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1.
分光光度法测定水溶液中的有机酸含量 总被引:7,自引:0,他引:7
利用水溶液中的有机酸在高氯酸羟胺(HAP)和N,N′-二环己基碳酰亚胺(DCC)存在的条件下生成的羟肟酸,以及羟肟酸在酸性高氯酸铁溶液中显色的性质,建立了一种分光光度测定水中有机酸含量的方法。对显色剂的酸度、浓度、加入体积、HAP和DCC的浓度、加入体积以及显色反应的温度、反应时间对吸光度的影响进行了考察。结果表明,该显色反应在反应条件:0.0687mol/LHAP1.0mL、0.6mol/LDCC0.5mL、震荡均匀后室温下放置反应15min、0.02mol/L酸性高氯酸铁溶液(高氯酸浓度0.3mol/L)显色条件下具有最大的吸光度;并对正丁酸、正戊酸、苯甲酸进行了线性关系考察。结果表明,该检测方法具有仪器简单、操作方便、线性范围较宽、准确度高等优点,可用于那些不易从水溶液中萃取的有机酸的测定,也可用于液相色谱洗脱液中有机酸的测定。 相似文献
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石墨炉原子吸收法测定食品中痕量铅 总被引:7,自引:0,他引:7
样品经硝酸和高氯酸分解后,加入磷酸二氢铵作基体改进剂测定铅,方法快捷,准确,经济,精密度≤14%,回收率92%~104%,检出限0.4ng/mL,用于多种食品中铅的测定,结果令人满意。 相似文献
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原子吸收光谱法测定植物叶中微量重金属 总被引:2,自引:0,他引:2
王喜全 《理化检验(化学分册)》2007,43(5):360-361
用浓硝酸与高氯酸混酸消解植物叶,其中铜、锌及锰含量较高,可直接用火焰原子吸收光谱法测定;铅、镉及铬含量较低,用石墨炉原子吸收光谱法测定;铅和镉含量甚微,受基体及共存元素干扰严重,用标准加入法消除干扰。 相似文献
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从酸性、中性或碱性溶液里,微量高铼酸根都可以相当完全和高氯酸四苯基鉮共沉淀。在碱性溶液中,用共沉淀法可使微量高铼酸根与大量钼酸根及其他阴离子分离。如果钼的含量特别大.再沉淀一次可使分离完全。将沉淀溶解於热水後加入高氯酸,可使其中的高铼酸转入溶液,并可直接进行比色测定。本文提出一种简单、迅速而易於控制的新方法以测定辉钼矿中的铼。精密度与准确度与蒸馏法、萃取法接近。 相似文献
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采用氟化铵-盐酸-硝酸-高氯酸溶解样品,加入氢溴酸除去样品中的砷、锑、锡等共存元素,加入硫酸将样品中的铅转化为硫酸铅沉淀,通过过滤与其它元素分离,滴定前加入巯基乙酸掩蔽铋,在乙酸-乙酸钠缓冲体系下,以二甲酚橙为指示剂,建立了采用EDTA络合滴定法测定分银渣中铅含量的方法。实验方法用于测定分银渣中的铅含量,测定结果的相对标准偏差(RSD,n=11)为0.32%~0.90%,加标回收率为100%~102%。能够满足日常测定需求。 相似文献
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三辛胺萃取盐酸、硝酸和高氯酸的动力学研究 总被引:2,自引:0,他引:2
胺类萃取酸是萃取化学研究中常见问题之一.关于三辛胺萃取酸的平衡,文献[1]已有记载,但它萃取酸的动力学研究却报道甚少,本文用恒界面池法研究了它对盐酸、硝酸和高氯酸的萃取动力学. 实验所用三辛胺(TOA)系进口分装,纯度≥99%;正辛烷(稀释剂),化学纯;盐酸、硝酸及高氯酸均为优级纯.水相酸的浓度用HM-20E型pH计(日本TOA)监测;动力学实验装置及仪器同前文.实验时先向恒界面池中加入100ml的含酸水相,然后加入一定体积的正辛烷,再小心加入一定体积的TOA浓溶液,使有机相总体积达100ml,同时记录pH 相似文献
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马丽 《中国无机分析化学》2013,3(3)
应用电感耦合等离子体发射光谱法测定锌精矿中的铟,确定了最佳工作条件,选择了最佳分析谱线,并利用标准加入法和基体匹配法确定了该方法的准确性。样品用氟化氢铵、盐酸、硝酸、高氯酸溶样,用盐酸浸取。本法与萃取分离盐酸羟胺示波极谱法测定的铟含量结果一致。方法准确,快速,加标回收率为99.6%~101.7%,相对标准偏差为0.97%~2.1%。 相似文献
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Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence. Studies show that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF)[4]no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr)[5]So there is potential for the design of new chromium drugs[6].Chromium compounds have been used in medicine for centuries and there is potential for the design of new chromium drugs.2-Mercaptonicotinic acid(MN) displays the interesting biological activity. Chromium( Ⅲ )2-mercaptonicotinate is a common and effective biologically active form of Chromium. The test of biological activity indicated that may be useful in treating of diabetes. In this paper, we reported the The synthesis route is as follow:The structure of the complex has been characterized by IR, elemental analysis, MS,atomic absorption spectroscopy, X-ray powder diffraction and TG-DTA analysis.They indicate that the structure of Chromium 2-mercaptonicotinate.HPLC is used for determination of the purity. Studies show that the complex has a good biological activity for supplement tiny dietary chromium,lowering blood glucose levels, lowering serum lipid levels and increasing lean body mass. 相似文献
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Kakali Mukherjee Rumpa Saha Aniruddha Ghosh Bidyut Saha 《Research on Chemical Intermediates》2013,39(6):2267-2286
Chromium can exist in different oxidation states (e.g. 0, III, VI). Chromium can be both beneficial and toxic to animals and humans depending on its oxidation state and concentration. At low concentration, Cr(III) is essential for animal and human health. Chromium(VI) compounds are highly soluble, mobile and bioavailable compared to trivalent chromium. Chromium(VI) is dangerous for humans due to its toxicity and carcinogenic properties. The presence of hexavalent chromium in waste water is a potential hazard to aquatic animals and humans. Various methods are adopted for the removal of hexavalent chromium from industrial effluents. Among these different techniques, biosorption is the most promising one. In this process, the various components present in biomaterial reduce the toxic hexavalent chromium to non-toxic trivalent chromium. Algae, fungi and bacteria have biosorption properties, and cell walls are responsible for biosorption of dead biomaterial. But this process removes chromium from waste water very slowly. So for chemical modification of biosorbents, optimization of biosorption parameters is required to increase the effectiveness of this process. 相似文献
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The adsorption of Chromium(VI) from aqueous solutions was studied on different commercial grades of granular activated carbon namely Filtrasorb F‐400, F‐300, F‐200 and F‐100. The adsorption of Chromium (VI) on F‐400 carbon was found to be maximum in comparison to the other grades of carbon. The Chromium (VI) adsorption process in dilute aqueous solutions agreed with the Langmuir and Freundlich models and also obeyed first order kinetics. Metal sorption characteristics of as received activated carbons were measured in batch experiments. The maximum removal (60–65%) for different grades of raw carbon was observed at 25 °C with an initial concentration of 15.16 mg dm?3. It is evident from the study that granular activated carbon holds a particular promise in the removal of metal ions from aqueous solutions. 相似文献
