[Study on selenium and polysaccharide distribution in different time ginkgo leaf].

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 x 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 x kg(-1) and purity is 20.20%; In September the condition is the faint yellow solid powder 31.60 g x kg(-1) and purity is 8.68%; In November is in turn the cream color solid powder 83.57 g x 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.