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A new sequential injection spectrophotometric method was proposed for the determination of metoclopramide and tetracaine hydrochloride. The method was based on the detection of an unstable red intermediate compound resulting from the reaction of metoclopramide or tetracaine hydrochloride with potassium dichromate, in the presence of sodium oxalate, in sulfuric acid solution. The related reaction mechanisms of this new method have been studied. The experimental conditions were optimized for the stopped-flow and continuous-flow sequential injection models. For continuous flow, the linear range for determination of metoclopramide, the detection limit and the sampling frequency were 13-130 μg ml−1, 9.4 μg ml−1 and 40 samples per hour, respectively. For stopped flow, they were 3-42 μg ml−1, 1.0 μg ml−1 and 18 h−1, respectively. Adopting the continuous-flow model for tetracaine hydrochloride, the linear range was 25-300 μg ml−1, and the detection limit was 18.0 μg ml−1 with sampling frequency of 40 h−1. This method has been used to determine metoclopramide and tetracaine hydrochloride in pharmaceutical preparations, and the results are compared with those determined by the pharmacopoeia method. Statistical analysis reveals that there was no evidence of significant difference between the methods. 相似文献
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盐酸丁卡因与赤藓红的荧光猝灭反应及其分析应用 总被引:1,自引:0,他引:1
在pH 4.0的弱酸性介质中,盐酸丁卡因(TA·HCl)与赤藓红(ET)形成1∶1的离子缔合物,导致赤藓红溶液荧光猝灭。当分别于最大激发/最大发射(λex/λem)525 nm/556 nm进行测量时,荧光猝灭值(ΔF)与TA·HCl浓度在0.28~4.8 μg·mL-1范围呈良好的线性关系。该方法灵敏度高,检出限为0.083 μg·mL-1。考察了共存物质的影响,表明方法有良好的选择性。据此发展了一种高灵敏、简便快速测定微量TA·HCl的新荧光分光光度法。该法用于人血清及尿样中盐酸丁卡因的含量测定,结果满意。文章还研究了反应体系的荧光特性,并结合量子化学AM1计算对荧光猝灭机理进行了讨论。 相似文献
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The interactions of bovine serum albumin (BSA) with two local anesthetics, procaine hydrochloride (PCH) and tetracaine hydrochloride (TCH) were studied using spectroscopic methods such as fluorescence and ultraviolet visible (UV-vis), and electrochemical techniques including cyclic voltammetry (CV) and differential pulsed stripping voltammetry (DPSV). The results obtained from these techniques turned out that both PCH and TCH could bind to BSA. The binding constants (KA) and the number of binding sites (n) of the two drugs with BSA at different temperatures were determined, respectively. At 291 K, KA was found as 2.40×104 and 1.42×104 L mol−1 and n was 1.03 and 0.99 for PCH-BSA and TCH-BSA, respectively. According to van’t Hoff equation, the thermodynamic parameters, ΔG, ΔH and ΔS, were obtained, showing the involvement of hydrophobic and electrostatic force in these interactions. Based on the theory of the Förster energy transference, the distance between the acceptor (PCH or TCH) and the donor (BSA) were determined as 2.32 and 3.62 nm for PCH and TCH, respectively. The effects of Fe3+, Cu2+, Mg2+, Mn2+, Zn2+ and Ca2+ on the binding of PCH or TCH to BSA were also evaluated. 相似文献
4.
Sergio Antonio Fernandes Luiz Fernando Cabeça Anita Jocelyne Marsaioli Eneida de Paula 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):395-401
Cyclodextrins (CD) and calixarenes are complexing agents that have been successfully used as pharmaceutical drug carriers,
to improve the bioavailability of medicines. The aim of this work was to investigate the complexation of the local anesthetic
tetracaine 1 with β-cyclodextrin 2, as well as with p-sulphonic acid calix[6]arene 3. 1H NMR experiments were carried out in D2O, i.e., with the charged tetracaine species 1. HR-DOSY 1H NMR allowed determination of the fraction of complexed population (%p
bound = 55% and 70%) and the apparent association constants (K
a = 1358 and 3889 M−1), respectively, for 1/2 and 1/3. These results confirm that a strong association takes place between 1 and 2, while the 1/3 complex is even more stable, due to the negatively charged sulphonic groups of 3. Studies conducted at pH 10 revealed that the association of the uncharged form of 1 with 3 is considerably weaker, while that with 2 increased significantly (K
a
= 6597 M−1), protecting the anesthetic against alkaline hydrolysis. 1H-ROESY 1D NMR experiments allowed determination of the host-guest relative positions, revealing that the proposed topologies
for the 1/2 and 1/3 complexes were quite different. The complexation of 1 with either 2 or 3 is being investigated in view of its potential use in new therapeutic formulations, designed to increase the bioavailability
and/or to decrease the systemic toxicity of tetracaine, in anesthesia procedures. 相似文献
5.
Elena Lorente Alberto Rodríguez Emilio Aicart Elena Junquera 《Colloid and polymer science》2007,285(12):1321-1329
The use of colloidal organized media, such as micelles, to solubilize tetracaine hydrochloride (TC.HCl), a local anaesthetic
drug, in aqueous solution has been studied by means of fluorescence spectroscopy at 298.15 K. Because tetracaine molecule
is a fluorescent probe, changes in the fluorescence emission spectra of the drug when it is solubilized by the micelles enable
the study of the micelles–drug association process through the calculation of the association constants. Two kinds of micelles
have been selected to solubilize the drug: non-ionic micelles and cationic micelles. Complementary conductometric experiments
were also done to determine the critical aggregation concentration of the surfactants in the presence of the drug. The micelle–drug
association process has been also analyzed by deconvoluting the fluorescent of the drug into several Gaussian components,
each of which assigned to the solubilization of the drug within different microenvironment inside and outside the cationic
and/or non-ionic micelles. 相似文献
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