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朱定祥 《广东微量元素科学》2009,16(3):11-16
对铬及其化合物辅助降血糖、降血脂、减肥、延缓衰老、增强免疫力等生理功能、作用机制及其在保健食品中的使用情况进行了阐述,为其在未来的保健食品中得到更好应用提供依据。 相似文献
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Chromium is one of the essential trace elements to our body and present mainly in its trivalent form in body fluids. It is believed that chromium plays a key role in carbohydrate and lipoprotein metabolism and its variation is closely related with diabetes and arteriosclerosis. However, its existing state and relationship have not been thoroughly understood due to the trace amount of chromium in body and the absence of proper sample preparation method for speciation analysis. 相似文献
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Chromate and cyanide have been determined by their ability to displace iodate from sparingly soluble lead iodate. The released iodate is treated with acidified iodide to give iodine, which is determined either by titration with thiosulphate, or spectrophotometrically as its blue complex with starch. Chromium(III) has been determined as chromate after its oxidation with peroxydisulphate. Sulphate, iodide, bromide, chloride, fluoride, oxalate, tartrate, phosphate and thiocyanate do not interfere. Thiosulphate, sulphite, sulphide, hexacyanoferrate(II) and molybdate ions vitiate the results. Silver, mercury, barium and iron(III) should be masked. Mixtures of cyanide, thiocyanate and halides have been analysed by using complementary procedures that employ the iodates of lead and mercury, and bromine oxidimetry. It has been shown that cyanide or thiocyanate interferes in the determination of iodide by oxidation to iodic acid, because of formation of cyanogen bromide. 相似文献
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《印度化学会志》2021,98(11):100216
Rice bran, a green and low-cost adsorbent, is used for Chromium (VI) and Copper (II) remotion from its aqueous solution. The influence of different process parameters in a fixed-bed on the removing efficiency has been investigated. The results show that the removal efficiency is higher at a minimum flow rate, low metal ion concentration, and higher bed height. The adsorption studies show that the rice bran has a better affinity to Chromium (VI) than Copper (II). Different kinetic models are used for the prediction of the column performance. This study shows that rice bran could be a potential and eco-friendly adsorbent for chromium (VI) and copper (II) removal and is suitable for developing countries like India. Multiple linear regression and ANN-based genetic algorithm modelling have been applied successfully to predict both metal ions' percentage removal separately. 相似文献
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Chromium pentacarbonyl complexes of some dihydro- and tetrahydro-thiophenes and their sulfoxides have been prepared. In the sulfide derivatives the chromium is readily seen to be attached to the sulfur atom. The sulfoxide functionality also acts as a ligand for chromium, and by means of IR and mass spectra and the ESCA technique it was tentatively concluded that chromium is bonded to the sulfur atom of the sulfoxide. This assignment was confirmed by an X-ray analysis of 2,5-dihydrothiophene-1-oxide chromium pentacarbonyl. 相似文献
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The speciation of chromium and arsenic in their two common oxidation states is determined by the use of selective preconcentration and energy-dispersive x-ray spectrometry. Chromium(VI) and arsenic(III) are recovered by precipitation with dibenzyldithiocarbamate and filtration. Chromium(III) and arsenic(V) are determined in the filtrate by coprecipitation with hydrated iron(III) oxide. The chromium and arsenic content of each precipitate is determined by use of x-ray spectrometry. 相似文献
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L. T. McClendon 《Journal of Radioanalytical and Nuclear Chemistry》1978,42(1):85-91
Chromium is recognized to be an essential trace element in several biological systems. It exists in many biological materials
in a variety of chemical forms and very low concentration levels which cause problems for many analytical techniques. Both
instrumental and destructive neutron activation analysis were used to determine the chromium concentration in Orchard Leaves,
SRM 1571, Brewers Yeast, SRM 1569, and Bovine Liver, SRM 1577. Some of the problems inherent with determining chromium in
certain biological matrices and the data obtained here at the National Bureau of Standards using this technique are dicussed. 相似文献