scholarly journals Flow-Injection Spectrophotometric Determination of Phenolic Drugs and Carbamate Pesticides by Coupling with Diazotized 2,4,6-Trimethylaniline

1999 ◽  
Vol 82 (4) ◽  
pp. 937-947 ◽  
Author(s):  
Lluis Alvarez-Rodriguez ◽  
Esteve-Romero Josep ◽  
Imma Escrig-Tena ◽  
M Celia Garcia Alvarez-Coque
Keyword(s):  
Flow Injection ◽  
Sodium Dodecyl ◽  
Coupling Reaction ◽  
The Self ◽  
Micellar Media ◽  
Carrier Stream ◽  
Diazonium Ion ◽  
Phenolic Drugs ◽  
Aqueous Micellar Medium

Abstract A flow-injection (FI) spectrophotometric system is proposed for the determination of phenols and carbamates. In the FI manifolds, the solutions of phenols or carbamates (the latter after hydrolysis with NaOH) were injected into a diazonium ion carrier stream at pH 9.5 (buffered with tetrahydroborate), which was formed by mixing 2,4,6-trimethylaniline (TMA) with nitrate in a sodium dodecyl sulfate aqueous micellar medium. Absorbance was measured at 550 nm. The system combines the advantages derived from the use of TMA for the coupling of phenols in basic micellar media, because of the inhibition of the self-coupling reaction of the reagent, with the precision and speed of the FI procedures. Other diazotized reagents produced excessive blank signals. The procedures were successfully applied to the determination of phenolic drugs (epinephrine, acetaminophen, and guaiacol) in pharmaceuticals and carbamates (bendiocarb, benfuracarb, carbaryl, carbofuran, methiocarb, promecarb, and propoxur) in pesticide products and water samples.

scholarly journals Selective and Stability-Indicating Methods for the Simultaneous Determination of Mexiletine Hydrochloride and/or Its Related Substance: 2,6-Dimethylphenol

2008 ◽  
Vol 91 (4) ◽  
pp. 720-730
Author(s):  
Tarek S Belal ◽  
Rim S Haggag ◽  
Rasha A Shaalan
Keyword(s):  
Sodium Dodecyl ◽  
Coupling Reaction ◽  
Parent Drug ◽  
Related Substance ◽  
Selective Determination ◽  
Stability Indicating ◽  
Spectrophotometric Methods ◽  
First Derivative ◽  
The Stability

Abstract Four simple, rapid, sensitive, and selective analytical procedures were developed for determination of mexiletine hydrochloride (MX) and/or its related substance: 2,6-dimethylphenol (DMP). The latter is a synthetic impurity for which a maximum pharmacopeial limit is defined. The first method depends on derivative-ratio spectrophotometry, for which the first-derivative signals of the ratio spectra at 259 nm ( = 3 nm) are selected for the determination of MX. The second method is based on the spectrofluorometric measurement of MX in alkaline solution in the presence of 15 mM sodium dodecyl sulfate micellar medium at 292 nm (Ex 260 nm). The third method is based on liquid chromatographic (LC) separation of MX and DMP on an RP-C8 column with a mobile phase consisting of 50 mM Na2HPO4acetonitrile (60 + 40, adjusted to pH 2.4), and quantification of the analytes is achieved with UV detection at 212 nm based on peak area. The fourth method uses the coupling reaction of DMP with 2,6-dibromoquinone-4-chlorimide (DBQC) in borate buffer to form an intensely colored product that was spectrophotometrically measured using first-derivative amplitudes at 670 nm ( = 6nm) for the determination of DMP. Different variables affecting each method were carefully investigated and optimized. The reliability and analytical performance of the proposed methods, including linearity, range, precision, accuracy, and detection and quantitation limits, were statistically validated. The first 3 methods were successfully applied for the stability-indicating determination of MX in laboratory-prepared mixtures with DMP, as well as for the determination of MX in capsules. Also, the LC and the DBQC spectrophotometric methods permitted the selective determination of DMP in the presence of a large excess of the parent drug at or near the pharmacopeial limit (0.11).

scholarly journals Micelle Enhanced Spectrofluorimetric Determination of L-ascorbic Acid Based on Laccase-linked Coupling Reaction Using Flow-injection Stopped-flow Technique.

