离子色谱法测定乙二胺四乙酸二钠中氨基三乙酸

建立了离子色谱检测食品添加剂乙二胺四乙酸二钠(EDTA-2Na)中的氨基三乙酸(NTA)的方法,采用KOH溶液为流动相,IonPac AS11-HC分析柱分离,电导检测器检测。在3个加标水平下,平均回收率范围为91.3%~100.1%,方法的检出限为0.1μg/m L。方法可用于EDTA-2Na中NTA含量的检测。     

碘-淀粉体系褪色光度法测定食品中甲醛

建立了碘-淀粉体系褪色光度法测定甲醛含量的方法。适量的碘与淀粉溶液形成最大吸收波长为580 nm的蓝色配合物,加入适量的Na OH后,I2与Na OH生成的Na IO能定量地将甲醛氧化成甲酸,过量的Na IO则歧化生成Na IO3和Na I。将反应液调成酸性后,Na IO3与Na I反应重新生成I2。结果表明,加入甲醛的含量在0~75 ng/m L范围内时,碘-淀粉溶液与甲醛反应前后的吸光度差ΔA(y)与ρ(x)呈良好的线性关系,线性回归方程为y=0.0063x+0.0013,线性相关系数r=0.9971。方法用于新鲜鱿鱼中甲醛含量的测定,结果与乙酰丙酮法一致。     

pH值对水热合成黄铁矿型CoS2微晶的影响

本文以EDTA-2Na为辅助剂,Na2S2O3.5H2O为硫源,运用水热法制备了黄铁矿型CoS2微晶,研究了溶液pH值对产物结构和形貌的影响。采用X射线粉末衍射仪(XRD),扫描电子显微镜(SEM)对产物的结构和形貌进行了表征。实验结果表明,溶液为酸性环境时(pH=1、3)可得到纯相的黄铁矿型CoS2微晶,形貌为微米尺寸的空心球壳。溶液为中性和碱性环境时(pH=7、11),产物出现少量杂相,形貌变为规则的八面体晶粒。讨论了这些CoS2微晶的形成机制。     

在线预处理对乙二胺四乙酸二钠离子色谱分离的影响及其应用

1引言乙二胺四乙酸二钠(EDTA-2Na)作为食品添加剂,能够对原料中的微量金属离子进行络和,防止金属离子对产品质量的缓慢破坏作用[1],常用在果蔬罐头、八宝粥等食品中,同时也可作为蛋白洗涤液中的添加剂,既增加舒适度又提高溶液杀菌能力。但是含量过高,会刺激皮肤和粘膜,引起哮喘等疾病,国家标准规定食品中最高限量为     

燃煤电厂脱硫浆液中汞迁移转化及添加剂对石膏中汞稳定性影响

以某300 MW超低排放燃煤机组现场脱硫浆液为研究对象,考察了浆液中汞迁移转化及添加剂对其影响行为,探讨了固相石膏中汞的热释放特性和环境风险。结果表明温度升高仅导致气相Hg~0增加,而浆液pH升高会导致气相和固相中汞含量均有增加,Cl-或SO_4~(2-)浓度升高既可以抑制浆液中汞还原为Hg~0也可以促进固相石膏中汞含量增加,而SO_3~(2-)浓度升高虽然有利于汞富集于固相但会引起Hg~(2+)部分转化为Hg~0。Na_2S、EDTA-2Na或DTCR-4添加剂与Hg~(2+)反应分别生成HgS、Hg(EDTA)2或-[Hg-DTCR]-n,使浆液中75%以上汞转移至固相石膏中,并抑制了Hg~(2+)还原为Hg~0,其中DTCR-4对汞的固化效果最好,但热稳定性依次为Gypsum+EDTA-2Na Gypsum+DTCR-4 Gypsum+Na_2S Gypsum,主要原因是所生成Hg(EDTA)2、-[Hg-DTCR]-n和HgS(black)的稳定性差异所致。进而采用TCLP、SPLP和MEP三种方法获得了样品中汞的化学稳定性为Gypsum Gypsum+Na_2S Gypsum+EDTA-2Na Gypsum+DTCR-4,其原因是石膏中水溶态汞、酸溶态汞和可氧化态汞含量的差异所致。     

