黄原酯棉纤维柱分离-氢化物发生-原子荧光光谱法测定大米中的镉和铅量

采用黄原酯棉柱分离-氢化物发生-原子荧光光谱法测定大米中的镉和铅的含量。大米样品采用硝酸-高氯酸(4+1)混合酸消解,以5mL·min-1流量经黄原酯棉柱吸附分离后,用氢化物发生-原子荧光光谱法进行测定。镉和铅的质量浓度均在一定的范围内与其荧光强度呈线性关系,镉和铅的检出限(3s/k)依次为0.85,4.5μg·kg-1。对5μg·L-1的镉、铅混合标准溶液连续测定11次,两者测定值的相对标准偏差依次为1.5%,2.3%。方法用于大米样品分析,加标回收率在94.0%~105%之间。     

黄原酯棉富集分离（CdI4）^2——罗丹明6G—明胶体系双波长光度法测定…

基于罗丹明６Ｇ与（ＧｄＩ４）＾２－络阴离子的缔合反应，建立了双波长分光光度法测定痕镉的新方法。方法选择性好，灵敏度高，摩尔吸光系数ε＝２．１４×１０＾５Ｌ．ｍｏｌ＾－１．ｃｍ＾－１。本法与黄原酯棉富集分离要结合，已成功地应用于天然水中痕量镉的测定。     

石墨炉原子吸收法测定食品中痕量铅、镉

本文研究了巯基棉富集分离及基体改进剂与石墨炉原子化法相结合的铅、镉连续检测法,并对几种类型的食品进行了试验。该法可准确测定多种类型食品中痕量铅、镉。一、仪器与试剂     

黄原酯棉富集分离（CdI_4）~（2－）－罗丹明6G－明胶体系双波长光度法测定

基于罗丹明６Ｇ与（ＣｄＩ_４）~（２－）络阴离子的缔合反应，建立了双波长分光光度法测定痕量镉的新方法。方法选择性好，灵敏度高，摩尔吸光系数ε＝２．１４×１０~５Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１）。本法与黄原酯棉富集分离相结合，已成功地应用于天然水中痕量镉的测定。     

单扫示波极谱法同时测定土壤中有效态铜铅镉

在ｐＨ５．４的硝酸－乙酸钠介质中，Ｃｕ＾２＋（ｐｂ＾２＋，Ｃｄ＾２＋）－７－碘－８羟基喹啉－５－磺酸－氯化四苯胂络合物产生灵敏络合吸附法，比较了五种浸提剂对不同土壤中有效态铜，铅，镉的浸提能力。在ｐＨ４．７的乙酸－乙酸钠缓冲溶液中，用巯基棉富集分离铜，铅，镉，用本法测定土壤中有效态铜，铅，镉，结果满意。     

黄原脂棉分离-石墨炉原子吸收光谱法测定咸味食品中Pb~(2+)

利用单因素试验对黄原脂棉吸附溶液中Pb~(2+)的条件进行了实验优化,结果显示:在pH=5.0的溶液体系中,于温度20℃,振荡吸附15min,黄原脂棉对Pb~(2+)的吸附效果最佳;吸附的Pb~(2+)用6.0mL 3.0mol/L HCl,于40℃下解吸15min,可将Pb~(2+)从黄原酯棉上完全洗脱。采用石墨炉原子吸收光谱法,将该条件用于测定咸味食品中痕量Pb~(2+),结果表明:黄原脂棉能有效消除盐类基体给测定Pb~(2+)带来的干扰,方法的相对标准偏差为1.56%~2.31%(n=6);回收率为97.0%~102.7%;检出限为0.047mg/kg。本法灵敏、准确、可靠,可用于咸味食品中痕量Pb~(2+)的测定。     

巯基棉分离富集-ICP-AES测定高盐体系中痕量的铅、镉

采用巯基棉富集分离,电感耦合等离子体原子发射光谱法（ICP-AES）测定了高盐水样中痕量的铅、镉。研究表明,pH值为7时,巯基棉同时富集铅、镉的效果最好,可成功分离基体元素,以盐酸（1.5mol/L）溶液洗脱,铅、镉的加标回收率在95.0%~105.0%,相对标准偏差RSD为3.8%~9.7%。     

巯基棉分离富集-电感耦合等离子体原子发射光谱法(ICP-AES)测定高盐体系中痕量的铅、镉

采用巯基棉富集分离,电感耦合等离子体原子发射光谱法(ICP-AES)测定了高盐水样中痕量的铅、镉。研究表明,pH值为7时,巯基棉同时富集铅、镉的效果最好,可成功分离基体元素,以盐酸(1.5mol/L)溶液洗脱,铅、镉的加标回收率在95.0%~105.0%,相对标准偏差RSD为3.8%~9.7%。     

黄原酯棉富集双波长分光光度法测定天然水中镉

五十年代出现的离子交换纤维是在纤维的高分子链上带有离子交换基团的离子交换材料。由于其比表面较常用的离子交换树脂大,且交换基团配置在纤维表面,故吸附、解脱速度快,交换效率高,在富集和分离元素方面得到了实际应用。其中黄原酯棉(CottonCellulose Xanthate,简称CCX)与巯基棉比较,又具有制备简单,无巯基乙醇酸恶嗅味,     

