title: Spectrophotometric analysis of alkaloids with picrolonic acid.
abstract: The spectroscopic characteristics of the interaction of alkaloids with picrolonic acid were studied. In solvents of low and intermediate polarity, the presence of alkaloids caused a red shift of the 322 nm band of nonionized picrolonic acid to 355 nm, corresponding to the anionic resonance band. There was also a considerable increase in absorptivity, which was dependent on both the basicity (pKa) and molar concentration of the alkaloid present. Arylamines, aromatic N-heterocycles, and alkaloids lacking an aliphatic amine moiety did not show observable shifts. The interaction was developed into a spectrophotometric assay for the following alkaloids in pharmaceutical preparations: atropine, ephedrine, codeine, emetine, quinine, and strychnine. The method is sensitive to 2 mug alkaloid/ml, with an accuracy of not equal to 1.5% and a standard deviation of not equal to 1.05 - 1.31%.
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D007202:Indicators and Reagents; D009578:Nitrobenzenes; D011720:Pyrazoles; D047069:Pyrazolones; D013053:Spectrophotometry
chemical_list: D000470:Alkaloids; D007202:Indicators and Reagents; D009578:Nitrobenzenes; D011720:Pyrazoles; D047069:Pyrazolones; C010291:picrolonic acid