A sensitive spectrophotometric method was used for the determination of Dopamine (DM) in a basic medium via its oxidative coupling by Mesalazine (MES), which was exploited as a reagent and Na2S2O8 as an oxidizing agent, the measurement was at a wavelength of 522 nm. The proposed method was successfully applied for the determination of dopamine (DM) in the pharmaceutical preparation (ampules). It was valid within a concentration range of 2.7 31.25 -1 and the linear regression was R2 = 0.9977. The important analytical parameter include: molar absorptivity (0.45x104 l.mol1.cm-1), the Sandell's sensitivity index (0.03343 µg/cm2), limit of detection (LOD) and limit of quantification (LOQ) were (0.37 and 1.23 µg.ml-1), respectively. It also succeeded in giving acceptable ttest values.
A simple, rapid, sensitive, accurate, precise, and cost-effective spectrophotometric method has been developed to estimate dopamine in pure and pharmaceutical dosage forms based on the redox reaction of dopamine in an acid medium with Yttrium(III) ion as an oxidizing agent. The latter suffers reduction to Yttrium(II) ion and reacted with 1,10-phenanthroline to form a colored product peaking at 510 nm. Beer's law is obeyed in the concentration range of 0.5-10 μg mL−1 with a molar absorptivity of 1.16x104 L mole−1 cm−1, Sandall's sensitivity of 0.0131 μg.cm-2 ,the recovery rate of dopamine in pharmaceutical dosage was in the range of 98.97 to 101.57%. The effects of variables such as oxidizing agent, reagent concentration, time of oxidation reaction, surfactant, formation constant of the complex, have been investigated to optimize the procedure. The results have been validated analytically and statistically. The proposed method has been successfully applied to estimate dopamine in pharmaceutical dosage forms.
A new fast and simple selective method for the simultaneous determination of lisinopril dihydrate and amlodipine in combined drugs was developed using the fourth derivative spectrum method, based on the zero-crossing-point technique for the determination of compounds in drugs. The wavelength values for lisinopril dihydrate and amlodipine in solvent medium were found to be (203, 207, and 231 nm) and (215, 254, and 277 nm), respectively, with the average obeying Beer’s law in the range of lisinopril dihydrate 2.0 to 45.0 µg/mL and amlodipine 2.0 to 35.0 µg/mL. Lisinopril dihydrate has molar absorptivity regions (9227.76-11700.28 L/mol.cm, 203 nm), (15320.74-20795.59 L/mol.cm, 207 nm), and (2207.60-3311.40 L/mol.cm, 231 nm), while amlodipine (5886.72-10914.96 L/mol.cm, 215 nm), (5518.8-6418.16 L/mol.cm, 254 nm) and (1676.08-1921.36 L/mol.cm, 277 nm). The recovery rate of lisinopril dihydrate in the pharmaceutical dosage forms range was 95.13 to 102.60% and amlodipine 95.14 to 102.80%. The results of the relative error showed that the interferences did not affect the method of estimating these compounds. The proposed method has been successfully applied to estimate pharmaceutical dosage forms.
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