甲醛肟分光光度法测定三氧化钼及金属钼中微量锰

微量锰的比色测定方法,常用高锰酸盐比色法。此法虽较特效和准确,但在分析三氧化钼及金属钼中的微量锰时,需经沉淀分离,操作繁琐,且灵敏度达不到要求。用甲醛肟比色测定锰,前人已进行很多工作,我们在前人工作的基础上,拟定了用甲醛肟分光光度法测定三氧化钼及金属钼中微量锰的方法,具有灵敏、准确和操作简便等特点,适用于含锰量为1×10~(-4)％—4×10~(-3)％的样品分析。 (一)主要试剂 1.铜试剂:4％(新鲜配制,过滤后使用)。 2.甲醛肟溶液:1M,取盐酸羟胺7克溶于水中,加入38％甲醛20毫升,     

醇胺溶液吸收二氧化碳的实验研究

CO2的减排和有效利用受到人们的广泛关注.以二乙醇胺(DEA)、三乙醇胺(TEA)、N-甲基二乙醇胺(MDEA)溶液为对象,采用鼓泡吸收装置考察了醇胺的种类及浓度对CO2吸收速率和吸收容量的影响,研究了吸收前后溶液pH的变化,以及醇胺溶液再生后的情况.实验表明,醇胺溶液浓度增大有利于CO2的吸收,相同条件下DEA和TEA的吸收效果好于MDEA,醇胺溶液吸收CO2后pH由接近于11降至7左右,TEA的再生效果好于DEA.     

电感耦合等离子体质谱法测定富铀矿样中的微量钍

建立电感耦合等离子体质谱(ICP–MS)法测定富铀矿样中微量钍的方法。富铀矿样经Na_2O_2分解,用乙二胺四乙酸二钠(EDTA-2Na)–三乙醇胺(TEA)–H_2O_2溶液提取,以Mg(OH)_2作载体共沉淀提取液中的过氧化钍,使钍与大部分金属离子和UO_2~(2+)分离。沉淀用2 mol/L热HNO_3溶液溶解,定容后用ICP–MS法测定。该方法消除了样品中高含量铀组分对仪器进样系统的污染。钍的质量浓度在0~100μg/L范围内具有良好的线性关系,线性相关系数为0.999 7,钍的检出限为0.185μg/L。测定结果的相对标准偏差为2.23%~5.91%(n=6),用该法测定3种国家标准物质,测定值与标准值的相对误差小于4.96%。该法样品分解彻底,铀分离较充分,检测速度快,检出限低,测定结果稳定可靠,适用于富铀矿样中微量钍的测定。     

硫氰酸盐双波长分光光度法测定高铅矿石中钼量

在常规的硫氰酸盐光度法测定钼的硫酸介质中,加入80g·L-1乙二胺四乙酸二钠盐(EDTA-2Na)溶液7mL,使48mg·L-1以下共存的铅(Ⅱ)无法生成硫酸铅,不干扰钼的测定,应用此条件测定了含铅量较高的矿石中钼的含量。样品(0.100 0~0.500 0g)于高铝坩埚中,用过氧化钠3g融熔,熔块用水浸出,定容至100mL,分取部分试液,加入EDTA-2Na溶液7mL后按常规条件显色,用双波长方法以460nm(λ1)为测定波长,650nm(λ2)为参比波长测量吸光度(A),计算ΔA(Aλ1-Aλ2)。钼的质量浓度在6.0mg·L-1以内与相应的ΔA之间呈线性关系,方法的检出限(3s/k)为8.1×10-3 mg·L-1。应用此方法测定了2个CRM(GBW 07238,GBW 07285)中的钼量,测定值与认定值相符,测定值的相对标准偏差(n=9)依次为2.8%,1.2%。     

