Effect of Hydrophobic Chain of Dye Molecule and Surface of Active Crystal on the Organized Assemblies Formation of Dyes

Four derivatives of 5,5',6,6'-tetrachlorobenzimidazolocarbocyanine iodide with different long alkyl chain substituents in N-position of polymethine chromophore have been used for investigating the influence of hydrophobicity of dyes on the aggregation.It has been found that all dyes formed monomeric species in methyl alcohol. However, after addition of water to CH_3OH to change the polarity of the solvent, difference between dyes appeared.Addition of inorganic salt facilitated the J-aggregation of easy soluble dye, but it seems useless for the sparely soluble dye.Platelets cut from AgBr polycrystal or pressed AgBr powder have been used as substrate for adsorbing dyes. After addition of hexanoic acid, eventually the J-aggregate on AgBr surface could be destroyed.Voltammetry is a useful tool to investigate the interaction between dyes and AgBr. Experimental results showed that the longer the carbon chain substituents is, the stronger the interaction between AgBr and dyes would be.     

Error of DIAL-measured Ozone Concentration and a Three-Wavelength Inversion Technique

Sensitivity of the error in the stratospheric ozone concentration measured by DIAL to the scattering property of the stratospheric aerosol is studied through both theoretical analysis and numerical experiment in this paper, and based on the sensitivity, a three-wavelength lidar inversion technique is proposed for a simultaneous determination of ozone concentration profile, aerosol backscatter coefficient profile and its size distribution in the stratosphere. It is found from the sensitivity study that there is a considerable effect of the stratospheric aerosol on accuracy of the ozone concentration solution. If the aerosol scattering is neglected, a large error of the solution can be obtained, especially when there is the stratospheric volcanic cloud, the error can be up to 100%. According to numerical experiments, a great improvement of the ozone concentration solution is obtained by using the present three-wavelenght inversion method.     

On-line electrolytic dissolution of solid metal samples and determination of copper in aluminium alloys by flame atomic absorption spectrometry

A flow-injection system was developed in which alloy metal samples are electrolytically dissolved and the dissolved samples are analysed by flame atomic absorption spectrometry (FAAS). The effects of electrolyte composition and electrolysis parameters on the dissolution of the sample were studied. The method was used for the determination of copper in aluminium alloys. Electrolyte solutions consisting of 0.2–1.0 M nitric acid are better than other electrolytes tested with regard to both alloy sample dissolution and determination of copper by FAAS. The peak height increases linearly with the electrolysis time or current within a certain range. The detection limit depends on the sensitivity of the detector used, and can be improved by increasing the electrolysis time or current. Generally, aluminium alloys containing 0.5–10% copper can give suitable signals for FAAS determination. The reproducibility of electrolysis and determination is about 4% for the same sampling points and 5% for different sampling points on the alloy sample.     

The Observation of Strong Absorption of the Yttrium Lα Line in Sialon Ceramics

 β-sialon ceramics sintered with yttria additives have been studied with the use of an electron probe X-ray analysis (EPMA). Sialon ceramics were prepared from a carbothermally derived β-sialon powder and then sintered in a nitrogen atmosphere with yttria admixture. The above process was followed by annealing in flowing nitrogen. Scanning electron microscope (SEM) observations have shown that the sintered material contains a glassy phase (Y-Si-Al-O-N) on the grain boundaries. X-ray diffraction (XRD) after annealing in nitrogen revealed the presence of a considerable amount of yttrium aluminium garnet (YAG). The higher voltage of 30 kV was used in order to excite the yttrium K_α radiation (14.96 keV) at an appropriate overvoltage ratio because in some phases of the material, the disappearance of the yttrium L_α line has been observed during EPMA examination at an accelerating voltage of 15 kV in energy dispersive spectra (EDS). The intensity of the yttrium K_α line was sufficiently high, while the Y L_α line was not seen in the ED spectrum. Because the position of the yttrium L_α line (1.922 keV) is very close to the Si (K) absorption edge (1.84 keV), the strong absorption at this edge is probably responsible for the effect. This result should be considered as a serious warning in the case of EPMA (EDS) studies on compounds or mixtures suspected to contain both silicon and yttrium, because at electrons energies lower than 15 keV, the presence of yttrium in materials can go unnoticed. In wavelength dispersive spectra (WDS) obtained at 15 keV the intensity of the yttrium L_α line was also very low but measurable.     

