盐酸介质-火焰原子吸收光谱法快速测定铁矿石中钾钠铅锌

以氢氟酸溶解铁矿石,加高氯酸除去硅和氟,在稀盐酸介质中,使用空气-乙炔火焰原子吸收光谱仪测定铁矿石中钾钠铅锌。通过实验确定了原子吸收光谱仪测定钾、钠、铅、锌含量的最佳工作条件,并对样品称样量、测量钾、钠、铅、锌含量的各标准曲线及检出限分析后,运用此方法测定铁矿石样品中钾、钠、铅、锌含量,相对标准偏差(n=10)均小于±5%。     

热脱附-气相色谱法测定无机材料中微量水分

1　引　　言目前 ,国内外水分测定的方法很多 ,如热分析失重法、吸收法和卡尔·费休法等。气相色谱法具有分析速度快、灵敏度高的特点 ,常用于液体中的水分测定 ,而在固体中测定水分含量尚未见报道。本实验采用热解吸与气相色谱法结合 ,成功用于固体材料中微量水分和无机化合物中的结晶水的测定 ,并对解吸时间、温度和载气流速等条件做了研究。2　实验部分2 .1　仪器与试剂　GC 16A气相色谱仪 ,热导池检测器 (TCD) ,PYR 2A裂解器 (日本岛津公司 )。色谱柱 :0 .6m× 0 .32mmporaparkN不绣钢填充柱。碳酸钙 (分析纯 )、膨润土、活性白土…     

氧屏蔽空气-乙炔火焰原子吸收光谱法测定铁矿石中的镓

镓是一种稀散元素,岩石矿物中的含量一般都很低。空气-乙炔火焰原子吸收测定镓,灵敏度低,手续繁多。近年来,氧屏蔽空气-乙炔火焰在原子吸收分析中应用,部分元素的灵敏度有较大提高。本文将这种火焰用于铁矿石中镓的原子吸收测定。低含量经萃取分离浓缩后喷雾有机相,高含量直接喷洒水溶液可以测定0.001％以上的镓。该方法简便快速,分析结果有较好的重现性和准确度。     

甘氨酸锌相对分子质量与锌含量标准的研讨

甘氨酸锌是新一代氨基酸系列补锌产品，在国标GB2760-1996食品添加剂卫生标准中被确定为食品营养强化剂，其备注中对甘氨酸锌中的锌含量标注为31．8％。作者通过对甘氨酸锌产品的研制和结构分析认为此值有误，应予更正。含结晶水的甘氨酸锌相对分子质量为231．51，锌含量为28．24％；不含结晶水的甘氨酸锌相对分子质量为213．51，锌含量为30．62%。     

挥发性气体生成-电位法测定铜合金和铁矿石中的锡

铜合金和铁矿石中的锡常采用极谱法测定。由于主体元素和共存元素对锡波的干扰,大都需要进行预处理分离,操作繁琐。我们根据锡(Ⅱ)可被硼氢化物还原生成锡化氢,而与溶液中的干扰组分相分离。锡化氢由载气携带流过电化池的一个多孔金膜电极的表面而被氧化。电化池所产生的电位响应与原始溶液中锡的含量有线性关系。我们在前文中把这种方法称为挥气电位法。利用这种方法可以测定许多物质如Hg、As、Sb、Sn,S,CN和Cl等等离子。本文测定了铜合金和铁矿石中的锡。方法的优点是:(1)利用锡化氢的挥发性与气敏电极测定相结合,既消除了共存元素的干扰,又免去了吸收气体的装置;(2)电化池响应快,灵敏度高;(3)取样少,溶样时间短,测定快速,设备简单。     

气相色谱法测定香水中乙醇含量的研究

本文建立了香水中乙醇含量的气相色谱检测方法.选用强极性的Agilent DB-WAXETR毛细管色谱柱(60 m×0.32 mm×0.5 μm),进样口温度180℃,分流比100∶1,进样量1μL,载气为高纯氮气,升温程序:90℃保持14 min,以30℃/min升至180℃,保持3 min,FID温度200℃.结果表明,乙醇含量在2％～20％的范围内有良好的线性(r2=0.99986),回收率为99.33％～101.00％.建立的方法简便、快速、准确,可用于检测香水中的乙醇含量.     

