 g·kg-1,纯度为17.60%.三个季节的固体粉末经过脱蛋白后的紫外光谱在260和280 nm处均无吸收峰,红外光谱进一步证明得到的固体粉末为银杏叶多糖.同时,采用ICP-MS测定了银杏多糖和不同采摘期银杏叶中微量元素含量,证明微量元素含量也是随着季节发生变化.
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