Application of Tungsten-Rhodium Permanent Chemical Modifier in Slurry Analysis: Determination of Cadmium

 A tungsten-rhodium coating on the integrated platform of a transversely heated graphite atomiser (THGA) was used as a permanent chemical modifier for the determination of Cd in sediment slurries by electrothermal atomic absorption spectrometry. Slurries were ultrasonicated during 20 s before being delivered to the previously W-Rh treated platform. The permanent W-Rh modifier remains stable by approximately 250 measurements when 20 μl of slurries containing up to 1.0% m/v are delivered into the atomiser. In addition, the permanent modifier increases the tube lifetime up to 720 analytical firings. Also, when the W-Rh permanent modifier was employed, there was less variation of the slope of the analytical curves during the total atomiser lifetime, resulting in a decreased need of re-calibration during routine analysis, increasing the sample throughput. The atomiser lifetime was limited to the THGA wall durability, because the W-Rh treated platform was intact after more than 720 analytical firings. Detection limits based on integrated absorbance for 1.0% m/v slurries were 1.5 ng g⁻¹ Cd for 250 μg W +200 μg Rh permanent modifier and 11.5 ng⁻¹ Cd for 5 μg Pd +3 μg Mg(NO₃)₂. Results for the determination of cadmium in sediment slurries using the W-Rh permanent modifier were in agreement with those obtained with dissolved sample solutions by using Pd + Mg(NO₃)₂, since no statistical differences were found by the paired t-test at the 99% level. Received September 6, 1999. Revision December 1, 1999.     

火焰原子吸收分光光度法测定维血康颗粒中总铁

建立火焰原子吸收分光光度法测定维血康颗粒中总铁的含量,火焰类型选择空气–乙炔,测定波长为248.3 nm,测定时间为4.0 s,燃气流量为0.9 L/min,以氘灯作为背景校正。铁的质量浓度在2.4~28.8μg/mL范围内与吸光度呈良好的线性,线性相关系数r~2=0.999 8。6次测定结果的相对标准偏差小于1.0%,样品加样回收率为93.89%,方法检出限为0.011 3μg/mL。该方法具有准确度高,稳定性、重复性好等优点,可用于维血康颗粒中总铁含量的测定。     

Determination of fluoride in complex liquid matrices by electrothermal atomic absorption spectrometry with in-furnace oxygen-assisted ashing

A new chemical method is reported for the determination of total fluoride in complex liquids and suspensions, such as fruit juices, urine, serum and blood. It is based on the formation of the A1F radical in a graphite furnace afterin situ oxygen-assisted ashing of the untreated sample. The absorbance of this radical is measured at 227.45 nm. The method is relatively easy to use and provides a low detection limit (14 ng/ml) and reasonable reproducibility (5–10%).     

灵芝及虫草菌丝体中微量元素含量的分析

利用原子吸收光谱法和分光光度法对人工培育的灵芝,灵芝孢子粉,虫草菌丝体中具有重要生理意义的元素锌,铁,锰,镁,锗进行了检测,比较了灵芝子实体,灵芝孢子粉,虫草菌丝体中５种元素的含量,探讨了５种元素的药理作用。     

褐钇铌矿族矿物的可见光光致发光谱和吸收谱研究

测定并讨论了白云鄂博变生态和退火晶态褐钇铌矿族矿物在 4 88 0和 51 4 5nm激光激发下的光致发光谱。分析表明 ,该族矿物的发光中心是Er3 和Eu3 ,其中褐钇铌矿的发光主要由Er3 产生 ,而Eu3 和Er3 的共同发光构成褐铈铌矿的发光谱。可见光吸收谱显示 ,Nd3 可能是该族矿物光致发光的重要敏化剂。