空气-乙炔火焰原子吸收法测铬时的干扰及消除

对空气-乙炔火焰原子吸收法测铬(Cr)时共存元素对其测定结果的干扰进行研究。结果表明,当ρ(共存元素)/ρ(Cr)100时,Mg、Co、Al、V、Ni、Fe、Na、Ca对Cr测定有影响,而K、Mn、Zn、Mo、Pb、Si、Cu均不影响Cr的测定;当ρ(共存元素)/ρ(Cr)为10和30时,加入1%HNO_3和2%NH_4Cl可消除干扰;当ρ(共存元素)/ρ(Cr)30时,加入5%HCl和超过1%的NH_4Cl可消除干扰;5%HCl作为介质消除Cr测定干扰的效果要优于1%HNO_3介质。     

微波消解法测定铅锌冶炼厂废旧除尘布袋及其飞灰中重金属的应用研究

以广东某铅锌冶炼厂的废旧除尘布袋及其布袋上的飞灰为实验材料,以HNO3-H2O2-HF对布袋及飞灰进行微波全量消解,采用BCR三步浸提法提取飞灰中Cu、Zn、Pb、Cr、Ni、Cd 6种重金属,并利用火焰原子吸收仪器检测布袋及飞灰中6种重金属的含量及飞灰中各形态含量。结果表明,铅锌冶炼厂废旧布袋和飞灰中重金属含量较高,远大于《国家土壤环境质量标准》(GB 15168—1995)三级标准值。不同重金属在飞灰中的形态分布差异较大,Ni主要以残渣态和酸可交换态为主,Cu和Pb以残渣态为主,Zn的4种形态分布都较均匀,Cd、Zn潜在的迁移性最强。     

大气预浓缩仪-GC/FPD测定环境空气中的痕量硫化物

采用大气预浓缩仪-GC/FPD建立了环境空气中7种含硫化合物的测定方法。结果表明,经惰性化改造后的大气预浓缩仪-GC/FPD测定系统的基线低,对硫化物无残留。7种化合物的线性回归方程的相关系数均在0.995以上,高、中、低3种浓度的空白加标回收率分别为98.6%~105.3%、99.1%~103.7%、85.7%~99.7%,除硫化氢的相对标准偏差为10.9%外,其余6种含硫化合物的相对标准偏差可控制在6.9%以内。当进样体积为400 m L时,方法的检出限在0.10~1.1 ng/m3。CO2、H2O对实际样品的测定无干扰。因此,该方法能够满足目前监测工作的要求,更加适用于环境空气中痕量含硫化合物的测定。     

Stable carbon isotope analysis (δ13C values) of polybrominated diphenyl ethers and their UV-transformation products

Polybrominated diphenyl ethers (PBDEs) are frequently detected in food and environmental samples. We used compound specific isotope analysis to determine the δ¹³C values of individual PBDEs in two technical mixtures. Within the same technical product (DE-71 or DE-79), BDE congeners were the more depleted in ¹³C the higher brominated they were. In contrast, the products of light-induced hydrodebromination of BDE 47 and technical DE-79 were more enriched in ¹³C because of more stable bonds between ¹³C and bromine. As a result, the δ¹³C values of the irradiated solution progressed diametrically compared to those of the technical synthesis. The ratio of the δ¹³C values of BDE 47 to BDE 99 and of BDE 99 to BDE 153 are thus suggested as indicators to distinguish native technical products from transformation products. Ratios <1 are typical for native congeners (e.g. in DE-71) while the reversed ratio (>1) is typical of transformation products.     