热解吸收-冷原子荧光光谱法测定水泥中痕量汞

将热解吸收技术应用于冷原子荧光光谱法测定水泥样品中痕量汞含量。采用自制的石英管加热550℃处理样品,用0.01mol·L-1高锰酸钾溶液作为吸收液吸收释放出的汞蒸气,用盐酸羟胺还原过量的高锰酸钾后直接进样测定。试验中优化了仪器的工作参数和试验条件。分析中采用载气及屏蔽气的流量依次为400mL.min-1及1 000mL.min-1。荧光强度与汞的质量浓度在2μg·L-1以内呈线性关系,方法的检出限(3σ)为0.020μg·L-1。应用此法分析土壤标准样品(GBW 07405),测定值(0.30μg.g-1)与证书值(0.29±0.03μg.g-1)相符;方法用于测定水泥中汞含量,加标回收率在97.0%～107.0%之间,相对标准偏差(n=5)在0.7%～4.1%之间。     

HG-AAS法测定不锈钢食具浸泡液中的砷

研究了利用氢化物发生原子吸收法测定不锈钢食具浸泡液中痕量砷的反应体系.对载气流速、硼氢化钠溶液的浓度、5％抗坏血酸-5％硫脲溶液添加量和介质酸度的影响,以及基体和共存离子的干扰等条件进行了研究.样品加标回收率为95.8％～106.2％,测定结果的相对标准偏差不大于2.8％,方法检出限为0.12 μg/L.该方法适用于不...     

超声雾化进样微波诱导等离子体原子吸收光谱法测定银的某些影响因素研究

本文将超声雾化技术与MIP-AAS联用,以“L”型吸收管代替“T”型吸收管作为AAS测量的吸收池,采用水冷凝和浓H_2SO_4吸收相结合去溶,研究TUSN-MIP-AAS方法测银时的某些影响因素,讨论了微波前向功率,载气流速、去溶系统、溶液酸度、共存离子及易也离元素等对吸收信号的影响,本法所得的测银的特征浓度为0.01μg/ml(328.1nm)和0.03μg/ml(338.3nm),相对标准偏差为7.5％.     

X射线荧光光谱法测定铁矿石的化学成分

利用助熔剂,将铁矿石样品在高温下熔融成玻璃圆片,从而消除矿物结构效应,并降低基体效应的影响,研究了熔样的条件和灼烧减(增)量对全铁分析结果的影响,应用经验系数法校正了基体的吸收激励效应,提出了铁矿石的X射线荧光光谱法,测定了铁矿石中TFe、P、SiOz、A12O3、CaO、V2O5、TiO2、MgO等8种化学成分.     

水蒸气对甲烷在金属铁表面还原NO行为的影响

采用程序控温电加热水平陶瓷管反应器,在N2气氛和模拟烟气气氛中、300~1100℃下,研究了水蒸气对甲烷在金属铁表面还原NO行为的影响,并对反应前、后铁样品进行了X光衍射(XRD)、扫描电子显微镜(SEM)及X光电子能谱(XPS)等表征。结果表明,水蒸气对甲烷在金属铁表面还原NO行为的影响较小。在N2气氛中,水蒸气参与了金属铁的氧化;与无水蒸气时相比,水蒸气存在时NO还原效率有所下降。当水蒸气含量从2.5%增加到7%时,由于水蒸气对金属铁的氧化导致其表面形成疏松的微观孔隙,使得NO的还原效率随水蒸气含量的增加而提高。甲烷则参与了铁氧化物的还原,使铁样品表面形成相对致密的Fe3O4和FeO氧化层,不利于NO与金属铁的接触,使得NO的还原效率低于无甲烷时的结果。在模拟烟气条件下,水蒸气使得甲烷在金属铁表面还原NO的效率增加;在1050℃下,反应段过量空气系数SR1=0.7和燃尽段过量空气系数SR2=1.2时,含7%的H2O和无H2O条件下脱硝效率分别为96.7%和90.6%。而在湿烟气中SO2使NO还原效率略有下降。持久性脱硝实验结果表明,当反应温度为1050℃时,在含7%的H2O、0.02%的SO2的模拟烟气中,1.14%的甲烷在金属铁表面持续50h都能保持90%以上的脱硝效率。     

Determination of cadmium in river water by sequential metal vapor elution analysis

Determination of cadmium in river water by sequential metal vapour elution analysis (column temperature; > 1500 K) with argon and hydrogen carrier gas and with atomic absorption spectrometric detection is described. The column is made of a molybdenum capillary tube (i.d. 1.22 mm) and the temperature is 1760 K. The cadmium vapor was separated from those of calcium, iron and sodium. The calibration graph was linear up to 15 μ/ml. Relative standard deviations of 0.8–4.3% were obtained in the range 1 to 15 μ/ml. Cadmium in spiked samples (river water) was determined. The results were in good agreement with the amount spiked.     

