共查询到10条相似文献,搜索用时 140 毫秒
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示波极谱法测定地质样品中痕量碘的样品分解方法比较 总被引:2,自引:1,他引:2
分别用半熔法、热解法、碱熔法,酸蒸馏法分解地质样品,极谱法测定痕量碘。比较了4种分解方法的效果。指出了半熔法为最佳。 相似文献
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在红外测试中,固体样品通常采用红外压片等方法进行前处理.通过对香豆素分别采用红外压片法、薄膜法和石蜡油糊法进行测试,发现薄膜法比压片法制样更加简便快捷、用量少、可回收,而且薄膜法制样还能避免压片过程中出现的碎片和粘片现象,测试时能够得到高质量的红外谱图. 相似文献
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M.G. Marmorino 《Journal of mathematical chemistry》2003,34(1-2):59-66
An alternative to the Temple method for calculating a lower bound to the ground-state eigenvalue of an operator is presented. The method presented is an improvement and generalization upon a similar method [M.G. Marmorino, J. Math. Chem. 32 (2002) 19–29]. For the system tested the lower bound of the current method is significantly superior to the Temple method and the previous method. Furthermore, the current method (like its predecessor) is able to generate a lower bound when the Temple method fails. 相似文献
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蔗糖酯的合成研究进展 总被引:2,自引:0,他引:2
综述了蔗糖酯的合成方法及工艺的研究进展,并对其反应机理进行了阐述.蔗糖酯的合成方法主要有四种:溶剂法、微乳化法、无溶剂法以及酶催化法.溶剂法采用DMF或DMSO为溶剂,但是这两种溶剂均有毒,限制了蔗糖酯在食品等行业的应用.微乳化法采用丙二醇或水代替溶剂法所使用的有毒溶剂,并加入乳化剂,使反应体系近似为均相体系.无溶剂法则是通过在反应体系中加入乳化剂或表面活性剂等使熔融相成均一相,反应平稳.但是一般无溶剂法反应温度较高,反应不易进行,产率低,且产品质量得不到保证.酶催化合成法是一种新的生物合成方法,采用生物酶代替传统的催化剂合成蔗糖酯,该法催化活性高、反应条件温和、选择性强、产物易分离等优点.文中还对蔗糖酯粗品的纯化工艺进行了介绍. 相似文献
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A computer-assisted method is presented for optimization of mobile phase composition in reverse-phase and normal-phase HPLC. The method is based on window diagrams, but only three preliminary tests are required. The method is successfully applied to two examples and there is good agreement between predicted and experimental results. Optimal values for ion concentration and pH in ion chromatography from a published optimization method are compared to values calculated using the computer-assisted method presented in this paper. The same results are obtained, but the method presented here is simpler and faster than previously published one. 相似文献
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Yunqing Han Haixiang Chen Naian Liu 《Journal of Thermal Analysis and Calorimetry》2011,103(2):679-683
A simple and precise incremental isoconversional integral method based on Li-Tang (LT) method is proposed for kinetic analysis
of solid thermal decomposition, in order to evaluate the activation energy as a function of conversion degree. The new method
overcomes the limitation of LT method in which the calculated activation energy is influenced by the lower limit of integration.
By applying the new method to kinetic analysis of both the simulated nonisothermal case and experimental case of strontium
carbonate thermal decomposition, it is shown that the dependence of activation energy on conversion degree evaluated by the
new method is consistent with those obtained by Friedman (FR) method and the modified Vyazovkin method. As the new method
is free from approximating the temperature integral and not sensitive to the noise of the kinetic data, it is believed to
be more convenient in nonisothermal kinetic analysis of solid decompositions. 相似文献
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目前,地质样品中有机碳的测定方法有干烧法(高温电炉灼烧)和湿烧法(重铬酸钾氧化)两大类。另外还有ICP-AES法、微波消解法、过硫酸钾法、电导法、石墨电热消解法、比色法等,然而这些有机碳测定方法仍然存在许多不尽如人意的地方。干烧法要求实验条件苛刻,操作繁琐,不易掌握,受碳酸盐的干扰。湿烧法虽然操作比较简单,但方法受样品中还原性物质的干扰,如氯根、亚铁等,上述方法都有待完善和优化改进。如:探索因不同样品基体差异而产生的干扰元素消除方法;寻找更合适的指示剂;本文采 用重铬酸钾-容量法测定地质样品中的有机碳,在220±10℃恒温电热板上,用0.4 mol/mL重铬酸钾溶解样品。通过优化熔矿温度、熔矿时间、熔剂浓度的优化选择,进行了氯离子的干扰试验。样品中含氯化物低的样品通过加入0.1 g硫酸银消除,样品中含氯化物高的样品通过高温灼烧减量消除。氧化指示剂选用邻菲啰啉或苯二氨基苯甲酸。本方法适用于土壤、水系沉积物、岩石等地质调查样品中有机碳的测定,方法相对标准偏差(RSD)在0.80%~4.41%之间,准确度(RE)在-3.15%~+1.15%之间。通过标准物质验证,方法技术指标满足地质行业规范DZ/T0130.4-2006中有机碳的分析要求,建立了一种简单、快捷、经济、准确的测定地质样品中有机碳的测定方法,满足地球化学调查批量样品生产的需要。 相似文献