用基体改进剂与平台石墨炉原子吸收法直接测定植物油中痕量铅

近年来,石墨炉原子吸收法出现了L＇vov平台,基体改进,石墨管改进等行之有效的技术。文献报道了基体改进剂结合平台技术测定鱼和牡蛎等食物中的铅,取得了满意的结果。但这一技术用于油样测定尚未见报道。本文采用磷酸氢二铵作基体改进剂,使灰化温度提高到900℃,使大量有机物在此温度下除去,残余的背景吸收用氕灯校正。使用石墨平台技术,有效地消除了基体干扰。建立了不用化学预处理,用校正曲线直接测定油中铅的简便方法。     

石墨炉原子吸收光谱法直接测定铁镍基高温合金中的锡

建立石墨炉原子吸收光谱法直接测定铁镍基高温合金中的锡元素。通过研究基体效应、溶样酸、基体改进剂、灰化温度、原子化温度以及不同激发光源类型,确定最佳测定方案:用2 m L盐酸和0.4 m L硝酸溶解合金样品,灰化温度为1 200℃,原子化温度为2 200℃,选用0.003 mg Pd(NO_3)_2和0.03 mg NH_4H_2PO_4作为基体改进剂。在空心阴极灯(HCL)和无极放电灯(EDL)两光源条件下,标准工作曲线的线性相关系数均大于0.999,分别对GBW 01632和GBW 01634的测定结果与认可值进行t检验(α=0.05),均无显著性差异,短期稳定性好(RSD5.0%,n=8),锡的检出限分别为0.82μg/L(HCL)和0.75μg/L(EDL)。该方法无需萃取或其它复杂的前处理过程,测定结果准确、可靠,可实现铁镍基合金样品中锡的直接测定。     

石墨炉原子吸收光谱法测定高纯铜中锡的研究

研究了纯铜中锡在平台石墨炉原子吸收光谱法中某些行为对测定的影响,其中包括铜和基体改进剂抗坏血酸对锡的灰化温度和原子吸收的影响,盐酸、硝酸和柠檬酸的影响,铜－锡空心阴极灯在锡共振线２２４．６ｎｍ的光谱干扰,氘灯和自吸收法校正扣除背景的比较以及锡的价态和不同溶样方法对分析结果的影响。     

石墨炉原子吸收法测定渗透水中的铍

本文用塞曼效应石墨炉原子吸收法测定铍，以抗坏血酸作基体改进剂，使测定铍的灵敏度提高，并且提高了灰化温度和降低原子化温度，增强抗干扰能力。利用抗坏血酸的增感作用直接测定了渗透水和水系沉积物中的痕量铍。     

石墨炉原子吸收法测定渗透水的铍

本文用塞曼效应石墨炉原子吸收法测定铍，以抗坏血酸作基体改进剂，使测定铍的灵敏度提高，并且提高了灰化温度和降低原子化温度，增强抗干扰能力，利用抗坏血酸的增感作用直接测定了渗透水和水系沉积物中的痕量铍。     

石墨炉原子吸收光谱法直接测定电子级二乙二醇甲醚中铅

采用石墨炉原子吸收光谱法,直接测定了电子级二乙二醇甲醚(DGME)中的Pb含量。对吸收谱线、基体改进剂、仪器分析条件如灰化温度、原子化温度等进行了研究。分析线选择283.3 nm,以25 g/L草酸加10 g/L NH4H2PO4溶液作复合基体改进剂,灰化温度800℃,原子化温度1400℃,线性方程为y=0.0066ρ(μg/L)+0.0715,相关系数R=0.9961。方法相对标准偏差3.7%,检出限为0.144 ng/m L。     

石墨炉原子吸收分光光度法测定茵栀黄注射液及其中的铅镉

采用石墨炉原子吸收分光光度法(GFAAS),通过对波长、光谱带宽、灯电流、干燥温度、灰化温度、原子化温度的选择来确定最佳条件,直接测定经浓HNO3和H2O2消解法预处理的茵栀黄注射液及4味药材金银花、茵陈、栀子、黄芩中Pb、Cd的含量。用体积分数为0.002%柠檬酸作基体改进剂,提高了灰化温度,消除了背景干扰,改善了原子化吸收峰,提高了测定灵敏度。线性回归方程为APb=0.0033c 0.04072,相关系数为rPb=0.9991,检出限为4×10-8mg/L;ACd=0.0889c 0.2158,rCd=0.9995,检出限为2×10-9mg/L。方法回收率为99.0%～110%,相对标准偏差小于2.5%。     

基体改进剂效应塞曼无火焰原子吸收光谱法测定化探样品中痕量银

地球化探样中痕量银(0.0X ppm)不经分离富集直接测定是困难的。现有文献多采用分离富集处理后用无火焰原子吸收测定。采用基体改进剂手段,但未见用于任何样品中痕量银的分析。本文应用基体改进剂技术研究了痕量银在石墨炉原子吸收测定中的原子化条件和基体的干扰及排除。试验了用铱、钯、铂等作为基体改进剂,当加入15微克铱时,灰化温度可提高至1000℃。拟定了加入基体改进剂后的直接测定程序。本法灵敏度为4.5×10~(-12)g/l％,测定     

