热导法测定航空用铝合金中氢含量

建立热导法测定航空用铝合金中氢的含量。使用数控车床将试样加工成长圆棒,再将其锯切成小圆棒进行分析,讨论了RHEN 602测氢仪的重要参数如分析参数、元素参数、电极炉参数、温度维持程序等,其中坩埚预排气周期为4次,表面氢分析功率为850 W,内部氢分析功率为1 300 W,表面氢和内部氢积分时间分别为120 s和330 s,温度维持采用程序升温。讨论了氢含量测定结果的影响因素,确定坩埚需进行3次以上的空白运行,以减少试样空白对测定结果的影响。载气纯度应大于99.999%,设备稳定3 h以上,试样质量在2~5 g之间,标准样品与试样牌号系列一致且含量高于试样。标准样品验证结果相对偏差为1.39%,航空用2219铝合金板材样品测定结果的相对标准偏差为12.60%(n=10),满足样品检测的重复性技术要求。该法可用于铝合金中氢含量的测定。     

火花源原子发射光谱法测定线材中9种元素

建立了火花源原子发射光谱法测定直径为8～12mm的小规格线材中的碳、硅、锰、磷、硫、镍、铬、铜和钒等9种元素含量的方法。试样经切割和打磨后,按规格及钢种选择对应的自制夹具固定,垂直于磨样机打磨试样的端面。用随V型板专用的定位夹具将样品定位在火花源原子发射光谱仪激发孔中心位置,使试样支架中心和电极中心对齐。盖好顶盖,用氩气吹扫火花室5s,采用能量为0.2J、频率为100Hz激发光激发样品。在优化的仪器工作条件下,试样中9种元素可在10min内完成测定。采用块状光谱国家标准样品制作校准曲线,用校正公式消除了共存元素的干扰及由标准试样和实际试样形状差异带来的系统偏差。结果显示:9种元素的质量分数均在一定范围内与其对应的响应值呈线性关系,检出限(3s)为1.5～18.1μg·g~(-1);用此方法分析实际样品,所得测定值与参考文献使用的其他方法的基本一致,测定值的相对标准偏差(n=11)均在5%以内。     

微波消化-石墨炉原子吸收法测定食用油脂中的铜

用微波消化技术对各种食用油脂试样进行预处理，针对样品特性，优化较佳的微波消化条件与操作参数，建立了用微波消化－石墨炉原子吸收法测定食用油脂中的铜，减少了样品处理过程中的损失，回收率为92.4%-96.2%；RSD为3.0%-3.6%, 检出限为0.05mg/kg。     

应用ICP-AES同时测定生物和环境试样中的微量元素

应用ＩＣＰ－ＡＥＳ同时测定生物和环境试样中的微量元素魏路线张保军（武汉汽车工业大学微观分析中心，武汉，４３００７０）本文报道了组合型等离子发射光谱仪在生物和环境样品分析中的应用．对人发、模拟酸雨提取液和电厂煤燃烧排放的粉尘试样中多种痕量金属元素进行同...     

直读光谱法测定钢铁中常规元素结果准确性的探讨

为提高ARL 4460直读光谱仪测定钢铁中8种常规元素分析结果的准确性,对一些主要的影响因素特别对碳及硫量测定的影响因素做了试验,并对其结果作了探讨,从中得到了一些有利于提高测定准确性和精密度的方法和措施,主要有以下几点:①改变了仪器出厂时设定的光源参数(冲洗时间由10s降为2s,预燃时间由7s降为6s,曝光时间由8s降为3s);②测定碳、硫、磷须用99.999%的高纯氩,且应控制其压力在0.30 MPa左右;③试样表面要干净平整,纹路清晰,应用细砂砂轮机处理试样表面;④制备定碳样品时,样品温度不能高于40℃,且保持其起始状态的纹路粗细程度;⑤分析室环境温度应保持恒定(25℃左右),每8h进行一次工作曲线的校正;⑥测定硫的试样若温度过高,宜先将其冷却至接近室温再作分析,且在分析时应至少取3个分布均匀的激发点,且需根据试样特点作现场校正曲线,用控制试样进行类型标准化。     