饮用水源中有机磷农药的应急预处理技术研究

有机磷农药的大量生产和使用对饮用水安全造成了潜在的巨大威胁。为了在饮用水源突发有机磷农药污染时保证饮用水安全,在水源水中进行了高锰酸钾氧化、粉末活性炭（PAC）吸附、臭氧氧化、O3／PAC和O3／H2O2 5种预处理技术对4种有机磷农药（乐果、敌敌畏、马拉硫磷和甲基对硫磷）的去除效果对比研究。实验结果表明,当水中乐果、敌敌畏浓度为266肛g／L、3．6μg／L时,0．5mg／L的高锰酸钾不能将其去除达标（国家生活饮用水卫生标准,GB5749—2006）;PAC对乐果和敌敌畏的吸附效果良好,20mg／L的PAC能将低浓度的乐果（241μg／L）和中低浓度的敌敌畏（3．0～9．3μg／L）去除达标;臭氧对4种农药均有较好的去除效果,当CT（浓度×时间）值为17mg·min／L时,除高浓度的乐果（729μg／L）和甲基对硫磷（276μg／L）外,其余农药均可以去除达标;采用O3／PAC和O3／H2O2高级氧化预处理,高浓度的乐果（629～710μg／L）和甲基对硫磷（364～428μg／L）均可迅速去除达标。     

对正确理解和实施GB/T 5169.15：2008的探讨

GB/T5169.15：2008是关于电工电子产品着火危险试验500W火焰试验火焰的标准,详细规定了产生500W试验火焰的装置和确认方法。由于试验火焰是否满足标准要求,将直接影响试验结果的正确性,所以需要对试验火焰进行确认。在进行火焰确认时,发现一些需要注意的问题,现在提出与各位专家进行探讨。     

瓦斯爆炸引起沉积煤尘爆炸传播实验研究

运用井下大型实验巷道对瓦斯爆炸诱导沉积煤尘爆炸进行实验研究,并对几次实验结果进行对比分析。通过对爆炸压力以及火焰产生、发展、传播过程进行的分析,得出瓦斯爆炸引起沉积煤尘爆炸过程中压力波存在回传现象;在煤尘刚开始参与爆炸处,爆炸超压有一个较长的持续时间;爆炸火焰的传播速度在铺有煤尘段迅速上升,最后有一平缓的上升阶段,过了煤尘段开始下降;火焰区长度约为煤尘区长度的2倍等规律。实验研究发现的规律为有效的预防瓦斯煤尘爆炸事故提供了理论依据。     

基于浓度敏感性分析的甲烷机理简化

随着数值模拟技术的发展,化学反应机理开始应用于燃烧过程的重构和深入分析。详细机理是通过大量的实验研究得到的,其包含了大量的化学反应动力学信息,可以较为完备的描述化学反应过程,但是由于详细机理过于庞大一般不能直接运用到数值模拟中去,很有必要在研究特定问题时对详细机理进行一定的简化。介绍了PCAS机理简化方法,并运用该方法对甲烷燃烧的详细机理进行了简化研究,通过简化得到的101步简化机理与详细机理吻合较好。     

测定地表水及饮用水中硫酸盐的两种方法探讨

通过比较两种监测分析方法,分析了测定硫酸盐分光光度法的影响因素、存在问题,以及火焰原子吸收法的优点,提出对不同浓度范围的硫酸盐,宜采用合适的分析方法,以减小测定的误差,提高测定结果的准确性和科学性。     

Validation of a QuEChERS-based gas chromatographic method for analysis of pesticide residues in Cassia angustifolia (senna)

A simple multi-residue method based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was established for the determination of 17 organochlorine (OC), 15 organophosphorous (OP) and 7 synthetic pyrethroid (SP) pesticides in an economically important medicinal plant of India, Senna (Cassia angustifolia), by gas chromatography coupled to electron capture and flame thermionic detectors (GC/ECD/FTD) and confirmation of residues was done on gas chromatograph coupled with mass spectrometry (GC-MS). The developed method was validated by testing the following parameters: linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effect, accuracy–precision and measurement uncertainty; the validation study clearly demonstrated the suitability of the method for its intended application. All pesticides showed good linearity in the range 0.01–1.0 μg mL^?1 for OCs and OPs and 0.05–2.5 μg mL^?1 for SPs with correlation coefficients higher than 0.98. The method gave good recoveries for most of the pesticides (70–120%) with intra-day and inter-day precision < 20% in most of the cases. The limits of detection varied from 0.003 to 0.03 mg kg^?1, and the LOQs were determined as 0.01-0.049 mg kg^?1. The expanded uncertainties were <30%, which was distinctively less than a maximum default value of ±50%. The proposed method was successfully applied to determine pesticide residues in 12 commercial market samples obtained from different locations in India.