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在弱酸性介质中,钍与半二甲酚橙形成红色的络合物。因为显色反应的灵敏度较低,半二甲酚橙通常不用作光度法测定钍的显色剂,而仅用作络合滴定法测定钍的指示剂。我们在实验中发现,在溴化十六烷基三甲基铵存在下,钍与半二甲酚橙形成深红色的三元络合物,使显色反应的灵敏度大大提高。本文报导了钍-半二甲酚橙-CTMAB三元络合物的形成条件、络合物的性质,并提出了应用该显色体系测定矿石中钍的可能性。 相似文献
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本文设计、合成了一组新的不对称变色酸双偶氮胂类稀土显色剂。对新试剂进行了提纯鉴定,确定了组成及结构,研究了它们与稀土、钍、锆的显色反应性能。实验证明,试剂分子结构对其反应性能的影响有一定的规律性。其中o-As-DBN试剂是较优良的钍显色剂,毫克级的稀土、铀不干扰测定。 相似文献
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新的不对称变色酸双偶氮衍生物的合成及其结构对稀土、钍、铋显色反应的影响张华山,张军锋,黎心懿(武汉大学化学系,武汉,430072)关键词变色酸双芳基偶氮衍生物,稀土,钍,铋,分光光度法变色酸双偶氮衍生物是光度法测定稀土、钍等金属的重要显色剂。其中多卤... 相似文献
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氟离子选择性电极法测定钍氟各级稳定常数 总被引:1,自引:0,他引:1
硫酸体系钍氟各级稳定常数对稀土冶炼生产实践具有重要的指导作用.采用溶解度法测定了室温(25 ℃)下不同酸度的钍氟共存区,采用氟离子选择电极测定不同浓度氟化氢溶液中的游离氟浓度,得到氢氟各级稳定常数.然后根据钍氟共存区图,配制一系列硫酸钍、氢氟酸和硫酸的混合液,测定各溶液中的游离氟浓度,从而得到钍氟各级稳定常数.结果表明,H与F的第1,2级稳定常数分别为k1=664.4,k2=47.9,Th和F的第1,2,3级稳定常数分别为k16.27×105,k2=9.68×104,k3=5.36×104. 相似文献
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合成并研究了新显色剂二溴邻羧基偶氮羧胂(CAsA-DBC)用于光度法测定微量钍.在盐酸(1 19)介质中,钍与显色剂发生灵敏反应,生成稳定的蓝色配合物,其物质量比为nTh(Ⅳ);nCAsA-DBC=1:2,最大吸收在640 nm波长处,表观摩尔吸光率为1.11×105L·moL-1·cm-1,钍的质量浓度在20ug/25 mL以内符合比耳定律,线性回归方程A=0.093 2 C 0.000 5,相关系数为0.999 1.在试验条件下,大量常见的金属离子如钙、镁等以及与钍伴生的铀不干扰微量钍的测定.利用拟定方法对几种海产品中痕量钍作了测定,分析结果的相对标准偏差(n=5)均小于3.1%,并求得回收率在99.3%-103.5%之间. 相似文献
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报道了在不同的酸度下乳化剂OP对2,4,6-三卤代偶氮氯膦与钍(IV)显色反应抗干扰能力的影响研究表明,在酸度高达4.8mol/L的HCl中,乳化剂OP的加入能明显地提高显色反应的选择性,而灵敏度没有明显降低,三溴偶氮氯膦与钍的显色体系尤其明显,可不经任何分离掩蔽手段直接测定独居石中的钍(IV)。 相似文献
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反相高效液相色谱测定在乙醇酸和草酸存在下的乙醛酸含量 总被引:4,自引:0,他引:4
采用反相高效液相色谱分离测定了乙醇酸和草酸共存下乙醛酸的含量。色谱柱为Hy-persil ODS-C18柱(4.6 mm×100 mm,5μm),流动相为乙腈-水,检测波长为210 nm。探讨了流动相的pH及其配比对分离度和灵敏度的影响。以峰面积对乙醛酸浓度(g.L-1)作图所得校正曲线的线性回归方程为Y=1.934×103X+0.067×103(r=0.999 9),方法的检出限(2S/N)为5×10-7g.L-1。方法的测定回收率为98.1%~100.4%,相对标准偏差为0.4%。 相似文献
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煤酸异构化制对苯二甲酸 总被引:6,自引:2,他引:6
进行了煤氧化产物煤酸(水溶酸WSA)钾在催化剂碳酸镉的存在下,异构化制对苯二甲酸(TPA)的研究。主要考察了催化剂用量、二氧化碳初压、反应温度和反应时间对TPA产率的影响。结果表明,在催化剂存在下煤酸可以转化成TPA。单独煤酸钾异构化时,较佳反应条件:温度430 ℃~450 ℃,压力4.0 MPa,催化剂CdCO3用量4%,反应时间2 h。煤酸钾与苯甲酸(BA)钾混合异构化时,较佳反应条件与单独煤酸钾时基本相同。单独煤酸钾在较佳条件下异构化时,粗TPA产率达34%左右,相当于根据其中有效成分苯多羧酸(BPCA)计算的理论产率的75%左右,选择性较好。煤酸钾加苯甲酸钾在较佳条件下异构化时,粗TPA产率可达68%,扣除假定BA自身岐化生成TPA理论产量之后,则煤酸的TPA产率高达70%,比煤酸单独异构化TPA产率(34%)高1倍。粗TPA经精制可得纯度99%以上的精TPA。 相似文献
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Abstract This review presents the characteristic reactions of the alkoxy group of the acid diesters of phosphorous acid (RO)2 P(O)H: transesterification—with the phosphorus atom as the reaction center; alkylation—with the α-carbon atom as the reaction center; dealkylation—with the α-carbon atom as the reaction center. The possibilities of these reactions in the synthesis of end products with various structures and compositions are demonstrated. The perspectives for the practical application of these esters of phosphorous acid are discussed. 相似文献
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用紫外分光光度法检测盐酸中的微量乙酸。确定了乙酸的最大吸光度和相关线性范围。检测了不同浓度的乙酸在 10 % (体积分数 )盐酸中的线性关系。认为在 10 %盐酸中 3 8g·L- 1的乙酸呈良好的线性关系。该方法简便、实用、快速。适用于氯乙酸合成生产线的盐酸检测。 相似文献
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Abstract— Photolysis of polyribobromouridylic acid with 313 nm light at neutral pH caused extensive debromination and a loss of A280 (280–nm absorbance) without comparable increase in A260 . At an exposure of 190μE/cm 2 , strand breakage occurred on the average of one break every 170 BrU residues. Little if any pyrimidine hydrate was produced. Exhaustive RNase hydrolysis of photolysed polymer gave a mixture of mononucleotides and oligonucleotides. The mononucleotide fraction was found to be composed of unaltered BrUMP and contained little if any UMP. Irradiation of the polymer at alkaline pH caused little or no debromination or spectral change. 相似文献
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为了提高酸敏变色记录材料的图象稳定性能,进行了添加苯酚、水杨酸、乙酸、苯甲酸等酸性添加剂的试验。其光谱特性显示,加入适量的苯酚、水杨酸添加剂后,图象的稳定性能得到改善,而乙酸、苯甲酸添加剂却不能起到这种作用。试验中采用核磁共振技术作了检测,在加入苯酚添加剂时有氢质子释放,抑制了醌式结构向初始状态的回复,改善了图象的稳定性能。 相似文献
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Abstract— An important regulator of numerous physiological processes in higher plants is abscisic acid (ABA), which is photoisomerized from the more biologically active cis isomer to the nearly inactive trans isomer by natural sunlight. It is possible that this photoisomerization is a UV control mechanism in functions regulated by ABA.
The quantum yields of both the cis to trans and trans to cis photoisomerizations were measured by an initial velocities method under various conditions of pH and oxygen concentration at room temperature. The yield for photoisomerization of cis-ABA ranged from 0.25 at pH 3.0 to 0.11 at pH 7.0. Oxygen partially quenched the process. The quantum yield varies only slightly with wavelength.
The quantum yield of photolysis of cis-ABA is reported for pH 3.0 as 0.06. This yield also varies slightly with wavelength and is relatively insensitive to oxygen. This relatively high yield explains the loss of potency of ABA during UV irradiation.
Phosphorescence of cis - and trans-ABA is observed in methanol at 77 K. Onset of the emission is at 350 nm. The emission spectra is the same for both isomers.
From these results a mechanism of UV action on plants based on the photoisomerization of the inactive trans-ABA to the biologically active cis isomer is proposed. 相似文献
The quantum yields of both the cis to trans and trans to cis photoisomerizations were measured by an initial velocities method under various conditions of pH and oxygen concentration at room temperature. The yield for photoisomerization of cis-ABA ranged from 0.25 at pH 3.0 to 0.11 at pH 7.0. Oxygen partially quenched the process. The quantum yield varies only slightly with wavelength.
The quantum yield of photolysis of cis-ABA is reported for pH 3.0 as 0.06. This yield also varies slightly with wavelength and is relatively insensitive to oxygen. This relatively high yield explains the loss of potency of ABA during UV irradiation.
Phosphorescence of cis - and trans-ABA is observed in methanol at 77 K. Onset of the emission is at 350 nm. The emission spectra is the same for both isomers.
From these results a mechanism of UV action on plants based on the photoisomerization of the inactive trans-ABA to the biologically active cis isomer is proposed. 相似文献