SPE-GCMS法分析饮用水源水中痕量半挥发性有机物

采用C 18固相萃取柱富集,乙酸乙酯、二氯甲烷和丙酮混合溶剂以1∶1∶1比例洗脱、自动固相萃取的前处理方法,气相色谱质谱连用,分析水源水中33种半挥发性有机物,并与液液萃取前处理方法进行比较。结果表明:在500~5 000μg/L范围内,33种SVOC线性良好,相关系数0.990,回收率为70.1%~114.2%,相对标准偏差为2.4%~13.4%,方法检出限为0.06~0.25μg/L;而且该方法较液液萃取,检出样品种类多。适用于饮用水源水中半挥发性有机物的监测。     

Identifying opportunities for expert-mediated triangulation in monitoring wildlife trade on social media

Wildlife trade has rapidly expanded on social media platforms in recent years, offering an easy means for traders to access international markets. Investigating this trade activity poses a complex challenge to researchers seeking to understand online trade and moderators seeking to disrupt illicit and harmful activity. Current survey methods frequently rely on text-based searches and focus on posts in which the advertisement is explicit. However, such approaches risk overlooking a growing volume of relevant content, particularly outside social media groups. We used posts from pages promoting West African birds for trade as a case study to explore the availability of information for making inferences about trade activity on social media, specifically information indicating that trade activity was occurring or that could be used to infer trade routes. We recorded 400 posts from 12 pages that we inferred either promoted or facilitated wildlife trade, of which 19.7% were explicit advertisements and 23.8% contained taxa-related terms. In the remaining 341 posts, profile information was the most common indicator of trade activity, but a variety of indicators (e.g., images of birds in trade and trade enquiries) were identified across imagery, text, and comments. We identified multiple types of geographical information that could help infer trade routes and thus the likely legality of trade, although most were relatively rare and sometimes contradictory. Our findings suggest that triangulating multiple types of information from within, across, and beyond posts is vital for effectively identifying and interpreting wildlife trade content on social media. Therefore, were commend that expert-mediated triangulation should be integrated in and used alongside automated detection systems and moderating practices of social media companies.     

固相萃取-高效液相色谱法测定水中氯酚类化合物

采用固相萃取-高效液相色谱法测定水中7种氯酚类化合物,Waters OASIS WAX柱萃取效率最高,最佳萃取时间和洗脱时间分别为60和5 min。该法的线性范围为1.0~40 mg/L,检出限为0.015~0.5μg/L,精密度为0.558%~2.22%,回收率为83.2%~105%。该法适用于地表水及饮用水中氯酚类化合物的检测。     

C_(18)-固相萃取/气相色谱法检测水中氯酚类

采用C18柱对水环境样品进行固相萃(SPE),用GC-ECD测定的方法检测水中的氯酚类物质,方法的检出限可低至ng/L数量级,三种氯酚的回收率约为80%,方法操作简便,试剂消耗少,灵敏度高,重现性良好,适于水环境中氯酚类的监测.     

水中天然有机物混凝过程的光学在线监测及控制

以腐殖酸为去除对象，用光散射颗粒分析仪（PDA）对水中天然有机物的混凝过程进行在线监测，结果表明PDA输出信号（FI曲线）的特征值与絮凝体粒径和有机物去除率之间具有相关性，在弱酸性（pH=5.0)T和中性（pH=7.0)条件下，通过合理控制混凝剂投量，腐殖酸的TOC去除率可达50％，UV254去除率可达80％－90％，但pH=7.0时的投量为pH=5.0的5倍以上，在pH＝5．0的条件下，吸附电和中是有机物混凝的主要机理，但在混凝剂投量非常高的情况下，卷扫絮凝也起重要作用。在pH=7.0条件下，卷扫絮凝则是有机物混凝的主要机理。