Effect of ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) on the growth, stabilization and morphology of silver nanoparticles

The effect of ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA) in stabilizing different shapes of silver nanoparticles have been examined by electronic absorption spectroscopy and transmission electron microscopy. The silver nanoparticles were prepared by two methods, i.e. γ-irradiation and chemical reduction method. Two types of effects of EGTA were identified which lead to the formation of truncated triangular silver nanoplates and chain—like silver aggregates respectively. Time-dependent infrared attenuated total reflectance (ATR-FTIR) studies showed that the nature of adsorption of EGTA on the silver nanoparticle surface influences the shape of the nanoparticles. Pulse radiolysis studies showed the mechanism of formation of the initial silver nanoclusters.     

Selective chelatometric titration of strontium in aluminium alloys with ((ethylenedioxy)diethylene dinitrilo)tetra-acetic acid

Strontium is determined in aluminium alloys by chelatometric titration using ((ethylenedioxy)diethylene dinitrilo)tetraacetic acid (EGTA, or Titriplex VI) as titrant and calcium solution as back-titrant, whilst different chelatometric indicators are compared. A liquid-liquid extraction procedure with sodium diethyl-dithiocarbamate as chelate and MIBK as organic solvent, combined with masking and correction methods are used to obtain better selectivity. The standard deviation and coefficient-of-variation have been found to be 3 ppm and (0.5–1.5%), respectively.     

外源Ca2+、La3+和EGTA处理对辣椒叶片热激反应的影响

以湘研十号辣椒为材料 ,研究了外源 Ca2 、L a3 和 EGTA处理对热胁迫下叶片生理代谢的影响 .结果表明 :Ca2 处理能降低热胁迫下细胞质膜的透性 ,而 L a3 和 EGTA处理略增加了细胞质膜透性 ;Ca2 处理能够降低 As A和 GSH在热胁迫下的氧化 ,而 L a3 和 EGTA处理却没有这种作用 ;Ca2 处理的叶绿素 a和叶绿素 b在热胁迫下降解较慢 ,L a3 和 EGTA处理的则降解较快 .本文认为 ,Ca2 处理能够提高辣椒叶片的抗热性 ,而 L a3 和 EGTA处理却在一定程度上降低了其抗热性 .     

EDTA冠醚衍生物——Ⅷ.两个长桥链双冠醚的合成

前文报道的由EDTA桥联的水溶性双冠醚,虽然对碱土金属离子的配位有其特点,但可能是由于桥键不够长和二个刚性苯环的存在,桥键上两个羧甲基不但不起配位协同作用,反而阻碍了两个冠醚环的靠近,从而未显示出预期的高络合特性。为此,我们按下式合成了两个更长桥键的双冠醚1和2:     

Ag(Ⅰ)-EGTA螯合体系共振散射法测定痕量银

在Walpole缓冲介质和十二烷基苯磺酸钠(SDBS)溶液中,Ag(Ⅰ)与乙二醇-双-(2-氨基乙基醚)四乙酸(EGTA)可形成较稳定的无色螯合物微粒,使得体系的共振散射信号增强.该螯合物微粒在313 nm处产生1个较强共振散射峰.研究表明,在最佳实验条件下,Ag(Ⅰ)浓度在5.4×10-3～2.7 μg/mL范围内与共振散射强度△I呈较好的线性关系,检出限为0.17 ng/mL.该方法用于废胶片中痕量银的测定,结果较满意.     

Evaluation of Calcium - Arsenazo III Stoichiometry in the Presence and Absence of Egta at Various pH

