针对目前胞内微囊藻毒素提取方法步骤复杂且提取效率低的现状,提出了一种高效的快速提取藻胞内毒素的方法体系,采用对鲜藻进行匀浆超声后测定含水量,1.5 m L 75%甲醇溶液一次性、低温静置提取干重为2~5 mg藻样12 h的步骤。该方法测定胞内毒素MC-RR和MC-LR的相对标准偏差依次为4.1%和4.6%(n=9),检测方法的最低浓度可达0.03 mg/g;对比试验表明该方法和Harada方法、沸水浴方法对胞内藻毒素提取效率无差异显著性,但Harada方法操作过程繁琐、沸水浴提取方法对HPLC色谱柱有一定损伤,2种方法实际应用价值均不大。总之,该方法简单高效,可充分满足微囊藻胞内毒素含量的HPLC检测所需稳定性和精度的需要,适用于常规实验室进行大批量藻类样品的毒素快速提取分析工作。
[Objective] This study was conducted to explore the spatial distribution of carbon and nitrogen in the sediments of Xiangxi River, which was the biggest tribu- tary near the Three Gorges Dam. [Method] Sediment samples were collected using customized cylindrical samplers at three sites along Xiangxi River estuary in May, 2015 to measure the contents of total carbon, total nitrogen and an isotope of car- bon δ^13C. [Result] The total carbon content in the sediments varied from 1.74% to 3.52%, and the total nitrogen content varied from 0.1% to 0.3%. The average total carbon content in the sediments near the estuary was lower than in the upstream. The total carbon content in the sediments near the estuary gradually decreased with depth increasing. However, the variations in total nitrogen content in both horizontal direction （along the river from the estuary to the upstream） and vertical direction were not so obvious as in total carbon content. The isotopic analysis showed the δ^13C value increased with depth increasing. The overall δ^13C near the estuary was lower than that in the upstream. [Conclusioal The results will provide scientific refer- ences for the distribution of biogenic elements in sediments of Xiangxi River and the evolution process of aquatic ecosystem.
