Murad I.H Helaleh

Use of integral and differential methods for the determination of l-dopa in pure form and pharmaceutical preparations

A new simple and selective kinetic method for the determination of L-dopa, using differential and integral methods, is described. The spectrophotometric measurements were recorded by measuring the increase in absorbance at 300 nm. The concentration range was valid from 5-35 ppm. The complex ratio showed a (1:2) of L-dopa with respect to sodium hydroxide, with formation constant 5.06 x 10(6) and molar absorptivity of 3.85 x 10(3) l mol-1 cm-1.

A simple kinetic method for the assay of nalidixic acid in formulations

Abstract A simple selective kinetic method for the assay of nalidixic acid in solid state and pharmaceutical preparations is described. The reaction of nalidixic acid with persulfate in alkaline medium was carried out at 75°C. The correlation coefficient was found to be 1.0000. The activation parameters and the factor of the linear least square equation were calculated. The proposed method is suitable to determine nalidixic acid in the range 10–120 μg/ml.

Indirect spectrophotometric determination of benzylpenicillin and cloxacillin in pharmaceutical preparations

An indirect spectrophotometric method for the determination of benzylpenicillin and cloxacillin is based on extraction of iodine produced by reduction of potassium iodate in acidic medium, where hydrolytic cleavage of a β-lactam is achieved with sodium hydroxide. Beers law is obeyed within the concentration ranges 0.04–0.8 mg ml−1 benzylpenicillin and 0.02–0.5 mg ml−1 cloxacillin. The precision, accuracy of the method and the effect of foreign substances were studied. The results have been statistically compared with those using the ammonium vanadate method. An oxidation mechanism is proposed.