Spectrophotometric investigations of the assay of physiologically active catecholamines in pharmaceutical formulations.
Two simple, sensitive, and accurate spectrophotometric methods are proposed for the determination of levodopa (LD), methyldopa (MD), dopamine hydrochloride (DP), and pyrocatechol (PC) in pure and pharmaceutical preparations. The methods are based on measurement of the absorbances of tris(o-phenanthroline)iron(II) (method A) and tris(bipyridyl)iron(II) (method B) obtained by the oxidation of the catecholamines by iron(III) in the presence of 1,10-phenanthroline and 2,2'-bipyridyl at 510 and 522 nm, respectively. The absorbances were found to increase linearly with increases in the concentrations of the catecholamines, results which were corroborated by the calculated correlation coefficients (0.9990-0.9996). Beer's law was valid over the concentration ranges of 0.04-0.6, 0.06-0.75, 0.06-0.65, and 0.05-0.70 microg/mL in method A and 0.02-1.0, 0.04-1.3, 0.05-1.0, and 0.06-1.1 microg/mL in method B for PC, MD, LD, and DP, respectively. The common excipients and additives did not interfere in their determinations. The proposed methods were successfully applied to the assay of LD, MD, and DP in various dosage forms. The results were validated by statistical analysis.
Nagaralli
Basavaraj S
BS
Karnatak University, Department of Chemistry, Dharwad-580 003, India.
Seetharamappa
Jaldappa
J
Melwanki
Mahaveer B
MB
Ramesh
Kunabevu C
KC
Keshavayya
Jathi
J
D002395:Catecholamines / Q000032:analysis*; D002396:Catechols / Q000032:analysis; D004298:Dopamine / Q000032:analysis; D007202:Indicators and Reagents; D007980:Levodopa / Q000032:analysis; D008750:Methyldopa / Q000032:analysis; D010618:Phenanthrolines / Q000737:chemistry*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets
D002395:Catecholamines; D002396:Catechols; D007202:Indicators and Reagents; D010618:Phenanthrolines; D012996:Solutions; D013607:Tablets; C035612:iron(2+)-tris(bathophenanthroline); D007980:Levodopa; D008750:Methyldopa; D004298:Dopamine