Trace-matrix separations for high-purity chromium,molybdenum and tungsten with cellulose collectors

Trace metals (20 elements) in high-purity chromium, molybdenum and tungsten are collected and preconcentrated by precipitation and adsorption on cellulose collectors. The compound methods allow the application of AAS and ICP-AES as determination methods for the production control of highly pure refractory metals under routine conditions.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Estimation of boron isotope ratios using high resolution continuum source atomic absorption spectrometry

In the production of ¹⁰B enriched steels, the production–recycling process needs to be closely monitored for inadvertent mix-up of materials with different B isotope levels. A quick and simple method for the estimation of boron isotope ratios in high alloyed steels using high resolution continuum source flame AAS (HR-CS-FAAS) was developed. On the 208.9 nm B line the wavelength of the peak absorption of ¹⁰B and ¹¹B differs by 2.5 pm. The wavelength of the peak absorption of boron was determined by fitting a Gauss function through spectra simultaneously recorded by HR-CS-FAAS. It was shown that a linear correlation between the wavelength of the peak absorption and the isotope ratio exists and that this correlation is independent of the total boron concentration. Internal spectroscopic standards were used to compensate for monochromator drift and monochromator resolution changes. Accuracy and precision of the analyzed samples were thereby increased by a factor of up to 1.3. Three steel reference materials and one boric acid CRM, each certified for the boron isotope ratio were used to validate the procedure.     

Determination of inorganic and methylmercury in fish by cold vapor atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry

Simple and rapid analytical procedures for the determination of Hg²⁺ and methylmercury in fish were proposed after careful optimization of chemical and instrumental parameters for Hg measurement by cold vapor (CV)/hydride generation (HG) atomic absorption spectrometry (AAS) and CV/HG inductively coupled plasma atomic emission spectrometry (ICP-AES). Quantitative extraction of Hg species avoiding any inter-species conversion was achieved by fast microwave assisted solubilization of fish tissue with relatively low amount of tetramethylammonium hydroxide (TMAH) or 6 mol L^− 1 HCl. After careful optimization of chemical parameters selective determination of Hg²⁺ in the presence of excess of methylmercury is attained by using continuous flow CV AAS, 1% m/V SnCl₂ as reductant and 0.1 mol L^− 1 HCl as reaction medium. Simple calibration curve prepared with aqueous standard of Hg²⁺ is recommended for its quantification. Both Hg²⁺ and methylmercury could be determined simultaneously with equal sensitivity by CV/HG ICP-AES directly in the diluted TMAH solution obtained after extraction with 1% m/V NaBH₄ as reductant. Quantification of the sum of Hg²⁺ and methylmercury against calibration curve prepared with aqueous standard of methylmercury is suggested. It should be mentioned that batch hydride generation system with quartz tube heated in air/acetylene flame could also be used for simultaneous determination of both Hg species in fish extracts, with standard additions calibration. The validity of the developed analytical procedures for selective determination of Hg²⁺ and methylmercury (by difference between the total Hg and Hg²⁺) is confirmed by the analyses of certified reference material DOLT-1 and reference material IMEP-20. Very close agreement between certified values and analytical results was found.     

微波消解样品-在线稀释进样-原子吸收光谱法测定锂电池中锂

样品经微波消解及在线稀释进样,采用火焰原子吸收光谱法测定锂电池中锂的含量。在优化的试验条件下,锂的线性范围为0.01～2.5 mg·L~(-1)。该法用于测定锂电池中锂的含量,回收率在94.0%～104.0%之间,相对标准偏差(n=7)在1.6%～4.5%之间。     

Determination of Hg and Pb in compact fluorescent lamp by slurry sampling inductively coupled plasma optical emission spectrometry

Mercury and lead were determined in an extraction solution applied to compact fluorescent lamps by axial view inductively coupled plasma optical emission spectrometry (ICP OES). The solution contained 50% v/v HNO₃ and 10% v/v H₂O₂. The compact fluorescent lamps were treated by removing the socket and breaking the rest of the lamp inside the solution, followed by placing the mixture in an ultrasonic bath for 1 h. The mixture was filtrated in a coarse paper filter and the resulting extraction slurry was analyzed. The determination of Pb in the slurry required calibration by the analyte addition technique, while for Hg, external calibration was adequate. The quantification limits (10 s, n = 7), for Hg (194.164 nm) and Pb (220.353 nm) were, respectively, 10 and 30 µg per lamp. Analysis of spiked samples demonstrated reasonable accuracy of the method, with recoveries in the range from 99 to 120% for Hg and from 91 to 107% for Pb. Fifteen analyzed samples showed Hg masses per lamp in the range from 1.6 to 27 mg, and six samples were above the limit allowed by the European Community that is 5 mg per compact lamp. The values for Pb were between 0.07 and 0.75 mg per lamp. By filtrating the slurry in a membrane filter, and analyzing the resulting solution, it was found that all Hg was extracted to the liquid phase of the slurry, while a fraction of about 40% m/v of Pb is retained in the solid particles. The lamp cover glass, after extraction of the phosphor layer, was also analyzed for Hg and Pb. The concentration of Hg in the glass is quite low; however, the Pb content is high.     