新型黄原酸壳聚糖对铅离子的吸附及机理研究

以壳聚糖为原料,先合成O-羧甲基壳聚糖,再和二硫化碳反应制备出新型黄原酸壳聚糖,使用元素分析、FT-IR、UV和TG对其结构进行表征。比较了壳聚糖、O-羧甲基壳聚糖和黄原酸壳聚糖对铅离子的吸附能力,并研究黄原酸壳聚糖对水溶液中铅离子的吸附性能,探讨了铅离子溶液的pH值对吸附的影响和黄原酸壳聚糖对铅离子的吸附热力学。结果表明,黄原酸壳聚糖对铅离子吸附量是壳聚糖的8.37倍,平衡吸附量可达600.6mg/g。XPS表明,吸附过程主要通过吸附剂中的氨基、羧基和黄原酸基团与铅离子发生作用完成。     

Simultaneous determination of lead and nickel in uranium by square-wave polarography

A sensitive method for the simultaneous determination of trace lead and nickel in uranium is described. These elements are separated from uranium by anion exchange and then determined by square-wave polarography using the alkaline cyanide solution as supporting electrolyte. The procedure is applicable to uranium metal and its compounds containing as little as 1 p.p.m. of lead and nickel.     

Environmental cadmium, lead and nickel contamination: possible relationship between soil and vegetable content

Summary The cadmium, lead and nickel content of soils of four agricultural areas exposed to different degrees of environmental pollution and vegetables grown there were measured by Atomic Absorption Spectrophotometry (AAS). In order to ascertain the possible relationship between the heavy metal content of soils (total and extractable) and of vegetables grown in them, the correlation between the two was calculated. The highest correlation values between metal content of soil and vegetables are these corresponding to nickel: the total metal content in soils and leaves-stems are linear (p<0.01). The extractable metal content of soils and leaves-stems are linear (p<0.1). Therefore, soil seems to be the main contributor to nickel content of plants (leaves-stems). In the case of cadmium a statistically significant linear correlation (p<0.01) was observed between total metal content in soil and in leaves-stems and a negative one between extractable metal content of soils and that of roots-bulbs. For lead a negative correlation was found between extractable metal content of soils and leaves-stems. In any case, the lead content of soils is not the main factor that influences the lead content of vegetables. Anthropogenic and environmental factors play a more important role than the lead in soils in the lead content of vegetables.     

纳米二氧化硅对镍电沉积影响及在复合镀层中的化学键合状态

用线性扫描伏安法和电位阶跃法研究了n-SiO2/Ni复合电刷镀体系的电化学响应,探讨了纳米颗粒的影响;用X射线光电子谱研究了复合镀层中n-SiO2/Ni颗粒表面与基质金属间的相互作用．结果表明纳米颗粒使金属沉积过电位显著降低,电流效率、金属成核率及晶体生长速度增加,纳米颗粒对金属镍电结晶有明显的催化效应;n-SiO2/Ni表面氧的不饱和化学键与表面扩散过程中吸附态金属Ni原子键合形成Ni-O键,纳米颗粒与基质镍以化学键方式结合．     

Effect of catalyst transition metal and ancillary ligand on syndiospecific polymerization of styrene

In the coordination polymerization of styrene, selected transition metal complexes of metals other than group 4 elements and non-metallocenes have been investigated in comparison to a known half-metallocene titanium complex with regard to the catalytic activity as well as to the thermal and molecular properties of the polymers synthesized. Whereas iron catalysts lead to syndiotactic polystyrenes, catalysts with nickel as the transition metal result only in atactic polymers with an enhanced isotactic content.In addition to the influence of the transition metal, the effect of a broad variation of the ancillary ligands of a specific half-sandwich titanocene, octahydrofluorenyl titanium trimethoxide, on polymerization activity and polymer properties has been investigated and discussed in detail.     

Determination of metals in urine by direct injection of sample,high-performanc liquid chromatography and electrochemical or spectrophotometric detection

A method for the rapid and simultaneous determination of copper, nickel and lead in urine is described. Direct injections of freshly acidified and filtered (0.45-μm) urine samples were made onto a reverse-phase separator column with a guard column for sample clean-up. By complexing the metals with a dithiocarbamate ligand included in the mobile phase, the metal complexes could be detected electrochemically (copper and nickel) or spectrophotometrically (copper, nickel and lead). The procedure is shown to provide a convenient method for the determination of copper and nickel at normal to occupationally exposed levels of urinary output (electrochemical detection) after direct injection of samples. Spectrophotometric detection methods were insufficiently sensitive for direct determinations of copper and nickel at some of the lower levels found in urine. The spectrophotometric detection of lead is subject to interference by u.v.-absorbing constituents present in urine and is restricted to detection of lead in persons over-exposed to lead, unless additional clean-up procedures are applied.     

