In this study, a new, rapid and sensitive batch and flow injection-merging zones spectrophotometric methods for the determination of hydroquinone in a pure material and in pharmaceutical preparation were proposed. These methods were based on the oxidative-coupling reaction of HQ with 2,4-dinitrophenylhydazine (DNPH) in the presence of sodium periodate and sodium hydroxide to form a dark brown water slouble dye that is stable and has maximum absorption at 530 nm, graphs of absorbance versus concentration show that Beer's low is obeyed over the concentration rang of 1-40 and 3-300 μg.ml-1 of hydroquinone, with detection limits of 0.162 and 0.510 μg.ml-1 of hydroquinone for batch and FIA methods, respectively. The optimized FIA system is

This paper concerned with development of a spectrophotometric method for the determination of paracetamol, based on the diazotisation and coupling reaction with anthranilic acid in basic medium, to form an intense yellow coloured, water-soluble and stable azo-dye which shows a maximum absorption at 421nm. Beer’s law is obeyed over the concentration range of 1.0-10 µg/ml; with molar absorptivity of 2.1772×104 L.mol -1.cm-1 and Sandell’s sensitivity index 6.9446 µg.cm-2. The method has been applied successfully for the determination of paracetamol in pharmaceutical formulation. 

     Simple and rapid spectrophotometric determination of furosemide (FUR) has been investigated .The method is based on acid hydrolysis of FUR to free primary aromatic amine and diazotization followed by coupling with 3, 5 di methyl phenol (3, 5-DMPH) at basic medium. The absorbance was measured at 434 nm, the method was optimized for best condition, and beers’ law is obeyed over the range of 0.4-50 µg.mL^-1 with molar absorptivity and sandal’s sensitivity 1.3899 x10⁴ L moL^-1 .cm^-1 and 0.0238x10⁴ µg.cm^-2 respectively. Analysis of solution containing nineteen different concentrations of FUR gave a correlation coefficient of (0.9999) a

A simple, and rapid spectrophotometric method for the estimation of paracetamol has been developed. The methods is based on diazotisation of 2,4-dichloroaniline followed by a coupling reaction with paracetamol in sodium hydroxide medium. All variables affecting the reaction conditions were carefully studied. Beer's law is obeyed in the concentration range of 4-350 ?gml?1 at 490 nm .The method is successfully employed for the determination of paracetamol in pharmaceutical preparations. No interferes observed in the proposed method. Analytical parameters such as accuracy and precision have been established for the method and evaluated statistically to assess the application of the method.

Verapamil Hydrochloride (VH) has been determined spectrophotometrically by using Methyl Orange (MO).  In our previous researches MO was used for determination of Mexiletine Hydrochloride [1]. The method was based on complexation between (MO and VH).  After shaking and diluting the complex solution with D.W, the pH was adjusted with NaOH and HCl to pH 4. The colored complex formed between VH and the reagents were transferred into separating funnels and extracted using 4.5 ml CH2Cl2 and were shaken for (4 minutes).  The extracted organic layer was used for the preparation of the calibration curves for spectrophotometric measurements of VH at 437nm.  The blanks were carried out in exactly the same way throughout the whol

Simple, rapid and sensitive spectrophotometric method was proposed for the analysis of metoclopramide hydrochloride (MPH) in pure form as well as in pharmaceutical tablets. The method is based on the diazotization reaction of MPH with sodium nitrite in hydrochloric acid medium to form diazonium salt, which is coupled with 1-naphthol in sodium hydroxide medium to form azo dye, showing absorption maxima at 550 nm. Beer’s law is obeyed in the concentration range of 0.4 – 18 µg mL-1 of MPH with detection limit 0.5448 µg mL-1. The molar absorptivity and Sandell’s sensitivity are 3.4969 × 104 L mol-1 cm-1 and 0.0101 µg cm-2, respectively. The method was successfully applied to the determination of MPH in pharmaceutical tablets with

New, simple and sensitive batch and reverse FIA spectrophotometric methods for the determination of doxycycline hyclate in pure form and in pharmaceutical preparations were proposed. These methods based on oxidative coupling reaction between doxycycline hyclate and 3-methylbenzothiazolinone-2-hydrazone hydrochloride (MBTH) in the presence ammonium ceric sulfate in acidic medium, to form green water-soluble dye that is stable and has a maximum absorbance at 626 nm. A calibration graph shows that a Beer's law is obeyed over the concentration range of 1-80 and 0.5-110 ?g.mL-1 of DCH for the batch and rFIA respectively with detection limit of 0.325 ?g.mL-1 of DCH for r-FIA methods. All different chemicals and physical experimental paramete

A simple, cheap, fast, accurate, Safety and sensitive spectrophotometric method for the determination of sulfamethaxazole (SFMx), in pure form and pharmaceutical dosage forms. has been described The Method is based on the diazotization of the drug by sodium nitrite in acidic medium at 5Cº followed by coupling with salbutamol sulphate (SBS) drug to form orange color the product was stabilized and measured at 452 nm Beer’s law is obeyed in the concentration range of 2.5-87.5 ?g ml-1 with molar absorptivity of 2.5x104 L mole-1 cm-1. All variables including the reagent concentration, reaction time, color stability period, and sulfamethaxazole /salbutamol ratio were studied in order to optimize the reaction conditions. No interferences were

         A spectrophotometric reliable, rapid and sensitive method has been developed and validated for  the determination Ketotifen fumarate  . A method was described for the determination of Ketotifen Fumarate  in pure form or pharmaceutical formulations, a colored ion-pair complex formation reaction among ketotifen fumarate and acid-dye bromophenol blue at pH 3.0 was used for the colorimetric determination of the drug. The complex formed was extracted into chloroform and the maximum absorbance of the solution was measured at 413 nm against blank. The calibration curve calculated obey Beer's law over the concentration range of 0.4-16 μg/ml and the regression equation was A=0.069

A simple, accurate and sensitive spectrophotometric method for the determinaion of epinephrine is described . The method is based on the coordination of Pr (III) with epinephrine at pH 6. Absorbance of the resulting orange yellow complex is measured at 482 nm . A graph of absorbance versus concentrations shows that beer 's low is obeyed over the concentration range (1-50)mg.ml-1 of epinephrine with molar absorpitivity of ( 2.180x103 L.mol-1.cm-1 ), a sandell sensitivity of (0.084 mg.cm-2 ), a relative error of (-2.83%) , a corrolation coffecient (r= 0.9989) and recovery % ( 97.03 ± 0.75 ) depending on the concentration.This method is applied to analyse EP in several commercially available pharmaceutical preparations