离子色谱-直接电导法测定碱土金属和过渡金属离子

本文报道离子色谱-直接电导法测定碱土金属和过渡金属离子。研究了流动相pH值、乙二胺浓度及柠檬酸和酒石酸浓度对金属离子分离的影响。结果表明,以乙二胺-柠檬酸为流动相可以同时分离碱土金属和过渡金属离子。用乙二胺-酒石酸作为流动相可以分离碱土金属离子。方法检出限为0.09~1.88 mg/L,加标回收率为97.6%~98.7%。该方法用于叶面肥试样的分析,结果良好。     

芳香族羧酸的高效液相色谱法测定及其在药品分析中的应用

建立了反相高效液相色谱同时测定苯甲酸、水杨酸、邻苯二甲酸、对羟基苯甲酸、对氨基苯甲酸和邻甲苯甲酸6种芳香族羧酸的方法.以ZORBAX ODS反相色谱柱为分离柱,采用紫外检测方法,研究了流动相组成、淋洗梯度和检测波长对芳香族羧酸分离效果的影响.在优化色谱条件下,即流动相为乙酸水溶液(50 mmol·L-1,pH 3.5) -甲醇(60 ∶ 40),紫外检测波长为230 nm,流速为1.0 mL·min-1,色谱柱温度为30 ℃,6种芳香族羧酸在25 min内达到基线分离.方法的检出限为0.21 ～ 0.99 mg·L-1,平均加标回收率为99.7% ～100.1%,相对标准偏差小于0.60%.将方法用于足君清酊剂和水杨酸苯甲酸松油搽剂两种药品的分析,结果满意.     

离子色谱法同时测定离子液体中的三氟乙酸根、氟硼酸根及卤素离子

采用离子色谱-直接电导检测法同时测定了离子液体中的三氟乙酸根(CF3COO~)、氟硼酸根(BF4~)及卤素离子(F~、Cl~、Br~)。实验采用Shim-pack IC-A3阴离子交换色谱柱,分别选用邻苯二甲酸氢钾、邻苯二甲酸+三(羟甲基)氨基甲烷、对羟基苯甲酸+三(羟甲基)氨基甲烷+硼酸为淋洗液,考察了淋洗液种类和浓度、乙腈浓度、色谱柱温度对分离测定三氟乙酸根、氟硼酸根及卤素离子的影响。确定的最佳色谱条件为: 以1.2 mmol/L邻苯二甲酸氢钾为淋洗液,柱温45 ℃,流速1.0 mL/min。在此条件下,可同时分离上述5种阴离子,且色谱峰形对称。所测阴离子的检出限(以信噪比为3计)为0.01～0.50 mg/L,保留时间和峰面积的相对标准偏差(n=5)分别不大于0.2%和1.2%。将方法应用于测定离子液体中的三氟乙酸根、氟硼酸根及卤素离子,加标回收率为98.0%～103.2%。该方法简单、准确、可靠,具有较好的实用性。     

Synthesis and characteristics of nanostructured Li(Co1/3Ni1/3Mn1/3)O2 cathode material prepared at 0 °C

Special synthetic conditions at 0 °C were used to prepare nanostructured Li[Ni_1/3Co_1/3Mn_1/3]O₂ via chemical coprecipitation synthesis. The precursor preparation shows platelet shape with thickness of 10 nm and width of 100 nm. After calcination, the particles change to spherical or rectangle shape with a size of 100~200 nm. The nanostructured Li[Ni_1/3Co_1/3Mn_1/3]O₂ shows a well-ordered layered hexagonal lattice with low cation mixing. Galvanostatic testing showed good electrochemical properties and high rate capability, which may be due to its unique morphological and structural characteristics. Synthesis at 0 °C effectively prevented growth of the precursor particles and produced nanosize Li[Ni_1/3Co_1/3Mn_1/3]O₂, which gave improvement in high rate performance and favoring the future use of this cathode material for high power applications.     

Hydrothermal synthesis,structure and properties of copper–bipyridine complexes substituted mono-vacant Keggin arsenotungstate

A new arsenotungstate, [H₂AsW₁₁O₃₉][Cu₃(2,2′-bipy)₃(H₂O)₂(OH)]·2H₂O (1) (2,2′-bipy = 2,2′-bipyridine), has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, UV–Vis, TG and single-crystal X-ray diffraction. The compound 1 represents the first example of copper–bipyridine complexes substituted mono-vacant Keggin polyoxotungstate containing As^V. Compound 1 exhibits fluorescent property at room temperature. Furthermore, compound 1 has been used as a solid bulk-modifier to fabricate bulk-modified carbon paste electrodes (1-CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1-CPE have been studied in detail.     

Hydrothermal synthesis, structure and properties of a new arsenotungstate

A new arsenotungstate, Na[{Cu(2,2′-bpy)(imi)}{Cu(2,2′-bpy)}₂AsW₉O₃₃As(OH)]·8H₂O (1) (2,2′-bpy=2,2′-bipyridine, imi=imidazole), has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The compound 1 represents the first example of an unusual trilacunary arsenotungstate substituted simultaneously arsenide fragment and copper complexes. The compound 1 was used as solid bulk modifier to fabricate bulk-modified carbon paste electrodes (1-CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1-CPE have been studied in detail. Magnetic measurement for 1 shows the presence of antiferromagnetic interactions within the Cu²⁺ cations.