电感耦合等离子体质谱（ICP-MS）法测定碳质板岩样品中铂族元素

碳质板岩属黑色岩系,与多种金属(包括贵金属)成矿有密切的联系。按照常规的分析方法,硫镍试金溶剂配方都不能对贵金属元素有较好的富集,影响贵金属元素的测定。根据石墨岩中样品的成份特征,对测定铂族元素的常规硫镍试金配方进行了改进,增加了硝酸钾和氧化镁,且无需加入锇稀释剂。通过实验选择了合适比例配料,熔融后粉碎镍扣,加入盐酸分解,碲共沉淀剂富集。过滤沉淀用王水溶解。用电感耦合等离子体质谱(ICP-MS)法测定,Lu作内标,对碳质板样品中的铂族元素进行了测定。结果表明,加标回收率为85%～105%,能够满足碳质板岩中铂族元素的分析测定要求。     

Trace element determination in vitamin E using ICP-MS

Vitamin E supplements are either isolated from plants sources or prepared synthetically. Isolation from plants includes eight different tocopherol structures. Vitamin E synthesis includes seven different stereoisomers, which involves the use of several catalysts that may lead to trace element contamination in the vitamin. The use of ICP-MS is an ideal technique for detecting these trace elements. However, the oily nature of the samples requires the development of a sample preparation methodology. This study was done upon the request of synthetic vitamin E manufacturers to test the trace metal purity of their samples. In this work, the comparison of an acid microwave digestion and emulsion preparation is discussed. Cromium, nickel, tin and lead were found in the synthetic vitamin E analyzed and 200, 60, 9 and 45 ppb were the concentrations found respectively for these elements.Digesting the samples gives slightly lower detection limits compared to the emulsion preparation.     

Atomic spectrometric methods for the determination of metals and metalloids in automotive fuels - A review

Gasoline, diesel, ethanol and more recently also biodiesel are the four types of fuel used for automobile, truck and other transportation vehicle. The presence of metallic and metalloid species in automotive fuels is undesirable, except in the form of additives in order to improve specific characteristics of the fuel. Metallic or metalloid elements may derive from the raw product, such as nickel and vanadium in petroleum-based fuel or phosphorus in biodiesel, or they may be introduced during production and storage, such as copper, iron, nickel and zinc in case of petroleum-based fuel and alcohol or sodium and potassium in the case of biodiesel. The most famous additive to fuel is undoubtedly lead, the use of which has been banned or drastically reduced now in many countries of the world. The problems related to the trace element content may be economic, such as fuel degradation and poisoning of automotive catalysts, and/or environmental, such as the emission of metal compounds to the atmosphere. The analytical methods that have been developed for metal and metalloid quantification in automotive fuel are reviewed in this article. The main atomic spectrometric techniques used for trace metal and metalloid determination in fuels, particularly atomic absorption spectrometry with flames, graphite furnaces and with chemical vapor generation, and inductively coupled plasma coupled with optical emission and mass spectrometry are presented, including the different sample preparation procedures proposed for these techniques.     

Modification of the(SiO_2/MgO/MgCl_2)·TiCl_x Ziegler-Natta Polyethylene Catalysts Using the Third Metal Elements

Various(SiO_2/MgO/MgCl_2)·Ti Clx Ziegler-Natta catalysts modified by the third metal elements were synthesized by the co-impregnation of water-soluble magnesium and the third metal salts. Several key factors including the electronegativity of the third metal elements, catalyst performances in ethylene homo-polymerization, ethylene/1-hexene copolymerization and hydrogen response were systematically investigated. Both the catalyst performance and the polymer properties are influenced by the introduction of the third metal elements. Compared with the unmodified(SiO_2/MgO/MgCl_2)·Ti Clx Ziegler-Natta catalyst, activity and 1-hexene incorporation are enhanced by the introduction of zirconium, vanadium, aluminum and chromium, while deteriorated by the addition of ferrum, nickel, molybdenum and tungsten. Correlations of the catalyst activities and 1-hexene incorporation ability with the electronegativity of the third metal elements are discovered. It is found that the lower electronegativity of the third metal elements leads to the catalyst with higher activity and higher α-olefin co-polymerization ability. The polyethylene produced by a nickel modified catalyst showed broad molecular weight distribution(MWD) and the lowest average molecular weight(MW), while by using a ferrum modified catalyst, the resulting polyethylene had the highest MW, reaching the ultra-high MW area. Vanadium and chromium modified catalysts demonstrated the best hydrogen response.     

Simultaneous determination of seven trace impurities (Al, As, Cr, Fe, Ti, V and Zr) in high-purity nickel metal and nickel oxide by coprecipitation and inductively coupled plasma-atomic emission spectrometry

Nickel is not coprecipitated with lanthanum hydroxide in ammonium hydroxide solution because it forms rapidly soluble nickel ammine complexes. This behaviour is used for the separation of Ni matrix from trace elements. These are simultaneously and quantitatively coprecipitated with lanthanum hydroxide at pH 10.0 and separated from the Ni matrix. Seven trace elements (Al, As, Cr, Fe, Ti, V and Zr) in Ni metal and 3 certified elements (Cr, Fe and Ti) in a standard reference material of nickel oxide have been simultaneously determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES).