螯合树脂在线富集——火焰原子吸收光度法测定水中微量Cu,Pb,Zn,Cd

对螯合树脂在线富集，火焰原子吸收光度法进行了条件试验。试验证实方法对Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ４个元素检出浓度可达μｇ／Ｌ级，校准曲线性、样品重现性及准确度可满足测定要求。     

原子吸收法测定海水中铁含量的不确定度评定

为了保证海水中铁元素含量的检测质量,更好地深入了解铁在整个海水体系的生物地球化学中扮演的角色,需科学地评定检测结果的分散性。文章依据《测量不确定度的评定与表示》(JJF1059-1999)的理论,以浙江近海海水为例,评定原子吸收法测定海水中铁含量的不确定度。测得浙江近海样品中铁的浓度为5.2μg/L,扩展不确定度U=0.8μg/L(k=2)。通过对各不确定度分量进行评定发现,利用该方法测定海水中铁含量时,对其合成标准不确定度的主要贡献来自于样品制备过程,尤其是萃取过程。     

Vulcan_(42)消解—原子荧光测定土壤和沉积物中的砷汞

建立了全自动样品处理系统Vulcan 42-原子荧光光度法测定土壤和沉积物中砷和汞的方法。准确称取0.2500 g样品,经Vulcan42全自动消解系统消解后,采用原子荧光光度计测定砷和汞的含量。运用该方法砷的检出限为0.11 mg/kg,回收率在96%¹01%之间,相对标准偏差(n=6)在1.3%101%之间,相对标准偏差(n=6)在1.3%⁴.5%之间;汞的检出限为0.003 mg/kg,回收率在90%4.5%之间;汞的检出限为0.003 mg/kg,回收率在90%¹08%之间,相对标准偏差(n=6)在0.5%108%之间,相对标准偏差(n=6)在0.5%⁴.7%之间。     

苏州河表层沉积物中总汞测定的研究

采用金汞齐富集-冷原子吸收光谱法直接测定苏州河表层沉积物中的总汞。结果表明:该方法在0.00～200ng范围内呈良好线性关系,检出限为0.005mg/kg(样品以0.2g计)。实际样品测定的RSD为1.24%～4.36%,加标回收率为91.8%～101%。与原子荧光光谱法相比,两种方法测定的结果没有显著差异。     

火焰原子吸收法测定水中的总铬

用火焰原子吸收光谱法测定水中总铬,乙炔流量100L/h、燃烧头高度为9mm、狭缝宽度0.2 nm时,灵敏度和重现性最好.1 mg/L铬溶液中盐酸含量5％、氯化铵含量0.5％时,吸光度较高,相对标准偏差最低.该方法操作简便,灵敏度好,精确度和准确度高,便于推广,适合水中总铬的测定.     

地表水和地下水中的砷、硒同时测定

通过利用双道原子荧光法,同时对地表水和地下水样品中砷、硒进行测定,具有操作更加简单、监测分析速度快、节省试剂等优点。     

流动注射-氢化物发生-原子荧光光谱法测定土壤中铅

采用流动注射-氢化物发生-原子荧光光谱法测定土壤中的铅,工作曲线线性关系良好,检出限为0.25 mg/kg,相对标准偏差＜3.5%,加标回收率为93.0%～105%.该方法简便快速,测定结果准确可靠.     

Responses of a soil bacterium, Pseudomonas chlororaphis O6 to commercial metal oxide nanoparticles compared with responses to metal ions

The toxicity of commercially-available CuO and ZnO nanoparticles (NPs) to pathogenic bacteria was compared for a beneficial rhizosphere isolate, Pseudomonas chlororaphis O6. The NPs aggregated, released ions to different extents under the conditions used for bacterial exposure, and associated with bacterial cell surface. Bacterial surface charge was neutralized by NPs, dependent on pH. The CuO NPs were more toxic than the ZnO NPs. The negative surface charge on colloids of extracellular polymeric substances (EPS) was reduced by Cu ions but not by CuO NPs; the EPS protected cells from CuO NPs-toxicity. CuO NPs-toxicity was eliminated by a Cu ion chelator, suggesting that ion release was involved. Neither NPs released alkaline phosphatase from the cells’ periplasm, indicating minimal outer membrane damage. Accumulation of intracellular reactive oxygen species was correlated with CuO NPs lethality. Environmental deposition of NPs could create niches for ion release, with impacts on susceptible soil microbes.     

Nanocatalyzed biodiesel synthesis from the oily contents of Marine brown alga Dictyota dichotoma

This research article demonstrates biodiesel synthesis through the methanolysis of the oily contents (4.02 ± 0.27% w/w on dried basis) of Dictyota dichotoma collected from the coast of Hawksbay, Pakistan. The metal oxides (CaO, MgO, ZnO, and TiO₂) used as nanocatalysts were refluxed (5% K₂SO₄), calcinated (850 °C) and characterized by Atomic Force Microscopy (AFM) which produced 93.2% w/w FAME (biodiesel) at relatively mild condition (5% catalyst, 65 °C, 3 h, 18:1 molar ratio) using CaO. Whereas, MgO, ZnO, and TiO₂ produced 92.4%, 72.5%, and 31.8% w/w FAME, respectively at elevated condition (225 °C). Thus, CaO was considered to be the best catalyst among the others. This tri-phase reaction require continuous fast mixing and the yield depends on the reaction parameters like catalyst amount, temperature, reaction time and molar ratio (methanol: oil). The reusability of these heterogeneous catalysts simplified the purification step, reduced the waste generation and make the final product technically and economically viable.     

石墨炉原子吸收法快速测定水中的四乙基铅

用三氯甲烷萃取水中的四乙基铅,直接上石墨炉原子吸收仪进行测定。结果表明,方法相对标准偏差为5.9%,平均回收率在90.4%~108%之间,检出限为1.3×10-5mg/L。准确度高,精密度好。