棉纤维的N-异丙基丙烯酰胺接枝共聚及产物的温敏性研究

以硝酸铈铵(CAN)、过硫酸钾(KPS)及H2O2/H2A(双氧水/抗坏血酸)为引发体系,采用溶液自由基接枝法制备了具有温敏性的棉纤维N-异丙基丙烯酰胺接枝共聚物(cotton-g-PNIPAAm);在上述3种引发剂作用下的接枝反应可以达到的接枝率(G)排序为G(H2O2/H2A)>G(KPS)>G(CAN);研究了其他因素如引发剂浓度、反应时间、反应温度和单体浓度等对接枝率的影响,得出了优化的接枝反应条件;接枝样品的FTIR分析图谱和SEM观察均表明样品表面已接枝了聚N-异丙基丙烯酰胺;DSC分析显示,棉纤维N-异丙基丙烯酰胺接枝共聚物的低临界溶解温度(LCST)与纯的聚N-异丙基丙烯酰胺凝胶(LCST=32.48℃)相似,约为32~33℃;接枝率的变化对试样LCST的影响很小,但其可逆焓变(ΔH)会随接枝率的提高而增加;采用滴水试验法(AATCC 79)和毛效试验法(FZ/T 01071)检测棉纤维的N-异丙基丙烯酰胺接枝共聚物在不同温度时的吸水性变化,显示试样具有温敏特性,其中接枝率介于25%~45%的试样温敏性较高,过低或过高的接枝率均不利于获得高的温敏性;棉纤维的N-异丙基丙烯酰胺接枝共聚物试样的可逆焓变(ΔH)随试样膨胀/收缩时间变化的研究和分析结果表明,棉纤维的N-异丙基丙烯酰胺接枝共聚物对温度变化的响应比纯聚N-异丙基丙烯酰胺凝胶快.     

植物试样中总糖量的预处理及光度法测定

试样中总糖量的经典测定方法 ,需在沸水浴回流萃取 6ｈ ,操作繁杂 ,消耗试剂及试样量大 ,且一次只能浸提一个样品 ,测定结果易受环境干扰[1] 。近年来 ,微波用于分析样品的预处理 ,特别是生物样品中组分含量的测定 ,日益受到重视[2 ,3 ] ,原因是生物体内各组分一直处于动态变化之中 ,为了准确监测目标产物在代谢过程中的含量 ,必须及时终止新陈代谢活动 ,并将其迅速提取出来。微波加热的高选择性、高穿透性、温升 (降 )快、加热均匀等特点恰好可满足上述要求。本文建立了一种借助微波辐射能迅速灭活植物细胞内糖酶、快速制备总糖量光度分析…     

NEWS

纳米金材料( Au NPs)的广泛应用使其以多种渠道进入环境体系,从而对生物体的健康构成潜在威胁。因此,检测环境样品特别是水体环境中的微量纳米金对于环境监测和纳米粒子的生物安全性研究具有重要意义。然而在实际样品分析中,由于样品基质复杂,纳米粒子的浓度极低且存在易团聚等问题,在仪器分析之前必须辅以合适的样品前处理技术。目前用于纳米粒子分离富集的样品前处理技术较少,且存在操作繁琐、耗时长等问题。武汉大学化学与分子科学学院胡斌教授课题组近期提出了聚合物整体柱毛细管微萃取与等离子体质谱( ICP-MS)在线联用新方法,实现了环境水样中羧基功能基修饰Au NPs的测定,该方法具有灵敏度高、选择性好、样品通量大、试样消耗量少、操作简单、无需消解等特点。     

