0000000000016784
AUTHOR
A. R. Maurí Aucejo
Determination of tyrosine and phenylalanine by derivatization with nitric acid and differential pulse polarography
Abstract The determination of tyrosine and phenylalanine by differential pulse polarography, after separation by thin-layer chromatography and derivatization with nitric acid to form the nitro compounds, is proposed. Experimental conditions for the derivatization treatment are established and the polarographic determination is optimized.
Apparent content curves: new analytical applications
Analytical possibilities of apparent content curves for ternary systems are studied. The mathematical method proposed is applied to UV-Vis spectrophotometric and fluorimetric techniques. Samples containing fluoresceine/eosine/acridine and methyl red/methyl orange/cresol red are resolved by fluorimetry and UV-spectroscopy, respectively. Results obtained are in agreement with the theoretical contents in both cases.
Use of the Apparent Content Curves for the spectrophotometric identification of substances: identification of amphetamines
The possibility of identification of substances which have similar spectral behaviour by means of Apparent Content Curves has been studied. This study is carried out with absorption, excitation and emission spectra of several amphetamines of widespread pharmaceutical use. Results obtained show that amphetamine, phenylpropanolamine, pseudoephedrine, phenylephrine, epinephrine, dopamine and methoxyamphetamine can be identified with a probability of >95%.
Determination of Caffeine in Analgesic Formulations Using the Apparent Content Curves Method
Abstract The determination of caffeine by UV spectroscopy in pharmaceutical samples, containing different compounds which provide spectral interferences as aspirin, paracetamol, chlorfeniramine or propylphenazone, is carried out. The proposed procedure is based on the apparent content curves method in order to resolve binary, ternary and multicomponent mixtures. Results obtained are, in all cases, in agreement with contents found by a HPLC procedure used as reference method.