A simple, rapid, accurate and precise spectrophotometric method is proposed for the determination of atenolol in both pure form and in its pharmaceutical formulation. The method is based on the oxidation of atenolol with chromate in acidic medium of 1N H 2 SO 4 , the residual amount of oxidizing agent is then reacted with indigo carmine dye in the presence of oxalate as a catalyst, the increase in the absorbance of the dye, which is proportional to the amount of the determinants atenolol is then measured at 610 nm. Beer's law is obeyed in the concentration range of 30-1500 µg/25 ml with a molar absorptivity of 0.73×10 4 l.mol-1 .cm-1 , Sandell's sensitivity index of 0.364 μg.cm-2 , and a relative standard deviation of ± 0.263 to ± 0.376% depending on the concentration level. The limit of detection (LOD) and limit of quantification (LOQ) are 0.3259 and 1.0863 μg ml −1 , respectively. The proposed method has been applied successfully to the determination of atenolol in pure and pharmaceutical preparation.

A spectrophotometric method is proposed for the determination of some drugs containing amino group such as mesalazine, metoclopramide and dopamine in pharmaceutical formulations. It was simple, precise, accurate, rapid, and based on the oxidation of each drug with chromate as an oxidizing agent in the presence of 1N hydrochloric acid. Then indigo carmine is reacted with residual chromate in the presence of a catalysis factor (sodium oxalate). Increasing in absorbance's value of the color system is proportional to the amount of the three drugs which is measured at the selected wavelength of 610 nm. The proposed method is obeying Beer's law in the ranges of (1-40, 2-44 and 2-52) ppm for the concentration of mesalazine, metoclopramide and dopamine respectively. Molar absorptivity was 0.191×104, 0.449×104 and 0.191×104 L.mol-1.cm-1 mesalazine, metoclopramide and dopamine respectively. While, Sandell's sensitivity index of 0.0806, 0.0667 and 0.0806 μg.cm-2 mesalazine, metoclopramide and dopamine respectively. The proposed spectrophotometric method has a good recovery when it is applied for the determination of the three drugs in pure form and pharmaceutical doses.

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Aims: Design of technical methods for the determination of Furosemide in its pure and pharmaceutical dosage form using spectral methods. Study Design: planned and executed to estimate Furosemide by using Visible spectrophotometric in pure and pharmaceutical dosage form. Place and Duration of Study: Laboratory of Analytical Research, chemistry department, college of Science, University of Mosul ,Mosul-Iraq, during the period of April 2021 to August 2021. Methodology: Furosemide, the commercially known drug Lazix, which is important in the treatment of heart diseases and high blood pressure. This study was carried out using JASCO V – 630, double-beam computerized UV-Visible spectrophotometer, with 1 cm matched cell, and HANA pH meter was used for reported pH readings. Results: The reaction between Furosemide and bromo-phenol blue, xylenol orange, and chromazorol S. The decreasing in the intensity of the resulted colored complex was measured using bromo-phenol blue, xylenol orange, While the increasing of the color intensity was measured in the method (C). These three methods were based on charge transfer reaction. The limits of Beer's law for method (A) 0.4-32µg. mL-1, method (B) 1-32 and method (C) were 0.8-32 depending on the level of concentration, while the values ​​of the molar absorption coefficient 1.4×104, 2.1×104 and 1.57×104 l.mol-1.cm-1 for the first, second and third method respectively. Sandel's significance also was calculated for these three methods, 0.0157 μg.cm-2 for the first method, 0.0236 μg.cm-2 for the second method, while the third method was 0.0210 μg.cm-2. The method has been successfully applied for the determination of furosemide in its pure form and in some of its pharmaceutical preparations Conclusion: The proposed methods were validated in terms of linearity, range, Accuracy, precision, Specificity, Robustness. The proposed methods were successfully applied to the estimation of Furosemide in pharmaceutical dosage form, method (B) was experimentally considered as a best method depending on the best values of molar absorptivity, stability of the resulted complex, and the linearity of the method (B) .

Chromate ions CrO4 −2 have been used in three simples, rapid, an accurate spectrophotometric method. These methods were suggested to estimate mefenamic acid in its pure form and pharmaceutical preparations. These methods were different from each other with reactants components, and they are similar as, indirect methods and depends on oxidation – reduction reaction. So that, Method 1, based on oxidation reduction reaction between mefenamic acid and chromate ion in presence of acidic medium and sodium oxalate to form a water soluble, and stable pinkish-violet colored complex with 1,5-diphenylcarbazide as a reagent which was measured at λmax 545 nm. Method 2 depends on oxidizing mefenamic acid with chromate ions in presence of sodium oxalate as a catalyst agent and acidic medium to form with indigo carmine λmax at 610 nm. water soluble and stable blue complex. Finally, method 3 based on the reaction between mefenamic acid and chromate ion in presence of sodium oxalate and acidic medium to form with chrome azurol S a red complex measured λmax at 512 nm. These three methods have been followed Beer’s law at (2-40,1.2-40 and 2-36) μg/mL methods 1,2 and 3 respectively, while molar absorptivity and Sandall’s sensitivity 0.84×104, 0.54×104 and 1.08×104 1.mol−1.cm−1 and 0.0287, 0.0446 and 0.0223 μg.cm−2 for methods 1,2 and 3 respectively. The suggested methods were applied successfully to determination of mefenamic acid in pharmaceutical formulation with good recoveries.