用正相高效液相色谱与气相色谱相结合分离多氯联苯和有机氯农药的方法研究

以电子捕获毛细管气相色谱为测定手段,探讨了用正相高效波相色谱分离多氯联苯和有机氯农药的可能性,并将该方法应用于海洋沉积物样品中有机氯农药的测定。     

凝胶渗透色谱-气相色谱同时测定糙米中拟除虫菊酯、有机氯农药和多氯联苯的残留量

基于凝胶渗透色谱（GPC）对脂类和色素的优良分离能力,系统研究了其对有机氯农药、拟除虫菊酯农药、多氯联苯和糙米基体的分离行为。介绍了一种可同时测定糙米中35种拟除虫菊酯、有机氯农药和多氯联苯的方法。样品用乙酸乙酯提取,凝胶渗透色谱净化,气相色谱-电子捕获检测法(GC-ECD)检测,外标法定量。在低、中、高浓度3个添加水平上的回收率分别为70.1%~107.4%,70.3%~109.9%和70.8%~109.5%,相对标准偏差（RSD）为2.3%~13.3%;有机氯农药和多氯联苯的检出限为0.07 μg/k     

气相色谱法测定虾中有机氯农药和多氯联苯残留量

建立了气相色谱法检测虾中12种有机氯农药(OCPs)和7种多氯联苯(PCBs)残留的方法。捣碎匀浆后的样品采用正己烷/二氯甲烷提取,H2SO4(浓)净化,气相色谱仪电子捕获检测器进行分析测定。有机氯农药和多氯联苯的定量限为0.3~1.5μg/kg;在虾中2,10,20μg/kg添加水平的平均回收率为70.6%~102%,相对标准偏差为2.4%~6.2%。方法适用于虾中有机氯农药和多氯联苯的定性定量分析。     

气相色谱-质谱联用测定艾叶中持久性有机污染物

本文建立了气相色谱-质谱(GC-MS)联用测定艾叶中持久性有机污染物的分析方法。样品以正己烷和丙酮为提取剂,经提取液浓H2SO4和硅胶柱净化后,通过GC-MS联用测定19种有机氯农药和多氯联苯残留。结果表明,在25、50、100ng/g添加水平下平均回收率分别为71.0%~93.6%、79.7%~105.9%、85.1%~108.7%,相对标准偏差(RSD)分别为2.4%~11.6%、1.1%~8.6%、0.9%~7.5%。使用该方法分析不同批次的艾叶发现主要残留物为有机氯农药,其次是低氯取代的多氯联苯。方法简便高效,精密度好,可用于艾叶中持久性有机氯污染物的分析。     

不同方法提取海岸带沉积物中多氯联苯及有机氯农药测定的比较

针对海岸带沉积物基质的复杂性,以美国国家标准技术研究院研制的海洋沉积物标准样品(SRM 1944)为研究对象,采用气相色谱-电子捕获检测器进行测定。比较了索氏提取、加速溶剂萃取、超声波辅助提取对其中多氯联苯(PCBs)和12种有机氯农药(OCPs)的提取效率。结果表明:索氏提取的回收率在87.9%~104%之间,加速溶剂萃取在80.1%~106%之间,超声波辅助提取在78.6%~93.8%之间,并用实际海岸带浅层沉积物样品进行验证。     

超声波溶剂提取-气相色谱法测定烟草及烟草制品中19种有机氯农药残留

建立了超声波溶剂提取-气相色谱法同时测定烟草及其制品中19种有机氯农药残留。样品采用正己烷-丙酮超声提取,经Florisil固相萃取柱净化后,采用气相色谱-电子捕获检测法(GC-ECD)进行检测。结果发现,19种有机氯农药加标回收率均在72%以上,相对标准偏差(RSD)在0.1%～9.0%,能满足当前烟草中有机氯农药残留的同时快速检测要求。     

气相色谱法测定禽蛋中微量有机氯农药及多氯联苯的残留

建立了以正己烷振荡提取，以及PCB2和PCB209为内标的快速检测禽蛋中微量有机氯污染物的气相色谱法。与传统的索氏提取法相比，在保证足够的准确度，精确度和灵敏度的前提下，具有前处理简单，测试成本低，标本用量少的特点。而且可同时测定有机氯农药和典型的多氯联苯类化合物的残留，特别适于检测食品中的微量有机污染物。用该方法测试的结果表明，标准全蛋粉添加ng/g级待测物时，各种待测物的回收率为84．31％－116．77％（3次测定平均值）；相对标准偏差为6％－18％（7次测定平均值）；最低检出量为0.07ng/g-0.35ng/g。中国部分城市市售鸡蛋中的有机氯农药以p,p'-DDE的检出量最高，p,p'-DDT次之；多氯联苯的检出量很低，大多数样品中多氯联苯的总检出量低于10ng/g。在所检出的多氯联苯中，绝大部分为含氯低的（氯原子数为3－5）的氯化物。     

