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31.
采用电感耦合等离子体发射光谱(ICP-OES)对啤酒中钙和锶进行测定。通过对硝酸酸度的选择实验、仪器测定的背景扣除及实际样品的测定和加标回收实验,建立了简捷、快速、准确、稳定的ICPOES法测定啤酒中Ca、Sr的分析方法。 相似文献
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Commercial mixed-phase aluminum oxide was used as a heterogeneous catalyst support, providing slightly basic properties which are well-suited for the condensation of bio-ethanol to C4 hydrocarbons, such as 1-butanol. Different metals (Cu, Ni and Co), at various metal loadings were deposited on the support. Consequently, the catalytic reactions were carried out in a continuous laboratory-scale fixed bed reactor operated at 240 °C and 70 bar. The catalysts were characterized by means of XRD, TEM, FT-IR, XPS and ICP-OES. Different metals were found to give entirely different product distributions. With the best catalysts, the selectivities towards 1-butanol close to 70% were reached, while the ethanol conversion typically varied between 10 and 30% – strongly depending on the metal applied. It was observed that low loading of copper and high loading of nickel were responsible for the formation of 1-butanol, whereas cobalt and high loading of copper resulted in the production of ethyl acetate. The reaction was found to be extremely sensitive to catalyst preparation conditions and procedures such as metal loading, calcination/reduction temperature and, thereby, to the formation of corresponding crystallite structure. 相似文献
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S.T. Ali N.R. Munirathnam C. Sudheer R.C. Reddy M.R.P. Reddy T.L. Prakash 《Materials Letters》2007,61(7):1512-1516
A viable method utilizing leaking of high pure hydrogen gas into the distillation retort ambience maintained at 8.0 × 10− 3 Torr was devised to minimize the incorporation of trace oxygen in cadmium and the possibility of forming cadmium oxides during purification using selective vaporization. Hydrogen leaking at the rate of 5 standard cubic centi-metre per minute (sccm) during distillation at soaking temperature of 450 °C reduced trace oxygen from 230-350 ppm for raw cadmium of 3N8 (99.98%) purity and from 5-10 ppm for distilled cadmium of 6N purity. This can be compared to the presence of 30-38 ppm oxygen in cadmium distilled under simple-vacuum of 2.1 × 10− 3 Torr achievable in the system. A detailed comparison between distillation under simple-vacuum and hydrogen leaking is presented with reference to purity, distillation rate, soaking temperature, and mean free path of distillate vapors. 相似文献
35.
Alberto Angioni Maddalena Cabitza Maria Teresa Russo Pierluigi Caboni 《Food chemistry》2006,99(3):525-529
Levels of four of the major pollutant heavy metals were assessed by ICP-OES in virgin olive oil monocultivar samples. The data showed high variability within cultivars for lead and zinc, whereas, for cadmium and copper, no statistical difference was observed. The influence of the cultivar and the stage of ripening of olives on heavy metal content was assessed; zinc was the only metal with a great variability within the first and the second harvest. All olive samples were processed with the same milling apparatus. 相似文献
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连续五年用中国计量科学研究院研制的标准溶液对等离子体发射光谱仪(ICP-OES)进行监测,建立一种基于休哈特控制图(SCC)对仪器性能进行核查、校准和评价的方法,以确保测试数据的有效性。结果表明,灵敏度较高的元素如Cu和Ba等元素检出限五年中有上升趋势,其余四元素为正常模式或周期模式。六元素重复性指标均无明显上升或下降趋势。经相关分析,各元素两两之间重复性指标均正相关;Zn、Mn两元素相关性较高(r=0.942);Zn、Ba元素相关性较低(r=0.654),其余元素相关性介于两者之间。通过对判据异常点Zn检出限的分析,表明某些符合检定规程要求的指标,也有可能是异常点。通过建立控制图的方法可有效对仪器性能进行评价和证明,弥补规程周期长等缺点,便于及时发现和解决测试中的问题,对类似仪器也有借鉴意义。 相似文献
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A slurry nebulisation technique was applied for elemental analysis of bituminous coals SARM 18, SARM 19 and four coals from three different seams in Witbank, South Africa, by inductively coupled plasma optical emission spectroscopy (ICP-OES). Major elements (Al, Ca, Fe, Mg, S, Si and Ti) and trace elements (Ba, Cr, Mn, Ni, Sr, V, Zn and Zr) in coal were determined. Various slurry preparations were evaluated using two dispersants (glycerol and Triton X-100) and by varying the concentration of dispersants, between 0.1% and 1.0% (v/v). The effect of initially solubilising the ground coal in N,N-dimethylformamide (DMF) was investigated by varying the volume of DMF added. The effect of wet grinding with DMF was investigated. Wet grinding with DMF was shown to drastically reduce particle sizes (50.0% < 0.28 μm and 90.0% < 6.17 μm) as compared to dry grinding (50.0% < 5.25 μm and 90.0% < 11.1 μm). The reduced particle sizes and increased transport efficiency of the coal slurries led to improved analytical recoveries of elements in the reference coal, SARM 18. The best analytical recoveries for all elements were achieved using 0.1% Triton X-100 with 10.0% DMF. Results obtained by ICP-OES after wet grinding of the coal with DMF, using 0.1% Triton X-100, also gave excellent recoveries (Al, 100%; Ca, 103%; Cr, 106%; Fe, 102%; Mg, 100%; Mn, 104%; Ni, 109%; Si, 102%; Ti, 95.0%; and V, 108%). The results obtained with 10.0% DMF and 0.1% Triton X-100 were in agreement with certified values for all selected elements according to paired t-test at the 95.0% confidence level. Selected elements (Al, Ca, Fe, Mg, Mn, Si, Ti and V) were also analysed with X-ray fluorescence for comparison with results obtained from ICP-OES. Analysis by ICP-OES of microwave digested coal was also carried out. It is suggested that the DMF slurry technique could be used for routine analysis of bituminous coals. 相似文献
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Namhoon Kim Changkyu Kim Soyoung Jung Youngae Park Youngju Lee Juyeon Jo 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(7):1238-1246
Food-grade titanium dioxide (TiO2) is a common and widespread food additive in many processed foods, personal care products, and other industrial categories as it boosts the brightness and whiteness of colours. Although it is generally recognised as safe for humans, there is a growing interest in the health risks associated with its oral intake. This study quantified and identified TiO2 nanoparticles present in confectionery foods, which are children’s favourite foods, with inductively coupled plasma optical emission spectrometry (ICP-OES) and transmission electron microscopy (TEM). A reliable digestion method using hot sulphuric acid and a digestion catalyst (K2SO4:CuSO4 = 9:1) was suggested for titanium analysis. Validations of the experimental method were quite acceptable in terms of linearity, recoveries, detection limits, and quantification limits. Of all the 88 analysed foods, TiO2 was detected in 19 products, all except three declared TiO2 in their labelling. The mean TiO2 content of candies, chewing gums, and chocolates were 0.36 mg g?1, 0.04 mg g?1, and 0.81 mg g?1, respectively. Whitish particles isolated from the confectionery foods were confirmed as TiO2 nanoparticles via TEM and energy dispersive X-ray spectroscopy (EDX), in which nanosized particles (<100 nm) were identified. 相似文献