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Coupling reaction and complex formation for the spectrophotometric determination of physiologically active catecholamines in bulk, pharmaceutical preparations and urine samples of schizophrenic patients
Author(s) -
Nour ElDien Faten A.,
Frag Eman Y. A.,
Mohamed Gehad G.
Publication year - 2010
Publication title -
drug testing and analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.065
H-Index - 54
eISSN - 1942-7611
pISSN - 1942-7603
DOI - 10.1002/dta.123
Subject(s) - urine , chemistry , chromatography , coupling (piping) , materials science , biochemistry , metallurgy
A simple and sensitive spectrophotometric method for the determination of three catecholamines namely dopamine hydrochloride (DO.HCl), dobutamine hydrochloride (DOB.HCl) and vanillymandelic acid (VMA), in both pure form or in their commercially available pharmaceutical formulations or urine samples of schizopherinic patients is described. The method is based on the reaction of diazotized 4‐aminoantipyrine (4‐AAP) with catecholamines in a basic medium (pH = 10–11) to yield pink‐coloured products having absorption maxima at 500, 505 and 480 nm for DO.HCl, VMA and DOB.HCl, respectively. Before carrying out Beer's Law, different experimental conditions, such as time, temperature, sequence of addition, and pH are optimized. The coloured species obeyed Beer's Law in the range of 47.4–417.2, 59.45–445.9 and 67.57–405.4 mg/L for DO.HCl, VMA and DOB.HCl, respectively. The molar absorptivity values as obtained from Beer's Law data were found to be 2.979 × 10 4 , 4.39 × 10 4 and 1.036 × 10 4 L mol −1 cm −1 , while Sandell's sensitivity values were observed to be 3 × 10 −3 , 4.4 × 10 −3 and 1.3 × 10 −3 µg cm 2− for DO.HCl, VMA and DOB.HCl, respectively. Common excipients did not interfere with the proposed method. The results of the proposed method compare favourably with those of official methods. The proposed method offers simplicity, reliability, rapidity, and accuracy compared to the existing methods. Copyright © 2010 John Wiley & Sons, Ltd.