石墨炉原子吸收法直接测定全血中镉和铅

直接测定人体血镉和血铅较为困难。本文介绍用铂作基体改进剂以提高镉、铅的灰化温度,在灰化阶段除去产生高背景吸收的蛋白,而不发生镉、铅的挥发损失。实现了不需消化样品、络合提取等复杂的化学前处理,用石墨炉原子吸收法和校正曲线直接测定。同时应用衬钽技术,大大延长了石墨管的使用寿命。     

钴和硝酸镁作为通用基体改进剂的研究

研究钴和硝酸镁作通用基体改进剂的可能性，文中提出了基体改进剂使银，砷，金，镉，镓，锗，铟，铅，锑，硒，锡，铊等元素在石墨炉原子吸收中允灰化温度大的提高，从而消除基体干扰。对钴和硝酸镁作基体改进剂与常用的基体改进剂进行了比较，结果令人满意。     

Direct determination of tin in tap waters by electrothermal atomization atomic absorption spectroscopy

Summary A method is described for the direct determination of tin in tap waters by electrothermal atomization atomic absorption spectroscopy (ETA-AAS), using magnesium-nitric acid and palladium-magnesium as chemical modifiers. The charring and atomization temperatures and times, and the amount of modifier were optimized. The calibration and addition graphs, detection limit, quantitation limit, precision, accuracy, interferences and characteristic mass were also investigated. The method was applied to the determination of tin in tap water samples.     

Binary modifiers for the determination of zinc in pure copper and nickel-based alloy by longitudinal Zeeman electrothermal atomic absorption spectrometry

The determination of zinc in pure copper and nickel-based alloy was successfully accomplished with a longitudinal Zeeman-effect correction and end-capped transversely heated graphite atomizer. Since aqua regia (an acid mixture of nitric acid and hydrochloric acid, 1:3, v/v) was used as the dissolving reagent, volatile ZnCl₂ was formed. Consequently, less Zn was found in the sample. EDTA could improve the atomic absorption profiles. Binary modifiers, EDTA + Pd(NO₃)₂ and EDTA + Mg(NO₃)₂, were effective for eliminating the chloride interference and the spectral interference from Cu I 213.853 nm. The experimental results obtained with and without the modifiers were compared. Increase of 200 °C in the pyrolysis temperature resulted from the addition of binary modifiers for both pure copper and nickel-based alloys. For pure copper, the atomization temperature increased from 1400 to 1600 °C whereas the atomization temperature increased from 1100 to 1600 °C for nickel-based alloys. The analytical performance of the proposed method was evaluated. Zinc contents in the pure copper and nickel-based alloy standards determined with both binary modifiers agreed closely with the certified values. The recovery ranged from 93 ± 2 to 104 ± 6% at 95% confidence level. The detection limits obtained by the binary modifiers of EDTA + Pd(NO₃)₂ and EDTA + Mg(NO₃)₂ were 0.77 and 0.31 pg, respectively.     

Determination of thallium by furnace atomic absorption spectrometry

The analytical conditions for the determination of thallium by graphite furnace atomic absorption spectrometry were studied and optimized using the peak-height mode. The charring-atomization curves for thallium from different atomization surfaces were constructed and the optimum charring and atomization conditions were established. These atomization surfaces included pyrolytic graphite-, tantalum-, zirconium- and tungsten-coated graphite tubes. The effects of different inorganic acids on the absorbance of thallium from different surfaces were studied. Using tungsten carbide-coated tubes, the interference effects due to hydrochloric and perchloric acids were eliminated. The matrix modification technique was also investigated for increasing the maximum permissible charring temperature for thallium. The matrix modifiers used included tungsten, zirconium, nickel and tantalum. The effect of adding these modifiers were studied in the presence of different acids. Tungsten increased the maximum permissible charring temperature from 400 to 1000 °C.     

不同改性组分对Cu-ZnO基催化剂低温甲醇合成性能的影响

通过共沉淀法制备了Al、Zr和Ce改性的Cu-ZnO基低温甲醇合成催化剂,采用氮气物理吸附、H2-TPR、CO2-TPD、N2O滴定、XRD和TEM等技术对其进行了表征,并考察了改性组分和煅烧温度对其在170℃下合成气制甲醇催化性能的影响。结果表明,经Zr改性的Cu-ZnO基催化剂,其低温甲醇合成性能较好;随着煅烧温度的降低,Cu在催化剂表面的分散度逐渐变大、颗粒逐渐变小,所得到的催化剂其活性也较高;其中,未经煅烧的Cu-ZnO/ZrO2催化剂的活性最佳,其甲醇时空产率为106.02 g/(kg·h),选择性达87.04%。     

采用偏振塞曼原子吸收分析直接测定磷酸盐中微量铁

高浓度基体中测定微量铁时,排除基体干扰,多是采用络合萃取、沉淀分离等方法。Inovc等人用二巯基顺丁二氰与铁以1:3络合,其络合物与四丁基铵阳离子(tba⁺)生成离子对,用MIBK萃取后进行测定,手续繁杂费时,灵敏度仅为0.039μg/ml 1%abs,范键同志在测金属铬中的铁时,采用不分离的方法,溶样后直接测定,方法简单,但指出磷酸在火焰中对铁有抑制作用。     