Fructose-selective calorimetric biosensor in flow injection analysis

A highly selective, interference free biosensor for the measurement of fructose in real syrup samples was developed. The assay is based on the phosphorylation of d(−)fructose to fructose-6-phosphate by hexokinase and subsequent conversion of fructose-6-phosphate to fructose-1,6-biphosphate by fructose-6-phosphate-kinase. The heat liberated in the second reaction is monitored using an enzyme thermistor. The major advantages of this biosensor are rapid and selective measurement of fructose without the need to eliminate glucose and inexpensive FIA-based, mediator-free calorimetric measurement suitable for regular fructose analysis. This method was optimised for parameters, such as pH, ionic strength, interference, operational stability and shelf life. Good and reproducible linearity (0.5-6.0 mM) with a detection limit of 0.12 mM was obtained. Fructose determination in commercial syrup samples and spiked samples confirmed the reliability of this set-up and technique. The biosensor gave reproducible results with good overall stability for continuous measurements over a period of three months besides a useful shelf life of six months. The method could be used for routine fructose monitoring in food samples.     

原子吸收光谱法测定磷酸酯化梨渣吸附的Cr（Ⅵ）离子

通过原子吸收光谱法研究了在不同pH值、吸附剂量、吸附质浓度和吸附时间条件下磷酸酯化改性梨渣吸附Cr（Ⅵ）离子的效果。溶液初始pH 4.5时,Cr（Ⅵ）离子的吸附达到最大值;酯化梨渣≥10g.L-1能除去Cr（Ⅵ）为100μg.L-1溶液中的86.5%的Cr（Ⅵ）离子。酯化梨渣对Cr（Ⅵ）离子的吸附符合Langmuir等温模型,其最大吸附能力为67.56μg.g-1。Cr（Ⅵ）离子达到吸附平衡的时间为90min,准一级反应动力学方程可描述酯化梨渣对Cr（Ⅵ）离子的吸附过程。     

原子吸收光谱法测定重金属铬的含量

以火焰原子吸收光谱法测定重金属铬含量为宗旨,考察了雾化器流量、乙炔流量、氧化剂流量、燃烧头高度、基本改进剂等因素,结果发现,通过实验条件优化,校正系数从0.998265提高到0.999998,该方法能最大程度改善火焰原子吸收光谱法测定铬元素灵敏度低的问题,具有快速、准确、灵敏度高等优点,为与人类密切相关的食品、药品、化妆品、医疗器械等产品中重金属铬含量测定提供一定的参考。     

Determination of potentially toxic heavy metals in traditionally used medicinal plants for HIV/AIDS opportunistic infections in Ngamiland District in Northern Botswana

The determination of four potentially toxic heavy metals, arsenic, chromium, lead and nickel in twelve plant species used for the treatment of perceived HIV and AIDS-associated opportunistic infections by traditional healers in Ngamiland District in Northern Botswana, a metal mining area, was carried out using atomic absorption spectrometry. The medicinal plants; Dichrostachys cinerea, Maerua angolensis, Mimusops zeyheri, Albizia anthelmintica, Plumbago zeylanica, Combretum imberbe, Indigofera flavicans, Clerodendrum ternatum, Solanum panduriforme, Capparis tomentosa, Terminalia sericea and Maytenus senegalensis contained heavy metals in varying quantities: arsenic 0.19–0.54 μg g⁻¹, chromium 0.15–1.27 μg g⁻¹, lead 0.12–0.23 μg g⁻¹ and nickel 0.09–0.21 μg g⁻¹ of dry weight. Chromium was found to be the most abundant followed by arsenic and lead. Nickel was undetectable in nine plant species. M. senegalensis contained the largest amounts of arsenic, chromium and lead. All metals determined were below the WHO permissive maximum levels. The possible maximum weekly intakes of the heavy metals following treatment regimes were insignificant compared to the provisional tolerable weekly intake levels recommended by WHO and the Joint FAO/WHO Expert Committee on Food Additives. This suggests that heavy metal exposure to patients originating from consumption of traditional medicinal plant preparations is within non health-compromising limits.     

流动注射在线过滤稀释原子吸收法测定诺氟沙星

提出了流动注射在线过滤稀释原子吸收法测定诺氟沙星的新方法。药物浓度在0．1－0．8mg/mL范围符合比耳定律，回收率为97．9％－102．4％，相对标准偏差为1．7％。方法可用于诺氟沙星胶囊测定。