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41.
顶空气相色谱法测定水中苦味酸   总被引:1,自引:1,他引:0  
建立了顶空气相色谱法测定水中苦味酸的新方法,将10 mL水样中的苦味酸衍生化后,直接取顶空气进样,保留时间定性,外标法定量。结果表明,该法在0~25μg/L浓度范围内有良好的线性关系(r=0.999 5),加标回收率为90.2%~107.6%,相对标准偏差为6.8%,检出限为0.02μg/L,能同时满足饮用水源地水和废水中苦味酸的测定要求。  相似文献   
42.
阐述了各种静电危害和消除静电的方法,指出了防止静电危害的劳动防护措施。  相似文献   
43.
毛细管柱顶空气相色谱法测定水中氯代苯研究   总被引:7,自引:0,他引:7  
大口径毛细管柱顶空气相色谱测定水中氯苯类的方法 ,具有简便、快速、干扰少、灵敏度高等特点。 0 .2 5mL顶空气体进样 ,二氯苯和三氯苯的检出限为 0 .0 1~ 0 .1 μg/L ,灵敏度高于萃取法 40~ 1 0 0倍 ,更有利于地表水中氯苯类有机物的测定。  相似文献   
44.
水环境中非离子表面活性剂生物降解性的研究   总被引:1,自引:0,他引:1  
本文对两种非离子表面活性剂(Tx-100、Oπ-10)在静态生活污水中生物降解性进行了初步研究。结果表明:Tx-100、Oπ-10具有较强的生物可降解性。水体中高浓度的Tx-100、Oπ-10一般在五天之后降解率可达97%,而且微生物对这两种非离子表面活性剂的降解能力基本相同。降解前后水体中CODcr、BODs值变化不大,说明非离子表面活性剂对该水域的污染并不明显。因此。可以认为Tx-100、0π-10是值得推广使用的表面活性剂。  相似文献   
45.
静态顶空气相色谱法测定工业废水中的甲醛和苯酚   总被引:7,自引:0,他引:7  
建立了静态顶空取样,气相色谱直接分析水产中甲醛和苯酚的方法。该方法有良好的重现性,甲醛、苯酚连续监测定6次的相对标准偏差分别为1.9%和4.7%,甲醛、苯酚的检测限分别为0.50mg/mL和0.30mg/mL,方法简便,快速,基底干扰小,适用于工业废水中甲醛和苯酚的同时,快速测定。  相似文献   
46.
Summary. Host plant volatiles which attract insect herbivores for egg-laying are of principal interest with respect to insect ecology and evolution. Direct applications concern population monitoring and control through behavioural manipulation. Identification of behaviourally active plant secondary metabolites is essential also for plant breeding for insect resistance. Grapevine moth females Lobesia botrana are attracted by upwind flight to green grape berries Vitis vinifera. The headspace of grape berries was collected on air filters. A solvent extract of these filters, released from a sprayer, attracted females in the wind tunnel. The results demonstrate that volatile cues mediate attraction of grapevine moth females to grape berries, and that headspace collections capture the essence of this odour signal. The air filter extracts were examined by gas chromatography coupled with electroantennographic detection, and the compounds eliciting a consistent antennal response in L. botrana females were identified by mass spectrometry. The headspace collection apparatus was calibrated for collection efficiency of the active compounds. Their recovery rate ranged from 35 % for methyl salicylate to 83 % for (E,E)-α-farnesene. A synthetic ten-component blend was then formulated. The blend consisted of compounds eliciting an antennal response, formulated in a blend ratio corrected for differences in collection efficiency. Subsequent wind tunnel tests showed that female attraction to this synthetic ten-component blend was not significantly different from attraction to grape berries, or to headspace collections of the same berries. At a release rate of 35 ng/h of the most abundant compound (E)-β-caryophyllene, 20 % of the test females approached the source of sprayed headspace collections and the ten-component synthetic blend, respectively. In comparison, 100 g of green berries, releasing the main compound (E)-β-caryophyllene at a rate of ca. 4.7 ng/h, attracted 10 % of the females by upwind flight followed by source contact.  相似文献   
47.
两次相平衡/气相色谱法测定水中挥发性氯代烃   总被引:3,自引:0,他引:3  
本文选择6种水中挥发性氯代烃作为研究对象,提出了两次相平衡/液上气相色谱法测定水中挥发性有机物的方法,系统推导了气液等体积和非等体积平衡,只分析气相就可测定水相浓度的理论关系式,研制了可变相平衡器。  相似文献   
48.
M.F. Macedo  P. Duarte   《Ecological modelling》2006,190(3-4):299-316
Phytoplankton productivity is usually determined from water samples incubated at a number of irradiance levels during several hours. The resultant productivity-irradiance (PE) curves are then used to estimate local and/or global phytoplankton production. However, there is growing evidence that these curves, referred as static, underestimate phytoplankton photosynthesis to a great deal, by assuming a stable response to light over the incubation period. One of the drawbacks of static PE curves is the overestimation of photoinhibition.In this work, three one-dimensional vertically resolved models were developed as simply as possible, to investigate differences between static and dynamic phytoplankton productivity in three marine ecosystems: a turbid estuary, a coastal area and an open ocean ecosystem. The results show that, when photoinhibition development time is considered (dynamic model), the primary production estimates are always higher than when calculated with the static model. The quantitative importance of these differences varies with the type of ecosystem and it appears to be more important in coastal areas and estuaries (from 21 to 72%) than in oceanic waters (10%). Thus, these results suggest that primary production estimates, obtained under the assumption of a static behaviour response to light, may underestimate the real values of global phytoplankton primary production. Calculations suggest that the quantitative importance of this underestimation may be larger than the global missing carbon sink.  相似文献   
49.
The possibility of dust explosions by static electricity in a malt grain silo was investigated. Two kinds of experimental equipment were applied. One was to supply electrostatic charge in order to investigate the charge build up characteristics. The other was to transport the malt grain pneumatically in order to investigate the frictional charge accumulation in the transportation system.

The particle charge of the pulverized malt grain was in the order of 10−14 C. The particle charge of the malt grain was in the order of 10−9 C and the pipe charge in the transport system was also in the order of 10−9 C. The charge accumulated on both the pulverized particle and the grain particle were small in view of the incendiary potentiality. However, attention must be paid when the particles are dumped into isolated space. There might be a charge accumulation that will lead to the ignition of the dust cloud.  相似文献   

50.
建立了用于饮用水源水中61种挥发性有机物(VOCs)同时进行分析的气相-动态顶空进样-气相色谱-质谱法(D-HS-GC-MS),VOCs包括集中式生活饮用水地表水源地特定项目中的31种VOCs。用D-HS-GC-MS法对水样中VOCs进行分析,获得良好的标准曲线线性关系(均大于0.995,溴二氯甲烷除外),除乙醛、丙烯醛、丙烯腈和环氧氯丙烷的方法检出限分别为15 g/L、13 g/L、11 g/L和11 g/L外,其余VOCs的方法检出限均介于0.10~0.58 g/L,饮用水源水实际样品加标回收率和RSD分别为75.8%~116%和1.16%~21.6%(n=3)。气相-动态顶空进样法相对于常见的吹脱捕集法具有不直接接触样品的优势,避免了仪器被样品污染,用于饮用水源水中几十种VOCs的同时分析,在常规监测中可节省大量的人力物力投入。  相似文献   
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