Titanium as a chemical modifier for the determination of cobalt in marine sediments

The determination of cobalt in marine sediments by electrothermal atomic absorption spectrometry was studied using no modifier and magnesium and titanium as modifiers. Titanium is one of the major sediment constituents, which widely affects the cobalt determination and it was studied as a chemical modifier since it was the only concomitant that increased the cobalt signal in the concentration range usually found in sediments. The performance of Mg and Ti as chemical modifiers was compared relative to maximum pyrolysis and atomization temperatures, linear calibration range, sensitivity and matrix effects. The pyrolysis curves showed that the analyte could be stabilized up to 1400 °C when either Ti or Mg(NO₃)₂ was present, while only 1000 °C could be used in the absence of a modifier. The optimum atomization temperature was 2500 °C in all cases. Analytical curves were compared using no modifier, 5 μg Ti and 100 μg Mg(NO₃)₂ as modifiers, and the linear range found was up to approximately 4 ng Co whether a modifier was used or not. With Ti as a chemical modifier, analytical curves for cobalt in aqueous solution and in a synthetic matrix resulted in the same sensitivity (m₀=55 pg), whereas the use of Mg led to characteristic mass values of 59 and 72 pg in aqueous solution and in a synthetic matrix, respectively, showing some matrix effect. The detection limits (3σ, n=10) were 0.4 μg g⁻¹ using no modifier and 0.3 μg g⁻¹ with Ti as a modifier in the original matrix. A reference estuarine sediment NIST 1646 with a non-certified content of 10.5 μg g⁻¹ Co was analyzed and the found value of 10.9±2.4 μg g⁻¹, (n=3), using Ti as chemical modifier and calibration against aqueous standards, was in good agreement with the recommended value.     

采用钯基体改进剂石墨炉原子吸收法测定纺织品中的可萃取铅

纺织品标准中对铅的限量极为严格,但萃取汗液基体成分复杂,背景吸收干扰强烈,为解决纺织品中的可萃取铅检测的困难,建立了一种采用基体改进剂的石墨炉原子吸收光谱法,测定纺织品中的可萃取铅。通过比较两种基体改进剂,优化实验条件,确定了以钯-硝酸镁为基体改进剂、灰化温度1 200℃、原子化温度2 300℃的实验条件。结果表明,以钯-硝酸镁为基体改进剂更能有效降低纺织品可萃取铅的基体干扰,并且具有良好的精密度(2.6%~3.3%)和准确度(加标回收率94.3%~105.6%)。     

MgH_2+20%(w)MgTiO_3复合材料的吸/放氢性能(英文)

为了降低MgH2的吸放氢温度,提高其吸放氢动力学性能,本文通过球磨方法制备了MgH2+20%(w)MgTiO3复合储氢材料,并研究了其储氢性能.X射线衍射(XRD)结果表明,MgTiO3在与MgH2球磨过程中生成Mg2TiO4和TiO2,并且Mg2TiO4和TiO2在体系的吸放氢过程中保持稳定,能够对MgH2的吸放氢过程产生催化作用.程序升温脱附和吸/放氢动力学测试结果表明,添加MgTiO3后MgH2的初始放氢温度从389°C降至249°C.150°C下的吸氢量从0.977%(w)提高到2.902%(w),350°C下的放氢量从2.319%(w)提高到3.653%(w).同时,MgH2放氢反应的活化能从116kJ·mol-1降至95.7kJ·mol-1.与MgH2相比,MgH2+20%(w)MgTiO3复合材料的热力学与动力学性能均有显著提高,这主要是由于球磨和放氢过程中原位生成的TiO2和Mg2TiO4具有良好的催化活性.     

石墨炉原子吸收光谱法测定氯化钠、溴化钾和碘化钾中痕量铁铜铅铋

氯化钠、溴化钾、碘化钾在石墨炉原子吸收光谱法测定铁、铜、铅、铋时产生强的背景。提高灰化温度和时间能消除或降低此干扰。铅和铋的测定能用铂或钯作基体改进剂,但是铂的效果更好。     

One-step Synthesis and Gas Sensing Properties of Hierarchical SnO2 Materials

Hierarchical tin oxide(SnO₂) architectures were synthesized with a facile hydrothermal method. In the hydrothermal synthesis, sodium dodecyl benzene sulfonate(SDBS) surfactant plays an important role as structure-directing reagent. The synthesized samples were characterized by powder X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM) and high-resolution transmission electron microscopy(HRTEM). The results clearly reveal that the hierarchical architectures of SnO₂ were composed of aggregated nanosheets with a thickness of about 100 nm. A possible mechanism for the formation of the SnO₂ hierarchical architectures was proposed. In addition, the gas sensing properties of the as-prepared products were investigated and it was found that the sensor based on the special SnO₂ hierarchical architectures exhibited a high response and good selectivity to NO₂ at the optimal working temperature of 160 ℃.