高压粉末制样-偏振能量色散X射线荧光光谱法测定生物样品中24种元素

<正>X射线荧光光谱法(XRFS)因制样简单、精密度好、多元素同时测定等特点在地质、冶金、环境、建材等科学领域得到广泛应用[1-4]。XRFS测定植物和动物样品中各元素的方法也时有报道[5-10],但是由于生物样品的特性,采用一般制样方法(压力为220~440 MPa)很难将生物样品压制成表面平整、光滑致密的适合XRFS分析的样片,某些类型的生物样品甚至难以直接压制成型,样饼表面的试样粉     

一种简易的多次内反射红外装置的试制

通常的红外吸收光谱图是用红外光对样品进行透射(见图1a),样品吸收了其特征波长的光能,剩余部分的光进入分光器分光,再记录下来。这样,相当多的材料,如硫化橡胶、织物、涂层、纸张、泡沫塑料等样品,由于很难制备出很薄的试样,其厚度正适合于透射法可测的范围,试样厚度稍厚,红外全部透不过去,就难于得到其红外吸收光谱图。近年来由于 Harriek、Fahrenfort 等提出的内反射(Internal Reflection)技术的发展,上述困难就不复存在了,无须特殊制备试样,即可获得满意的谱图。内反射红外装置已成为近年来红外光谱仪必备附件之一。本文将介绍我们在 UR-10型红外光谱仪上,试制上述附件的情况。(一)原理先简要地介绍内反射原理。如将样品紧贴在一晶体表面上(晶体的材料是选择可以透过红外,折光指数又很大的物质,最常用的有 KRS-5晶体与锗晶体),当光束对样品与晶体的界面的入射角大于其临界角时,就发生全内反射(Total Internal Reflec-tion)即光能没有损失,全部反射了出去,其光路如图1b 所示,全内反射发生在样品完全不吸收红外时的情况。若样品对红外有特征吸收,那么反射出的能量就受到衰减,因为衰减是发生在试样的特征吸收峰处,所     

Lithium-fusion sample preparation method for radio frequency glow discharge optical emission spectroscopy (rf-GD-OES): analysis of coal ash specimens

The use of lithium-fusion sample preparation methods for the analysis of powder-form specimens by radio frequency glow discharge optical emission spectroscopy (rf-GD-OES) has been evaluated for the test case of coal ash samples. The development of an elemental analysis technique for chemically complex coal ashes presents a challenge in terms of having simple sample preparation, providing accurate results, and minimizing analysis time. The adopted sample preparation procedure for the coal specimens involved a standard lithium fusion methodology. This procedure circumvents many problems associated with the common compaction methods employed for GD analysis of inorganic powders. It was found that coal ashes prepared as glass disks using a mixture of lithium compounds as the host matrix and analyzed by rf-GD-OES provide good plasma stabilization, with analyte optical emission signals stabilizing in ∼1 min and exhibiting ∼2% RSD variations for sputtering times of up to 10 min thereafter. The evaluation of discharge operating parameters and the assessment of approaches to quantitative analysis were also investigated. Discharge parameters of an rf power of 30 W and an Ar discharge gas pressure of 4 Torr yielded rapid signal stabilization and optimized S/B ratios. Sample-to-sample precision of better than 7% RSD was achieved for repetitive samplings (in the same sample locations) for species present at the parts-per-million level in the sample. Limits of quantification could not be adequately evaluated as the levels of the target analytes in the fusion components (i.e. lithium compounds) were above the method detection limit. It is believed that the general methodology holds promise for rf-GD analysis of a range of inorganic solids in powder form.     