4，5-二甲氧基邻苯二甲醛在水中铵氮检测中的应用及测定方法

本发明公开了4,5-二甲氧基邻苯二甲醛在水中铵氮检测中的应用及测定方法。具体的测定方法包括：（1）在铵氮工作液中依次加入EDTA-4Na溶液、4,5-二甲氧基邻苯二甲醛溶液、亚硫酸钠溶液,然后用氢氧化钠溶液调节体系的pH值,反应平衡后,在λex=379 nm下,测定400～600 nm的荧光曲线,记录最大发射波长处的荧光强度,做出工作曲线;（2）将样品溶液在最大发射波长处的荧光强度根据工作曲线定量样品溶液中的铵氮含量。本发明所述方法中,4,5-二甲氧基邻苯二甲醛与铵氮的反应平衡时间缩短至50 min,且反应产物的最大激发波长红移至接近可见光区,为便携式铵氮在线荧光检测仪的研制奠定基础。     

Fabrication of Covalently Linked PAH/PVS Layer-by-layer Assembled Multilayers via a Post-photochemical Cross-linking Strategy

A post-photochemical cross-linking strategy was successfully demonstrated to enhance the stability of polyelectrolyte poly(allylamine hydrochloride)(PAH)/poly(vinylsulfonic acid sodium salt)(PVS) multilayers. Conventional polyelectrolyte multilayers of PAH/PVS are usually fabricated through electrostatic layer-by-layer(LbL) assembly, resulting in poor stability, especially in basic solutions, which leads to the urgent demand for converting weak electrostatic interactions into covalent bonds to enhance the stability of the multilayers. This stability problem has been ultimately addressed by post-infiltrating a photosensitive cross-linking agent, 4,4'-diazostilbene-2,2'- disulfonic acid disodium salt(DAS), into the LbL assembled films to initiate the photochemical reaction to cross-link the multilayers. The obviously improved stability of the photo-cross-linked multilayers was demonstrated through experiments with basic solution treatments. Compared to the complete decomposition of uncross-linked multilayers in basic solution, over 74.4% of the covalently cross-linked multilayers were retained under the same conditions, even after a longer duration of basic solution treatment.     

Zeta Potential,Size, and Semiconductor Properties of Zinc Sulfide Nanoparticles in a Stable Aqueous Colloid Solution

A stable aqueous colloid solution of zinc sulfide (ZnS) nanoparticles was obtained by chemical condensation using ethylenediaminetetraacetic acid disodium salt. The mechanism of prolonged aggregative stability of solution at pH 7–8 with ~7-nm nanoparticles was determined as a result of the zeta potential measurements by dynamic light scattering. The blue and red shifts of the fundamental absorption edge of zinc sulfide semiconductor nanoparticles associated with the small size of nanoparticles and the defective state of their surface were found by optical spectrophotometry.     

纳米荧光粒子YVO_4∶Eu的合成及其在指纹显现中的应用

以柠檬酸为络合剂,在水相中合成了悬浮稳定性较好的稀土YVO4∶Eu溶胶,采用XRD、TEM、荧光光谱等技术,研究了稀土荧光粒子的尺寸、形貌、晶胞参数及发光性能.结果表明合成的YVO4∶Eu荧光粒子为四方晶系,粒径约为10nm,分散性较好;在pH=9.0时合成的Y0.7VO4∶Eu0.3溶胶具有最大的荧光强度,其最大发射峰在619nm;经乙二胺四乙酸二钠表面修饰后的Y0.7VO4∶Eu0.3纳米荧光粒子能够清晰地显现出光滑客体上的指纹,颜色为红色.     

Use of hydroxylamine hydrochloride in the titrimetric determination of manganese in pyrolusite

A procedure is described for the determination of total manganese in pyrolusite. The sample is decomposed with hydroxylamine hydrochloride solution. The residue left after filtration is fused with sodium carbonate and extracted again with hydroxylamine hydrochloride solution. A suitable aliquot is titrated with EDTA at pH 10, with Eriochrome Black T as indicator, after masking of interfering elements.     

Electrochemical synthesis of Co(II) chelate complexes

The Co chelate complexes with acetylacetone, ethylenediaminetetraacetic acid, and its disodium salt were synthesized electrochemically and studied by the elemental analysis, UV-VIS, IR, and thermogravimetry methods in combination with isothermal heating of the samples.     