Natural iron ore as an oxygen carrier for biomass chemical looping gasification in a fluidized bed reactor

Chemical looping gasification (CLG) of biomass was performed in a thermogravimetric analyzer (TG) reactor together with a fluidized reactor with natural iron ore oxygen carrier under inert atmosphere. TG experiments indicated that iron ore can provide oxygen source for biomass conversion in the form of lattice oxygen. In the fluidized bed experiments, the influences of reduction temperature on CLG of biomass were emphatically investigated in terms of gas distribution and solid characters. The gas yield and carbon conversion increased, but the tar content decreased in the temperature range of 1,013–1,213 K. In this temperature range, the conversion of oxygen carrier increased from 24.11 to 53.59 %. X-ray diffraction analysis shows that more FeO was generated with temperature increasing. Scanning electron microscope analysis indicates that sintering was observed at elevated temperature. An optimum mass ratio of biomass/oxygen carrier (B/O) of 0.67 was obtained with aim of achieving maximum gasification efficiency of 76.93 %.     

Selected ion flow tube mass spectrometry analyses of stable isotopes in water: Isotopic composition of H3O+ and H3O+(H2O)3 ions in exchange reactions with water vapor

A new method has been developed for the determination of the isotope abundance ratios of deuterium, D, and oxygen-18, 18O, in water vapor (and water) using selected ion flow tube mass spectrometry (SIFT-MS). H3O+ ions are injected into the helium carrier gas where they associate with the H2O and HDO molecules in a sample of water introduced into the carrier gas. The D and 18O contents of the product cluster ions H8DO4+ and H9(18)OO3+ at m/e = 74 and 75, respectively, are determined by reference to the majority cluster ion H9O4+ at m/e = 73. Allowance is made for the contribution of the H8(17)OO3+ ions to the m/z = 74 ions. Absolute isotopic ratios are measured within seconds without the need for precalibration of the SIFT-MS instrument, currently to an accuracy of better than 2%.     

Linearization of calibration curves by aerosol carrier effect of CCl4 vapor in electrothermal vaporization inductively coupled plasma mass spectrometry

Carbon tetrachloride vapor as gaseous phase modifier in a graphite furnace electrothermal vaporizer (GFETV) converts heavy volatile analyte forms to volatile and medium volatile chlorides and produces aerosol carrier effect, the latter being a less generally recognized benefit. However, the possible increase of polyatomic interferences in inductively coupled plasma mass spectrometry (GFETV–ICP-MS) by chlorine and carbon containing species due to CCl₄ vapor introduction has been discouraging with the use of low resolution, quadrupole type MS equipment. Being aware of this possible handicap, it was aimed at to investigate the feasibility of the use of this halogenating agent in ICP-MS with regard of possible hazards to the instrument, and also to explore the advantages under these specific conditions. With sample gas flow (inner gas flow) rate not higher than 900 ml min⁻¹ Ar in the torch and 3 ml min⁻¹ CCl₄ vapor flow rate in the furnace, the long-term stability of the instrument was ensured and the following benefits by the halocarbon were observed. The non-linearity error (defined in the text) of the calibration curves (signal versus mass functions) with matrix-free solution standards was 30–70% without, and 1–5% with CCl₄ vapor introduction, respectively, at 1 ng mass of Cu, Fe, Mn and Pb analytes. The sensitivity for these elements increased by 2–4-fold with chlorination, while the relative standard deviation (RSD) was essentially the same (2–5%) for the two cases in comparison. A vaporization temperature of 2650 °C was required for Cr in Ar atmosphere, while 2200 °C was sufficient in Ar + CCl₄ atmosphere to attain complete vaporization. Improvements in linear response and sensitivity were the highest for this least volatile element. The pyrolytic graphite layer inside the graphite tube was protected by the halocarbon, and tube life time was further increased by using traces of hydrocarbon vapor in the external sheath gas of the graphite furnace. Details of the modification of the gas supply for HGA-600MS furnace and the design of the volatilization device are described.     

Determination of phosphorus in steel with a stabilized-temperature graphite furnace and zeeman-corrected atomic absorption spectrometry

The determination of phosphorus in steel by graphite furnace a.a.s. is plagued by a spectral interference from the iron matrix which results in overcompensation when a continuum-source background corrector is used. Zeeman background correction using an alternating transverse magnetic field at the furnace eliminates this problem and allows a routine determination of phosphorus down to 0.002% in steel. Lanthanum is an effective matrix modifier for the phosphorus determination, but its enhancing effect depends largely upon the tube material used and the sample matrix. A 0.2% lanthanum solution was found to be optimum. The stabilized-temperature platform furnace concept allows an interference-free determination of phosphorus in steel, down to 0.002%, directly against aqueous standards. Atomizing the sample from a pyrolytic graphite platform in an uncoated graphite tube provides the optimum environment for a phosphorus determination.     