固相萃取净化-气相色谱法测定沉积物中15种持久性有机氯农药EI北大核心CSCD

通过比较不同固相萃取柱对沉积物提取液的净化效果和对气相色谱微电子捕获检测器(GC-ECD)基线的影响,建立了沉积物中15种有机氯农药的气相色谱分析方法。10 g风干的沉积物样品加入1 g Cu粉和3 g无水Na2SO4用100 m L石油醚-丙酮(1:1,V/V)于索氏抽提系统提取60个循环,提取液用石墨化炭黑(Pesticarb)固相萃取柱净化,GC-ECD测定。方法学结果表明,沉积物中15种有机氯农药具有良好的线性关系,检出限0.035~0.464μg/kg,定量限0.12~1.55μg/kg,经Pesticarb-SPE净化15种有机氯农药平均回收率为94.8%,相对标准偏差为1.6%~6.8%。方法应用于西溪湿地表层和底层沉积物监测,32个样品中,除了艾氏剂,其余农药均有不同程度的检出。     

固相萃取净化-气相色谱法测定沉积物中15种持久性有机氯农药

通过比较不同固相萃取柱对沉积物提取液的净化效果和对气相色谱微电子捕获检测器(GC-ECD)基线的影响,建立了沉积物中15种有机氯农药的气相色谱分析方法。10 g风干的沉积物样品加入1 g Cu粉和3 g无水Na2SO4用100 m L石油醚-丙酮(1:1,V/V)于索氏抽提系统提取60个循环,提取液用石墨化炭黑(Pesticarb)固相萃取柱净化,GC-ECD测定。方法学结果表明,沉积物中15种有机氯农药具有良好的线性关系,检出限0.035~0.464μg/kg,定量限0.12~1.55μg/kg,经Pesticarb-SPE净化15种有机氯农药平均回收率为94.8%,相对标准偏差为1.6%~6.8%。方法应用于西溪湿地表层和底层沉积物监测,32个样品中,除了艾氏剂,其余农药均有不同程度的检出。     

液-液萃取富集-气相色谱法测定水中有机氯农药和多氯联苯

采用正己烷作萃取溶剂提取并富集水样中有机氯农药(OCP's)和多氯联苯(PCB's),所得提取液经浓缩至约0.5mL并定容至1.0mL后,用气相色谱法-电子捕获检测器测定水中有机氯农药和多氯联苯。采用Rtx-5MS和Rtx-1701双柱法根据与标准物质的保留时间相对比进行定性分析;采用Rtx-5MS柱对被测组分按外标法进行定量分析。结果表明:各种农药质量浓度均在0.5～40μg·L~(-1)范围内与峰面积呈线性关系。有机氯农药和多氯联苯的检出限(3s)在0.001 1～0.004 7μg·L~(-1)之间。用标准加入法测得其回收率在83.3%～112.1%之间,相对标准偏差(n=7)在4.4%～9.4%之间。     

Solvent extraction separation of In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/ with sulphoxides

Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated.     

Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes

Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/₂, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of⁹⁹Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/₃, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material.     

Simultaneous propane dehydrogenation andco2hydrogenation overCrOx/SiO2catalyst

Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO₂(DH-CO₂) reactions in the presence and absence of the CrO_x/SiO₂ catalyst have been studied between 673 and 873 K. It was found that the CrO_x/SiO₂ catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the dehydrogenation of propane to propene in the presence of CO₂on CrO_x/SiO₂can be facilitated by the RWGS reaction.</o:p>     

Direct synthesis of dimethyl carbonate ?from CH3OH AND CO2 by H3PW12O40/CexTi1-xO2 catalyst

Summary Ce_xTi_1-xO₂ and H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ showed a better catalytic performance than the corresponding Ce_xTi_1-xO₂, due to the bifunctional catalysis of Br?nsted acid sites (provided by H₃PW₁₂O₄₀) and base sites (provided by Ce_xTi_1-xO₂). H₃PW₁₂O₄₀/Ce_0.1Ti_0.9O₂ showed the highest catalytic performance among the H₃PW₁₂O₄₀/Ce_xTi_1-xO₂ catalysts.     