1997 ◽  
Vol 13 (Supplement) ◽  
pp. 67-70 ◽  
Author(s):  
Houping Huang ◽  
Ruxiu Cai ◽  
Takashi Korenaga ◽  
Xinxiang Zhang ◽  
Yi Yang ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Flow Injection ◽  
Coupling Reaction ◽  
Stopped Flow ◽  
Spectrofluorimetric Determination

Fluorescence Enhancement of Carbendazim in the Presence of Cyclodextrins and Micellar Media: A Reappraisal

2005 ◽  
Vol 59 (7) ◽  
pp. 873-880 ◽  
Author(s):  
Rubén M. Maggio ◽  
Gisela N. Piccirilli ◽  
Graciela M. Escandar
Keyword(s):  
Sodium Dodecyl ◽  
Fluorescence Emission ◽  
Hexadecyltrimethylammonium Bromide ◽  
Micellar Media ◽  
Experimental Conditions ◽  
Decyltrimethylammonium Bromide ◽  
Spectrofluorimetric Determination ◽  
Organized Media ◽  
Organized Assemblies

This study focuses on the spectrofluorimetric behavior of the pesticide carbendazim in the presence of selected organized assemblies and also on their potential analytical applications. The relatively weak fluorescence emission band of carbendazim is significantly enhanced by micellar media formed by sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and decyltrimethylammonium bromide. The influence of the surfactant structures, concentrations, and working experimental conditions on the fluorescence spectra of carbendazim was thoroughly evaluated and discussed. Although the interaction of carbendazim with different cyclodextrins is rather weak, it was corroborated that the fluorescence intensity of this compound in the presence of (2-hydroxy)propyl β-cyclodextrin is increased by a factor of two. Among the studied organized media, the cationic surfactant hexadecyltrimethylammonium bromide produced the largest signals for the compound of interest. Consequently, the optimal working conditions for the spectrofluorimetric determination of carbendazim in the presence of the latter detergent were analyzed, concluding that previous literature reports should be reconsidered.

scholarly journals Batch and Flow-Injection Spectrophotometric Determination of Procaine HCl in Pharmaceutical Preparations Via Using Diazotization and Coupling Reaction

2012 ◽  
Vol 9 (3) ◽  
pp. 521-531
Author(s):  
Baghdad Science Journal
Keyword(s):  
Flow Injection ◽  
Diazonium Salt ◽  
Pharmaceutical Preparations ◽  
Coupling Reaction ◽  
Standard Addition ◽  
Water Soluble ◽  
Spectrophotometric Methods ◽  
Colored Product ◽  
Average Sample

Simple and sensitive batch and Flow-injection spectrophotometric methods for the determination of Procaine HCl in pure form and in injections were proposed. These methods were based on a diazotization reaction of procaine HCl with sodium nitrite and hydrochloric acid to form diazonium salt, which is coupled with chromatropic acid in alkaline medium to form an intense pink water-soluble dye that is stable and has a maximum absorption at 508 nm. A graphs of absorbance versus concentration show that Beer’s law is obeyed over the concentration range of 1-40 and 5-400 µg.ml-1 of Procaine HCl, with detection limits of 0.874 and 3.75 µg.ml-1 of Procaine HCl for batch and FIA methods respectively. The FIA average sample throughput was 70 h-1. All different chemical and physical experimental parameters that affecting on the development and stability of the colored product were carefully studied and the proposed methods were applied satisfactorily for the determination of Procaine HCl in an injections samples using the standard addition method.

scholarly journals Influence of Valsartan on the thermodynamics of micellization of anionic surfactant Sodium Dodecyl Sulphate

2016 ◽  
Vol 63 (2) ◽  
pp. 30-36
Author(s):  
L. Stopková ◽  
A. Hriňaková ◽  
Ž. Bezáková ◽  
F. Andriamanty ◽  
V. Žufková
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Anionic Surfactant ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Uv Spectrophotometry ◽  
Micellar Media ◽  
Different Temperatures ◽  
Enthalpy And Entropy

AbstractIn this manuscript was investigated behaviour of drug valsartan by micellar media of anionic surfactant sodium dodecyl sulphate. As the method was used electrical conductivity for the determination of critical micelle concentration at different temperatures (T = 293.15 - 313.15 K), as well as calculated thermodynamic parameters like standard Gibbs free energy, enthalpy and entropy of micellization. According to contribution of Gibbs free energy is the process of micellization primarily controlled by entropy. Solubilization of valsartan was studied in surfactant system at 298.15 K and physiological conditions pH 7.4 using UV-spectrophotometry at different concentration range (0.001 - 0.07 mol/l) of sodium dodecyl sulphate. The solubilization of drug was observed with increasing concentration of surfactant in aqueous solution.

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