A thin layer photocell based on a tris(2,2'-bipyridine)ruthenium complex immobilized in a membrane containing an electronically conductive polymer

A thin layer photocell was constructed in which tin oxide (Nesa glass) modified with a tris(2,2'-bipyridine)ruthenium complex immobilized in a polyvinylcinnamate membrane was used as the working electrode, platinum was used as the counter electrode, and an aqueous solution containing the disodium salt of ethylenediaminetetraacetic acid was placed between the electrodes. The photocell generated a photocurrent under visible light irradiation. The generation of photocurrent was considerably enhanced when the working electrode was modified by the addition of the tetracyanoquinodimethane salt of poly-4-vinylpyridine and neutral tetracyanoquinodimethane.     

一种1,10菲啰啉-5,6-二酮及其单肟的高效合成方法

1,10菲啰啉5,6二酮(2)与1,10菲啰啉5,6二酮单肟(3)作为稠杂环共轭配体,既具有良好的配位特性,又是重要的有机合成反应中间体。由化合物2和它的衍生物与金属离子形成的配合物可以用于抗肿瘤药物、DNA探针、非线性光学材料、超分子组装分子骨架、自旋交叉配合物等许多领域。化合物3则用于有机光致变色化合物螺噁嗪的合成。化合物2无法直接用氧化剂氧化1,10菲啰啉(1)得到。它最初是从化合物1用混酸硝化制备5硝基1,10菲啰啉的废水中分离得到的,产率1%。Amouyal等[1]改进此方法,将产率提高到20%。随着应用研究的需求,对它的合成研究一直没有间…     

一种1, 10-菲啰啉-5, 6-二酮及其单肟的高效合成方法

1,10-菲啰啉-5,6-二酮(2)与1,10-菲啰啉-5,6-二酮单肟(3)作为稠杂环共轭配体,既具有良好的配位特性,又是重要的有机合成反应中间体.由化合物2和它的衍生物与金属离子形成的配合物可以用于抗肿瘤药物、DNA探针、非线性光学材料、超分子组装分子骨架、自旋交叉配合物等许多领域.化合物3则用于有机光致变色化合物螺噁嗪的合成.     

Synthesis and properties of α-sulfo carboxyl disodium salt

The synthesis and properties of α-sulfo carboxyl disodium salt (SCDS) were studied in detail for the first time in this paper. SCDS was synthesized via saponification reaction of fatty acid methyl ester sulfonate sodium (MES). FT-IR was used to characterize the molecular structure of target product. The yield of disodium salt was greater than 98% by two-phase titration. The performance of SCDS was studied and was compared with raw materials MES, conventional anionic surfactant AES and nonionic surfactant AEO₉. The result shows SCDS can reduce the surface tension of the solution to 27.89?mN/m at critical micelle concentration (CMC). The wetting ability of SCDS was significantly enhanced with the increase of temperature. The emulsification effect of SCDS on the soybean oil is better than that on the liquid paraffin. Surprisingly, SCDS has a good foamability and foaming stability.     

Dérivés de l'imidazo[2,l-b]thiazole. IX. Comportement du phénacyl-3 dihydro-5,6 imidazo[2,1-b]thiazole et du phénacylidène-3 tétrahydro-2,3,5,6 imidazo[2,1-b]thiazole vis-à-vis du chlorhydrate d'hydroxylamine

The reaction of hydoxylamine hydrochloride with two imidazothiazoles, having a ketonic carbonnyl group, leads to two types of compounds according to the quantity of the sodium acetate used. 3-Phenacyl-5,6-dihydroimidazo[2,1-b]thiazole hydrochloride gives logically the corresponding oxime, isolated in salt form or as a base depending upon the quantity of sodium acetate added. Furbase depending upon the quantity of sodium acetate added. Furthermore, a systematic allylic rearrangement was observed with migration of thiazole double bond to the adjacent nuclear position. 3-Phenacylidene-2,3,5,6-tetrahydroimidazo[2,1-b]thiazole gave directly in the absence of sodium acetate, a rearranged oxime salt. On the other hand, in the presence of sodium acetate, we obtained a hgydroxylamine which was characterized by a double bond in the 2,3-position of the thiazole ring. It is noteworthy that no transformation of the hydroxylamine into the oxime or vice-versa occurs whatever the pH of the solution. These different compounds have no fungistatic activity in contrast to the corresponding ketones.