Electrical and optical characteristics of a radio frequency glow discharge atomic emission source with dielectric sample atomization

A parametric study has been conducted on a radio frequency powered glow discharge atomic emission spectrometry (rf-GD-AES) source to evaluate its performance in the direct analysis of non-conducting solid materials. These experiments include both the emission and electrical characterization of this system with respect to discharge power, pressure, limiting anode orifice diameter, and sample size. The rf-GD-AES source has been demonstrated to operate interchangeably between conducting and non-conducting sample materials; however, the energy dissipated within the plasma appears to be reduced with the dielectric samples, resulting in lower emission intensities and sputtering rates. The power losses have also been found to be a function of the size, or thickness, of the sample materials. Despite these limitations of the system, preliminary emission data demonstrate that the rf-GD-AES system can be successfully employed in the direct, trace analysis of non-conducting sample materials.     

Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.     

Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.     

New hardware for radio frequency powered glow discharge spectroscopies and its capabilities for analytical applications

A new radio frequency (rf) hardware is developed for glow discharge spectroscopic methods. The resulting features and its capabilities for analytical applications are discussed. The electrical equipment developed allows to work as quickly, stably, reliably and easily as known from the direct current (dc) mode. Moreover, the rf power measurement has been improved. The hardware has been developed, optimised and tested for glow discharge optical emission spectroscopy (GDOES), but nevertheless it is possible to use it for all procedures applying glow discharge sources.     

New hardware for radio frequency powered glow discharge spectroscopies and its capabilities for analytical applications

A new radio frequency (rf) hardware is developed for glow discharge spectroscopic methods. The resulting features and its capabilities for analytical applications are discussed. The electrical equipment developed allows to work as quickly, stably, reliably and easily as known from the direct current (dc) mode. Moreover, the rf power measurement has been improved. The hardware has been developed, optimised and tested for glow discharge optical emission spectroscopy (GDOES), but nevertheless it is possible to use it for all procedures applying glow discharge sources.     

Hydrogen effects on copper,zinc and nickel atomic emission lines in argon radiofrequency glow discharge optical emission spectrometry

The effect of hydrogen (0.5%, 1% and 10% v/v) added to the argon plasma gas on the emission spectra of selected atomic lines for copper, zinc and nickel has been studied by radiofrequency glow discharge optical emission spectrometry (rf-GD-OES). Conductive homogeneous samples containing different concentrations of the elements under study in different matrices have been investigated. Results show different trends of the emission intensity lines with increasing hydrogen concentration in the rf-GD, depending on the line characteristics. In most cases, the emission yields of the lines under study did not change or increased when hydrogen was added to the discharge (no decreases were observed). The emission yields of certain lines showed much higher increases than other lines of the same element (for example, lines 213.86 nm of Zn and 231.10 nm of Ni). Our experiments indicate that such notorious increases could be related with the possible decrease of the self-absorption when hydrogen is added to the discharge. Overall, the results obtained for the emission yield changes of certain lines of a given element in different matrices (with different analyte content) showed that while for resonance emission lines very notorious increases are observed, the values for non-resonance lines do not change significantly (specially if the matrices employed are similar).     

A simple and rapid method for determination of boron in fast breeder reactor components

The present paper describes a new analytical method developed for direct determination of boron in steels using radio frequency glow discharge optical emission spectrometer. “Single parameter alternative method” technique has been used to optimize the various experimental conditions of glow discharge plasma such as forward power, gas pressure inside plasma chamber, pre-integration time, and integration time. Different emission lines for boron were studied and inter element interference effect is also discussed in the paper. A complete statistical analysis has been done to validate the developed method. A RSD of less than ±5% is achieved for boron in the range of 0.0010–0.020% in Steels using this method.     

Radio-frequency glow discharge ion source for high resolution mass spectrometry

A radio-frequency powered glow discharge ion source has been developed for a double-focusing mass spectrometer. The sputtering and ionization of conducting, semiconducting and insulating materials have been realized using a 13.56 MHz generator to supply the discharge operating potential. The glow discharge ion source operates stably at argon pressures of 0.1–1 hPa and radio frequency powers of 10–50 W. The influence of discharge parameters and gas inlet system on sputtering rates and ion signal intensities for semi-insulating gallium arsenide wafers has been investigated.