Abstract

The calcium titration experiments were performed with 9 uM and 100 uM concentrations of Arsenazo III (Az) at various pH°s in the presence as well as in the absence of ethylene glycol-bis-(2-amino ethylether)-N,N°-tetra-acetic acid (EGTA). Analysis of results indicated that in the presence of EGTA in 9 uM Az solutions the Ca-Az stoichiometry changes from 1:1 to two Ca binding with one Az (2:1) upon increase in pH from 6.55 to 7.26. In the same systems but without EGTA the binding stoichiometry remains 1:1 throughout the pH range 6.55 to 7.32. In case of 100 uM Az III, however, EGTA has no effect on Ca-Az stoichiometry and it is 1:1 in the above pH range. An estimate of dissociation constants (K_D) in EGTA containing systems showed a simultaneous decrease in K_D by three orders of magnitude with a change in stoichiometry from 1:1 to 2:1 in the case of 9 uM Az III. At 100 uM dye concentration, with no change in 1:1 binding stoichiometry, K_D also remained constant throughout the pH range studied. We suggest that at lower dye concentration a competition between Ca-Az and Ca-EGTA binding causes this change in stoichiometry. The discrepancy among the previous reports about Ca-Az stoichiometry appeared to be due to change in pH in the presence of EGTA.     

高钡合金中钡含量的快速测定方法

文中拟定了高钡合金中钡含量的快速测定方法。该法以三乙醇胺 (TEA)、酒石酸钠(Tart)联合掩蔽铁、铝的干扰 ,在 pH >12的体系中 ,用EGTA滴定 ,求得钡的含量。方法简便、快速 ,结果准确可靠。     

物理和化学法合成钙离子敏感MRI造影剂对比研究

以聚乙烯亚胺(PEI)为添加剂,在聚乙二醇(PEG)中高温热解乙酰丙酮铁(Fe(acac)3)合成超顺磁性氧化铁纳米粒子(PEI/PEG-SPIONs),再与钙离子螯合剂EGTA分别通过物理混合法和EDC/sulfo-NHS化学法合成了对钙离子敏感的磁共振成像(MRI)造影剂EGTA-SPIONs/P(物理混合)和EGTA-SPIONs/C(化学法).PEI/PEG-SPIONs、EGTA-SPIONs/P和EGTA-SPIONs/C分散于HEPES缓冲液中的电泳粒度分别为27.6±3.2 nm、32.1±5.2 am和36.1±4.8nm;加入Ca2后EGTA-SPIONs/P和EGTA-SPIONs/C的平均电泳粒度均趋于变大,呈双峰分布,再加入EDTA后,平均电泳粒度又都趋于减小.MRI测试结果表明,当Ca2浓度从0.8 mmol/L增加到1.2mmol/L时,EGTA-SPIONs/P和EGTA-SPIONs/C样品的T2值分别增加了33;和33.5;;将0.8 mmol/L EDTA加入混合0.8 mmol/L Ca2+的EGTA-SPIONs/P和EGTA-SPIONs/C的分散液中,其T2值分别降低了14;和42;.EGTA-SPIONs/P及EGTA-SPIONs/C对Ca2浓度的增加均有反映,但Ca2+@EGTA-SPIONs/P的EDTA逆转效果不如Ca2+@EGTA-SPIONs/C的明显,化学法合成的EGTA-SPIONs/C更适合作为钙离子敏感剂.     

高效液相色谱法测定药品中的乙二醇二乙醚二胺四乙酸

建立了高效液相色谱分析方法用来测定药品中乙二醇二乙醚二胺四乙酸(EGTA)含量,通过检测EGTA与Cu²⁺的配合物EGTA-Cu来检测EGTA。采用Ultimate-AQ C18色谱柱(250 mm×4.6 mm, 5 μm),流动相为乙腈-四丁基氢氧化铵水溶液(质量分数约0.3%四丁基氢氧化铵水溶液,醋酸调pH 6.50)-醋酸钠溶液(35 mmol/L醋酸钠,醋酸调pH 6.50)(20:20:60, v/v/v),检测波长为245 nm,流速为1.50 mL/min,柱温为40 ℃,进样量为100 μL。结果表明,EGTA质量浓度在0.10~15.00 mg/L范围内线性关系良好(R=0.9998);以信噪比(S/N)为3及10确定检出限和定量限,分别为0.05 mg/L和0.17 mg/L;样品加标平均回收率为98.34%~99.03%, RSD为1.08%~3.33%(n=9)。该方法操作简便,具有分离度好、灵敏度高、重复性好、回收率高等特点,适合药品中EGTA含量的检测,为EGTA检测提供了一种有效的检测方法。