An investigation of the promotional effect of propylene or propane traces on the activity of sulfatedPt/g-Al2O3andPt-Sn/g-Al2O3inCH4combustion

Summary A strong promoting effect of the presence of C₃H₈or C₃H₆was determined for the combustion of CH₄in excess oxygen, over pre-sulfated 1%Pt/g-Al₂O₃and pre-sulfated 1%Pt-2%Sn/g-Al₂O₃catalysts.</o:p>     

LixNi0.8-yCo0.2ZnyOp的合成及电化学性能研究

A series of single-phase Li_xNi_0.8-yCo_0.2Zn_yO_p(0.96 ≤x≤ 1.10， 0 ≤y≤ 0.05， 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method， in which LiOH·H₂O， Zn-doped spherical Ni(OH)₂ and Co₂O₃ were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD， SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine， narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity， but also a better cycling stability characterization than the un-doped one. The Li_1.06Ni_0.75Co_0.22Zn_0.03O_2.03 material has an initial reversible capacity as high as 160.5mAh·g^-1; and a first discharge efficiency 89.2%， and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles.     

Crystal structure of Na3PO4 · 12H2O

The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is $\text{C2}\text{c}$ and a unit cell contains eight formula units. The unit cell dimensions of $\text{Na}{}_3\text{PO}{}_4\text{·}\text{1}\text{2}\text{H}{}_2\text{O}$ are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO₆ octahedra. The hydrogen bonding scheme is given.     

Visible light-sensitive yellow TiO2−xNx and Fe-N co-doped Ti1−yFeyO2−xNx anatase photocatalysts

Nitrogen substituted yellow colored anatase TiO_2−xN_x and Fe-N co-doped Ti_1−yFe_yO_2−xN_x have been easily synthesized by novel hydrazine method. White anatase TiO_2−δ and N/Fe-N-doped samples are semiconducting and the presence of ESR signals at g ∼1.994-2.0025 supports the oxygen vacancy and g∼4.3 indicates Fe³⁺ in the lattice. TiO_2−xN_x has higher conductivity than TiO_2−x and Fe/Fe-N-doped anatase and the UV absorption edge of white TiO_2−x extends in the visible region in N, Fe and Fe-N co-doped TiO₂, which show, respectively, two band gaps at ∼3.25/2.63, ∼3.31/2.44 and 2.8/2.44 eV. An activation energy of ∼1.8 eV is observed in Arrhenius log resistivity vs. 1/T plots for all samples. All TiO₂ and Fe-doped TiO₂ show low 2-propanol photodegradation activity but have significant NO photodestruction capability, both in UV and visible regions, while standard Degussa P-25 is incapable in destroying NO in the visible region The mid-gap levels that these N and Fe-N-doped TiO₂ consist may cause this discrepancy in their photocatalytic activities.     

Carbon black and propylene oxidation over Ru/CoxMgyAl2Oz catalysts

The effects of Co_xMg_yAl₂O_z mixed oxides composition and ruthenium addition on the oxidation of propylene and carbon black (CB) were investigated. Different reactive cobalt and ruthenium oxide species were formed following calcination at 600 °C. The addition of ruthenium was beneficial for the CB oxidation under “loose contact” conditions and for propylene oxidation when the cobalt content was intermediate to low. The calculated activation energy for CB oxidation was decreased from 151 kJ mol⁻¹ for the uncatalyzed reaction to 111 kJ mol⁻¹ over the best catalyst.     

Structure refinement, dielectric, pyroelectric and Raman characterizations of Ba1−xLax(1−y)/2Euxy/2Nax/2TiO3 solid solution

The perovskite-type oxides Ba_1−xLa_x(1−y)/2Eu_xy/2Na_x/2TiO₃ (0?x?0.5 and xy=0.04) were synthesized and characterized by X-ray diffraction as well as dielectric measurements and Raman spectroscopy. The crystal structure of these ceramics has been determined by the Rietveld refinement powder X-ray diffraction data at room temperature. These compounds crystallize at room temperature in tetragonal space group P4mm for 0?x?0.1 and in the cubic group for 0.2?x?0.5. The phase transition temperature T_C (or T_m) decreases as x content increases. The degree of diffuseness of the phase transition is more pronounced for higher x content, implying the existence of a composition-induced diffuse phase transition of the ceramics with x?0.1. The evolution of the Raman spectra was studied as a function of various compositions at room temperature. The polarization state was checked by pyroelectric measurements.