Preliminary studies on flow-injection in situ trapping of volatile species of gold in graphite furnace and atomic absorption spectrometric determination

Volatile species of gold in acidified medium were generated at room temperature by the reduction of NaBH₄ using a flow injection vapor generation (FI-VG) system, and trapped in situ on the graphite furnace inner wall to get ETAAS detection. Reaction coil inner-wall and inside of the gas–liquid separator were conditioned by passing through a liquid containing micro amounts of Pd(II) and sodium diethyldithiocarbamate (DDTC) and NaBH₄. The FI manifold design, the precondition of the FI-VG system and the effect of temperature parameters for ETAAS are discussed. Optimization of the FI and chemical parameters, such as effect of sample acidity, effect of sodium tetrahydroborate concentration, effects of the flow rates for sample, reagent and carrier gas, effects of HCl and DDTC concentration in rinsing solution were investigated. A detection limit of 0.8 ng/ml (3σ) was obtained with a 40 s trapping time and a sampling frequency of 50/h. The precision of 2.2% R.S.D. (n=11) was obtained at 50 ng/ml level. The method was used for the determination of gold in ore sample digest solution. The recoveries of gold in ore sample digest dilute solution by spiking of 25 ng/ml gold were 90–106%. The results obtained were in good agreement with those obtained from direct ETAAS.     

Decomposition of Chloromethanes in Gliding Discharges

Gliding discharge plasma was used for decomposition of tetrachloromethane and trichloromethane. Air containing 8000 ppm or 20 ppm of water vapor was the carrier gas. The course and yield of the process were studied as a function of initial concentration of tetrachloromethane and trichloromethane, gas flow rate, and water vapor content. The conversion was high in all cases—it reached 90% for tetrachloromethane and 100% for trichloromethane. The conversion rate of the chloromethane compounds increased with increasing initial concentration of these compounds in the reaction mixture. Changing the water vapor content in the reaction mixture from 20 ppm to 8000 ppm increased the conversion rate of chloromethanes.     

Determination of benzene alkyl derivatives in heavily loaded environmental aqueous samples by means of combination of distillation and purge and trap-gas chromatography-mass spectrometry

Simple distillation was used to prepare aqueous environmental samples (especially those with high content of accompanying dissolved and suspended organic and inorganic matter) for determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) by means of purge and trap (PT) coupled to gas chromatography-mass spectrometry (GC-MS). The PT step was carried out with a laboratory-built device in which alalytes desorbed from a Primary trap (macrotrap) are focused in a microtrap (also with sorbent) and moisture is removed from purge gases by a Nafion tube (walls selectively permeable to water vapor). Recoveries, if only the first 10 ml distillate was collected, were of the order of 40% at optimum distillation parameters. At a probability level of 95% recoveries were independent of concentration in a studied concentration range of 0.50–30 ppb. Enrichment factors for distillation were of the order off 20. Real samples, i.e., raw and treated waste water were analyzedc for BTEX content by the developed medthod.     

Determination of cadmium by an improved double chamber electrothermal vaporization inductively coupled plasma atomic emission spectrometry

An improved double chamber electrothermal vaporization (ETV) system was designed. A new inner chamber and its bottom plate made of quartz glass were attached with carrier support gas inlet port for the determination of cadmium by inductively coupled plasma atomic emission spectrometry (ICP-AES). The use of the inner chamber in combination with the plate played important roles to transport the metal vapor efficiently into argon ICP. Ten-μl sample aliquots were dried at 100 °C and subsequently heated at 1000 °C on the tungsten boat furnace. The evolved vapor was swept into the ICP source through PTFE tubing and the inner chamber by a 0.8 l/min H₂ (7%)-Ar carrier gas. The performance parameters of ETV-ICP-AES such as temperature program and gas flow rate were evaluated using cadmium standard solution. Under the optimized experimental conditions, the best attainable detection limit at Cd II 214.438 nm line was 0.2 ng/ml with linear dynamic ranges of 50 to 10,000 ng/ml for cadmium. The instrumental precision expressed as the relative standard deviation (RSD) from ten replicate measurements of 10,000 ng/ml for cadmium by ETV-ICP-AES was 0.85%. The present method has been successfully applied to the determination of cadmium in zinc-base materials.