A simple, sensitive, and accurate spectrophotometric method for the determination of Mefenamic acid is described. The method is oxidative coupling reaction of Mefenamic acid with metol using potassium periodate as an oxidizing agent in alkaline medium to form a water-soluble product, that is stable and has a maximum absorption at 533 nm. Beer’s law is obeyed in a concentration range of 2.4-24 μg/ml Mefenamic acid with a molar absorptivity of 7.2x103 L/mol.cm. The proposed method has been successfully applied to the determination of Mefenamic acid in various pharmaceutical preparations.

A simple, rapid and sensitive spectrophotometric method for determination of trace amounts of Promethazine hydrochloric in aqueous solution is described. The method is based on using the oxidative coupling reaction of promethazine hydrochloride with 4-amino 2-hydroxy benzoate reagent in acid medium in the presence of N-bromo Succinimide to produce an intense green colour, water soluble, product which exhibit maximum absorbance at 605.5 nm. Beer's law is obeyed over concentration range of (2-32µg/m1), with a molar absorptivity 7540.68 l/mol.cm, Sandel index of 0.04255 µg / .The average recovery is 100.7703 %, relative standard deviation of 0.3101 to 0.8474 % and D.L of 0.40825 µg/ml.

This research includes the development of spectrophotometric method for determination of Tetracycline via oxidative coupling with the N,N-Diethyl-p-phenylene diamine reagent in presence of oxidizing agentN-Bromosuccinimide in the alkaline medium oxidation time 15 min to form a colored-dye violet, which dissolved in water and showed the highest intensity of absorption at λ max 552nm, the method has been obeyed Beer's Law in the concentration range (10-32µg. ml-1), with molar absorptivity of 10579 L. mol-1. Cm-1 , Sandel Index value 0.0454 µg. cm-2 , the detection limited 0.329 µg. ml-1 , with correlation coefficient 0.9942 , the relative standard deviation of the method does not exceed 0.302% the proposed method was applied successfully for the determination of Tetracycline Hydrochloride on pharmaceutical preparation by both the direct and standard addition methods for three concentrations, the recovery ranged between 98.8-102.71%. the evaluations of results of this method was a achieved applying t and F tests. The results showed that there is no significant difference between the proposed and standard method, and thus the proposed

A new and simple spectrophotometric method was used for the determination naproxen by oxidative coupling with metol the presence of N –Bromosuccinimide in acid medium, Absorbance of the obtained colored products was measured at the corresponding optimum wavelengths 535 nm, Beer’s law is obeyed over the concentration of 0.8-17.6 μg/ml, and The molar absorptivity of 9.07×103 L/mole.cm, Sandal’s sensitivity index of 0.02538 μg.cm-2. The detection limits were 0.1730 μg/ml and the quantitative limit 0.5768/ml, the correlation coefficient of 0.9981and recovery range from 100.21 – 98.27%. The method was successful to determine naproxen in drug tablets formulation.

This research involves the development of spectrophotometric method for determination of pyridoxine hydrochloride by oxidative coupling reaction with N,N-dimethylparaphenylenediamine dihydrochloride (DMPPDAD ( in a basic medium (pH 11.6) in the presence of  potassium ferricyanide to produce an intense green colour, soluble in water, stable product and absorbs at 650 nm. Beer's law was in the linear range 6-30 μg/ml of pyridoxine hydrochloride, the molar extinction coefficint, Sandellʼs sensitivity index and detection limit were 4.338 × 103 L. mol-1.cm-1 , 0.0474 μg.cm-2 and 0.756 μg/ml respectively. The RSD value was 0.63 - 1.41% depending on the concentration. This method was applied successfully to the determination of pyridoxine hydrochloride in pharmaceutical preparation samavite B6 tablet with recovery of not less than 99.5%.